kind of English Oker which yet perhaps was no fitter than other to a convenient shape though till it was altered by the fire it discovered no Magnetical Quality yet after it had been kept red-hot in the fire and was suffered to cool in a convenient posture it was enabled to exercise Magnetical operations upon a pois'd Needle EXPER. XIII AS for the Abolition of the Magnetical vertue in a body endow'd with it it may be made without destroying the Substantial or the Essential Form of the body and without sensibly adding diminishing or altering any thing in reference to the Salt Sulphur and Mercury which Chymists presume Iron and Steel as well as other mixt bodies to be composed of For it has been sometimes observed that the bare continuance of a Loadstone it self in a contrary position to that which when freely placed it seems to effect has either corrupted or sensibly lessened the vertue of it What I formerly observed to this purpose I elsewhere relate and since that having a Loadstone whose vigor was look'd upon by skilfuâ— persons as very extraordinary and which whilst it was in an Artificers hand was therefore held at a high rate I was careful being by some occasions call'd out of London to lock it up with some other rarities in a Cabinet whereof I took the key along with me and still kept it in my own Pocket But my stay abroad proving much longer than I expected when being returned to London I had occasion to make use of this Loadstone for an Experiment I found it indeed where I left it but so exceedingly decayed as to its attractive power which I had formerly examin'd by weight by having lain almost a year in an inconvenient posture that if it had not been for the circumstances newly related I should have concluded that some body had purposely got it out in my absence and spoiled it by help of the fire the vertue being so much impaired that I cared little to employ it any more about considerable Experiments EXPER. XIV And this corruption of the Magnetical vertue which may in tract of time be made in a Loadstone it self may in a trice be made by the help of that Stone in an excited Needle For 't is observ'd by Magnetical Writers and my own Trials purposely made have assured me of it that a well pois'd Needle being by the touch of a good Loadstone excited and brought to turn one of its ends to the North and the other to the South it may be a contrary touch of the same Loadstone be deprived of the faculty it had of directing its determinate extreams to determinate Poles Nay by another touch or the same and even without immediate Contact if the Magnet be vigorous enough the Needle may presently have its direction so changed that the end which formerly pointed to the North pole shall now regard the South and the other end shall instead of the Southern respect the Northen pole EXPER. XV. AND to make it the more probable that the change of the Magnetism communicated to Iron may be produc'd at least in good part by Mechanical operations procuring some change of texture in the Iron I shall subjoyn a notable Experiment of the ingenious Doctor Power which when I heard of I tryed as well as I could and though perhaps for want of conveniency I could not make it fully answer what it promised yet the success of the trial was considerable enough to make it pertinent in this place and to induce me to think it might yet better succeed with him whose Experiment as far as it concerns my present purpose imports that if a Puncheon as Smiths call it or a Rod of Iron be by being ignited and suffered to cool North and South and hammered at the ends very manifestly endow'd with Magnetical vertue this vertue will in a trice be destroyed by two or three smart blows of a strong hammer upon the middle of the oblong piece of Iron But Magnetism is so fertile a Subject that if I had now the leisure and conveniency to range among Magnetical Writers I should scarce doubt of finding among their many Experiments and Observations divers that might be added to those above delivered as being easily applicable to my present Argument And I hope you will find farther probability added to what has been said to shew that Magnetical operations may much depend upon Mechanical Principles by some Phaenomena recited in another Paper to which I once committed some promiscuous Experiments and Observations Magnetical FINIS Experiments and Notes ABOUT THE MECHANICAL ORIGINE OR PRODUCTION OF Electricity By the Honourable ROBERT BOYLE Esq Fellow of the R. Society LONDON Printed by E. Flesher for R. Davis Bookseller in Oxford 1675. Experiments and Notes ABOUT THE MECHANICAL ORIGINE OR PRODUCTION OF Electricity THat 't is not necessary to believe Electrical Attraction which you know is generally listed among Occult Qualities to be the effect of a naked and solitary Quality flowing immediately from a Substantial Form but that it may rather be the effect of a Material Effluvium issuing from and returning to the Electrical Body and perhaps in some cases assisted in its Operation by the external air seems agreable to divers things