last mention'd Experiment it appears that it is possible Even by Weights to measure how far Nature is dispos'd to prevent or fill Vacuities since a small difference in Weight determin'd by depressing or permitting the Sucker to rise how far Nature's Abhorrency of a Vacuum depended on the Causes we have so often mention'd But here it may be requisite to advertise that by Vacuities I do not mean Spaces altogether void of Matter but void of such as may be perceiv'd so that I take the Word Vacuum in the Common not the strict and Philosophical Sense of the Word But lastly from this XXXIII Experiment it appears that the Weight of the Atmosphere we live in is stronger than what Men usually think it is And probably near the Northern Pole it is much stronger Since if what Varenius observes the Air is so condens'd in Nova Zembla as to hinder the Motion of a Pendulum except moved by a heavier Weight than what is usually made use of in our Climate EXPERIMENT XXXIV Attempts to weigh light Bodies in our Receiver TO try whether the Aequilibrium of two Bodies of an equal Weight in the Air but of unequal Dimensions would be lost in our Receiver as it usually is in Water by Reason of a greater Quantity of Water buoying up against that whose Dimensions are most extensive I took a Bladder half full of Air and ty'd it to one end of our Balance which turns with the 32 part of a Grain which being counterpois'd with a Weight in the other Scale we let it down into the Receiver and having clos'd it up upon an Exsuction of the Air we found the Bladder to dilate and manifestly to preponderate but upon admitting the Air into the Receiver again the Bladder was over-pois'd by the Weight but leaving them in the Receiver all night the Bladder imbib'd so much of the External Moisture as to weigh that end of the Balance down a good way yet the Bladder being dry'd a little they were both brought to an Aequilibrium And the like Experiment we try'd with a piece of Cork instead of the Bladder and observ'd that the Receiver being Evacuated as well as upon a reingress of the Air the Cork manifestly preponderated EXPERIMENT XXXV Of the Cause of Filtration and the Rising of Water in the Syphons c. The Cause of Filtration TO try whether in Filtrations the rising of the Water might not proceed from the Impulse of the Air we made use of a Syphon of Glass represented by the Third Figure which is made of two strait Pieces and a crooked one which joyns the other two together the Junctures being well clos'd The longer Leg of the Syphon was pervious only at the small End so as to suffer the Water to pass through it but both the ends of the shorter Leg were equally pervious the Diameter of their Bore being ¼ of an Inch. The length of these two Pipes was about a Foot and a half that the Rarifi'd Air in the Receiver when it was pretty well exhausted might not raise the Water included in the Pipe too high The shorter Leg of the Syphon being immers'd two or three Inches in a Vessel of Water the other end was fastned to the Cover which things being done and the Receiver clos'd up we began to pump The Result of which was that the Water dropp'd out of the lower Leg of the Syphon as if it had been expos'd to the open Air till the Receiver was in some measure exhausted and then several Bubbles rising in the Water gather'd together at the Top of the short leg'd Syphon where expanding themselves they stopp'd the Course of the Water that in the longer Leg being suspended in the Tube and ceasing to drop and the Water in the shorter Leg was so far depress'd as not to be above a Foot high But as soon as the External Air was let in again it enter'd in at the small Orifice of the longer Tube and ascending through the Water contain'd in the Pipe joyn'd with the former which was lodg'd in the upper Part of the short leg'd Tube But to prevent what Inconveniences ensu'd the rising of these Bubbles the two foremention'd Tubes were placed so as to meet in the middle of a Glass Viol the Neck of the Viol being clos'd up with Cement and the Tubes being thus fix'd and they as well as the Viol fill'd with Water the Syphon represented by the Fifth Figure was plac'd in the Receiver with its shorter Leg in a Vessel of Water upon which the Pump being ply'd the longer Syphon continu'd to drop much longer than before but at the last the Bubbles which rose in the Pipes were so dilated in the Viol as to press down into the Ends of the Tube and interrupt our Experiment tho' what we observ'd gave us Reason to believe that the Air contributed to the Motion of the Water through the Syphons And here I shall subjoyn that I once had a very slender Pipe which when held upon the Surface of the Water in a Perpendicular Posture the Incumbent Atmosphere press'd so much more on the Surface of the External Water than that contain'd in the Tube that the Water was rais'd in the Tube and this Pipe being bent into a Syphon and plac'd with the shorter Leg in Water as Syphons usually are the Water of its own accord rose up in the shorter Leg and ran down the other and this Syphon being plac'd in our Receiver to try what Alteration of the Phaenomenon would appear there we could not discern any sensible one But tho' in this Tube just now mention'd the Water rises of its own accord yet if such a Tube be thrust a little way into the Mercury instead of rising the Mercury in the Tube will be below that which is without it EXPERIMENT XXXVI The Weight of Air in the Exhausted Receiver The subtle penetrating Power of some Spirits above that of the Air. The Cause why Air will not enter the Pores of some Bodies which Water will The Weight of the Air examin'd by an Aeolipile The Proportion betwixt the Gravity of Air and Water Betwixt Water and Quicksilver Conjectures concerning the Weight of the Atmosphere The Weight of the Air. NOtwithstanding the several Methods propropos'd by Galileo and others to try the Weight of the Air being willing to be further satisfi'd we caus'd an Oval Glass with a small Tube at one End to be blown at the flame of a Lamp And this Glass Bubble being of the size of a Hen's Egg was fix'd to one End of a Balance being counterpois'd by a Weight at the other End which being suspended in our Receiver and the Pump set on work the Bubble after three Exsuctions continu'd to preponderate more and more till the Air was let in again and then the Balance was reduced to its former Aequilibrium But having repeated the Experiment with an additional Weight of three Quarters of a Grain in the Scale opposite to the
a Long Leg and a Short One which were so bent as to lye Parallel almost to each other we pasted Papers upon each which were divided by Marks into Inches and each of those Inches into eight Parts and upon pouring Mercury into the Longer Tube we observ'd That the Air contain'd in the Shorter which was Hermetically seal'd at the Top by twenty nine Inches of Mercury was condens'd into half the Space it possess'd before from whence it appears that if it were able in so compress'd a State by Virtue of it's Spring to resist a Cylinder of Mercury of 29 Inches besides the Atmospherical Cylinder incumbent upon that it follows that it's Compression in the open Air being but half as much it must have but half that weight from the Atmosphere that lyes upon it in that Compress'd State But to be more exact See Fig. 4. Plate 2. we took a Tube represented by the Fourth Figure pasting upon the Shorter Leg a Paper divided into twelve Inches and each of those into Quarters and another upon the Longer Leg which made up several Feet which were likewise divided into Inches and those subdivided again into Quarters The Tube being thus Mark'd the Lower End was plac'd in a Wooden Box that the Mercury might run into it if the Pipe chanc'd to break And one being assign'd to pour in Mercury at the Top of the Tube another was plac'd to observe when the Mercury in the small Tube rose up to each of the Divisions abovemention'd and to take notice likewise how high it stood in the Long Tube at the same time where the several Observations were set down and are contain'd in the following Table A Table of the Condensation of the Air. A A B C D E 48 12 00 Added to 29 â…› makes 29 2 16 29 2 16 46 11 ½ 01 7 16 30 9 16 30 6 16 44 11 02 13 16 31 15 16 31 12 16 42 10 ½ 04 6 16 33 8 16 33 1 7 40 10 06 3 16 35 5 16 35 38 9 ½ 07 14 16 37 36 15 19 36 9 10 2 16 39 3 16 38 â…ž 34 8 ½ 12 8 16 41 10 16 41 2 17 32 8 15 1 16 44 3 16 43 11 16 30 7 ½ 17 15 16 47 1 16 46 â…— 28 7 21 3 16 50 5 16 50 26 6 ½ 25 3 16 54 5 16 53 10 13 24 6 29 11 16 58 13 16 58 2 8 22 5 ½ 34 15 16 64 1 16 63 6 11 21 5 ¼ 37 15 16 67 1 16 66 4 7 20 5 41 9 16 70 11 16 70 19 4 ¾ 45 74 2 16 73 11 19 18 4 ½ 48 12 16 77 14 16 77 â…” 17 4 ¼ 53 11 16 82 12 16 82 4 17 16 4 58 2 16 87 14 16 87 â…œ 15 3 ¾ 63 15 16 93 1 16 93 1 â— 14 3 ½ 71 5 16 100 7 16 99 6 7 13 3 ¼ 78 11 16 107 13 16 107 7 13 12 3 88 7 16 117 4 16 116 4 8 A A The Number of Equal Spaces in the Shorter Leg which contain'd the same Parcel of Air differently Expanded B The Height of the Mercury in the Long Tube by whose weight the Air in the Short one was compress'd C The Height of the Mercury which counterpois'd the weight of the Incumbent Atmospere D The Aggregate of the Columns B and C shewing what Pressure was sustain'd by the Included Air. E What that Pressure should be allowing the Pressures and Expansions to be Reciprocal Porportions But in Trying this Experiment whoever pours in the Mercury he must do it by degrees and according to the Directions of the other that takes notice of the Ascent of the Mercury below for if it be pour'd in without Caution it may rise up above the Marks plac'd on the Outsides before due Observations can be made Having by the weight of so vast a Cylinder of Mercury compress'd the Air into a Quarter of the Space it possess'd before we observ'd tho' it could not be sensibly condens'd further by Cold yet the Flame of a Candle brought near it gave us reason to think that a greater degree of Heat would have expanded it but fearing the Cracking of the Tube we durst not try it From the Experiment it appears That as the Air is more or less compress'd so it is able to counterpoise a Heavier or Lighter Cylinder of Mercury And that the Mercury was born up by the Spring of that condens'd Air appear'd by sucking up the Air out of the Tube when the Mercury was 100 Inches high in the Pipe for the Pressure of the incumbent Pillar of the Atmosphere being by that means taken off the Mercury was rais'd in the Long Tube by the Expansion of the Air in the Short Leg And not by any Funiculus since the Objector confesses that cannot raise more than a Cylinder of 30 Inches The Air 's Rarefaction consider'd But together with what hath been said it may not a little illustrate our Doctrin of the Spring of the Air to observe how much it's Spring is weaken'd accordingly as it is differently Expanded and Rarify'd A Table of the Air 's Rarefaction A B C D E 1 00 0 9 Substracted from 29 ¾ leaves 29 ¾ 29 ¾ 1 ½ 10 â… 19 â…› 19 â…š 2 15 â…œ 14 â…œ 14 â…ž 3 20 2 8 9 4 8 9 15 12 4 22 â… 7 â…› 7 7 16 5 24 â…› 5 â… 5 19 20 6 24 â…ž 4 â…ž 4 23 24 7 25 4 8 4 2 8 4 ¼ 8 26 0 0 3 0 8 3 23 32 9 26 â…œ 3 3 0 3 11 36 10 26 6 3 3 0 0 2 39 40 12 27 â…› 2 â… 2 23 48 14 27 4 8 2 2 8 2 â…› 16 27 â— 8 2 0 0 1 55 64 18 27 â…ž 1 â…ž 1 47 72 20 28 1 6 8 1 9 80 24 28 â…› 1 4 8 1 22 96 28 28 â…œ 1 â…œ 1 1 16 32 28 4 8 1 2 8 0 110 128 A The Number of Equal Spaces at the Top of the Tube which the same Parcel of Air was contain'd in B The Height of the Mercury which together with the Included Air counterpois'd the Pressure of the Atmosphere C The Pressure of the Atmosphere D The Aggregate of B to C representing the Pressure counterpois'd by the Included Air. E What that Pressure should be according to the Hypothesis In which Experiment it is to be Noted First That we made use of a Glass-Tube about 6 Foot long sealed at one End Secondly We had in Readiness a Glass-Pipe about the Diameter of a Swan's Quill which was mark'd with a Paper stuck upon it divided into Inches and half Quarters which being immers'd in the other Cylinder of Mercury and open at both Ends that the Mercury might rise in it it help'd to fill the other up And about an Inch of it's standing above the Mercury the Orifice was seal'd up so that an Inch of Air was contain'd in the Tube which by lifting up the Tube was gradually expanded to
it was to be noted That when first the Water appear'd in the Glass Tube they would be very numerous and form a Froth yet when the Pumping was further continu'd they grew less and less Secondly we observ'd that the Water made several Vibrations in it's Rise which tho' near a Foot at the first grew less and less Thirdly it may be observ'd that the Baroscope consulted before some time after was noted to have risen considerably so that had the Experiment been repeated again the Water would have been buoy'd up a good deal higher Now from this Experiment it appears how improbable it is what some Men teach concerning the Rise of Water in Spiral Pipes up to the Top of high Mountains since it is evident that it cannot be drawn higher than 36 Foot by a Sucking Pump EXPERIMENT XVIII About the Bending of a Springy Body in the Exhausted Receiver TO be satisfy'd how much the Elasticity of Bodies depends on the Influence of the Air I fix'd one End of a Whale-bone in a Trencher and ty'd a Weight to the other by which it was bent so low as almost to touch the Plane under it This being convey'd into our Receiver upon the Exhausting of the Receiver I could not perceive any Alteration EXPERIMENT XIX Concerning the making of Mercurial Gauges whereby to estimate how much the Receiver is exhausted SEveral Gauges have been made use of to discover when the Receiver is well exhausted as by suspending a Bladder which is almost empty of Air or by inverting a small Tube in which Spirit of Wine was contain'd but the former taking up too much Room in the Receiver and the latter not discovering whether the Receiver was exhausted or not till the Air contain'd was too much Rarefi'd for any Considerable Observations Therefore to enable me to make more Observations in the several Degrees of the Receiver's Exsuction I took a slender Pipe of Glass about 10 Inches long and as small as a Goose Quill and having melted it at a flame so as to soften it and make it apt to be bent I caus'd it to be put into the Form represented by Plate 5. Fig. 4. so that about an Inch of the lower Leg being fill'd with Air See Plate 5â— Fig. 4. and the rest of that as well as the greatest Part of the short one being fill'd with Quicksilver the Expansion of that Air might easily be perceiv'd by pasting a Piece of Paper upon that Tube divided into several exact Parts for as the Receiver is more or less expanded the Air in the longer Leg of the Gage will be extended to some of those Marks and if when the Air is so expanded the Experimenter desires to know at each of those Marks how much the Receiver is exhausted it will appear by letting in as much Water as the Capacity of the Receiver is able at that time to hold so that if when the Air is at any determinate Mark the Water be let in and it appears that the Air in the Receiver was so far Evacuated by observing how much Water will be admitted when the Air is expanded to each Mark the Gage for the future will not only inform us how much the Air is exhausted but by the help of the small Gage a larger may be made by putting both into an exhausted Receiver at once for by observing when the Air is expanded to each Mark in the little one how far it is expanded in the large one we may learn how much the Receiver is exhausted for the future by taking notice of the Expansion of the Air in the Leg of that larger Gage And This Gage is much more useful than some others First because the Mercury being a heavy Body the Air by expanding it self is less apt to make it run over or to make it's way in the Form of Bubbles through the Mercurial Cylinder as it would if other Fluids were made use of instead of it Secondly The longer Leg of the Gage is to be mark'd by sticking Wax or Knobs of Glass to the Pipe every Tenth being of a different Colour from the rest at equal Distances from each other which Divisions will be less subject to be rubb'd off than Papers which are also subject in some Experiments to be wet Thirdly The Leg of the Syphon in which the Air is included may be either seal'd up before it is divided by the aforemention'd Marks or after by drawing out the End of the Tube into a small Apex and when about an Inch of the Pipe is fill'd with Air it may be seal'd up by blowing a Lamp Horizontally upon the Apex Fourthly Where very Nice Observations are to be made and the Receiver admits of a longer Gage instead of Mercury we may make use of a Tincture of Roses or of Spirit of Wine with Cocheneel in which the Exsuction of the Air will be more nicely represented Fifthly We may vary the Mercurial Gage by ordering the shorter Leg so that it may have a Bubble about half an Inch Diameter at an Inch distance from the Basis of that Leg which Bubble must have a Pipe upon the upper Part of it to give way to the Air which Bubble hath this Advantage above the other that less Air may be contain'd in the Top of the longer Leg since the Mercury not being capable of being rais'd so high the Rarefaction of the included Air will be render'd more apt to be estimated by the Eye Sixthly This Gage is much more useful than those mention'd by other Authors because it gives us an Account of the several Degrees of the Air 's Rarefaction EXPERIMENT XX. An easie way to make the Pressure of the Air sensible to the Touch. The Pressure of the Air sensible to the Touch. THE Pressure of the Air will be made sensible to the Touch if a Tapering Tube of Brass whose Cavity at one end is an Inch and the other two Inches and an half wide be fix'd to the Pump instead of a Receiver for if when the larger Orifice is Cemented on the Pump one presses the Palm of ones Hand upon the smaller Orifice and the Pump be set on Work it will be a difficult Matter to take off ones Hand and not a little painful but the Pressure of the Incumbent Atmosphere will have a much more sensible Effect if the larger Orifice be upwards instead of the smaller EXPERIMENT XXI About the subsiding of Mercury in the Tube of the Torrecellian Experiment to the Level with the Superficies of the Stagnant Mercury THE lower Part of the Ball of a Bolt-head being circularly cut off we made use of it for a Receiver including a Baroscope in it and upon the first Exsuction the Mercury subsided from 29 Inches to 9 or 10 and by three Exsuctions more would be brought to a Level with the Stagnant Mercury but would rise to it's first Station again as the Air was admitted in flower or faster In which Experiment it is to be noted First
that upon the first Exsuction the Mercury was brought within an Inch of the Bottom and continu'd several successive Vibrations before it setled at 10 Inches high Secondly If instead of drawing any out Air be forced into the Receiver it will raise the Mercury higher than it 's former Station Thirdly The Receiver was so far exhausted as to make the Mercury subside to a Level EXPERIMENT XXII In Tubes open at both Ends when Nature's Abhorrency of a Vacuum cannot be pretended the Weight of Water will impell Quicksilver no higher in slender than in larger Pipes The suspension of Quicksilver equal in small and wide Pipes TO prove that the Weight of the Atmosphere may buoy up Mercury equall in large as in smaller Tubes I shall add the following Tryals The I. TRYAL Having put as much Mercury into a Glass Tube about two Foot and a half long as reach'd 3 or 4 Fingers the one End being sealed Hermetically we hung two Tubes by Strings to the Top of the former so that the lower Ends of them were immers'd in the Mercury which being done we pour'd Water upon the Mercury and observ'd the Mercury to be equally rais'd in the great Pipe as in the little one and the Water being suck'd out it proportionably subsided in each The II. TRIAL Having pour'd a Convenient Quantity of Quicksilver into a Tube of Glass near a Foot long and filled two Pipes of Mercury of an unequal Bore the one End of each being Hermetically seal'd we immers'd them in the large Tube contriving to open the lower Orifice when below the Stagnant Mercury and I observ'd that they not only both of them subsided to an equal Station but Water being pour'd upon the Stagnant Mercury the Weight of it buoy'd them up both alike in the Tube and the Water being successively suck'd out and put in again the the Mercury in the Tube proportionably fell and rose equally in both no difference proceeding from the Wideness of their Diameters in the Height of the Mercurial Cylinders EXPERIMENT XXIII At what Height Mercury Amalgamated with Tin as well as pure Mercury will be suspended HAVING fill'd a Glass Tube with Mercury Amalgamated with Tin and inverted it it did not fall below 31 Inches In trying this Experiment the following Particulars are to be noted First That if the Amalgama be too thick it will be apt to stick to the Tube and will likewise hinder several Aerial Corpuscles from flying away Secondly From hence it may be observ'd that as the Aequilibrium of Mercury and the Atmosphere varies so does it's Ascent in such Tubes Thirdly It would not be amiss here to consider whether these two Metals penetrate each others Dimensions as I have observ'd Copper and Tin to do and by forming a new Metalline Substance to render the Composition heavier than the Weight of the two single Ingredients EXPERIMENT XXIV A Method of making Barometers which may be carried to distant Countries TO make a Portable Barometer we took a Cylinder about 4 or 5 Foot long and having bent one End at the Flame of a Lamp so as to make the shorter Leg about a fourth Part as long as the other sealing up the End of the longer Leg we injected Mercury into the shorter Leg by a Tunnel till it was rais'd about 3 Inches in both Legs which being done and the Orifice of the shorter Leg being stopp'd with the Finger we inclin'd the longer Leg and so by successively filling the short Leg and inclining it so as to make it run into the longer we fill'd the longer Leg quite full of Mercury and by inclining it several times afterward and permitting the Bubble of Air which usually lies at the Top of the seal'd Head to run through the Mercurial Cylinder backwards and forwards we freed it from those Bubbles which are usually in it's Pores But besides this way of filling the Pipe we have with less Trouble done it by making use of a Tunnel which when the Pipe is a little inclin'd reaching a little above the Flexure of the Syphon will fill the Tube without much trouble And the Pipe thus fill'd with Mercury may by often erecting of it and shaking the Pipe so erected be freed from those Aery Particles which commonly lodge in the Pores of the Mercury See the whole Barometer Plat. 7. Fig. ig 2. The Barometer being thus order'd we contriv'd a Frame to carry it in which was made of a Piece of Wood in which a Gutter was cut for the Pipe to lie in the lower End of the Frame being likewise so contriv'd as to contain the short Leg of this Tube The Pipe being lodg'd in this Gutter we fix'd a Cover to one side of the Frame with little Highes the other when occasion requir'd being fastned with Hasps And because the Motion the Mercury would be put into would be apt to break the Pipe were there too much Liberty given it to move in or were there any Interstices betwixt the Pipe and the Gutter it is lodg'd in we took Care to lay Cotton both betwixt the Pipe and the Concave of the Frame and betwixt the Cover and it and that the empty Space which is usually above the Surface of the Mercury in Barometers might not be prejudicial we took Care to invert the Tube and to fill the remaining Space unpossess'd with Mercury either with an Addition of Mercury or with Water sealing up the Orifice of the shorter Tube Hermetically till it came to be us'd again and then the Superflous Mercury may be taken away by immersing a small Pipe in it which if the upper Orifice be stopp'd with ones Finger will take away so much as the Cavity of the immers'd Tube had receiv'd into it But if Water be made use of instead of Mercury it may be lick'd up with a Spunge And if by shaking of this Barometer in long Journeys any Particles should get out of the short Leg into the larger by successively inverting the Tube and permitting the Bubble of Air to pass backwards and forwards the Mercury in the long Tube may easily be freed from Bubbles Of what Use this Barometer may be in discovering the Weight of the Atmosphere in long Journeys both at Sea and at Land I shall leave to others to consider only I shall annex this Advertisement that sometime after I made this Barometer having carri'd it about 33 Miles I observ'd that it did not rise by ¼ of an Inch as high as it did before but whether it might be imputed to the narrowness of the Pipe or any other Accident I cannot yet determine EXPERIMENT XXV What Height the Mercury in Barometers will be suspended at at the Top of Hills Some Observations of the Height of Mountains especially the Pic of Teneriff HAVING observ'd the Height at which Mercury was suspended at the Bottom of a Hill and compar'd it with a Barometer made the ordinary ways it was observ'd that the Height it was suspended at at the Top