that may be observ'd in such Bodies and their manner of acting There are differing Hypotheses and all of them Mechanical propos'd by the Moderns to solve the Phaenomena of Electrical Attraction Of these Opinions the First is that of the learned Jesuite Cabaeus who though a Peripatetick and Commentator on Aristotle thinks the drawing of light Bodies by Jet Amber c. may be accounted for by supposing that the steams that issue or if I may so speak sally out of Amber when heated by rubbing discuss and expell the neighbouring air which after it has deen driven off a little way makes as it were a small whirlwind because of the resistance it finds from the remoter air which has not been wrought on by the Electrical Steams and that these shrinking back swiftly enough to the Amber do in their returns bring along with them such light bodies as they meet with in their way On occasion of which Hypothesis I shall offer it to be consider'd Whether by the gravity of the Atmospherical Air surmounting the Specifick Gravity of the little and rarifi'd Atmosphere made about the Amber by its emissions and comprising the light Body fasten'd on by them the Attraction may not in divers cases be either caused or promoted Another Hypothesis is that proposed by that Ingenious Gentleman Sir Kenelm Digby and embraced by the very Learned Dr. Browne who seems to make our Gilbert himself to have been of it and divers other sagacious men And according to this Hypothesis the Amber or other Electrick being chaf'd or heated is made to emit certain Rayes or Files of unctuous Steams which when they come to be a little cool'd by the external air are somewhat condens'd and having lost of their former
have done that the Iron bars of windows by having stood very long in an erected posture may at length grow Magnetical so that if you apply the North point of a poised and excited Needle to the bottom of the Bar it will drive it away attract the Southern and if you raise the magnetick needle to the upper part of the Bar and apply it as before this will draw the Northern extream which the other end of the bar expelled probably because as 't is elsewhere declared the bar is in tract of time by the continual action of the Magnetical effuvia of the Tarraqueous Globe turned into a kind of Magnet whose lower end becomes the North-pole of it and the other the Southern Therefore according to the Magnetical Laws the former must expel the Northern extream of the Needle and the later draw it EXPER. VIII I Have found indeed and I question not but other observers may have done so too that if a bar of Iron that has not stood long in an erected posture be but held perpendicular the forementioned experiment will succeed probably upon such an account as that I have lately intimated But then this virtue displayed by the extreams of the bar of Iron will not be at all permanent but so transient that if the bar be but inverted and held again upright that end which just before was the uppermost and drew the north-end of the needle will now being lowermost drive it away which as was lately observed will not happen to a bar which has been some years or other competent time kept in the same Position So that since length of time is requisite to make the verticity of a bar of Iron so durable constant that the same extream will have the same virtues in reference to the Magnetical needle whether you make it the upper end or the lower end of the bar it seems not improbable to me that by length of time the whole Magnetick virtue of this Iron may be increased and consequently some degree of attraction acquired And by this Consideration I shall endeavour to explicate that strange thing that is reported by some Moderns to have happened in Italy where a bar of Iron is affirmed to have been converted into a Loadstone whereof a piece was kept among other rarities in the curious Aldrovandus his Musaeum Metallicum For considering the greatness of its Specific Gravity the malleableness and other properties wherein Iron differs from Loadstone I cannot easily believe that by such a way as is mentioned a metal should be turned into a stone And therefore having consulted the book it self whence this Relation was borrowed I found the story imperfectly enough delivered The chiefest and clearest thing in it being that at the top of the Church of Arimini a great iron-bar that was placed there to support a Cross of an hundred pound weight was at length turned into a Loadstone But whether the reality of this transmutation was examined and how it appeared that the fragment of the Loadstone presented to Aldrovandus was taken from that bar of Iron I am not fully satisfied by that Narrative Therefore when I remember the great resemblance I have sometimes seen in colour besides other manifest Qualities betwixt some Loadstones and some course or almost rusty Iron I am tempted to Conjecture that those that observed this Iron-bar when broken to have acquired a strong Magnetical virtue which they dreamed not that tract of time might communicate to it might easily be perswaded by this virtue and the resemblance of colour that the Iron was turned into Loadstone especially they being prepossess'd with that Aristotelian Maxim whence our Author would explain this strange Phaenomenon that inter Symbolum habentia facilis est transmutatio But leaving this as a bare conjecture we may take notice that what virtue an oblong piece of Iron may need a long tract of time to acquire by the help onely of its position may be imparted to it in a very short time by the intervention of such a nimble agent as the fire As may be often though not always observed in Tongs EXPER. IX and such like Iron Utensils that having been ignited have been set to cool leaning against some wall or other prop that kept them in an erected posture which makes it probable that the great commotion of the parts made by the vehement heat of the fire disposed the Iron whilst it was yet soft and had its pores more lax and parts more pliable disposed it I say to receive much quicker impressions from the Magnetical effluvia of the Earth than it would have done if it had still been cold EXPER. X And 't is very observable to our present purpose what differing effects are produced by the operation of the fire upon two Magnetick bodies according to their respective constitutions For by keeping a Loadstone red-hot though you cool it afterwards in a perpendicular posture you may deprive it of its former power of manifestly attracting But a bar of Iron being ignited and set to cool perpendicularly does thereby acquire a manifest verticity Of which differing events I must not now stay to inquire whether or no the true reason be That the peculiar Texture or internal constitution that makes a Loadstone somewhat more than an ordinary Ore of Iron which metal as far as I have tried is the usual ingredient of Loadstones being spoiled by the violence of the fire this rude Agent leaves it in the condition of common Iron or perhaps of ignited Iron-ore whereas the fire does soften the Iron it self which is a metal not an Ore agitating its parts and making them the more flexible and by relaxing its pores disposes it to be easily and plentifully pervaded by the Magnetical steams of the Earth from which it may not improbably be thought to receive the verticity it acquires and this the rather because as I have often tryed and elsewhere mentioned EXPER. XI if an oblong Loadstone once spoil'd by the fire be thorowly ignited and cooled either perpendicularly or lying horizontally North and South it will as well as a piece of Iron handled after the same manner be made to acquire new poles or change the old ones as the skilful experimenter pleases But whatever be the true cause of the disparity of the fires operation upon a sound Loadstone and a bar of Iron the effect seems to strengthen our conjecture That Magnetical operations may much depend upon Mechanical Principles And I hope you will find further probability added to it by some Phaenomena recited in another paper to which I once committed some promiscuous Experiments and Observations Magnetical EXPER. XII IF I may be allowed to borrow an Experiment from a little Tract that yet lyes by me and has been seen but by two or three friends it may be added to the instances already given about the production of Magnetism For in that Experiment I have shewn how having brought a good piece of a certain
and other Vegetables And in the gross Empereumatical Oils of Woods and even in high Rectified Spirit of Wine which therefore some will have to be an Alcalizat liquor and others list it among Acids though I did not find it neither to be destroyed or much altered by being put upon Coral or salt of Tartar as would happen to an acid Menstruum nor yet by being digested with and distilled from sea Salt as might be probably expected from an Alcalizat one Aand among those very bodies which their Tasts perswade Chymists to reckon amongst Acids one may according to what I formerly noted observe so great a difference and variety of relishes that perhaps without being too severe I may say that if I were to allow Acids to be One Principle it should be only in some such Metaphysical sense as that wherein Air is said to be One Body though it consist of the associated effluviums of a multitude of Corpuscles of very differing Natures that agree in very little save in their being minute enough to concur to the Composition of a fluid aggregate consisting of flying parts But having dwelt longer than I intended on One Objection 't is time that I proceed to those that remain CHAP. V. ANother particular I am unsatisfied with in the Hypothesis of Alcali and Acidum is that 't is in divers cases either needless or useless to explain the Phaenomena of Qualities there being several of these produced destroyed or altered where there does not appear any accession recess or change of either of those two Principles as when fluid water by hard beating is turn'd into consistent froth and when transparent red Coral is barely by being beaten and sifted finely changed into a white and opacous powder and as