seal'd Glasses Sect. I. To separate Air from Liquors by boyling or by the Engin. Sect. I. To obtain Air by Corrosion especially with Spirit of Vinegar Sect. I. To separate Air by Sulphureous and Animal Menstruums Sect. I. To produce Air in Vacuo by Burning-Glasses and hot Irons Sect. I. To obtain Air from Gun-powder and other nitrous Substances Sect. II. The Air produc'd may be examin'd by trying whether it will Preserve or Revive 1. Animals 2. Flame 3. Fire 4. The Light of Rotten Wood Fish Sect. II. To examine it's Spring and the Duration of it as also it 's Weight and whether it will help to raise the smoak of Liquors TITLE VII Of the Accidental or less constant Ingredients of the Air. TITLE VIII Of Aqueous Particles in the Air and of it's Moisture and Dryness Of the Air 's Moisture and Dryness THO' Dryness be a Quality which only depends on this viz. That the Pores intercepted betwixt the stable Parts of a Body are not fill'd with any visible Liquor yet it hath a considerable Interest in the Changes of Bodies upon different Scores First In as much as the Body dry'd is depriv'd of Liquid Parts upon the Effects of which several of it's Operations depend Secondly Upon the Recess of those Parts evaporated the Texture of the Body may be so far chang'd as to acquire a disposition to act otherwise and to be acted on in a different manner to what it was before EXPERIMENT I. TO evince the Efficacy of the Air 's Moisture we suspended a Quarter of a hundred Weight by an Iron Ring at the End of a Rope which was about 3 Foot and a half long and 3 10 of an Inch in Diameter and when the Weight had stretch'd the Rope for 2 or 3 Days we plac'd a Board under it so that it might just rest upon it and then causing the Rope to be wet in about half an hour it shorten'd so much that the Weight would swing this way and that like a Pendulum without touching the Board yet the same Day the Rope was stretch'd again so that it touch'd the Board About Morocco which is an Inland Town tho' the Soil be dry and the Heat violent in the Day yet I am told by one who was there that the Nocturnal Air was so damp as to be able to make his Cloaths unfit to be worn till Air'd yet tho' the Air was very piercing neither the Knife in his Pocket nor the Sword in his Scabbard were subject to rust tho' the same Metal expos'd to the open Air was Air too moist cannot be wholsom The Air about Oakly and Brill in Buckinghamshire tho' a high Country is so moist in October that the Stair-Cases and Pictures will stand all over Dew which gathering in drops runs down in Streams and it is obser'd that the North and North-East side of the Houses are so moist that except the Rooms be air'd often the Furniture will rot Having made use of a Hydroscope which was made of a Box to whose Bottom a piece of Gut-string was fastend and the other End of it to an Index which lay upon the Top of the Box the Circumference of the Box was divided into Degrees or Partitions By which we could perceive that when Moist Vapours insinuated themselves into the Pores of the Lute-string it would be wreath'd and twisted up and the Index would be mov'd that way which the twisting of the Rope inclin'd it and when the Weather was dryer it would return back the other way EXPERIMENT II. ONE of these Hygroscopes being conveigh'd into a small Receiver when the Air was exhausted the Index did not sensibly alter it's Place in a long time till the External Air was let in again From which Experiment and some others try'd with a Thermoscope it appears that the Aether or that subtle Matter which succeeds in the Place of the exhausted Air is neither hot cold moist nor dry TITLE IX Of Clouds Mists and Fogs Of Clouds Mists and Fogs AN excellent Astronomer told me that of all the white Clouds whose Height he had measur'd in fair Weather he found none to exceed ¾ Quart of a Mile and very few above ½ a Mile A Mist at Sea driving towards the Shoar without any sensible Wind causes the Sea to swell more than a brisk Wind. It hath likewise been observ'd that Mists in some places rising about 30 Foot high have fallen down in a Dew again TITLE X Of Terrestrial Steams in the Air. Of Terrestrial Effluvia PIllars of Fumes have been divers times observ'd to rise from Ground which had several Veins of different Metal in it some ill scented some well scented and others inodorous and I have observ'd that the Charcoal made in Cornwall affords a manifest Arsenical and Sulphureous Smell beyond other Charcoal Jcournal des S avary III. 1685. Tel est par exemple ce nuage horrible d'une fumée epaisse qui s'eleva de la mer de Cretee au Commencement de l'Eestede l'an 721. et qui s'etant repandu dans l'air le fit parôistre tout en feu La mer n'en fut pas mesme exempte car les grosses Masses de pierres enflammées qu'on en vit sortier et qui se joignirent al ' Isle qu'on Nomme Hiera échauferent si fort les eaux qu'elles en bruloient les maines TITLE XI Of Salts in the Air. Of the Salts in the Air. THO' the Peripateticks teach that the Air is an Element and consequently a pure simple Body whose Qualities are moist and dry yet from what we have already deliver'd it appears that it is an Aggregate of various kind of Effluvia jumbled and mix'd together I mean the Air distinct from that Purer Substance Aether which I suppose diffus'd through the Interstellar Part of the Universe Amongst the Effluvia which rove up and down the Air I account Saline ones the Chief which is not unlikely since the Terraqueous Globe which continually emits Effluvia abounds with great Quantities of Marine Aluminous and Vitriolate Salts which impregnate the Air besides several Exhalations rais'd by the Sun-Beams from the Surface of the Earth and Water not to mention several other Saline Vapours which are dispersed in the Atmosphere and arise from Vulcanos as well as common Fires And as it is not improbable but that the Air plentifully abounds with Saline Effluvia so very likely besides Nitrous there are other kinds raised up and roving about in it as Common Salt and Vitriolate Salts and that which seems to prove that the Air in some places abounds with vitriolate Salts is that it hath been observ'd that Hinges have been corroded and rotted and other things prejudic'd upon a Vitriolate Soil whereas in Houses which stood on a Chalky Soil no such Effects were observ'd Besides on the Vitriolate Ground we took Notice of Saline and White Efflorescences upon the Surface of the Soil when beaten upon by the Sun-beams Besides which kinds
Receiver upon the Exsuction of the Air we observ'd that the Air which was contain'd in the Cavity of the Viol was so far expanded that tho' the Viol was able to contain above five Drachms of Water if filled and distended the empty Bladder which was large enough to hold five Ounces and half a Drachm In which Experiment the expanded Air possessed nine times as much space as it did before Expansion But to measure the Air 's Expansion more nicely we fix'd a Glass Bubble to one end of a Cylindrical Pipe hermetically sealed the Diameter of whose Bore was about a quarter of an Inch and having pasted a Piece of Parchment upon the outside of the Tube which was divided into twenty six equal Parts and mark'd with black Lines we fill'd the Cylinder almost full of Water so that after a few Tryals by inverting the Cylinder and stopping the open End with one's Finger we could perceive that as much Air might be permitted to rise up to the Bubble as was equal in Extension to the Breadth of one of those twenty six Divisions When this was done we fitted the open end of the Cylinder to a Glass Viol which was fill'd with Water to the Height of half an Inch all which being put together into a Pneumatical Receiver after a few Exsuctions the included Air was so much expanded as to extend it self to the Surface of the Water in which Experiment the expanded Air took up thirty one times as much Space as before And this Experiment being repeated in a Cylinder which afforded a larger space for the Air 's Expansion it took up above sixty times the space it did before And repeating the like Experiment with a Glass Pipe thirty Inches long part of it having a Hole in the Cover to stand out through by weighing the Water in a nice Pair of Scales together with the Pipe first with the Bubble of Air included and after when the Tube was wholly filled with Water we found That the Air which possessed but the Space of one Grain of Water had been expanded in the exhausted Receiver so much by its own 〈◊〉 〈◊〉 〈◊〉 〈◊〉 〈◊〉 as to take up 152 times its Space before Extension And since Marcennus affirms That the Air may be so expanded by Heat as to take up seventy times its Space I conveyed a Cylinder of the former Magnitude into the Receiver and found That upon the Exsuction of the Air in the Receiver that in the Cylinder descended down almost to the bottom of it the lower Surface of it being very convex and seeming several times to knock upon and rebound from the bottom of the Viol which was an Argument of the expansive Force of the Air since the Water it depressed upon the drawing out of the Air was much below the Surface of the Water contain'd in the Viol. EXPERIMENT VII What Figure best resists the Pressure of the AIR HAVING got a thin Glass Bubble which was large enough to hold about five Ounces of Water to which was fix'd a slender Neck about the Bigness of a Swan's Quill we moderately exhausted the Air out of the Receiver and then taking it out of the Pump we joyn'd the Neck of the Bubble to the lower Orifice of the Receiver stopping the Crannies with melted Plaster to prevent the Ingress of the Air and tho' the Glass was as thin as Paper yet upon turning the Key of the Stop-Cock and giving the Air included in the Bubble Liberty to expand the Bubble sustained the Pressure of the whole Atmosphere without being broke EXPERIMENT VIII The former Experiment illustrated WE took a Glass Alembick which was large enough to hold about Three Pints represented by the Seventh Figure The Rostrum E being hermetically closed In the Top of the Rostrum was a Hole into which one of the shanks of a Stop-Cock of an ordinary size was cemented the other being fixed with Cement in the upper Part of the Pump which being done and the upper Orifice of the Alembick being covered close with a Plate of Lead exactly adapted to it upon drawing the Air out of the Receiver the Glass presently cracked which Crack is represented by the Line a b and this Flaw extended it self further accordingly as the Air was more exhausted yet this Glass Vessel was near twenty times thicker than the Bubble And that the Figure of the former Glass enabled it so much better to sustain the Atmosphere was further confirmed by suspending one of the Bubbles hermetically sealed in the Receiver which so strongly resisted the Expansion of the Air contained in it as to continue whole when the Receiver was exhausted EXPERIMENT IX A Confirmation of the former Experiment An Experiment to shew that these Phaenomena exhibited in Vacuo Boyliano proceed not from a fuga Vacui c. A Confirmation of the former Experiment c. HAving put the end of a slender Glass Pipe into a Viol which was large enough to contain four Ounces of Water and fixed it to the Neck of the Viol with a Cement of Rosin and Pitch so that the end of the Pipe almost touched the bottom of the Viol as in Fig. 6 this Viol was conveighed into a small Receiver as much Water being put into it as wrought a little above the bottom of the Cylinder the upper End of the Pipe being most of it without the Vessel a Hole having been purposely made for it in the Top of the Receiver The Event of which Tryal was that upon drawing the Air out of the Pump the Weight of the Atmosphere internally pressing into the Pipe and the Spring of the Air within the Receiver not equally pressing against the sides of the Bottle which were exposed to it a Piece of the Bottle burst out of the side of it with such a Force as to crack the Receiver in several Places and having reiterated the Experiment with a round Glass Bubble the Leaden Cover of the Receiver was not only depressed by the Weight of the Atmosphere so as to thrust out one side of the Receiver but the Glass Bubble was cracked into Pieces with such violence as to tear a Bladder which it was encompassed with to keep it from breaking the Receiver in several Places Before I proceed to the next Experiment it may be requisite to advertise That though the larger Receivers are apt upon some Tryals to crack yet they are not rendered altogether useless since when the Air begins to be exhausted the ambient Atmosphere compresses the Lips of the Glass closer together But if the Crack be considerable it may be cemented with a Plaster made of Quick-lime and Scrapings of Cheese ground together very finely in a Mortar and made into a Paste with a little Water which being spread upon a Cloath about three Inches broad must be apply'd to the Crack EXPERIMENT X. Of the Flame of a Candle in a Receiver HAVING suspended a Tallow Candle in our Receiver we found That upon an Exsuction of
rose at the first Exsuction to the Top of the Pipe and when the Stop-cock was open'd it would run down through the Exhausting Brass Syphon From whence it appears that the Rise of Mercury depends not on Suction or a Fuga vacui whatever some Learned Men teach but is rais'd by the weight of the Atmosphere since a Baroscope consulted at the same time made it appear that the Atmosphere was able to suspend it at such a Height And as this is an Argument against those that dispute for a Fuga Vacui so it is against those that hold that it depends upon the Attraction of a Rarify'd Substance in the Top of the Pipe for tho' we could rarify the Air further by continuing the Action of the Pump yet the Mercury would not rise one jot higher ANNOTATION BUT the Syphon here mention'd being elsewhere made use of it may be requisite to Observe First The Pipe which bends so much is made of Metal to make it less subject to break Secondly The End of it which is joyn'd to the Stop-cock must be a little wider than any other Part to admit the Shank of the Stop-cock Thirdly The Cement which joyns the Brass Pipe and the Stop-cock being apt to be loose I rather make choice of one to which a Stop-cock is fix'd together with a Glass Syphon about 10 Inches high see Plate 5. Fig. 2. where the whole is represented And tho' this Additional Glass makes the Experiment longer and more tedious yet it is more useful and secure EXPERIMENT XIV The different Heights to which the Liquors may be elevated by Suction accordingly as their Specifick Gravity varies See Plate the Fifth Fig. the Third FROM Experiments already laid down it appearing to what Height Mercury may be rais'd in a Tube we may guess at what Height Water might be suspended by considering that it is 14 times lighter than the former But to be further satisfy'd I caus'd a small Pipe which branched it self into two see Plate the 5th Fig. the 3d So that a Cylinder being fix'd to each Branch the Liquors contain'd in the Vessels in which the lower End of the Pipe was immers'd would rise proportionably as their Specifick Gravity enabl'd them to resist the Pressure of the Atmosphere which being done and the Pump set on work Water rose in one of the Cylinders to 42 Inches and the Mercury in the other Tube not above 3 Inches so that the Water was fourteen times higher than the Mercury And to make the Experiment more satisfactory we let Air into the Receiver till the Water subsided to fourteen Inches and at the same time the Mercury was sunk to about an Inch for in this Experiment it was observ'd That the Proportion was not so exact as 1 to 14 precisely Specifies but thereabouts From this Experiment we may draw Arguments not only against what is taught concerning Nature's Abhorrency of a Vacuum but it may likewise more nicely inform us of the Specifick Gravity of Liquors For having put into one of the Vessels under the Glass Tubes Fresh Water and into the other Salt Water when the Fresh Water rose to 42 Inches the Salt Water was but 40 Inches high But having made use of a Brine made of Sea-salt melted in the Air instead of Salt Water when the Fresh Water was rais'd to 42 Inches the Brine did not exceed seven I likewise put into one of the Vessels when this Experiment was over a Solution of Pot-ashes and Common Water into the other and when the Water rose to 42 Inches the Solution was rais'd but to 30. EXPERIMENT XV. To what Heights Water and Mercury may be rais'd proportionably to their Specifick Gravities HAving put Mercury into a Bottle and pour'd Water into the Bottle upon the Mercury we immers'd one Pipe so low as to have it's End in the Mercury and another Pipe was likewise immers'd in the Water only which being fix'd by the help of a Cement in the Neck of the Bottle the whole was convey'd into the Engin and the Pipes being each divided into Inches by hard Wax with which they were mark'd we observ'd that the Water rose 15 times as high as the Quick-silver EXPERIMENT XVI The Former Experiment Illustrated HAving put Mercury into a short Tube and Water into one that was longer both of them being Hermetically seal'd at one End we inverted them both the End of each resting in a Distinct Vessel which being convey'd into the Receiver the Water in the Cylinder did not in the least subside till by Pumping out the Air the Mercury subsided within 3 Inches of the Bottom which was sooner than it ought according to Statical Rules which we conceiv'd to proceed from some Aiery Parts lodg'd in the Pores of the Water which rising to the Top of the Cylinder depress'd it by their Spring yet the Water when the Mercury subsided to the Height of an Inch was near as high as before EXPERIMENT XVII The greatest Height to which Water may be rais'd by Suction c. TO try how high Water might be rais'd by Suction in a Pump I provided a long Tube about thirty Foot long being made of several Tin Pipes closely joyn'd together with Soder and cover'd over with a Black Cement which to keep it from sticking to our Hands we cover'd with Plaster of Paris To the upper End of this Pipe was fix'd a Glass Tube about three Foot long and to the Top of that was fix'd another Pipe consisting of two pieces which made a right Angle with each other part of which was Parallel to the Horizon See Plate the Seventh Fig. 1. and the other Perpendicular the lower End being fix'd to the Engin which was plac'd upon a Flat-roofed House And a Vessel fill'd with Water being put under the End of the Pipe below the Pump was set on work and the Water after a few Exsuctions was rais'd to the middle of the Glass Tube emitting several Bubbles which proceeded from the Air formerly lodg'd in the Pores of the Water But the chief Aim of our Experiment being only to try to what Height the Water could be rais'd I caus'd the Pump to be nimbly ply'd till the Water could rise no higher which being done and the Height of the Water measur'd by a String we found it to be 33 Foot and about six Inches Quick-silver in a Baroscope at the same time standing at 29 Inches and about 3 eights of an Inch so that the Water was near fourteen times as high as the Mercury In which Experiment that the upper part of the Tube was sufficiently exhausted appear'd from several Circumstances as First If any Air got in at Crannies in the Pipe it would rise in Bubbles easily to be distinguish'd from those which rose from the Pores of the Water and tho' the Quantity of those Bubbles was considerable yet more Air being thrown out by the Pump than could get in it must needs be empty enough But In this Experiment
the Water would subside in a stream through the Spirit In warm Water the Ice would swim but in Oyl of Turpentine and the rectify'd Spirit of Wine it would sink like a Stone 3. A piece of Ice which was clear from Bubbles for as much as we could discern and very transparent would not sink in Water but another piece which in a Microscope appear'd to be full of Bubbles was nevertheless transparent and would float on Water 4. That the levity and expansion of Ice depends on the number of Bubbles dispersed through it is unquestionable but how it comes by those Bubbles is a matter that deserves our Inquiry And tho' Mr Hobbes attributes it to the Intrusion of some external airy Parts yet we observ'd That Water defended from the Intrusion of external Air was not without Bubbles when froze in a Glass hermetically sealed but being expanded the numerous Bubbles dispersed through it gave it a whitish Opacity and the same Phaenomena were afforded by Ice froze in Metalline Vessels 5. And that the Ice froze in the hermetically sealed Glass received not its Bubbles from the Air shut up with it is reasonable to believe First Since the Water must be expanded before it could divide that Air into Bubbles Secondly That the Air in the sealed Glass cannot be dispersed through the Ice and thereby cause it to expand appears since oftentimes it is so far compress'd by the swelling Ice that it breaks the Glass which it would not do could it be mixed with the Ice and dispersed through the freezing Water But Thirdly Were the expansion of Ice to be attributed to the insinuation of airy Parts it may be question'd How when Liquors begin to freeze at the bottom first the Air which is so many times lighter than Water can dive into the bottom of it and that too without being seen Fourthly If the Bubbles contained in Ice were deriv'd from the external Air depress'd through freezing Water Ice thaw'd would yield Air enough to fill as much space as the frozen Water possess'd more than the thaw'd Water 6. That the Bubbles contain'd in frozen Water are not adequately fill'd with Air tho' sometimes the Air that they contain be afforded by those airy Parts dispers'd through the Pores of Water and that they are often generated numerously notwithstanding a recess of the greatest part of that Air will appear from the following Experiments I. Water freed from Bubbles in Vacuo Boyliano and afterwards convey'd into a frigorifick Mixture expanded not so much as common Water nor was the Ice near so full of Bubbles II. Water which had been freed from Bubbles in our Prismatical Engine being froze contain'd few Bubbles but being thaw'd and then pour'd into a Glass-Cylinder it was powerfully expanded so far as to burst the Glass III. A Glass-egg with a narrow Stem being filled so far with Water that the surface of it rose an Inch within the Stem it was convey'd into a Receiver and whilst the Air was exhausting Bubbles rose so plentifully that the Liquor seem'd to boyl Which when it was in a great measure cleared of we placed it in a mixture of Snow and Salt and observ'd that the expanded Liquor being froze had risen a great way above its first height When it was placed in the open Air of such a temper as made it thaw leisurely we observ'd That the exterior part of the Ice was full of Bubbles But when that was dissolv'd the Ice in the middle was of an unusual Texture being void of Bubbles and not unlike a frosted piece of Glass whose aspereties were very thick set When the Ice was almost thaw'd we convey'd the Bubble into the Receiver but tho' the Air was exhausted we perceiv'd not that the Ice was sooner melted but the Water afforded a few Bubbles and in a little time some few appear'd in the Ice When the Ice was wholly thaw'd we took the Glass-Bubble out of the Receiver and found That the Water had subsided to its first Mark if not a little below it so that the Water when expanded rising three Inches in the Stem and the weight of the whole Water being but two ounces and a half the Ice seem'd to take up about a twelfth Part more than the unfroze Water 7. A Cylinder of Water being immers'd in a Mixture of Ice and Salt and that convey'd into a Receiver we found That when the Air was exhausted and the Water in a great measure freed from Bubbles the surface of it was considerably rais'd the Water in the bottom being turn'd into Ice as far as the Mixture wrought in which we perceiv'd besides a few large Bubbles small ones enough to render it opacous 8. To shew that the Bubbles perceivable in Ice are not filled with true and springy Air I shall subjoyn the following Experiment We plac'd a Glass-egg which was about as large again as an ordinary Egg in a mixture of Ice and Salt the Cavity of it being fiill'd with Water which rising up into the Neck stood about an Inch above the superficies of the frigorifick Mixture which circumscribed it the Diameter of the Stem being large enough to receive the end of my Finger The Particulars afforded by this Experiment were I. The Water did not sensibly subside before it began to freeze II. Some part of it began to swell in a quarter of an Hour III. In an Hour the Liquor rose 4 2 9 Inches and continu'd to rise till it was above five Inches ½ when we took it out IV. The frigorifick Mixture being below the surface of the Water it froze at the bottom first leaving the top of the Water uncongeal'd V. No Bubbles appear'd in the Water tho' the Ice was full of them some being as large as small Pease VI. We pour'd as much Sallet-oyl upon the Water as wrought two Inches in the Stem and then hermetically sealing the end of it up the Water subsided a little but was presently rais'd again to its former height in the Mixture about an Inch and a half of the Stem remaining above the Oyl filled with Air. VII The Glass-egg being weighed first in Air was left in the Water poised with its opposite weight VIII Upon the thawing of the Ice several Bubbles rose which vanish'd at the top IX The Water being thaw'd the Aequilibrium continu'd the same and subsided to its first Mark and no lower tho' it had parted with so many Bubbles X. The Glass being inverted the seal'd end was broke off under Water upon which some of it being forced up into the Pipe press'd the contain'd Air into less room than before XI The Water and the Oyl possess'd the same Places that they did before XII The Oyl being thrown out and so much Water put into the Stem as rais'd the surface as high as it was rais'd by Glaciation the Glass weighed 4374 Grains When fill'd to the lowest Mark it weighed 4152 and when empty 1032 so that the Water contain'd betwixt the two
fill'd so full as not to admit of any Air betwixt the Finger and the Mercury Thirdly before the Tube is quite fill'd it will be requisite to invert the Tube that the Air included in it may by ascending to the Top and upon a Re-inversion back again gather all those little Bubbles of Air which are dispers'd through the Mercury as it passes from one end of the Cylinder to another and to drain the Mercury more exactly you may by applying a hot Iron cause those less Bubbles which are not excluded by the former Method to break forth which will be promoted by shaking the Vessel upon every Drop of Mercury put into the Pipe By which Method having in a great Measure clear'd the Tube of Air I have in one that was pretty short rais'd the Mercury to no less than 30 Digits and an eighth EXPERIEMINT XVIII The Variation of the Rise of the Mercury in the Glass-Cylinder and the Reason of it consider'd HAving fill'd a Tube about 3 foot long with Mercury and plac'd it in a wooden Frame in the Window I observ'd the Mercury was sensibly depress'd in hot Weather by the Expansion of the Air which swam about it and rais'd again in Cold the Altitude very often varying without any manifest Cause So that in five Weeks time it had ascended and descended about two Inches the utmost descent below the Altitude of it's first Suspension being 9 16 of an Inch and it 's utmost Descent being 7 16 and it is not improbable but that the Variation of the Altitude of the Mercury would have been more considerable had the Experiment been try'd in a longer Tube and in the open Air. And here it may be seasonable to take notice that could there be any sensible Variation observ'd in the Altitude of the Mereury upon the Ebbing and Flowing of the Sea it would be of no small Moment in determining whether the Pressure made upon the Air by the Moon were any ways concern'd in causing the Ebbing and Flowing of it and such like Phaenomena But to return to what we observ'd further Having taken the Cylindrical Tube out of the wooden Frame on a snowy day we observ'd that the Mercury was rais'd Twenty nine Digits and three Quarters above the Basis which it lean'd on If it should be ask'd from whence these Variations in the Altitude of the Mercury proceeded I shall offer the following Considerations The Reasons why Mercury is not always equally suspended First That the Air above the Mercury being very weak and not able to make any strong Resistance to the Rising Mercury it may be esteem'd a Cause why it rises no higher because the Asmosphere is able to sustain no more of it forasmuch as the Mercury and the Atmosphere are ballanc'd in an Aequilibrium for the Resistance which the Air above the Mercury can make is so small that it would rise but very little higher were there none at all in the Top of the Tube Secondly We may consider that the External Air is subject to many more Alterations and Changes than the Internal contain'd in the Top of the Tube the latter being subject to be wrought on only by Heat and Cold But the former is subject to many and considerable Alterations besides those observable in this Experiment the Effect of its fainter Changes being evident by their Effects on bruis'd and feeble Bodies And that there are considerable Changes in the Air Considerable Changes in the Qualities of the Air. is further evident from what Kircherus during his Stay in Malta observes concerning Mount Aetna which he could see from that place on some days tho' on others which seem'd clear the Air was so condensed that he could not discern it and thet the like Changes of the Air have sensibly alter'd the Prospects of several Places is too commonly known to need further Instances And we our selves have often taken Notice of plentiful Steams and Exhalations in the Air by the use of Telescopes which could not otherwise be taken notice of which after a Showr of Rain would presently disappear And that such Steams do rise from the Earth hath been observ'd by Miners who are often too sensible of Damps which except timely prevented make the Air so thick and muddy as to put out their very Candles And that the Thickness of the Air may contribute to the raising of the Mercury in the Pipe appears from what hath been before observ'd in the Torrecellian Experiment And since the External Air is liable to be alter'd so many ways by the Mixture of insensible Corpuscles of Matter its Rarity and Density are sufficient to account for the several Variations in the Height of the suspended Mercury since accordingly as the Air is Rarifi'd its Pressure in Bodying up the Mercury must accordingly be varied EXPERIMENT XIX The subsiding of a small Cylinder of Water TO try whether a Cylinder of Water would subside in our Receiver as the Cylinder of Mercury did we fill'd a Cylinder of four foot long with it which being inverted and the lower end placed in a Glass Vessel we let it down in the Receiver and closed it up which being done and the Pump set on work we found that it did not in the least subside till such a Quantity of Air was exhausted as to leave the included Air so much weaken'd in its Spring as to be work'd upon and over-power'd by the weight of the Water and then upon every Suction it sensibly subsided tho' not so much as the Quicksilver for whereas the Quicksilver subsided till it fell within an Inch of the Basis the expanded Air remaining in the Receiver was able to bear up the Water a Foot high But the Experiment being try'd in a small Receiver the Quantity of Air included in that coming nearer to an Aequilibrium with the Cylinder of Water it sensibly subsided upon the first Exsuction and much lower upon the second and sometimes not much less than two foot and the Water in this as well as the former upon a reingress of Air rose to the Top of the Cylinder but with more Speed than the former EXPERIMENT XX. Conceening the Elater of Water TO evince that Water hath besides a notable one a languid Elater we fill'd a Glass Bubble with a long Neck term'd by the Chymists a Phylosophical Egg about a Span above the Bubble with Water where fixing a piece of Paper we conveigh'd it into the Receiver and found that after part of the Air was pump'd out the Water sensibly rose upon every Exsuction the breadth of a Barly-Corn and upon the ingress of the Air presently subsided to its former place Another Instance of the Air 's Expansion I obtain'd by filling a round Pewter Vessel with Water at a small Hole which being stop'd with Soder and the Vessel bruis'd in several places to compress the Water the Vessel being perforated with a Needle it spun out with Force enough to raise it a considerable height
Light to proceed from some Refractions from the Glass darkned within by those white Steams Secondly That since the Air abounds with Parts gross enough to appear in the Sun-beams and to reflect the Rays of Light which rise from Bonfires the Reflection might proceed from some gross Airy Parts within the Receiver Thirdly The Whiteness seem'd to proceed from the various Surfaces of the airy Parts reflecting one upon another like Looking-glasses so as to represent each other contiguous so Water or Eggs beaten to Froth lose their Transparency and appear white But further having immers'd the Neck of our Receiver in Water and set the Pump on work the Water being drawn in through a small Hole had its Parts so broken that the Receiver appear'd full of Milk rather than Water And if a Piece of Crystal be thrown very hot into cold Water it will crack and having so many new Surfaces within appears white Which Things being consider'd and weigh'd it may not be an improbable Guess That the aforementioned Phaenomena proceeded from the Parts of the Air displac'd as to their Posture and Situation as whilst in that Motion to disturb their former Continuity and Transparency And this Conjecture may be made probable by observing That the more Air was included the more conspicuous was the Whiteness but more especially by this viz. That having exhausted the Receiver and apply'd a Glass Bubble to the Hole in the Stop-cock so that there might be a Communication betwixt the Cavity of the Receiver and it upon the Exsuction of the Air out of the Receiver the Air in the Bubble was so disorder'd by so sudden a Disilition of it's Parts that it appear'd like Milk but upon a sudden Re-ingress of the Air became transparent again But if it should be objected That the Whiteness in Water turn'd into Bubbles may proceed from the Interposition of so Heterogeneous a Body as Air I should answer That I have in another Place mentioned two volatile Liquors which being mix'd produce a white consistent Body though both the Ingredients were transparent But having convey'd some Smoak into our Receiver and observ'd upon plying of the Pump That the Air remaining in the Pump became opacous we suspected that the Reason why the former mentioned Light sometimes appear'd and sometimes did not might proceed from some Parts of Matter swimming in the Air more at one time than another which was dispos'd more to cause such Reflections of the Rays of Light as to afford the fore-named Phaenomenon which is rendred probable by observing That the Receiver appear'd opaque when the Smoak settl'd about the Sides of it and it may further be illustrated by what we mentioned before of our smoaking Liquor where the Corpuscles of it being put into a new Motion became opacous instead of transparent And if it should be asked How the Air should abound with such various Parts of Matter I must answer That it is not an unusual Observation That the Air undergoes several and very frequent Changes for besides several Instances which might be added the Learned Josephus Acosta observes That in America There are Winds which naturally trouble the Water of the Sea and make it Green and Black others clear as Crystal Besides we observ'd That the Pendula as well as Scales suspended in our Receiver lost a great deal of their Brightness upon drawing out and letting in the Air. And I once made a Tincture of a certain Metalline Substance which would become turbid and clear successively for several times for which strange Phaenomenon no Reason could be given EXPERIMENT XXXVIII Of the freezing of Water and it's Expansion HAVING conveyed a Glass Vessel into our Receiver in the midst of which was contained a Cylinder filled with Water and enclosed with Snow and Salt upon plying of the Pump the Snow began to melt a little faster than we expected and the Receiver being pretty well exhausted the Water in the Cylinder began to freeze so that in a little time the Surface of the Ice was above that of the Water in which the Snow and Salt was dissolved and which swam about it The Superficies of the Water was concave and being held betwixt the Eye and the Light appear'd full of Bubbles And it is not a little strange That there should be so powerful an Expansion in Water froze as not only to burst Bottles in the Winter-time but as I am inform'd to separate the solid Parts of Metals so that Bell-Metal having been expos'd to the Wet and that Wet froze in the Pores of the Metal it would fly in Pieces and Cabeus in lib. 4. Meteor Aristot relates a no less memorable Account of Vessels made of Stone which would fly asunder upon the Expansion of the Moisture lodged in their Pores and froze there Where it is not a little strange That Cold should by freezing Water cause it to swell whereas the Effect it hath upon the Air is manifestly to condense it EXPERIMENT XXXIX A Phaenomenon taken notice of in the exhausted Receiver HAving put the End of a Glass Tube into an Oval Glass so that it almost touched the Bottom we cemented it to the Neck of that Oval and then conveying about six Spoons full of Water into the Egg we blew it so full of Air as to force the Water into the Pipe and to keep it suspended betwixt that Air shut up in the Viol and the external Air this Weather-glass represented by the Fourteenth Figure was plac'd in a small Receiver at the upper End of the Tube which was small being permitted to stand about five Inches above the Cover the middle of which it penetrated Upon pumping out the Air it was to be observ'd That the Water in the Pipe manifestly descended which was an Argument that no Sensible Heat was produced in the Receiver by the Action of the Pump since by barely applying my Hand to the outside of the Receiver that gentle Warmth so far rarify'd the Air in the Egg as to enable it to raise the Water in the Tube much higher than it was depress'd upon the Exsuction of the Air Tho' we will not thence infer that the Cavity of the Receiver was colder after than before the Air was pump'd out since the Pressure of the Air in the Egg together with the Weight of the Incumbent Atmosphere might in some measure cause the sides of the Glass to give way for want of an equal Pressure of the Air on the Convex and external Superficies of it which Guess may seem the more probable not only because the Springiness of Glass might contribute to the bending of it but likewise since upon a Re-ingress of Air the Water was rais'd up to it's former Height again But to return to our Experiment From hence it appears That if there be no Vacuum betwixt the concave sides of the Receiver and the Superficies of the Bubble every Substance fine enough to penetrate the Pores of Glass hath not it's Parts in an Agitation
Omnipotence Matter should be so extended as without any Addition to alter it's Dimensions And tho' our Author takes two Ways to explicate his Notion either upon a Supposition of the Parts of Matter being indivisible or divisible in infinitum yet since he explicates it neither of those ways so clearly as to make it intelligible I must confess I cannot acquiesce in them nor are the Difficulties at all made less by asserting That Matter may be virtually so extended as to possess more Space than is circumscribed by it since a virtual Extension is as unintelligible as Extension without the Term virtually joyn'd with it for since he seems to allow the Parts of Matter to be indivisible it rather prejudices the Doctrin of Rarefaction as taught by Aristotle than explains it since it is inconsistent to think That a Body whose Parts are circumscribed by a certain Space should fill a larger Space without being divided and removed out of the former Nor does it at all explain or render the Aristotelian Doctrin of Rarefaction to say That Matter may by Omnipotence be so ordered as to possess adaequately double the Space it did before since in Natural Philosophy it is not disputed what GOD can do but what he hath done But besides the Difficulties in our Author's Doctrin of Rarefaction there are no less in the Condensation which his Funiculus supposes for since he allows of no Vacuities in it it is impossible the Parts of it should be brought nearer than to touch one another without a Penetration of Dimensions which is wholly disallow'd of and by no means to be admitted in Nature for were that allowed two or three Thousand Bodies might be contained in a Space which every one of them by it self would fill which is altogether unintelligible CHAP. XVIII A Consideration concerning some Tryals of the Torrecellian and other Experiments ' at the Tops and Feet of a Hill The Height of Mercury suspended at the Top of a Hill FOr a further Proof against Our Adversaries Doctrin and for a Confirmation of ours I shall add the following Experiments And First The Famous Pecquet mentions an Experiment made by Monsieur Pascal at the Foot of a Mountain 3000 Foot high where when he ascended 150 Fathom the Mercury in the Cylinder was not buoy'd up so high as at the Bottom by two Inches and a Quarter and at the Top of the Hill it wanted 3 Inches of that Station which it was suspended at at the Foot of the Hill which is a strong Argument against our Adversary the Difference plainly appearing to depend on the different Length of the Atmospherical Cylinder which was abler to weigh up the Mercury at the Bottom than the Top of the Hill And Gassendus Tom. 1. P. 211. relates that the like was observ'd 5 times on the Hills at Auvergne And a very Noted Virtuoso Mr. J. Ball as well as that Ingenious Gentleman Mr. Townley have observ'd the like in England And it was by the last nam'd likewise observ'd that the Mercury included in the Top of the Cylinder was not able to depress the Mercury near so much at the Bottom as at the Top of the Hill But to discover the weight of the Air and it's Spring without going up to the Top of such high Mountains we made use of the following Weather Glass suspending Water in the Pipe instead of Mercury The Instrument was a Glass with a broad Foot and a narrow Neck A B and a slender Pipe of Glass C D which was open at both Ends and so plac'd that the lower End was not far from the Bottom A B and was so closely cemented at the Neck A See Fig. the First Plate the Second as to prevent the Internal Air I I from communicating with External K K unless it were through the Pipe C D And having conveig'd Water H H into the Glass AB which was pretty large and having blown so much Air into the Bottle as to raise the Water in the Tube above the Vessel upon the Leads of Westminster Abby When the Air was thought to be equally Cold and Condens'd within the Bottle as without we mark'd the Station of the Water F and letting it down by a String to the Ground the Water subsided an Inch where it's Station E being mark'd and the Vessel drawn up again the Water was rais'd to the Mark F again Which Experiment being again try'd had the like success And afterwards the Top of the Tube being broke we let it down within the Church the Surface of the Water in the Pipe being at G an Inch above the Water in the Glass where I observ'd that the Air so depress'd it when it came to the Bottom as to force the Water out of the Pipe into the Glass several Bubbles breaking through into the Capacity of the Glass and this Glass being drawn up to the Top of the Church again the Water was manifestly rais'd in the Tube again from whence it appears that the Atmosphere gravitates more Caeteris paribus the nearer the Surface of the Earth for the Experiment being repeated we found that as the Height at which it was try'd vary'd so the Elevation or Depression did Another Particular which may be a further Confirmation of our Hypothesis is That which is mention'd by Monsieur Paschal viz. That a Foot-Ball being weakly blown and carry'd to the Top of a Hill swell'd more and more as it was carry'd higher and as gradually grew lank when it was carry'd down the Hill again From whence it appears That as the Atmosphere is longer or shorter it makes a greater Gravitation and Pressure upon the Bladder To this I shall add an Experiment sent to Dr. Croon by a Learned Professor of Gresham Colledge See Fig. the Sec. Plate the Second which is the following Having Observ'd that in the Weather-Glass A B represented by the Second Figure which was about two Foot long the Water was suspended in the Pipe about thirteen Inches above the Superficies of the External Water at the Bottom of Hallifax Hill but being carry'd to the Top of the Hill it subsided an Inch and a Quarter to the Point D The Internal Air A C which was taken in at the Bottom dilating it self at the Top further by C D In which Experiment the Descent being much more considerable than what it ought to be in such a small Ascent by the bare Pressure of the Atmosphere diminish'd the Reason appears to be the Expansion of that Air included in the Top of the Weather-Glass as well as the Shortning of the Atmospherical Cylinder CHAP. XIX Experiments concerning the Measure of the Force of the Spring of Air compress'd and dilated TO make it evident That the Spring of the Air is able to do much more than we have attributed to it upon the Account of its Spring and Weight we try'd the following Experiments The Air 's Condensation measur'd Having pour'd Mercury into a Glass-Tube which consisted of