when a very flexible piece of fine silver being hammer'd is brought to have a brisk spring and after a while will instead of continuing malleable crack or cleave under the hammer and as when to dispatch and omit other instances a sufficiently thin leaf of Gold held between the Light and the Eye appears green Another thing of kin to the former that I like not in the Doctrine of Acidum and Alcali is that though the Patrons of it whilest they would seem to constitute but two Principles are fain as I lately intimated to make I know not how many differing sorts of Acids besides some variety of Alcalies yet their Principles are too few and narrow to afford any satisfactory explication of the Phaenomena For I fear 't will be very difficult for them to give a Rational Account of Gravity Springiness Light and Emphatical Colours Sounds and some other Qualities that are wont to be called manifest and much more of several that are confest to be occult as Electricity and Magnetism in which last I see not how the affirming that there is in the Magnet an Acid and an Alcali and that these two are of contrary Natures will help to explain how a Load-stone does as they speak attract the same end of a poised needle with one of its Poles which 't will drive away with the other and determine that needle when freely placed to point North and South and enable it to communicate by its bare touch the same Properties and abundance of other strange ones to another piece of Steel But I forbear to alledge particular Examples referrable to the several Qualities above-mentioned whether manifest or hidden because that in great part is already done in our Notes about particular Qualities in which 't will appear how little able the employing of Alcali and Acidum will be to afford us an account of many things And though I enlarge not here on this objection yet I take it to be of that importance that though there were no other this were enough to shew that the Hypothesis that is liable to it is Insufficient for the explication of Qualities and therefore 't will not I presume be thought strange that I add that as for those that would extend this narrow Chymical Doctrine to the whole object of Natural Philosophy they must do more than I expect they will be able before they can make me their Proselyte there being a multitude of Phaenomena in nature divers whereof I elsewhere take notice of in reference to the Chymists Philosophy in which what Acidum and Alcali have to do I confess I do not understand CHAP. VI. THE last thing which comprizes several others that seems to me a defect in the Doctrine of Alcali and Acidum is that divers if not most of those very things that are pretended to be explicated by them are not satisfactorily explicated some things being taken into the explications that are either not fundamental enough or not clearly intelligible or are chargeable with both those Imperfections And first I am dissatisfied with the very fundamental Notion of this Doctrine namely a supposed Hostility between the tribe of Acids and that of Alkalies accompanied if you will have it so with a friendship or sympathy with bodies belonging to the same tribe or Family For I look upon Amity and Enmity as Affections of Intelligent Beings and I have not yet found it explained by any how those Appetites can be placed in Bodies Inanimate and devoid of knowledge or of so much as Sense And I elsewhere endeavour to shew that what is called Sympathy and Antipathy between such bodies does in great part depend upon the actings of our own Intellect which supposing in every body an innate appetite to preserve it self both in a defensive and an offensive way inclines us to conclude that that body which though designlesly destroys or impairs the state or texture of another body has an Enmity to it though perhaps a slight Mechanical change may make bodys that seem extreamly hostile seem to agree very well and cooperate to the production of the same effects As if the acid spirit of Salt and the volatile Alkali as they will have it that is commonly called Spirit of Urine be put together they will after a short though fierce conflict upon a new contexture unite together into a Salt little if at all differing from Sal Armoniac in which the two reconciled Principles will amicably join in cooling of water dissolving some metalline bodys and producing divers other effects And so if upon a strong solution of Salt of Pot-ashes or of Salt of Tartar good Spirit of Nitre be dropt in a due proportion after the Heat and Tumult and Ebullition are over the Acid and the Alkalizat Salts will convene into such a Concretion as Salt-peter which is taken to be a natural body either homogeneous or at least consisting of parts that agree very friendly together and conspire to constitute the particular kind of Salt that Chymists call Nitre But the Sympathy and Antipathy that is said to be betwixt Inanimate bodys I elsewhere more particularly consider and therefore I shall now add in the second place That the Explications made of Phaenomena according to the