We made use of a Brass Hoop about 3 Inches high and 3 Inches and 2 10 in Diameter and Cementing a round Piece of Glass upon the one Orifice the other was joyn'd to the Receiver with Cement and upon drawing out the Air the Atmosphere press'd so strongly upon the Glass as to burst it asunder with a considerable Noise like that of a Pistol How far this may contribute to account for the Noise which accompanies the Explosion of Gunpowder in Pistols we leave others to consider EXPERIMENT VIII The breaking of the Glass Plates in the foregoing Experiment may be accounted for without a Fuga Vacui THAT the breaking of the Glass Plates did not depend on Nature's Abhorrency of a Vacuum appears hence for if instead of the former Brass Hoop we make use of a Vessel Figur'd like a Conus Truncatus or a Sugar-Loaf the Cone being cut off if the lower Orifice be large and the upper not above an Inch Diameter the Glass Plate Cemented to the larger Orifice will break when the Receiver is exhausted but if the smaller Orifice be upwards the Glass Cemented to it will be whole whereas did Nature's Abhorrency of a Vacuum cause the former it would have the same Effect in the latter Wherefore I rather think the Reason why the latter did not break as the former was because a small Basis of the Atmosphere presses upon it which it is abler to resist than a larger Plate of Glass EXPERIMENT IX A Bladder burst by the Spring of the Included Air. NOT to mention of what Advantage it might be to have a Good Method to break Bladders fill'd with Air in our exhausted Receiver by supplying it with Air speedily and without danger of letting in too much from without I shall intimate That if a blown Bladder be contain'd in an exhausted Receiver the Internal Air will be so powerfully expanded as to distend the Bladder and stretch it's Fibers which when taken out again and the Bladder at the Neck being ty'd something nearer than before the Bladder so distended with Air and not liable to give way a second time to the Spring of the Included Air the next time it is put into the Receiver it is apt to burst EXPERIMENT X. A Considerable Weight rais'd by the Spring of the Air included in a Bladder TO shew that the Force of the Air 's Expansion is so great that ¼ of a Bladder being fill'd with it is able to distend it so powerfully as to swell it up tho' a considerable Weight be ty'd to the Bottom of it to keep it from Rising we fill'd the fourth Part of a Bladder with Air and tying the Upper Part of it to the Stopple it was suspended in our Receiver with a Weight suspended by a String which was ty'd to the Bottom of it where we observ'd That upon the Exsuction of the Air the Included Air expanded it self and distending the Bladder shortned it so as to raise 15 pound weight And another Bladder having both Ends ty'd to the Stopple and a Weight suspended at the Middle of no less than 28 pounds the expanding Air rais'd that an Inch from the Bottom of the Receiver but when the Air was again admitted into the Receiver it fell down again EXPERIMENT XI Bubbles Hermetically seal'd broke by the Air included HAving clos'd a Glass Bubble Hermetically seal'd in our Receiver and pump'd out the Air more than usually in such Experiments about four Minutes after the Pump ceas'd to work the Bubble unexpectly flew into so many pieces and with such force as to be broke against the sides of the Receiver into a Powder as small as Sand But this sort of Glass being capable of stretching a little before it breaks may be a Reason why the Experiment does not always succeed the Spring of the Air contain'd in it being weaken'd by that Expansion of the Bubble EXPERIMENT XII Tryals representing the Force of the Spring of Vncompress'd Air upon Staple Bodies The I. TRYAL HAving cemented a Glass Plate upon the Brass Hoop mention'd in the Seventh Experiment and joyn'd the other Orifice of the Hoop with Cement to the Pump upon that a Large Receiver was fix'd So that the Hoop supply'd the place of a Receiver and the Receiver kept the Atmosphere from pressing upon it yet upon an Exsuction of the Air out of the Hoop the Spring of that contain'd in the Receiver broke the Glass Plate into an hundred pieces The II. TRYAL AND a Receiver shap'd like a Tumbler which was capable of containing only a sixth part of what the Large Receiver did being made use of the Spring of so small a Quantity of Air presently shatter'd the Glass Plate in pieces The III. TRYAL The Force of the Air 's Spring BUT a Large square Glass capable of holding a Pound being made use of instead of the Hoop and the Glass Plate upon the Exsuction of the Air it was broke in pieces both when the Large Receiver was whelm'd over it and likewise when a Receiver not much higher than it self was made use of In which Experiments we observ'd That the Air making a greater Pressure on the Sides of the Bottles than the Top first broke them And it was further observ'd in the last Experiments that the Glasses did not fly in pieces till some time after the last Exsuction But lest it should be question'd Whether the Glasses were broke by the Pressure of the Air in the Receiver we repeated one of the former Tryals with the Brass Hoop leaving a communication betwixt the Receiver and the Cavity of the Hoop a small Tube whose Cavity was no wider than the Diameter of a Hair being lodg'd in Part of the Cement and upon plying the Pump we found that the Air having a free tho' a small Vent out of the Receiver did not break the Plate as before Yet notwithstanding if the Air be suck'd out of the Hoop too fast that in the Receiver not finding quick Vent will break the Glass Plate the Pressure of the Air in the Receiver being too strong to be ballanc'd by the Resistance of the Air in the Hoop And for a like Reason a slender Pipe blown at the Flame of a Candle upon it's first Removal into the Cold hath it's sides if thin squeez'd nearer together the Pressure of the Outward Air being greater than the Resistance of the Internal EXPERIMENT XIII Suction is able to raise Mercury no highier in Pipes than the Weight of the Atmosphere impels it HAving fitted one End see Plate 5. Fig. 2. of a Brass bent Pipe to a Stop-cock See Plate the 5. Fig. the 2. and the other End to the Top of a Cylindrical Glass Pipe near 50 Inches long the lower End of it was immers'd in a Glass of stagnant Mercury And tho' the Pump was set on work yet was it not able to raise the Mercury above thirty Inches by frequent and reiterated Suctions But Water being substituted instead of Mercury it
Pillars to which the Feather is fastened being joyn'd to the upper Basis of the Bellows with Cement we fix'd a Weight to the Lower Basis and convey'd it into the Receiver See Fig. the Eighth where we observ'd upon the exhausting of the Receiver that the Air in the Bellows rais'd up the upper Basis together with it's Weight and the Air rising out at the Vent manifestly mov'd the Feather But when the Receiver was quite exhausted and the Weight upon the Upper Basis depress'd it violently we could not perceive that the Feather was in the least mov'd and the like was observ'd upon repeating the Experiment EXPERIMENT XXXVI The great and seeming Spontaneous Ascent of Water in a Pipe filled with a Compact Body whose Particles are thought incapable of imbibing it WE took a slender Pipe and having ty'd a Linen-cloth to the Iower Orifice we fill'd it with Minium and immerging it in Water in a Wide-mouth'd Glass about an Inch the Water ascended about 30 Inches and the Experiment being again repeated in another it rose 40 Inches In which kind of Experiments the following Particulars were to be observ'd First That other Powders being made use of instead of this the Experiment did not succeed so well nor was the Success much better when we made use of Ink instead of Water Secondly Our Experiment succeeded the better the finer and closer the Minium was But if the Pipe be too small the Event will not always be successful Thirdly We observ'd That the Water ascends not to it 's utmost under 30 Hours and sometimes longer Fourthly From hence it appears That the Water in our Tube rose without any swelling of the sides of the Tube which some Learn'd Men ascribe the Cause of Water's Rising in Filtres to Fifthly From hence it may be urg'd as probable That the Sap in Trees may rise after the like manner being promoted by Heat and a due Texture of Parts EXPERIMENT XXXVII Of the seeming spontaneous Ascent of Salts along the sides of Glasses with a Conjecture at the Cause of it I Have several times observ'd that the watery Part of a Solution of Sea-Salt or Vitriol being evaporated the coagulated Salts would creep up the sides of wide-mouth'd Glasses in which the Solution was contain'd and not only so but if the Experiment were longer continu'd they would rise over the sides of the Glass and cover the external Superficies with a Crust of Salt As for the Cause of so strange a Phaenomenon tho' I will not be positive in it yet it may not improbably depend on the like Cause as the Ascent of Water in the Tube mention'd in the foregoing Experiment For we may observe that the Edges of Water are not only above the Superficies of the rest of the Water but Sea-Salt as well as several others chrystallize at the Top of the Liquor they swim in and near the sides of the Glass their Coagulation being promoted by the Coldness of it which Salts when once the sides of the Glass is beset with them the Water may rise to the Top for the same Reason that it does in the slender Pipe before mention'd and Salts carri'd up to the Top of those and coagulating there still lay a further Bottom for their Ascent and so successively till they rise to the Top of the Viol And that there are Passages betwixt these saline Parts for the Water to ascend through appears since they may be broke off in Flakes separate from each other And if it should be thought that the Water in such an Ascent would dissolve the Salt it may be answer'd that the Water being so much impregnated with Salt already can imbibe no more and consequently for that Reason when it runs down the outsides of the Vessels coagulates by the way being too thick and full of Salts to continue long fluid EXPERIMENT XXXVIII An Attempt to measure the Gravity of Cylinders of the Atmosphere so that it may be known and express'd by common Weights The Weight of a Pillar of Air of a determinate size BEING desirous to know what was the Weight of an Atmospherical Cylinder of Air of a determinate Diameter I caus'd a Pipe to be made of Brass whose Diameter was an Inch and it's Length three one End of which being clos'd up with a Plate of Brass I counterpois'd it in a nice pair of Scales and found that it was able to contain about 137 Drachms 45 Grains of Mercury which being multiply'd by Tens a Cylinder of Mercury of 30 Inches and consequently an Atmospherical Cylinder able to counterpoise it must amount to 12 Ounces and about 6 Drachms And by weighing Water in this Tube before the Mercury was put into it the Water weighing 10 Drachms 15 Grains the Proportion of Water to Mercury seem'd as 13 18 41 to 1. But in estimating the Weight of a Cylindrical Pillar of Air it may be here requisite to advertise that I made use of a Brass Cylinder because the Cavities of a Glass Tube are unfit for such an Experiment since it is a hard thing to know whether the Bore of such Tubes be equal throughout their Diameter The Weight of a Cylinder of Mercury being thus found it will not be very difficult to know the Weight of a Cylinder of a different Diameter by the Assistance of the Doctrin of Proportions and the 14th Proposition of the 12th Book of Euclids Elements For since according to that Cylinders of equal Bases are to one another as to their Heights and since by the second Proposition of the same Element such Circles as the Bases of Cylinders are to one another as the Squares of their Diameters and since Mercurial Cylinders will bear the same Proportion in Weights as they do in Bulk The Rule will be That as the Square of the Diameter of the Standard Cylinder is to the Square of the Diameter of the Cylinder propos'd so will the Bulk of the former be to that of the latter and the Weight of that to the Weight of this so that the Square of one Inch being 1 and the Square of 2 being four the Weight of the latter will be four times the Weight of the former EXPERIMENT XXXIX The Attractive Virtue of a Load-Stone in the Exhausted Receiver TO try how far the Account given of the Attraction of a Load-Stone depended on what some Modern Philosophers teach viz. That the Effluvia of a Load-Stone pressing away the Air betwixt the Body attracted that Air helps the Attraction by pressing against the opsite side of the Stone We plac'd a vigorous Load-Stone in our Receiver having adapted a Cap of Steel to it to the lower side of which a Scale with 6 Ounces of Troy Weight was fix'd which being all the Load-Stone besides the Steel and the Scale was able to keep up all which being suspended at a Button which was on purpose on the inside of the Cover of the Receiver we observ'd that tho' the Receiver was exhausted as much again as
in this Experiment was that after some time the Water rising about an Inch in the Tube above the Surface of the Water without it we several times rais'd the Sucker 2 or 3 Inches and fuffered it to fall again without perceiving that the Water in the Tube was in the least Affected which is an Argument either of a Vacuum or that the Parts of that Aether are so fine that they exceed the Rarefaction of the Air so far as not to be able to effect what a Particle of Air does which is not above 1 500 part of the Quantity of a Pin's head a Particle of Air before Expansion of that Minuteness being able when the Receiver is exhausted to displace much more Water upon their Expansion than this Aether By which Experiment as well as what we have taken notice of the Reason I formerly assign'd for the rising of Water in Syphons seems to be confirm'd the Water in the Pipe made use of in these Experiments not being able to rise when the Air was exhausted tho' the Sucker was drawn up till Air was permitted to enter into the Receiver again EXPERIMENT III. Concerning the falling of a light Body in the Exhausted Receiver the Figure of it disposing it's Motion to be visibly alter'd by a small Resistance of the Air. TO discover whether so light Bodies as Feathers would be affected in their descent in the exhausted Receiver by any subtle Matter contain'd in it we fix'd a small pair of Tobacco-Tongs in such a Receiver as Fig. the Fourth Represents See Plate 1. Fig. 4. which was 22 Inches high and having joyn'd four Feathers together with Cement so as to lie across each other we fixed a small piece of Paper to them which being held in the Tongs the Feathers hung in an horizontal Posture And upon an Exsuction of the Air out of the Receiver till by a Mercurial Gage it seem'd void of Air we open'd the Tongs by turning the Stopple in the Cover of the Receiver a short String the one End of which was fixed to the Stopple and the other to the Tongs being by that means shortned upon which we observ'd that tho' these Feathers turned several times in the unexhausted Receiver yet the Experiment being often repeated we could not perceive them in the least to turn in the exhausted Receiver but to fall like a dead Weight and what was further to be observed was that the Descent of the Feathers was much quicker in the exhausted Receiver than when it was full of Air. Yet in this Experiment it was observed that the Phaenomena were less convincing than the former because we took notice that the Feathers fell without in the least turning when the Receiver was but half exhausted And we further noted in this Experiment that the Receiver being lengthened with a Cylinder of Laton cover'd over with Cement and kept from being press'd too much inward by the outward Air by a Case made of Iron Bars when the Air was let in again into the exhausted Receiver it made a considerable crackling Noise the sides of the Metalline Receiver which before were in some measure compress'd being again extended EXPERIMENT IV. Of the Propagation of Sounds in the Exhausted Receiver HAVING caused a Cylinder of Box to be turned See Plate 2. Fig. 1. with an Axle-tree at each End into the Cavity of the uppermost was received the Bottom of the Stopple and the Axle-tree at the Bottom was adapted to a Hoop of Brass fixed in the middle of a Trencher which was about 5 Inches broad and 3 thick and which had a piece of Lead fixed to the Bottom to keep it steady which being done a Wyer was fixed in the upper part of the Trencher and at the End which bent downwards was fixed a Bell and at another place of the same Trencher was fixed a Steel Spring to the upper part of which a piece of Steel was joyn'd at such a convenient Distance that when it was bent back by two Pegs placed at right Angles in the Cylinder which had several Holes made in it on purpose and the Spring on a sudden ceased to be pressed upon it would fly forcibly upon the Bell and give it a smart Stroak Things being thus ordered I caused the Receiver to be exhausted and tho' the Sound which was caus'd by turning the Cylinder fixed to the Stop-Cock so as to make the piece of Steel strike upon the Bell was scarce discernible yet as Air was gradually let in it became louder and more audible And the like Experiment being tryed by suspending a Watch which had an Alarum belonging to it by a piece of Thred which was tyed to a Glass Button purposely blown in the inside of a Receiver which was made of one entire piece so that it was less subject to break we ordered the Watch so that the Alarum should begin to go by the time that we were ready to make our Observations at which time one that held his Ear near enough to the Top of the Receiver perceiv'd that when the Air was wholly exhausted the Sound of the Alarum was scarce at all discernible but became much louder as the Air was gradually let in EXPERIMENT V. About the breaking of a Glass Drop in the Exhausted Receiver TO know the Reason why upon the Breaking of a Part of the solid Case of the Stem of a Glass Drop which upon it's first Formation falling into Water was kept full of Rarifi'd Air I say to know the Reason why such a Bottle flies in pieces when part of the Stem is broken off upon a sudden Ingress of External Air I caused the lower End of a Glass Drop to be fastened to a staple Body the Stem being tyed to one End of a String and the other End being fastened to the Turn-Key which being done and the Receiver exhausted the Stem was broke off by shortning the String whereupon the Bubble flew into a Thousand Pieces the Air inclosed expanding violently and endeavouring to rush out at that small Vent EXPERIMENT VI. About the Production of Light in the Exhausted Receiver TO try whether Light might be produced in the Exhausted Receiver without an Access of Air we made use of a Virtical Cylinder the lower Basis of which was fixed in a Staple Trencher and having fixed two pieces of Steel in the lower End of that Cylinder so as to rub forcibly against a Lump of Loaf-Sugar I observ'd that the Vitriol Cylinder being forcibly turn'd by the help of the Turning Key the Steel made Impressions strong enough upon the Sugar to cause it to afford not only several Flashes but little Sparks of fire EXPERIMENT VII The Production of a kind of Halo and several Colours in the Exhausted Receiver WE made use of a large inverted Cucurbite for a Receiver which being exhausted and a large Candle held on the Opposite side when the Stop-cock was turned to give way for the Air to pass out of the Receiver into the Cylinder the
bending P. in pressing up the Plug E. E. E. the Fingers might more vigorously draw up the Leaver L. T. T. A Rectangle of Iron compassing the Leaver L. L. and the Iron O. P. O. to keep it in such a Posture that the Plug may not fly out whilst the Air is compressed into the Globe A. A. I. I. An Elliptick Hole which is shut with a Valve that opens inward the Design of it is that what is amiss in the Globe may be seen and mended S. S. A Plate of Metal perforated with a Screw V. which sustains the Valve and keeps the Hole V. shut Q. A Hole for the Air which is to be pressed into the Globe to enter in at when the Sucker D. is pulled down to the lower End of the Tube C. C. The Method to press Air into this Globe is this I set my Foot upon the crooked End of the Sucker D. and then pulling up the Globe as soon as the Tube C. C. is full of Air I depress the Globe by which means the Air in the Tube is forced into it through the Valve F. and this Method being taken as long as the Air 's Spring would permit us to compress it any further the Air may be discharged if when the Plug D. is drawn out and a Bullet is put into the Tube instead of it the Plug E. E. E. be raised so that the End of the Iron Wire may open the Valve B. for the Air violently rushing out will drive the Bullet away with great Violence The Globe will be sooner filled with Air if half an Ounce of Water be put into the Tube C. C. before the Sucker D. for the Top of the Tube being filled with Water the Air will be forced clearly out of the Tube into the Globe And this Wind-Gun hath these Advantages above any other yet mentioned First that it is not so subject to be spoiled as those that have two Valves Secondly it is easily mended what is amiss being taken out at the Elliptick Hole Thirdly it is much more stanch the Crannies being stopped with Silver Soder which damages not the Leather on the Valve because it is put in after the Soder is cooled at the Elliptick Hole Fourthly several Bodies may be conveighed into it at the Elliptick Hole whereby we may be enabled to try several Experiments PLATE V. How Factitious Air may pass out of one Receiver into another A.A. A Metalline Plate perforated in the Middle B. B. To which a Stop-Cock is fixed the lower Orifice being made into a Male Screw D. C. Which is received by the Female Screw D. of the Copper Funnel D. C. See Fig. 2. E. E. A hollow Tube both of whose Ends are formed into a Female Screw to receive the Male Screw of the Stop-Cock B.B. See Fig. 1. F. F. The Receiver laid on the Plate A. A. and exactly fitted to it The Matter of which factitious Air is to be made is to be put into the Receiver F. F. and the Orifice of the Tunnel C. being placed on the Receiver and the Stop-Cock B. being open'd the Air is to be drawn out of the Receiver which being done the Stop-Cock is to be shut again and the Male Screw being taken out of the Female Screw in the Brass Tunnel the Receiver is to be immers'd in Water to keep External Air out As for the Degrees of Compression of the factitious Air they may be discover'd by the Mercurial Gage before mention'd To transmit this Air into another Receiver F. F. we make use of the small Tube E. E. Fig. the Second into each End of which the Stop-Cocks of two Receivers being screw'd and the Crannies stopp'd with Cement by turning the Stop-Cocks the Air may be let out of one into the other To discover the Rarefaction of the Air contain'd in which Receivers because they must be inverted we contriv'd the following Gage See Fig. 4. A. A. A Viol filled with Mercury up to the Superficies D. D. B. B. A Tube cemented in the Neck of it C. C. Another which passing through the Tube B. B. leaves room for a due intercourse betwixt the External and Internal Air the upper End of which must be seal'd and the other End open If this Gage be put into a Receiver when it is inverted both the Tubes will have the Air contain'd in them exhausted and will be ready to receive factitious Air as soon as the Stop-Cocks are turn'd to give an Intercourse betwixt them and then the Gage being inverted and the Mercury which lay below the Orifice of the Tube B. B. falling about the Pipe C. C. by rising up into it will shew the Degrees of the Compression of that factitious Air. PLATE VI. An Instrument by which Air may be filtrated through Water See Fig. 1. A. A. A Glass Receiver whose Orifice is adapted to the Plate B. B. which is perforated in the Middle by the Tubes C. C. D. D. which are cemented to it E. E. E. E. A Stop-Cock into which the lower Ends of the Tubes C. C. D. D. are inserted F. F. The Key of the Stop-Cock in which is made the Chink G. G. without any Perforation H. H. The Receiver to which the Stop-Cock is fix'd preventing an Ingress of outward Air and having a due Intercourse with the Pump I. I. L. L. A Glass Vessel M. The Stopple in the Top of the Receiver fasten'd with a Screw See Fig. 2. A Stop-Cock cut transverse so that the Insertions of the Tubes C. C. D. D. into the Stop-Cocks may be perceived The Use of this Instrument is as follows To try how much Air may acquire new Qualities in respect of a Body included with it we conveigh that Body into the Vessel and then pouring a sufficient Quantity of Water at the Orifice M. until the Receiver A. A. be half full and the Vessel L. L. swim up to the Top of it the Orifice M. is stopped up which being done and the Key so placed that the Tube C. C. may communicate with the Chink G. G. upon drawing down the Sucker the Air in the Receiver A. A. will pass through the Pipes C. C. and the Chink G. G. into the Receiver H. H. and from thence into the Pump Upon which the Chink in the Stop-Cock being turn'd so as to communicate with the Insertions of the Tube D. D. and then the Sucker being rais'd to the Top of the Cylinder the Air will be impell'd into the Tube D. D. and emerging through the Water will rise into the Top of the Receiver A. A. and by this Method we could strain it through Water as often as we had a mind to be inform'd what new Qualities it acquir'd in reference to the Bodies about it FIGVRE III. How the same Numerical Air may be sometimes condensed and sometimes rarified The Receiver A. A. being fix'd upon the Plate B. B. and the Stop-Cock C. C. being fix'd to the Perforation of the Plate B. B. The
Receiver so far that but one part of twenty of the Air was drawn out and then we observ'd the following Particulars First The Water except about the Fish afforded no Froth and but few Bubbles Secondly The Fish discharg'd several Bubbles at its Mouth and Gills and several after it rested half an hour stuck to its Fins and Tayl and other Parts these Bubbles by swimming would be shaken off but upon a little Rest they would appear about him again Thirdly Except at the latter End he seem'd to take in Air at his Mouth and Gills Fourthly After a while he lay on his Back and would swim in that Posture Fifthly In some time he mov'd more lively than at first An hour and half after he was included he seem'd clear of Bubbles but lay on his Back and was a little tumid yet as lively as before An hour and a ¼ after he was without Motion and stiff yet being excited by Motion he mov'd a little Air being let into the Receiver whilst he was under Water he sunk to the Bottom and seem'd a little reviv'd and being conveigh'd along with the Water into a Bason of fresh Water he was further recover'd yet could not lie on his Belly but turn'd from one side to the other his Belly seem'd much shrunk he was alive at 24 hours end and then was able to lie on his Belly TITLE VIII Of two Animals included with large Wounds in the Abdomen in the Pneumatical Receiver EXPERIMENT I. ABird in Vacuo A Small Bird whose Abdomen was open'd tranversly in about a Minute after we began to Pump had Convulsions in its Wings and being taken out was past Recovering tho' there was very little Alteration in its Lungs and the Auricles of its Heart continued to beat EXPERIMENT II. A Frog in Vacuo A Frog whose Abdomen was so much open'd that two curl'd Lobes of its Lungs came out at the Incisions was suspended by the Leg in a small Receiver which when it was in some Measure exhausted lay void of Motion its Abdomen and. Thigh being swell'd very much as if distended with some Aery Vapour One Lobe when the Frog was shut up appear'd full the other shrunk up and thus they continu'd till Air was let into the Receiver again and then the Body growing less tumid and the Lobe of the Lungs which was tumid subsiding it presently recover'd TITLE IX Of the Motion of the separated Heart of a cold Animal in the exhausted Receiver EXPERIMENT I. The Heart of an Eel in Vacuo THE Heart of an Eel being shut up in a Receiver upon a Tin Plate beat as in the open Air and the Receiver being exhausted grew tumid emitting several Bubbles out of it yet it continu'd to beat as fast or faster than in the open Air. The like Success we had with another EXPERIMENT II. THE Heart of another tho' tumid beat an hour in Vacuo and then beginning to fail I apply'd Heat to the Glass upon which it renew'd and continu'd it's Motions another hour at which time it 's Motion was renew'd by applying of Heat a second time at the end of the third hour the Motion which was but a trembling one could neither be promoted by the Air nor Heat TITLE X. A Comparison of Times wherein Animals may be kill'd by drowning or withdrawing of the Air. EXPERIMENT I. Sept. 10. Animals in an exhausted Receiver A Green-Finch being sunk in Water by a Weight was dead after it had lain half 0184 0108 V 3 a Minute without Motion EXPERIMENT II. A Sparrow which at the first moved very vigorously under Water being taken up after it had lain half a Minute without Motion was past Recovery EXPERIMENT III. A Mouse being immers'd half a Minute and some Seconds after some faint signs of Life tho not Convulsive dy'd EXPERIMENT IV. A Duck being immers'd by a Weight after it had lain quiet for a Minute was a little uneasie but being quiet at the end of the second Minute we took it out and in a little time it recover'd but being immers'd again in fresh Water it emitted several Bubbles at its Beak and Nostrils and in two Minutes time began to struggle At the end of four Minutes ceasing to emit Bubbles it began to gape which continu'd two Minutes and then its Head hanging carelesly down it seem'd dead being taken out a Minute after it was past Recovery EXPERIMENT V. A Duckling being immers'd with its Beak about 2 Inches under Water emitted Bubbles at its Beak which likewise arose from some place in its Neck about as far from its Eyes as from its Ears after which several times it endeavour'd to dive lower and having been moderately convuls'd hung its Head down as if dead at 3 Minutes end soon after a trembling Motion appeared in some parts of its Bill but that ceasing at the end of the 4th Minute it was taken out past Recovery EXPERIMENT VI. A Viper was so long kept in Vacuo that it seem'd dead but being kept all night over a digestive Furnace in a Glass Body was as lively as ever Then we immers'd it in a Glass Body stopp'd with a Cork and depress'd with a Weight where it lay a considerable time with very little Motion when four hours were almost past it swam above the Bottom of the Water and had several times put out its Tongue when a little more than seven hours were past it seem'd dead its Head and Tail hanging down without Motion N. B. Tho' several of these Animals seem to die a little sooner in Water than in Vacuo yet it does not certainly prove that the former kills them faster for in Water they are depriv'd of Air instantly In a Receiver by degrees which is evident from hence viz. That having provided a Receiver which could be exhausted at one suck the Animal contain'd in it would be dead in half a Minute TITLE XI Of the Accidents that happen'd to Animals in Air brought to a Considerable Degree but not near the utmost one of Rarefaction EXPERIMENT I. Aug. 18. A Linote being 3 hours in a Receiver Several Animals in Vacuo large enough to hold 4 ½ Pints seem'd sick but being taken out recover'd EXPERIMENT II. Aug. 18. A Linote being enclos'd in a Receiver half exhausted was not in danger of Death in less than 1 ¼ hour and then being expos'd to the Air Recover'd EXPERIMENT III. Sept. 9. A Lark being included in a Receiver of the former Magnitude together with a Gage when ¾ of the Air was exhausted in a Minute and half was taken with Convulsions and at the end of the second Minute was past Recovery EXPERIMENT IV. Sept. 9. A Green-Finch being shut up in the same Receiver half exhausted in a Minute was sick and threw Matter which she vomited upon the side of the Glass upon which she seem'd better and continu'd so for 3 Minutes and then being sick and vomiting as before she eat part of it up
Mercury being too heavy to be buoy'd up so high it will not be elevated higher than an Atmospherical Cylinder is able to raise it But those Modern Philosophers who allow not a Fuga Vacui ascribe the Ascent of such Liquors to an Impulse or Propagation of Motion by the Dilation of the Thorax for they think that the Lungs drawing in the Air the dilated Thorax propagates the Impulse till it reaches successively the Body suck'd for such thinking the Universe totally a Plenum think that such Matter not finding any other Place to move into does upon that score buoy up the Water or Mercury in the Pipe But if we consider how vast the Dimensions of the Air are and comparatively how inconsiderable an Impulse the Thorax by dilating can make it will scarce be thought that so slight a one will compress the whole Air so much as to make it impel the Body suck'd vigorously enough to rise to that height which Liquors may be rais'd to by Suction But the Ascent of such Liquors evidently depends on this that by Suction the Pressure is taken off the Surface of the Water within the Pipe and consequently it must rise and be buoy'd up by the Pressure of the Atmosphere on the stagnant Water To countenance my Opinion and to refute the others I have mention'd I shall offer the following Experiment viz. A small Bubble with a Stem being seal'd up when the Air was forc'd out by Rarefaction the Stem was broke under Water upon which the Water rush'd into the Cavity of the Bubble where if it be said to go into the Bubble to prevent a Vacuum those that say so allow dari Vacuum and subvert their own Principles and as for the Plenists upon the same Account we may ask them what became of that Air which was expell'd out of the Bubble and remain'd so till the Stem was broke since were the World an absolute Plenum before there could be no room for it without nor could there be such an empty Space within to receive the Water Besides if they say the external Air being condens'd and compress'd by that which is forced out of the Bubble occasions the Re-ingress of Water when the Stem is broke off it may justly be wonder'd that a cubic Inch of Air should be able to condense the Air so much that a Mile's distance from the place the Bubble was evacuated in it should be able to press the Water thus in again But by our Hypothesis it is accounted for without these Difficulties since the Resistance of the rarifi'd Air within the Bubble being disproportionable to the Pressure of the less rarifi'd Ambient Air it must consequently yield to it and give way to the Ingress of Water Our own Opinion propos'd and prov'd From what hath been said it plainly appears what our Hypothesis is which that I may confirm by the following Experiments I shall briefly intimate That the Ascent of Liquors by Suction in a Word depends on the External Pressure of the Air when it is taken off the internal Superficies of the Liquor in that Tube what that Pressure depends on we have elsewhere prov'd in our Physico-Mechanical Experiments of the Air 's Spring and Weight and therefore shall proceed to Experiments to confirm what we teach of Suction We took then a crooked Syphon whose shorter Leg was parallel to the longer which being hermetically seal'd and so much Water conveigh'd into the crooked End that it was of an equal Height in both Legs so much Air was contain'd in the Cavity of the shorter Leg as possesses an Inch and ½ The Instrument being thus prepar'd one was order'd to suck at the Top of the longer Leg and by all the Force and reiterated Suctions he was not able to raise the Water higher than the Air in the shorter Leg depress'd the Surface of that for when the Spring of that Air was so far weaken'd that it could not depress the Water subjacent the Water kept at the same Station being not above four Inches high which was not two Inches and an half higher than at first But as soon as the External Pressure of the Atmosphere was again admitted to the Surface of the Water in the longer Tube it was presently depress'd and the Air in the shorter Leg condens'd till the Water likewise rose in that to it's first Station For a further Confirmation of our Hypothesis about Suction I shall subjoyn Experiments to prove the following Propositions Our Hypothesis reduc'd to Propositions I. That a Liquor may be rais'd by Suction when the Pressure of the Air neither as it hath Weight nor Elastacity is the Cause of the Elevation II. That the Weight of the Atmospherical Air is sufficient to raise up Liquors by Suction III. That in some Cases Suction will not be made as according to the Hypothesis I dissent from it should although there be a Dilatation of the Suckers Thorax and no danger of a Vacuum tho' the Liquor should ascend The first Propositions prov'd To make out the first Proposition I made the following Experiment viz. I took an inverted Tube such as was formerly made use of for a Travelling Baroscope but something longer which being fill'd with Mercury it was inverted and the Mercury in the longer Leg stood above the Mercury in the shorter Leg as high as it usually does in an ordinary Barometer and then one was order'd to suck at the shorter Leg upon which the Mercury subsided in the longer and rose in the shorter the Mercury in the longer by it's own Weight depressing the subjacent and raising that when the equivalent Weight of the Atmosphere was taken off The second Proposition prov'd As for the second Proposition laid down viz. That the Weight of the Air is sufficient to raise Liquors in Suction It may easily be prov'd by Arguments drawn from our Physico-Mechanical Experiments and therefore here I shall only take notice of Phaenomena exhibited by our Travelling Baroscope for having got a Baroscope whose shorter Leg was something longer than ordinary we caus'd one by Suction to raise the Mercury up to the Top of it and then hermetically sealing it up we mark'd the place to which the Mercury had subsided in the longer which being done we unseal'd the shorter Leg and observ'd that the Pressure of the Atmosphere elevated the Mercury in the longer Leg 5 Inches The third confirm'd For a further Confirmation of the Doctrin laid down in this Proposition I shall subjovn the following Experiment We made use of a Travelling Baroscope whose shorter Leg was 2 Inches above the Surface of the stagnant Mercury and having seal'd up the End of the shorter Leg we open'd the End of the longer upon which the Weight of the Atmosphere being added to the Pressure made by the Cylinder of Mercury the Air contain'd in the shorter Leg was compress'd into half the Space it possess'd before This Experiment being try'd a second time had the like Success To
make it further appear how much the Ascent of Liquors depends on Pressure I took a Glass Syphon like the former and having hermetically seal'd up the shorter Leg I pour'd in so much Mercury as compress'd the Air in the shorter Leg into half the Space it possess'd before the Mercury in the longer Leg being at the same time about 30 Inches higher than in the other nevertheless the Mercury could not be rais'd by Suction above one Inch higher in the longer Leg whereas did the Ascent of Liquors depend on Nature's Abhorrency of a Vacuum it would have rose much higher there being no danger of leaving a Vacuum in the shorter Leg since the Air was compress'd into half the Space it naturally possesses so that the Reason according to our Hypothesis evidently appears to be this viz. that the Pressure of the Cylinder of Mercury and the compress'd Air being in a due Aequilibrium when by sucking the Air is drawn out of the longer the Air in the shorter expands it self so much as Pressure is taken off by the Removal of that Air and when it is expanded so far the Pillar of Mercury keeps it from expanding any further so that there being no other Force to raise and press the Mercury up it can be elevated no higher since the Air included in the shorter Leg acts only by Virtue of it's Spring and not as in the open Atmosphere by Virtue of it's Spring and Weight too so when it hath lost it's Spring it can propel the Mercury no higher To conclude this Discourse I shall here explain one Phaenomenon in Vacuo Boyliano which to some seems an Argument of Nature's Abhorrency of a Vacuum The Phaenomenon is That if ones Finger be apply'd to the Orifice of the Pipe that conveighs Air from the Receiver to the Pump the Pulp of one Finger will enter a good way into the Pipe and be very painful the Protuberant Part of it seeming to be drawn in by Attraction To which we give this brief Answer viz. That when first the Finger is plac'd there it receives an equal Pressure from the Air within the Pipe and from the Atmosphere but when that Air is drawn away the External Pressure finding no Resistance presses the fleshy Part into the Tube which is accordingly painful as the External Pressure in reference to the internal Resistance is greater or less To illustrate this Explication I shall add that having clos'd up one End of a Glass Pipe whose Diameter was an Inch with a piece of oyl'd Bladder and fill'd it full of Water it was immers'd in a tall Vessel full of Water the immers'd End of the Tube reaching almost to the Bottom of the Vessel and the other End emerging and standing open above the Vessel This being done we took Water out of the Tube till the Surface of it was considerably lower than the Surface of the Water in the Glass Body upon which the Bladder being more strongly press'd against by the Water in the Vessel than that in the Tube the Bladder was forc'd so much into the Cavity of the Tube as to form a Semi-Globe but if when the Water in the Tube and that in the Vessel were equally pois'd the uppermost Orifice of the Tube were stopp'd tho' the Pipe were so much immers'd that the Quantity of Water which press'd against the lower side of the Bladder were greater than that in the Tube yet would not the Bladder have the least Protuberance but if the Orifice of the Tube were left open to the Air the Bladder would suddenly be press'd so much into the Hollow of the Pipe that it 's Convex Superficies would represent a Semi-Circle The same Experiment being try'd with a Tube the lower End of which was so bent as to form a right Angle the Success was the same Nor did it vary when try'd in the straight Pipe with Wine instead of Water save that Wine not being specifically aeque-ponderant with Water a greater Quantity of Wine was requisite to settle them at first in a just Aequilibrium but when that Aequilibrium was lost by immerging the Tube into the Water the Bladder was rais'd so as to become protuberant in the Cavity of the Pipe CHAP. VIII Some Observations and Directions about the Barometer communicated by Mr. Boyle in the Phil. Transact of April 1666. Observations concerning Barometers THE Design of trying Barometrical Experiments in several Parts being only that by comparing Notes The Extent of Atmospherical Changes in Point of Weight might be the better estimated I shall lay down the following Directions for those whose Curiosity leads them that way First It will be requisite to note the Day and Hour in which Observations are made Secondly The Situation of the Place where the Barometer stands as to Height since by the Length of the Atmosperical Pillar of Air that presses upon it the height of the Mercury may vary tho' not always exactly for sometimes upon Changes in the Air not otherwise observable the Mercury will subside more than usually in that which stands furthest from the Center of the Earth when at the same time it does not proportionably subside in that which is plac'd in a lower Situation And It perhaps may be Worth Noting whether upon excessive Droughts when the Ground is parch'd and crack'd some subterraneal Effluvia may not rise which may add a specifick Gravity to the Air. Nor will it be needless when other Observations are making at the same time to observe the Weather as also what Winds blow and whether violent or more remiss for sometimes it is observ'd that when high Winds blow the Mercury is the lower tho' not always But to favour what hath been intimated viz. That the Alterations in the Weight of the Air depend on subterraneal Steams mix'd with it It hath been observ'd that after long Droughts upon a Shower of Rain so many Steams have been either prevented from rising or depress'd and precipitated that the Mercury hath subsided within 2 16 of an Inch. CHP. IX An Account of a new kind of Baroseope which may be call'd Statical communicated in the Philosophical Transactions of July 2. 1666. A new Baroscope describ'd HAving caus'd a Glass Bubble to be blown as large and thin as it possibly could be I counterpois'd it in a Pair of Scales which would turn with the 30th Part of a Grain which Ballance being suspended at a Frame both the Frame and the Ballance were placed by a good Baroscope from whence the present Weight of the Atmosphere might be learnt By which means I could discern Variations by which the Altitude of the Mercury was not alter'd above ¼ of an Inch. And it was not a little pleasant to behold that sometimes the Bubble would be counterpois'd but when the Atmosphere was very high it would manifestly preponderate and upon other Changes the Scales would preponderate on the other side and in some Days time again regain it's Aequilibrium so that by looking
Perpendicular to the Horizon and the lower End of it immers'd in Water This done we cover'd the Ball of the Bolt-head with a Mixture of beaten Ice and Bay-Salt upon which the internal Air being condens'd the Water rose up into the Stem and stood a good while Then having made a Mark at it's highest Station we fill'd the Vessel with Water and found that it yielded ℥ 19 and ʒvj the Weight of the Water which fill'd the Stem up to the Mark being ℥ j and ʒiij by which Number the former being divided the Quotient was 14 4 11 Drachms so that the Proportion of the two Quantities being as 11 to 158 The Space into which the Air was condens'd was to it 's former Space as 147 to 158 So that the highest Degree of Condensation it was then capable of made it lose of it's former Extent 11 158. N. B. First The Stem of the Glass ought to be long lest the Water upon the Air 's Condensation should rise into the Ball of it Secondly The Cylinder of Water was two Foot so that it might by it's Weight in some measure hinder the Ascent of more and so keep the Air from condensing to it's utmost Thirdly When the Water rose as high as it well could we observ'd it to rise and fall alternately for a little time Fourthly The Air may thus be further condens'd than by Winters Cold. But to shew that in the forgoing Experiment the Cold did not compress the Air immediately but partly in as much as it by stuffing up the Pores of the Water caus'd it to swell and so to compress the Air I took a new Glass Bolt-head with a short Neck and fill'd it full of Water so that when it was hermetically seal'd up the Liquor wrought within 3 Inches of the Top the sharp End which was made for the Conveniency of sealing being ¼ of an Inch long This being done the Bolt-head was plac'd in a Mixture of Snow and Salt upon which the Water ascended and compress'd the Air into the Conical Part upon which the Glass flew in pieces In which Experiment according to Dr. Wallis his Estimate the Air was compress'd into a 40th part of the Space it possess'd before Which is considerable above the utmost Compressure made in Wind-Guns where it is usually thought not to be compress'd into less than a 15th and according to Mersennus into an 8th part of it's former Space CHAP. XI Of the Admirably differing Extension of the same Quantity of Air rarified and compress'd The admirable different Extensions of the same Quantity of Air. THE first Thing I shall take notice of concerning the different Degrees of the Air 's Rarefaction and Condensation is That in our Climate tho' Cold will not condense it near into a 20th part of the Space it possess'd before yet it may be expanded to 70 times that Space Secondly The Air may be much more condens'd and rarifi'd by our Engins than by Heat or Cold the Proportion in respect of Expansion being as 1 to 70. But Thirdly Perhaps the Proportion betwixt the Degrees of the Air 's Condensation and Rarefaction will not be thought so great as what we have mention'd if we consider that the Air we make Experiments with here below is so much compress'd already by the Incumbent Atmosphere that for that Reason it is more inclin'd by it's Spring to yeild to an Expansive than a Compressive Force Fourthly It may be question'd how the parts of the Air which have a specifick Gravity come to be spread so thin in the Cavity of the exhausted Receiver since there is nothing in it for them to swim in and to bear them up Since the Proportion is so great betwixt the Parts of the Air and the Cavity of the Receiver they are contain'd in Fifthly It is not a little wonderful that Air should be so subject to vary it's Dimensions so that if we consider how far it may be expanded without the Assistance of Art elaborate Engins or Heat the Top of the Atmosphere must be extremely rare To conclude If we compare the utmost Degrees of Condensation and Rarefaction together the same Portion of Air may possess 520000 times the Space at one time that it did at another CHAP. XII New Experiments about the weakned Spring and unheeded Effects of the Air communicated in the Philos Transact of Decemb. 75. TO try whether as some Corrosions of Bodies in close Vessels increase the Spring of the Air so others may not weaken it and likewise to discover whether some Effects of the Air may not depend on some unheeded Qualities I made the following Experiments which I shall lay down when I shall have made some Tryals the Changes of Colour in Solutions of Copper by the Influence of the Air. EXPERIMENT I. Change of Colour in a Solution of Copper FILINGS of crude Copper being put into a Crystal Glass of a Conical Figure with as much Spirit of Salt as stood a Fingers breadth above the Filings we cover'd the Vessel with a Stopple exactly adapted to it upon a Solution of the Copper the Colour of the Liquor was a dark Brown but it soon lost that Colour and was clear again like common Water but when by taking out the Stopple the Liquor was again expos'd to the Air it first acquir'd a brown Colour upon the Top and that penetrating deeper into the Liquor by degrees it in a quarter of an hour was wholly tinged with a brown Colour again and so it successively laid down and re-acquir'd that Colour as it was stopp'd up or expos'd to the Air till at the last being kept up a Month it kept the brown Colour it had acquir'd in the Air unalter'd EXPERIMENT II. A Bottle of the same Liquor with the former and which was much clearer being expos'd to the open Air in half an hours time was not in the least alter'd but the Vessel being again clos'd up for two or three hours it acquir'd a faint Green and the Glass being again unstopp'd 24 hours the Green was deep enough but not very transparent EXPERIMENT III. ABout 3 Spoonful of the brown Tincture of Copper was shut up in a Receiver capable of holding ten times as much It retain'd it's Colour half a Year in Vacuo and then being expos'd to the Air it acquir'd a Green in about an hour without the Precipitation of any muddy Sediment EXPERIMENT IV. SOme of the aforemention'd Tincture being left a considerable time in a Window lost it's Colour and appear'd like common Water but towards the latter end of December being expos'd to the Air it acquir'd a faint and moderately transparent Green EXPERIMENT V. Filings of Copper and Spirit of Wine FILINGS of Copper and as much rectified Spirit of fermented Urine as rose an Inch above them being shut up in a Conical Glass with a mercurial Gage in some hours the Mercury in the seal'd Leg was depress'd EXPERIMENT VI. A Gage being shut up in a
to be slighted or suddenly laid aside since several Accidents may intervene in the Air on which those may depend As we know tho' Tides generally Ebb and Flow so as to answer the Theory given of them yet by fierce Winds and great Land-Floods the regular Course of them hath often been alter'd CHAP. XVIII A new Experiment and other Instances of the Efficacy of the Air 's Moisture The Efficacy of the Air 's Moisture THAT the Moisture of the Air hath had considerable Effects on Subjects far less tender and curiously contriv'd than Men's Bodies will appear from what follows and that the Moisture of the Air hath a considerable Influence and usually a bad one may well be argu'd from the Effects we have taken notice of on several Parts of Animals and that the Skins of Animals are sufficiently prepar'd to receive such Effluviums appears from what I have before observ'd viz. That Sheep's Leather being made use of for a Hygroscope plentifully imbib'd the Moisture of the Air and even Bladders which by Nature are made impervious to Urine are so dispos'd to imbibe the Moisture of the Air that the membranous Part put into a Pair of Scales and counterpois'd makes a good Hygroscope and not only these but Lute-strings which are made of the twisted Guts of Animals and even Bones the most solid Parts of Human Bodies will so far imbibe the Moisture of the Air as to swell considerably Nor are Animal Bodies alone capable of having their Pores penetrated by the Moisture of the Air but it insinuates it self into inanimate Bodies and swells the solid Parts of Wood and even Polish'd Marbles are observ'd to be so plentifully stock'd with moist Vapours as evidently to sweat nay even the Air it self is not without Vapours and moist Parts dispers'd through it in the Heat of Summer which will appear from the following Experiment Having fill'd a Bottle with Water and four Ounces of Sal Armon we counterpois'd it in a Pair of Scales and in an Hours time so many moist Particles in the Air were condens'd by this frigorifick Mixture that they first appear'd in the form of a Dew on the outside of the Glass and then ran down the sides of the Vessel till that Scale preponderated and weigh'd a Drachm more than the other But to proceed to Instances which shew the Force and Efficacy of moist Vapours when they penetrate solid Bodies It is no weak Argument of their Efficacy that we observe that by the powerful Insinuation of Moisture the Strings of Musical Instruments are swollen and broken nor is it in considerable that Doors and Door-Cases are so swollen in Rainy Weather as to open and shut with a great deal of uneasiness Marchasites burst by the Air 's Moisture Besides which Instances I have observ'd a Piece of Wood to encrease considerably in it's Weight in rainy Weather And I am told it is usual for musical Instruments to grow out of Tune not only the Wooden but the Metalline Pipes of Organs being apt to swell in wet Weather And not only by the help of Rain but the Moisture of the Air Marchasites have been swollen and burst asunder which I am apter to believe because I have observ'd Vitriolate Efflorescences upon the Surfaces of shining Marchasites caus'd by the Action of external Moisture on them and the Moisture of the Air hath so powerfully penetrated some Marchasitical Substances that they have burst asunder whereupon it appear'd that a greater Quantity of Vitriol was generated within their Substances than without To conclude what I have to say on this Subject I shall add the following Experiment to assist a Virtuoso to make an Estimate in known Measures of the mechanical Force of the Aerial Moisture I caus'd a Rope about 22 Yards long to be fasten'd at a convenient Height to an immoveable Body and then having fix'd a Pully to another stable Body about 18 Yards distant from the former the Rope lying upon the Pully was betwixt both almost in an horizontal Posture but to that End of the Rope which hung down from the Pully towards the Ground was fix'd a Weight of 50 Pound and to the upper Part of that an Index which being plac'd horizontally pointed to a Board which was divided into Inches and parts of Inches that we might discover the better the Ascent and Descent of it upon changes of Weather When the Weight had stretch'd the Rope as much as it could I observ'd that in one rainy Night the Weight was rais'd five Inches but the next Day proving a dry Day it was depress'd lower than before But a heavier Weight being made use of instead of the former June 4th in an hour and quarter the hundred Weight was rais'd ¼ of an Inch. The Sky being cloudy but without Rain June 6th In the Night which was cloudy it was rais'd about 3 Inches and an hour after that Observation was made it rose half an Inch more From whence it appears that the Force of the Air 's Moisture is considerable since the Rope that by it's Assistance rais'd the Weight was but about the third Part of an Inch Diameter being 3 10 and 4 decimal Parts of 1 10. CHAP XIX Of some unheeded Causes of the Insalubrity and Salubrity of the Air c. The Insalubrity and salubrity of the Air depends on subterraneal Vapours AMongst the several Causes on which the Salubrity and Insalubrity of the Air depend subterraneal Effluvia are in Effect most considerable which differ not only according to their respective Natures but according to Place and Time according to Place as they ascend from the superficial or deeper Parts of the Terraqueous Globe according to Time such as ascend daily and may be term'd ordinary Emissions or only at distant times the latter of which may be term'd periodical and sometimes fortuitous or irregular But notwithstanding the Vapours which rise from the Earth may be distinguish'd by these Distinctions yet since Nature offers her Phaenomena not so distinct but confusedly and together I shall sometimes consider the Terraqueous Steams in the more general Notion with reference to each of the Members of this Distinction But that I may deliver what I have to say more distinctly I shall lay it down in the following Propositions Proceed under the following Propositions having first observ'd that the Insalubrity of Marish and the Salubrity of Sandy Grounds may depend on some Effluvia which act not meerly or principally as they are Moist or Dry. PROPOSITION I. THE first Proposition is Prop. 1. That it seems probable that in divers places the Salubrity or Insalubrity of the Air considered in general may be in good part due to subterraneal Expirations especially to those I call'd ordinary Emissions Which may contribute to the preserving of Health either by promoting Respiration or by correcting noxious Particles in the Air and checking morbifick Ferments And indeed if we consider what a great variety of Bodies besides
grand cercle on trouvera qu' elle á en toute sa superficie Spherique 1649200 lieues quarrées C ' est à dire 103 095 000 000 000 toises quarr C est à dire 3711 420 000 000 000 pieds quarr Il's ensuit qu' un pied cube d'eau pese 72 livres Et parce qu' un prisme d'eau d'un pied quarre de base et de 31 pieds de haut pese 2232 livres Donc si la terre estoit couverte d'eau jusques à la hauteur de 31 pieds il y auroit autant de prismes d'eau de 31 Pieds de haut qu' elle a de Pieds quarrez en toute sa surface Ie scay bien que ce ne seroient pas des prismes mais des secteurs de Sphere et je neglige exprés cette Precision Et partant elle porteroit autant de 2232 livres d'eau qu' elle a de pieds quarrez en toute sa surface Done cette masse d'eau entiere peseroit 8283 889 440 000 000 000 livres Donc toute la masse entire de la Sphere de l'Air qui est au monde pese ce mesme poids de 8283. 889 440 000 000 livres C ' est à dire Huit Millions de Millions de Millions deux cent quarte vingt trois Mille huit cent quatre vingt neuf Millions de Millions quatre cent quarente Mille Millions de livres Mr. Pascal in his small Tract either Dela Pesanteur de l'Air or in that Del'Equilibre des liqueurs See Plate 7 Fig. 4. De caetero feci haud ita pridem experimentum ponderandi aeris quod pulchré successit nam sumptâ vitreâ lagenâ valde levi et ad lampadem sufflatâ ejus figurae qualem alibi excusam vides magnitudine parvae pilae quales habentur in sphaeristeriis non habente nisi minimam quandam aperturam per quam immittatur pilus in extremitate orificii sui B. ponderavi eam in lance valde exacta frigida pondus habuit 78 granorum cum dimidio Postea calefeci eam carbonibus impositam reposui in bilancem eo situ quo hic descriptum vides nimirum orificio in imum verso deprehendi eam vix habere pondus 78 granorum tum immergendo orificium in aquam refrigescere feci dum aer se condensat pro modo quo refrigescit lagena intravit tantundem aquae quantum aeris calor antea expulerat denique ponderans eam cum omni illa aqua deprehendi eam habere pondus 72 granorum dimidii plus quam antea unde concludo aerem qui per ignem expulsus erat se habere ad aquam quae in locum suum regressa erat uti ½ se habet ad 72 ½ aut uti se habet 1. ad 145. sed potui in eo errasse difficile quippè est in ea re omnino exactum essée Id saltem certò scio quòd pondus aeris hoc modo sit sensiblile prolixe hic deduxi processum meum ut si te eadem curiositas incessat possis id eodem modo perficere experimentum Vale. TITLE XVIII Of the Consistency of the Air it 's Rarity Density Fludity Subtily Of the Consistency of the Air c. A Thin but large Bladder having a third Part of the Air it was capable of containing remaining in it had it's Neck strongly tyed and at the other end a Weight was suspended of 14 Pound by a String which could not shrink ¼ of an Inch without raising the Weight from the ground But the Air in the Bladder was so far expanded by heat that the Weight was raised and would swing in the Air like a Pendulum The same Experiment being tryed with a 50 pound Weight before the expanded Air was able to raise the Weight the Bladder would burst To try whether the Corpuscles of the Air would penetrate into a Liquor exposed to the Ordinary pressure of the Atmosphere we poured a Urinous Spirit upon as much Filings of Copper as covered the bottom of a Cylindrical Vial so that the Spirit was the Breadth of 3 Fingers above the Filings which being done on that we poured so much Oyl of Almonds as covered the Spirit the Thickness of a Crown piece upon which the Vial being kept some days in a quiet place the Urinous Liquor did first acquire and then lose a blew Tincture When the blew was in a great Measure vanished the Bottle was kept unstopped a Minute and then stopped again in a short time the Urinous Spirit was tinged with blew which Colour in an hour extended it self all over the Liquor the Oyl upon the Top of it still remaining clear TITLE XIX Of the Heat and Coldness of the Air. TO shew that it is not without Reason that I Question what the Peripateticks teach about the Limits and Temperaments of the Air which they divide into three Regions I shall propose the following Particulars The Air at Morocco tho' excessive hot in the Day is Cold at Night as well as the Mountanous Parts thereabouts One who stayed a Year in Guinea tho' it is excessive hot told me that about 4 a Clock in the Morning he was ready to tremble with Cold. One told me that in Jamacia when he lay in his Hammock about 3 or 4 Foot from the Ground tho' he had much Cloths under him yet he perceived it Cold beneath and Hot above So that to shew that not only Liquors and Animal Bodies may be affected with the Summers heat but even Glass it self I shall intimate that Glass-stopples of Factitious Crystal being so fitted to Viols of the same tho' in Winter they would move about easily yet in the Summer they would not be pull'd out by the Assistance of a String till the Expansion of the Glass was taken off by being cool'd in Water I am apt to believe that several Effects which we are apt to attribute to the Heat of the Air putting the Parts of the Juices of our Bodies in Motion depend on some Effluvia rais'd by Heat from other Bodies and which swim in the Air. A large Piece of Amber being plac'd in the Summer in the Sun-Beams had its Parts put into such an Agitation as enabled it to emit Electrical Effluvia and to attract light Bodies which Power it would lose when remov'd out of the Sun-Beams again Mr. Nickson told me that near Hudson's Bay when they were a Leeward of certain floating Islands of Ice they were sensible of it by a new Access of Cold before they approach'd so near as to see them which was at 20 Miles distance He likewise told me that that Wind brought along with it a Foggy Air And that in that of Hudson's Bay where he winter'd the Rivers were not free from Ice from the latter End of October to the middle or end of May tho' the Latitude of Charlton Island most frequented by the English was of the same Latitude
shall alledge the following Experiment viz. That Experiments alledged against their Doctrine If a Bolt-head with a long Stem be made use of to try the Torrecellian Experiment with the space deserted by the Mercury in the Cavity of the Bolt-head and from whence the Mercury drove the Air continues void the Pendulous Cylinder remaining at 30 Inches without offering to ascend to prevent a Vacuum Nor will the Quick-silver rise ¼ of an Inch higher upon the application of cold Bodies outwardly tho' in a common Thermometer the same degree of Cold would make Water ascend several Inches To this I shall add another Argument taken from the consideration of sealed Weather-glasses see Plate 1. Fig. 3. in which it is observed See Plate 1. Fig. 3. That the Air instead of contracting upon an increase of Cold expands it self If it be said That the Water contracting the Air follows it to prevent a Vacuum it may be demanded Why since Nature causes the one to contract in common Glasses and the other in sealed ones to avoid a Vacuum she does not rather make the Air retain its natural extension than suffer it to be condensed and then put her self to double trouble in compelling the Water to ascend contrary to its nature But not to insist on these Arguments I shall rather urge that what is offered by them will not solve the Difficulty for whether the Water or Air be expanded into a large space since Glass is impervious to Air and Water I see not how a Vacuum interspersum and coacervatum can be avoided For if upon the expansion no other Body is added and penetrates the Glass to fill the space deserted by some Parts of the expanded Body there must remain Vacuities betwixt them Because it is impossible the same quantity of Matter should compleatly and adequately fill a greater space by being expanded the Parts of the Body being only able inadequately to fill it by receding from each other But were it allowed that upon the expansion of one of these Bodies and the condensation of the other a third Substance harboured in the space deserted by the one it may be questioned how such Matter should make its way out again Mr. Hobbes his Doctrine examined The second Opinion I shall take notice of is that of Mr. Hobbes which is to me partly precarious partly insufficient and scarce intelligible for tho' when he asserts That the coldness of Liquors depends on their being pressed with a constant Wind besides that he asserts it without Proof it will appear from an Experiment shortly to be alledged That Liquors sealed up in Glasses and suspended in Liquors not subject to freeze may be refrigerated tho' it appears not how they can be raked on by the Wind as his Hypothesis requires Secondly I see no necessity that the Cold should press upon the superficies of the Water in the Shank since by Cold it will be raised in a Weather-glassess kept in a still Place and void of any sensible Wind. Besides he ought to shew Why Air insensibly moved deserves to be styled Wind and how it is possible such a Wind should raise Water so many Inches by pressing upon it Nay further Water poured into a Bolt-head till it reaches into the Stem will subside when refrigerated and not rise And if the Ball of a Weather-glass be encompassed with a mixture of Ice or Snow and Salt the Water will readily ascend which how it will be explained by Mr. Hobbes's Hypothesis I do not see Thirdly Mr. Hobbes allowing not of a Vacuum I wonder he should tell us That by a bare Pressure the Water finding no other Place to recede into is forced to rise into the shank of the Weather-glass For since according to him the shank of the Weather-glass must be full before I see not how it should be able to receive the ascending Water except to use Mr. Hobbes's own words it can be fuller than full Besides it may be further alledged against Mr Hobbes his Doctrine that it gives us no account of the condensation of the Air by Cold in Weather-glasses in which the Water descends with Cold and rises with Heat Fourthly whereas Mr. Hobbes in explaining the depression of Water in Weather-glasses attributes it solely to it 's own Gravity it will easily appear that we must likewise have recourse to the spring of the included Air For if a Thermometer be placed in the Sun when the Water in the shank is but a little above the Surface of the Water without the Tube the rarified Air will depress the Surface of the Water in the Pipe below the other and sometimes so far that some of the rarified Air making it's way out of the Pipe as soon as the remaining Air is refrigerated again the Water will be able to rise up higher into the Tube than it did before A Modern Opinion examined The third and last Opinion I shall consider is one held by some modern Naturalists which ascribes the Ascent of the Water to the Pressure of the Air gravitating upon the Surface of that Water without the Pipe but supposes that the Air contained in it is contracted by Cold alone As for the first Part of this Hypothesis I readily Assent to it and the Author 's proposed but am apt to believe that the contraction of the included Air depends on the same Cause and that the spring of it being weakened by Cold it is condensed by the same Pressure of the Atmosphere the weight of the External Air over-powering the weakened Spring of the Internal In favour of this Opinion I shall add the following Experiments See Plate 1. Fig. 5. and First having filled a Vial capable of holding five or six Ounces half full See Plate 1. Fig. 5. and having inverted a Glass Tube into it about 10 Inches long much bigger than a Swan's Quill it being first sealed at one end and filled with Water the Orifice of the Vial was closed with Cement so that the External and Internal Air had no communication with each other It was placed in a Mixture of Snow and Salt till the Water in the Bottom of the Vial began to freeze yet notwithstanding so great a degree of refrigeration the Water in the Tube did not at all descend so that either the Air was not condensed by Cold or the Water descended not to prevent a Vacuum The Glass being left in this Posture in our absence the sealed end of the Pipe flew off being beaten out by the Intumescence of the freezing Water Having fixed another Pipe as the former which was some Inches longer and drawn very slender at the sealed end that it might easily be broken this was set to freeze as the other yet the Water descended not but as soon as the top of the Glass-Tube was broke off the external Air pressing upon the Water and by the intercourse of that upon the Air the Water in the Tube subsided 8 or 10 Inches but rose
again when the internal Air was rarified within half an Inch of the top and then the Apex being sealed up it was placed in Snow and Salt yet the Air in the top had it's Spring so weakened by refrigeration that it was not able to depress the Water tho' as soon as the Apex was broke off it subsided several Inches the external Air pressing upon it The Experiment being a third time reiterated with 3 ½ of Air in the Pipe when the Water in the Vial was in some measure froze it was able to expand it self a little But when the Apex was broke off the External Air depressed the Surface of the Water two Inches but being removed into a warm Room it ascended above an Inch higher than the uppermost Level Having put so much Water into a Vessel See Plate 1. Fig. 6. Such as Plate 1. Fig. 6. Delineates as was able to fill almost the whole Tube we caused a Mixture of Snow and Salt to be placed about the Ball of it yet we perceived not the Water in the least to rise but if at all it might well be ascribed to the the Intumescence of some airy Parts lodged in the Pores of the Water But the Apex of the Tube being broke off under Water the External Air forced the Water several Inches up into the Cavity of the Pipe Another Experiment we made with the following Vessel See Plate 1. Fig. 7 the Stem of this being no thicker than a Raven's Quill tho' several Inches long See Plate 1. Fig. 7. and the Ball being about as big as a Nutmeg we dropped a few drops of Water into the Stem which being suspended there betrayed very slight changes in the Rarefaction or Condensation of the internal Air. Watching therefore when the Air within had raised the Bubble up to the top of the Stem we immediately sealed it up and observed That tho' the sealed Glass was placed in a Mixture of Snow and Salt the Bubble did not in the least subside But if the Apex of the Stem was broke off the Bubble of Water would be sometimes depressed so low as to fall into the Ball of the Weather-glass And what was further remarkable was That when the Liquor was descending if the end of the Tube was sealed up the Water would immediately stop at the place it rested at when the Pressure of the Atmosphere was taken off Where it would continue till the Stem was broke open again and then the Water would be further depressed as the weight of the Atmosphere was able to over-power the Resistance made by the internal Air. Having made use of such a Vessel as Fig. 7. Plate 1. represents and conveyed a pretty Quantity of Water into both the Legs See Plate 1. Fig. 7. we sealed up the end of the bent Stem leaving so much Air above it as we thought convenient Which being done we placed the Ball of it in a frame in which the Tube hanging down we could cover the round Ball with Snow and Salt Upon which the Air in the Stem was able to expand it self so far that the Water in the longer Leg was raised the length of a Barly-corn higher than before and depressed as much in the other But when the end of the Stem was broke open the Water was raised 2 ¼ Inches in the longer Leg and depressed so low in the shorter that several Bubbles rose into the Cavity of the Ball. In which Experiment it cannot be supposed That the weight of the Water in the shorter Leg could be able to raise the Water in the other except by Virtue of it's Spring which being but small answerable to the Quantity of of it it cannot be expected that it should have any considerable Effect upon the Air in the other Leg tho' it's Spring were in some measure weakened by Cold. An Explication of the Figures in the first Plate Fig. 1. p. 12. A. The Ball or Egg. B C. The Stem D. The little Aqueous Cylinder Fig. 2. The open Weather-glass mentioned p. 16 22. Fig. 3. The Sealed Weather-glass or Thermoscope mentioned p. 16. Fig. 4. The Barometer or Mercurial Standard placed in a Frame B B. mentioned p. 17. Fig. 5. An Instrument mentioned p. 34. A. The Vial. B C. The Pipe cemented into the neck of the Vial open at C and sealed at B. Fig. 6. p. 35. A. The Bolt-head B. The small Stem B C. The Cylinder of Water enclosed Fig. 7. p. 36. CHAP. V. The Experimental History of Cold begun TITLE I. Experiments concerning Bodies capable of Freezing others BEfore we proceed to the natural History of Cold it perhaps may be necessary to consider what Bodies are capable of retaining such Qualities and what are not but that being a consideration not so necessary to our present purpose which is only to set down what Observations we have made in Bodies subject to be froze I shall only in short take notice That most Bodies except fire are susceptible of actual Cold and it is a Question whether even that be not rather a state of Matter in such a peculiar motion than a distinct and particular species of Natural Bodies since even Gun-powder and Spirit of Wine before they are set on fire by some other Body are actually Cold. But to proceed to what Observations relate to our Title Experiments of Bodies capable of freezing others 1. Bodies cold enough to freeze others are very few here in England Snow and Salt mixed being most remarkable which cool the Liquor contained in those Vessels which are closed up in such mixtures 2. Snow alone would not freeze Water as a Mixture of it and Salt does and tho' Water poured betwixt the Interstices of Snow or Ice freezes yet there is a great disparity betwixt exposing it to the Air and keeping it up in Vessels and tho' it is froze when covered with Snow in a Bottle all night yet that may proceed from the Coldness of the Air as well as the influence of the Snow 3. If Nitre Allum Vitriol Sal-Armoniack or Sugar be mixed in due Proportion with Snow they will enable it to freeze tho' not so intensely as common Salt 4. Spirit of Salt being shaken together with Snow in the Vials they caused a Dew which was gathered on the outside the Glass to be froze tho' the Mixture within was not and Oyl of Vitriol mixed with Snow in a thin Vial had the same Effect only more intensely 5. But not only these Acid Spirits had these Effects on the moisture of the Air condensed on the outside the Glasses but likewise Spirit of Nitre Spirit of Vinegar and Spirit of Sugar the former of these three being very powerfull tho' the latter were not so strongly frigorifick 6. Spirit of Urine mixed with Snow in a Vial froze the External moisture weakly but Spirit of Sal-Armoniack drawn from Quick-lime did it powerfully 7. Spirit of Urine and Oyl of Vitriol poured upon Snow froze moderately 8. Sal Gem with a
be expected that I should say something of the expansion of aqueous Humours and also of the degrees of the Condensation of Water and watry Humours But as for the first I doubt whether there be any expansion except of the watry Parts of them but if it may be of any use to direct us in making an estimate of the different Proportions they contain of Phlegm or other more spirituous Ingredients I would not discourage those whose Curiosity shall prevail with them to prosecute such Experiments And as for the condensation of Water by Cold tho' perhaps in hotter Climates it may be considerable yet I have not found it very sensible in all the Tryals I have made here Particulars referrable to the X Title 1. A Bolt-head whose Stem was 17 Inches above the Water being seal'd up and placed about 9 hours in a frigorifick Mixture the Water ascended 15 Inches ½ and afterwards ½ of ¼ of an Inch being neglected for an hour the seal'd end was blown off and the Bottom of the Glass broke in peices 2. Water freed from Air in our Receiver and seal'd up in a round Bolt-head in which the seal'd Apex was about 5 Inches above the Water afforded an Ice very free from Bubbles and having stood in a frigorifick Mixture about 2 hours it was raised 4 Inches and ⅜ The Conical Apex being broke with a noise and a seeming smoak we found Water unfroze under the Pipe and that the Air was condensed to a 20th Part of the space it possess'd before 3. The Globous part of a Glass-Egg 3 Inches Diameter was filled with Water and froze from the Bottom upwards after it had been Hermetically seal'd it rose 8 ½ Inches the length of the whole Stem being 10 Inches and a half But being a second time sealed up and froze with Ice in it it wrought not 4 Inches above its first station TITLE XI Experiments touching the Expansive force of Freezing Water Of the Expansive force of freezing Water 1. TO help us to make an estimate of the Expansive force of freezing Water We filled a Pewter-Bottle full of Water it being large enough to hold half a Pint In a frosty Night it crack'd the Bottle and the like success we had with frozen Water in a Pewter-box such as they keep Salves in And we found the Expansive force of Frost so strong That it burst a Bottle the thinnest part of which was 1 14 of an Inch and the thickest ◠86 It also broke an Earthen Bottle of Flanders-Metal the thinnest part of which was as thick as the strongest of the other 2. To make a more Determinate Estimate of the Expansive force of Frost we made use of a Brass-Cylinder to which we adapted a Plugg which falling a little way within the Cylinder rested upon the edges of it The length of the Cylinder was about 5 Inches and the breadth 1 ¾ The Experiment made in this Instrument was by filling it full of Water and then laying 56 pound weight upon the top of it And tho' it was a hard matter to cause the Mixture to freeze yet we were at the last able to do it and then we observ'd That the Expanded Ice lifted up the one side of the lower so high that the weight fell down but at another time it succeeded so well that the lower was uniformly raised the breadth of a Barly-corn Upon a gentle thaw the Superficial Parts being taken out the Ice appear'd full of Bubbles And in the Morning when it began to melt before the fire the weight being taken off several drops of Water dilated into numerous Bubbles issu'd out like a kind of Froth 3. Another way we took to measure the Expansive force of Cold was by driving a Wooden Plugg so fast into the end of the Brass-Cylinder That half a hundred weight and a quarter of a hundred might be suspended at it without pulling it out yet in two frosty Nights the expanding Water was able to raise it a quarter of an Inch. 4. There is one thing in these Tryals deserves to be taken notice of viz. That the Expansion of Air by Heat being sufficient to make it possess 70 times it 's former space yet the utmost degree Water by Glaciation will extend it self to is a ninth So that the former by Expansion acquires 60 times the space that Water does taking Mersennus his account of the Air 's Expansion to be true which comes short of what we have shewn it capable of being Expanded to 5. We endeavoured likewise to measure the force of Waters Expansion when congeal'd by enclosing it in a Iron-Globe whose Diameter was about 3 Inches and which had a Female Screw continued from it's Cavity to the out side to which was adapted Male a screw so close That we were forc'd to use a Vice to screw it in but our hopes were frustrated the Compactness of the metal as we suppos'd keeping the Liquor from freezing 6. It would be worth while to consider the cause of so powerful an Expansion since neither the Cartesian nor the Epicurean Doctrine are able to explain this Phaenomenon For the first only accounting Cold to be a Privation of Heat and depending upon the recess of those subtil Parts which he supposes Expansion to depend on according to him they should rather continue an Inactive Mass than retain such a Springyness And since according to Epicurus Expansion depends on an Insinuation of frigorifick Atoms It may well be question'd how parts of Matter which have such a free entrance into such Vessels should not rather find as easie a Passage out again as in without breaking them Besides in several Oyls and other Liquors which must receive those frigorifick Atoms we perceive not the least Expansion at all but they are rather condensed 7. How great the Expansive Force of congeal'd Wine Milk Urine and other Liquors is I shall leave it to others to enquire and shall only take notice That undoubtedly it is considerable since in the Dutch Voyage to Nova Zembla it was observ'd That even Iron-hoops were burst by the forcible Expansion of included Liquors And in Russia it hath been observ'd that tho' Beer and Wine would not burst Wooden Vessels yet Glass and Stone-Vessels would be often broken Particulars referrable to the XI Title 1. We took a Brass-Cylinder 2 Inches Diameter and having put a Bladder with Water ty'd close up in it so that upon Expansion it could not get out into the Cavity of the Cylinder we put a Plugg into it upon which were placed several weights which amounted to 120 Pounds yet the frigorifick Mixture being apply'd to the Cylinder the Water expanded rais'd the Plugg near half an Inch and the Experiment being repeated again the next Day the freezing Water raised 130 Pound-weight 2. An Iron-Barrel 14 Inches long and ⅜ of an Inch in Diameter whose sides were at the thickest Part 1 16 and at the least ◠16 was filled with Water and being buried in a Mixture
of Ice and Salt 2 hours it made an oblique crack in the Barrel Six Inches long and the Ice being taken out seemed full of Bubbles but very small ones and the like success we had with another Barrel of a Gun whose Muzzle and Touch-hole were stopped up with Metal nor had we less success when we buried a Pewter Bottle in a frigorifick Mixture both the Barrel of the Gun and the Bottle being burst in a quarter of an hour TITLE XII Experiments concerning a new way of Estimating the Expansive force of Congelation and of highly compressing Air without Engines A new way of Estimating the Expanâ—…e force of Congelation HOW far we were able to compress the Air by the Incumbent weight of a Cylinder of Mercury we have else where shewn but to reduce it to a greater degree of Condensation I made the following Experiments 1. Having filled a Glass-Egg with Water till it wrought about an Inch into the Stem we placed it in a Mixture of Snow and Salt and in a few hours the Surface of the Liquor was raised about 7 Inches and the Apex of the Stem being sealed up by a fresh application of Snow and Salt it was raised 8 Inches higher So that the Air being compressed into the space of an Inch possessed about nine Parts of ten of what it did before Whereupon the Stem being inverted and the seal'd end opened the Air which when the Stem was inverted rose up to the Ice and separated the unfrozen Water in the Stem from it powerfully expanding it self forced out about ten Inches of Water with Violence and Noise besides a great number of Bubbles ascended from the Bottom of the Glass to the Top. N. B. when the Air was compressed beyond seven Inches we several times observ'd That the Glass just above the Water on the inside was full of little drops of Dew which when the Apex was broke off Disappeared 2. A Vial whose neck was drawn out into a slender Pipe being filled till it wrought an Inch within the Pipe in a little time by the Expansion of the Water the Air being too much compressed the head of the Pipe flew off and the same happened to a round white Glass whose Stem filled with Air was about 3 Inches Nor was the success otherwise when we repeated the Experiment in a large single Vial whose Stem was four Inches long and it's Basis an Inch broad 3. An Oval Glass about the size of a Turkeys-egg with a neck almost Cylindrical was filled with Water within four Inches and a half and then a piece of Paper being pasted upon the Stem divided into half Inches and quarters and the Apex being sealed up by a moderate Heat the Surface of the Water was raised considerably but the Oval Part of the Glass being covered with a Mixture of Ice and Snow the Air was compressed into a 17th Part of the space it possessed before And the Ball of the Glass bursting afterwards with a considerable Noise the Ice appeared full of Bubbles which rendred it white and Opacous In another Glass whose Ball was larger in proportion to the Stem the Air was compressed into a 19th Part of it's former space before the Glass flew in pieces 3. And this way of trying how far the Air might be compressed and Water expanded by Cold we thought least Exceptionable because the Pores of Glass are more impervious to Air and Water than some Metalline Vessels for having broken open the Apex of the Stem of one of our Glass-Eggs we found that tho' the Water was but a little expanded yet not finding a way out at the Pores of the Glass the Water rose up a quarter of an Inch. TITLE XIII Experiments and Observations concerning the Sphere of Activity of Cold. Of the Sphere of Activity of Cold. IN estimating the Sphere of Activity of Cold we are not only to consider the Degree of it in the cold Body but also the Medium through which it is to pass and the Consistence and Texture of it as likewise the Instruments employ'd to receive or acquaint us with the Action of Cold Since from what hath been before laid down it appears That Weather-glasses give us a more nice account of the Degrees of it and that our Sensories may mis-inform us upon the account of their various Predispositions Besides the Sphere of Activity may be vary'd by the Bulk of the cold Body 1. But to consider the Sphere of Activity of small Pieces of Ice we have found it very small in comparison of the Atmospheres of odorous Bodies insomuch that I am perswaded we can have no sense of Cold without the immediate Contact of a cold Body since Ice approaching our Sensory or a Weather-glass affects neither tho' held as near as possibly they may without touching And the like hath been observ'd at Sea where in foggy Nights the Seamen have not been able to discern neighbouring Mountains of Ice Tho' by a Merchant who made the Observation in Greenland I am told That he perceived a manifest access of Cold upon the approach of a floating piece of Ice 2. And I am told that in Ispahan the Capital City of Persia the Ice being never much more than a Finger thick they usually pour Water upon it which as it runs over the Ice is in part froze by which means they thicken the Ice and preserve it in proper Conservatories This Experiment having been tryed in England by pumping of Water upon Flakes of Ice I found That the Pump-water being warmer than the Ice thawed it instead of increasing the Thickness of it And tho' here in England Water poured upon Snow promotes its Dissolution yet in Russia and Muscovy I am told That Water thrown upon Snow freezes it which they therefore make use of to incrustate several Bodies with Ice yet one thing is to be observ'd that generally at the same time the sharpness of the Air is so violent as to incrustate several Bodies with Ice when only Water is made use of so that in trying such Experiments we are to consider the Temperature of the Air at the same time which hath a great Influence in promoting or varying the Effects of such Tryals 3. How deep Frost penetrates into Water and Earth will be a very hard thing to determine since Earth especially may be more or less disposed to freeze according to the several Degrâ—es of Cold and its Duration the Texâ—â—â—… of the Earth and the Nature of the Juices dâ—â—â—…ed through it or subterraneal Steams Whence large Tracts of Land that lye over some Mines are always free from Snow good quantities of Lime-stone being near the Surface of the Earth 4. But tho' it be so difficult to know to what Depth Frost will reach yet that we may contribute as much as we can to the general History of Cold we shall add the following Notes After four Nights hard Frost the Ground in the Orchard was froze about 3 Inches deep and in the
or Rarefaction of Air increases not the positive Levity of Air we suspended a Bladder half full of Air with a Counterpoise at a ballance in our Receiver and tho' when the Air was exhausted the Bladder was sufficiently distended yet it seemed to retain the same weight whether dilated or contracted CHAP. III. New Experiments concerning an effect of the varying weight of the Atmosphere upon some Bodies in the Water Communicated in the Transactions of Feb. 24.1672 3. Of the Effects of the differing weight of the Atmosphere on Bodies under Water COnsidering that the Pores of most Liquors are plentifully stocked with Aery Particles and that upon that account the Atmosphere may according to its several degrees of weight have considerable Effects on them I caused three small Glass-Bubbles with slender Stems to be blown which were so equally poised in Water by their weight that a little thing would make them emerge or sink And I observ'd that these being put into Water contained in a wide-mouth'd Glass sometimes they would emerge and sometimes subside and sometimes emerge again as the Atmosphere varyed in weight or degrees of Heat and Cold. And it was easie to observe that when the Heat of the Air raised one of these Bubbles the heat of the Sun-Beams would so rarisie the Water included in them as to cause some of it to get out upon which the Bubbles emerged but when those Beams were intercepted the Water being condensed and getting into the Bubble again it would subside But when their subsiding depended on the weight of the Atmosphere if the Mercury in the Baroscope stood high the Heat of the Sun would not raise the Bubbles N. B. 1. That the Bubbles not being all equally poised sometimes one and sometimes two would rise as the Air was heavier or lighter and consequently capable of affecting the lightest only or all 2. The Success did not always answer for when the subsiding depended on some occult cause they would continue there as if some airy Parts had insinuated themselves into the Water 3. The fittest time for these Experiments and in which they best succeed is in the Spring the Air being more subject to vary in its Weight as well as other things CHAP. IV. New Experiments about the differing Pressure of heavy Solids and Fluids Of the different Pressure of Solids and Fluids ONE great reason why some Learned Men believe that the Air hath no such a considerable Pressure on subjacent Bodies as we teach is because they think it would be too heavy for Animal Bodies to live or move under it but since we have positive proof of it we may as well doubt whether the Load-stone be endewed with an attracting and other Virtues because we cannot understand how they are perform'd Besides Men being born under such a Pressure their Bodies seem not only accustom'd to it but proportionably strong But could we suppose a Man born somewhere without the incumbent weight of an Atmosphere doubtless such Bodies would not be so able as ours to resist its Pressure But it is urged by some that were there such a Pressure of the Atmosphere it would cause Pain but to this it may likewise be answered that our Bodies being from the Birth accustomed to it we only feel Pain upon some new unaccustomed and additional Pressure so when we are accustomed to wear heavy Cloaths we are not sensible of their weight nor are we sensible of the Heat of the Blood in our Heart because it 's habitual to those Parts whereas if our finger be put into the Heart of a newly dissected Animal we shall find it sensibly hot But further from what I have elsewhere laid down it appears that a Cubick Inch of Air will be able to resist the weight of the whole incumbent Atmosphere and that a little quantity of Air resists a further compression as well as a greater and I have likewise shewn that the Pores of the Parts of Animals whether fluid or consistent are plentifully stocked with numerous Aerial Bubbles which cause those Bodies to swell or expand in our exhausted Receiver And as for those membranous and fibrous Parts which are not altogether so porous they are of so strong and firm a Texture as to resist external Pressure upon that account Besides there is a great deal of difference betwixt the partial Pressure of a solid Body and the Pressure of an Ambient Fluid which presses uniformly and is resisted either by the solidity of the Parts or the Spring of those Airy Particles contained within their Pores And that the uniformness of the Pressure makes it less sensible is evident since it hath been observed that tho' the Atmosphere is so much lighter upon the tops of some high Mountains as not to elevate Mercury so high in a Baroscope by three Inches as at the bottom yet those that have been upon those Mountains tell us that they perceived no considerable difference in the Pressure of the Atmosphere above and below nor are Miners sensible of any great weight upon them tho' in deep Mines in Mountainous Countrys nor are Divers sensible of any Pressure when under Water but that Air weighs in Air and that Water weighs in Water I have elsewhere made it evident yet I don't think that a Diver is violently depressed by the weight of the incumbent Water since from what we have elsewhere delivered it appears that if a Man's Body were of an equal specifick Gravity with the Water the subjacent Water would sustain him but his Body being heavier than an equal bulk of Water the Surplusage of weight depresses it for which Reason in some Sea-Water which is near of the same specifick Gravity with their Bodies Divers find it very difficult to dive However it is not a little strange that at so great a depth as one hundred fathom Divers should not perceive a sensible Pressure especially upon their Thorax and Abdomen But I am apt to believe that the inadvertency of some of them rather than any thing else makes them not take notice of it or else the haste which they rise and sink in since I have been told by some that they have perceived a manifest Pressure when they sunk leisurely And I was likewise told by another that when he descended a great depth under Water the Blood was squeezed out of his Nose and Eyes and another who dived in a Leathern-case told me that it was so much pressed against his Thorax and Belly that he was forced suddenly to come up again But since these Relations are not altogether to be relied on I shall endeavour to give a Reason why the Pressure is no more sensible which I take to be the strong Texture of a Human Body and the uniformity of the Pressure As to the first to what I have said of the Resistance made by our Bodies to external Pressure I shall only add that a Bladder being tyed upon the end of a Cylinder about an Inch in Diameter
when the Air was exhausted the incumbent Pressure of the Atmosphere was not able to break it tho' when a Man's hand was placed there he was not able to raise it till some of the Air was let in again the Pressure which held his hand down being equivalent to a Cylinder of Water thirty foot high But to shew the effects of an uniform Pressure of Liquids upon Solids contained in them I shall subjoyn the following Tryals EXPERIMENT I II and III. Having placed an Egg betwixt two Bladders half blown in a Brass Cylinder and cautiously put a Plug upon them with as much weight upon it as amounted to thirty pound I placed them all in a Receiver and when the Air was exhausted tho' the expanding Bladders must needs press equally against the Egg and the Plug yet the incumbent weight was raised and the Egg when taken out as whole as before the weight it sustained in the Cylinder being not quite so much as the weight of the Atmosphere But tho' the Egg was able to sustain so much weight when pressed upon uniformly yet Weights being successively laid upon the same Egg exposed to the open Air four Pound weight crushed it in pieces And by further Tryals we found that an Egg-shell which had all the Yelk and White taken out as also a thin Glass Bubble being placed betwixt two Bladders as in the first Experiment neither of them was in the least cracked EXPERIMENT IV. To shew that what we have taught of the Nature of Fluids will hold in Water as well as Air if the Pressure be uniform we enclosed an Egg in a Bladder almost full of Water and putting it into the Brass Cylinder we heaped upon the Plug as many Weights as amounted to seventy five pound yet the Egg being taken out was as found as when first put in In which Instance it cannot be pretended that the Egg bore no weight by those that allow not Water to gravitate in Water since there was a considerable Pressure made by Metalline Weights which every body allows to weigh in Water From this Experiment and the other before mention'd of an Egg being broke by a partial Pressure it appears that the Strength of the Texture of a Humane Body together with the Uniformity of the Pressure of ambient Water may be the reasons why Divers feel no greater Inconveniency under Water for tho' their Thorax may be a little more compressed than other Parts yet that Part being naturally dilated and contracted a little Pressure may make no sensible Alteration But I have been told by a Diver that at a consicerable Depth he perceived a painful Pressure upon the Drums of his Ears 'till he contriv'd a way to guard them from that Inconveniency the reason of which Phaenomenon seemed to be no other than that in that Part there was not an equal internal Pressure to resist and counterballance the external Pressure of the Water CHAP. V. An Invention for estimating the Weight of Water in Water with ordinary Ballances or Weights Communicated in the Pub. Transact of Aug. 16. 1669. A Bubble about the bigness of a Pullet's Egg with a long Stem turned upo at the end was heated and when the Air was most of it expelled sealed up and then being by a convenient weight of Lead immersed under Water it was suspended at the end of a Ballance and counterpoised and then the Apex of the Stem being broke off with a Forceps so much Water got into the Cavity of the Bubble as required four drachms and thirty eight grains to reduce the Ballance to an Aequilibrium Which being done we drove out the Water by the help of a Flame of a Candle into another Glass which was counterposed and we found that it weighed four drachms and thirty grains which together with what was evaporated and lost and the weight of the Apex amounted to the weight first mention'd So that from hence it appears that Water weights as much in Water as it does in the open Air which according to the best Computation we could make succeeded a second time in a larger Bubble As for the Objections which Mr. George Sinclair hath made to this Experiment since it is the Opinion of our Author that he only differs from him in Expressions I shall wave what he there says as not at all requisite in this Place and shall only add what our Author hath said to explain what he means by Water weighing in Water viz. That it gravitates or weighs in as much as it tends downwards upon the account of its specifick Weight tho' it does not preponderate that is the Parcel of Water weighed hath but an equal Tendency downwards with the Ambient Water but upon an additional Weight it preponderates as much as the additional weight increases its Tendency towards the Center CHAP. VI. Hydrostatical Paradoxes made out by new Experiments BEfore I procced to the Hydrostatical Paradoxes I shall briefly intimate that tho' I can readily assent to the Hydrostatical Conclusions laid down in Monsieur Paschall's Discourse yet as for the Experiments he makes use of to prove them by I must own I am not satisfy'd with them since he makes use of such as require that a Man should sit under Water fifteen or twenty Foot with the end of a Tube leaning upon his Thigh But he neither acquaints us how a Man shall be able to continue there or how he shall discern the alterations in the Mercury or other Bodies at the bottom Besides such Experiments as he proposes require Tubes twenty foot long and Vessels as many foot deep which are hard to be got in England nor is it possible to obtain from a Tradesman Brass Cylinders or Pluggs made with so much Mathematical Exactness as he proposes Having therefore contriv'd a more easy way to demonstrate the Truths contain'd in the foregoing Paradoxes before I proceed to examine them I shall premise a word or two by way of Postulatum or a Lemma which consists of three Parts The first of which is That if a Pipe open at both ends and held perpendicular to the Horizon have the lower of them under Water there passes an imaginary Plain which touching the Orifice of the Pipe is parallel to the Horizon and likewise as to sense to the upper Surface of the Water To which it will be consonant secondly that as long as the Surface of the Water is even the Water incumbent on this Plain will equally press on all the parts of it But thirdly if there be a greater Pressure on one part of this Plain than another as when a Stone presses upon it the Water which lyes under that Stone will be displaced as the Stone subsides successively 'till it come to the Bottom But on the contrary if there be less Pressure on one part of that Plain than on another the Liquor will be raised on that part so high 'till the Liquor on that part of the Plain gravitates equally as the Water
incumbent on the other parts of it which will appear from the following Experiments And first If a Cylindrical Pipe open at both ends be held in a perpendicular Posture and the lower end be immersed three Inches in Water the Liquid within the Tube having a free Communication will be of an equal height with the external Water and in thin Tubes a little higher But if Oyl be gradually poured upon the Water without the Pipe the superficial Plain will have a greater Pressure upon it without than within and consequently the Water under the Tube finding not so great a Pressure within the Pipe as without it gradually rises 'till the external and internal Pressure upon the imaginary Plain be equal But since this will be further evident from what is contain'd in the following Paradoxes I shall proceed to them as soon as I have laid down the following Experiments to shew Air is not a Body devoid of Weight as some Peripateticks suppose The first is that a Glass Bubble being blown whose Capacity was short of two cubical Inches it was instantly hermetically sealed whilst hot and when it was cool being placed in a nice pair of Scales and then the Apex of the Stem being broke off the Air rushing in with a noise caused the Bubble to preponderate half a Grain tho' by breaking of the Stem under Water it appear'd that the rarify'd Air remaining in the sealed Glass possess'd one fourth of its Capacity Another time the same Experiment being tryed the Air contain'd seem'd to weigh near three quarters of a Grain and the Capacity of the Receiver being filled with common Water it weighed 905 Grains So that allowing the Air contain'd to take up one fourth and that the weight of the remaining Part was ¼ probably the weight of the whole was about a Grain and consequently the Water weighed little more than nine hundred times as much as an equal Bulk of Air. PARADOX I. paradox 1 That in Water and other Fluids the lower Parts are pressed by the upper If in a Glass of Water See Plate 2. Fig. 1. A B C D see Plate the second Fig. the first a Cylindrical Tube be immersed which contains Oyl of Turpentine and that Oyl be suspended there by keeping the upper Orifice close after it hath been suck'd up to a convenient height 'till the Pipe is depress'd to a convenient Depth in the Water if the lower end of the Pipe B Q be immersed 'till it reaches to the imaginary Surface G H and the Oyl X Q presses no more upon that imaginary Surface than the Water without the Tube then the Oyl will be suspended there and not be able to depress the Surface of the Water below it but if the Surface of the Oyl in the Tube be much above the Water and it presses more upon the imaginary Surface G H than the Water without then it will make its way through that Surface 'till the Oyl within and the Water without are brought to an Aequilibrium again so that they both equally press upon the Surface G H and the like will happen if the Tube be raised to the Surface D S and gradually on to the Surface L M for as the Pressure of the external Water grows less and less as the imaginary Surface is nearer the top of the Glass so the Oyl in the Tube growing preponderant falls out at the lower end of the Tube 'till the Tube T V being almost raised to the Surface L M but a little Water pressing upon that Surface the Oyl is almost wholly fallen out of the Cylindrical Cavity of it But if instead of raising the Pipe P Q it be depressed to the Position N O the Water incumbent on the Surface E F on the outside the Pipe being more powerful than the Cylinder or Oyl W AE which is only aequiponderant to a Cylinder of Water leaning on the Surface G H the Oyl must be buoyed up by the Pressure of the external Water and the Space O AE filled with Water so that the Oyl betwixt W AE and AE O being both aequiponderant to a Cylinder of Water they may equally press upon the Surface E F with the Water on the outside And agreeable to what hath been said it is that the Cylinder of Oyl X Q will be something above the Surface L M when the Tube is only immersed to the Surface Q. Since Oyl of Turpentine being specifically lighter than Water the Cylinder must be longer to press upon the Surface G H equally with a Cylinder of Water no longer than from the Surface L M to G H. And if a heavier Liquor than Water were made use of the Surface X must be more above L M than in Water otherwise it would not press equally upon the subjacent Surface From whence appears the Truth of the Proposition for if the Oyl be kept suspended at a different Height as the external Water is deeper to countervail it and if as it is raised from G H to I K the Oyl in the bottom of the Pipe is pressed out it must needs follow that it is pressed down by the weight of the incumbent Oyl since then the surface of the Water I K being not equally pressed upon from without as by the Oyl it is able to break that Surface and make its way out But before I proceed to the following Propositions I shall subjoin the following Advertisements First What we say of the Pressure of Fluids upon one another is to be attributed to heavy Fluids in general except some reason appears for a particular exception in some Places Secondly That in slender Pipes the Surface of the Liquor within is generally above the Surface of the external Thirdly Small Pipes are the fittest for these Experiments because in larger the emerging Oyl passing through the Water obscures the Light of what is design'd to be visible Fourthly We make use of Oyl of Turpentine rather than any other Liquor because clear and colourless and not apt to stain ones Cloaths and as for the offensive Smell that may be corrected with Oyl of Rhodium or any other odoriferous Oyl tho' any other Liquor may be made use of that will not mix with Water Fifthly Oyl of Turpentine may be tinged with Copper to render the Phaenomena within more visible for which reason we often employ a Decoction of Brasil instead of clear Water or of Log-wood or red Ink it self Sixthly the Figure of the Glasses may be what you please but the Pipes must be broader or longer as occasion requires Seventhly The Pipes are to be filled by sucking up the Air to a convenient Height and then stopping the Orifice above with ones Finger but if it be too high the Experimenter may let it out as he pleases by admitting a convenient quantity of Air in at the Top by gradually removing his Finger Lastly In such Experiments as require a considerable disparity betwixt the two mingled Liquors we may make use of Oyl of Tartar per
The weight of the Ball of Crystal we employed was to its bulk of Water as 2 57 100 to 1 and the weight of the Prism as 2 66 100 to 1. And this method of weighing Amber in different Liquors may not only acquaint us with their specifick Gravities but also from thence we may learn to know which are most Spirituous For tho' a piece of Amber weighed but 6 ¾ grains in Water yet in common red French Wine it weighed 8 ½ in Nants Brandy 17 ⅛ and in rectifyed Spirit of Wine 34 ⅛ This Hydrostatical method of estimating may likewise contribute to discover the strength of Acid Liquors those that are strongest causing the solid to weigh less as they are stronger the greater decrement of weight proceeding from the greater proportion it contains of Salts that are not Volatile It may likewise save the wasting of several Liquors as Spirit of Wine or Brandy in trying their goodness And further it may be imployed in estimating the intensive weight of Wine Beer Ale Mead Cyder c. and distinguish their goodness without consuming them But Amber will not be heavy enough to distinguish the strength of Oyl of Tartar per deliquium and such heavy Bodies since they are too heavy for it to subside in Besides the afore-mentioned there may be another use made of our Hydrostatical solid viz. To shew when Menstruums are of a convenient strength For that there is a peculiar degree of Spirituousness requisite in some Solvents is evident since if Aqua Fortis be too strong it will not be able to dissolve Silver no more than if it be too weak till it is diluted by an addition of Water and it is much more fit to dissolve filings of crude Lead when more dilute So rectifyed Spirit of Wine is not always the most proper Menstruum for gummy Bodies since it dissolves only the purest Resin and leaves the Mucilaginous Parts behind which may be as good in Medicine as the other and further we see that Gum Arabick and Tragacanth are not so easily dissolved in good Spirit of Wine as in weak Liquors and the like may be observed in dissolving Myrrh To what hath been said on this occasion there is one thing to be added that when this Expedient is made use of in Oyl of Vitriol or Tartar per deliquium it is necessary to put something into the Scale to compensate the lightness of the Horse-hairs since in such Experiments the specifick Gravity of the Liquors exceed the Gravity of the Hairs and consequently they will be apt to buoy up the Body immersed and misinform us in its true specifick weight To the afore-mentioned ways of Hydrostatically estimating Liquors we may add the following And first it may be done by filling a Vessel with a slender Stem successively with different Liquors and weighing them as also it may be done by a Brass Cylinder made heavier at one end than the other by which it may be made to float and to swim deeper or higher above the Water as the Liquor contained is heavier or another way is by fitting too Bubbles together with Cement by which their Stems being joined and the one caused to sink lowest by a Ballast of Mercury as the other is filled with a heavier or lighter Liquor it will manifestly preponderate Another way proposed by Mersennus is by weighing a Glass and a Stopple in Water and then filling the Bottle quite full and putting in the Stopple for the weight of the Glass and Stopple being deducted from the weight of the whole the remaining weight will be the weight of the Liquor proposed But instead of this we made use of a round Glass-Ball with a Glass Stopple which being first weighed in Air and Water and counterpoised there we were able to discover the weight of the Liquor contained and its proportion to the bulk of the Liquor it was weighed in and if the Bubble were too light to subside in some heavy Liquors we would bring it to a just weight by a Ballast of Mercury But since such Vessels as these are very hard to be got and some other inconveniencies attend it we think it less satisfactory than those other ways we made use of and proposed before A sixth Use that may be made of these Hydrostatical Tryals Use VI is in reference to several Medicinal Bodies for thus the Jucies of Plants may be weighed if when they are contained in our Hydrostatical Jar delineated in the Figure above they be hung at a nice Ballance in Oyl instead of Water since they are not subject to mix with it And by this means we may be satisfied whether Juices of Plants alter their specifick Gravity when kept a good while and after fermentation And by this method likewise we may be able to weigh Honey Vinegar Verjuce c. As also we may compare and weigh the Juices of Fruits of different kinds and the subordinate Species of each kind as also the several Juices in their several states of Crudity or Maturity But the use of this Hydrostatical Bucket being very tedious and difficult to those that are not very skilful in making Experiments the other will be more useful which are tryed with Amber But to what hath been already delivered on this subject I shall add that tho' in several Tryals made with precious substances a nice Ballance is requisite yet in most cases the difference betwixt Bodies is great enough to be discerned by a Ballance not altogether so nice for let the Ballance be never so nice there is difference in the Textures and Compositions of Bodies of the same Denomination for which as well as in defect of a nice Ballance allowances are easily made But perhaps it may be objected by some against the method I have been proposing that since I generally weigh most Bodies in Water it will be a hard matter to make them with any exactness since it hath been observed that most Waters themselves differ in specifick Gravity But to this I shall briefly answer that I have not perceived so considerable a difference as will frustrate these Experiments in which we require not a Mathematical but a Physical certainty CHAP. XII Hydrostatical Stereometry applyed to the Materia Medica IT being usual for Physicians in the descriptions of several Parts of the Materia Medica to signifie the size of Bodies by very indeterminate Terms I thought that they might be assisted by Hydrostaticks to give descriptions much more exact and satisfactory and for that end having made two hollow Brass Cubes whose Cavities being Cubical Inches contained 256 grains or a Cubical Inch of Water it being a Law in Hydrostaticks that whatever Body is weighed in Water it loses so much of its weight as an equal bulk of Water weighs I concluded it would thence follow that whatever solid was weighed in Water if in that fluid it lost 256 grains of its weight it might be said to be a Cubical Inch and as it lost more or
scarce discernable if at all as in Loadstones Ambergrease c. Those requiring a long time to make their Consumption discernible in which time we are not sure but the Weights themselves may have lost of their weight as well as the Counterpoise and consequently not be able to discover the loss those sustain But there are several other besides statical ways of trying whether Bodies emit Effluvia or not and there are several peculiar ways requisite to cause them to emit them as Glass c. affect the Nostrils upon an Attrition I had a Diamond as well as a Ruby which would be excited by a gentle heat in my Pocket or only by strokeing my Finger over the former tho' sometimes they would fail to be so easily or uniformly excited and it is not a little strange that upon the Tread of a Hare or Partridge Effluvia should be so long emitted as to give a Scent to Dogs several Hours after And if Load-stones and other Bodies may have Constant Atmospheres which are only to be discover'd by particular Bodies several other Substances not yet taken notice of may emit Effluvia which by peculiar Methods may be discover'd CHAP. IV. Of the Strange Subtlety of Effluviums Of the subtlety of Effluviums THE subtlety of the Effluviums will be most aptly represented by considering I. The strange extensibility of some Bodies whilst their Parts remain tangible II. The Multitude of visible Corpuscles that may be afforded by a small Portion of Matter III. The smallness of the Pores at which the Effluvia of some Bodies will get in IV. The small Decrement of Bulk or Weight that a Body may suffer by parting with great store of Effluvia And V. The great quantity of Space that may be filled as to Sense by a small quantity of Matter when rarify'd or dispersed And First I have observed that a Grain of Silver Wire amounted to 27 Foot or 324 Inches and since half an English Inch may be divided into a 100 Parts by diagonal Lines it must consist of 64800 true Metalline Parts which may be well conceived to be made of Parts yet more minute And I had a gilt Wire an Ounce of which made a Wire 1000 paces long allowing Five Foot to a Pace and 720 Foot above and had this Wire been drawn out to an equal smallness with the Silver Wire the Gold would have been divided to an indefinite number of Parts being sufficient to cover the superficial Area of so long a Wire And I have known Silk to be drawn out of the Mouth of a Worm which tho' it weigh'd but two Grains and a half was 300 Yards long But to evince the great extensibility of Matter we took six beaten Leaves of Gold the sides of whose Squares were 3 Inches and 2 8 which Number being reduced to a Decimal Fraction viz. 3125 100 and multiplyed by it self affords 10â—5â— 10000 for the Area of each and this multiplyed by 6 the Number of the Leaves amounts to 6313750 10000 square Inches for the Area of the six Leaves of Gold which weighed but 1 Gr. ¼ so that 4 Grains was extended to above 50 square Inches And if each of these Inches may by Lines drawn from opposite Points be divided each into 100 Parts one Grain of Gold must be divided into 500000 little squares discernable by a good Eye and if an Inch were divided into 200 Parts as I have one by me that is then a Grain may be divided into 2000000 of squares And to be satisfy'd further of the extensibility of Gold I enquired and was told that 8 Grains of Gold would gild an Ounce of Silver Wire as fine as a Hair and which would reach betwixt 90 and 100 Miles But supposing the Wire to be as fine as that first mentioned and that 8 Grains of Gold went to gild it a sheath of Gold weighing but 8 Grains may be extended so as to reach 60 times as much in weight of Silver Wire as it covers and consequently a grain of that Wire being twenty seven foot long the ounce of Gold would reach to 777600 foot i. e. 155 ½ miles and if this Gold Wire were cut into as small thongs or lists as posibly it might be it must reach to a stupendious length But secondly to shew into what a number of visible Corpuscles a Body may be divided we put an ounce of Water into an Aeolipile and having placed it upon a Chafing-dish of Coals we observed that Vapours streamed out or above sixteen minutes and considering a few intermitting gusts afterwards and what drops of Water were condensed in the top of it I guessed that had the whole been driven out in Vapours they would have continued twenty minutes N. B. to the Orifice of the Aeolipile we applied a long Tube twenty Inches long and an Inch in Diameter the remoter end being continued about six Inches longer and so far expanded that its Diameter was four or five Inches and by the help this Pipe we were able tho' not actly to measure the Extension of the rarified Vapours To this instance I might add the prodigious expansion of some Inflamable Bodies when turned into actual flame as Spirit of Wine c. Which being burnt in a Glass Lamp so contrived that the Surface of the Liquor was still Circular the waste made in ¼ of an hour was very small tho' the Physical superficies of the Liquor must needs be successively rarified and expanded and fly away in streams and if so little of this Liquor was able to afford matter for flame so long the same bulk of a more compact Body may easily be supposed to be capable of being expanded to much greater Dimensions And to these instances I shall add that half a grain of Gun-Powder being exploded under a Vessel whose Basis was eight Inches and its Altitude twenty and its figure such that it was more Capacious than a Cone of that size the exploded Gun-Powder was observed to fill the whole Cavity of the Vessel as to sense and successively issued out of the upper Orifice for half a quarter of an hour so that the Diameter of it being two Inches many Myriads of visible Corpuscles must be conceived to throng out in so long a time as they crouded out one after another But to make a kind of an estimate of the Expansion of this Substance we filled the Vessel full of Water and found that the weight of it amounted to 320000 half grains And if we suppose the specifick Gravity of the Gun-Powder to be as much again as that of Water we my probably guess the smoak to posses 500000 times the space that the Gun-Powder did And as a further Argument of the great minuteness of small Parts of matter I shall urge the smallness of Cheese-mites which being so small as not to be discernable to a naked Eye but when they move must be made of extremely fine Parts otherwise there would not be room enough for an Organical Body