ought to be in Motion p. 164 The Use of the Lungs in respect of the Body p. 169 To dilate the Ventricles of the Heart p. 174 How obstructing Respiration kills an Animal p. 178 Whether Air be mixed with the Mass of Blood p. 191 Whether Nitre be p. 192 And how p. 193 What Effects it hath upon the Mass of Humors in the Lungs p. 196 How Nitre depresses the Heat of the Blood p. 198 Pag. L. Read 41. 5. Occasion for Accension 53. 18. Motion for Notion 60. 2. Exploded 84. 8. Blood for Body OF THE HEAT OF THE BLOOD EVEN Philosophy in General is so Mysterious and so infinitely out of the reach of our short and weak Capacities that the best of Philosophers may truly be said to have but a slight and superficial Knowledg of it For if that small Part we know be compared with what we know not all our Knowledg is but as an invisible Speck those things to which it extends being inconsiderable if compared with that vast and endless Mass of the Universe But although that Part of the Universe which in some Measure lyes within the Cope of our Senses be small and inconsiderable when compared with the vast Extent of the whole Creation yet when we reflect on the vast Variety of Objects contained within those narrow Dimensions we find and must needs acknowledg it very considerable and superabundantly furnish'd with Matter for our Senses to work upon For the Extension of our Knowledg as to those Objects is bounded by Limits not very spatious notwithstanding the Diligence and Industry of Learned Men and the great Improvements made in most Parts of Knowledg The wisest Men and the most profound Philosophers must of necessity own that of those Things they know most their Knowledg is very imperfect We know but in Part and indeed so small a Part that it chiefly seems to inform us more sensibly of our Ignorance But so pleasant and desirable is Knowledg and we find so much uneasiness in Ignorance when once we have tasted of it that it 's impossible to abstain from a further Pursuit after it at least notwithstanding the vast disproportion betwixt our Knowledg and Ignorance which continually lyes in our way to discourage us And as we thirst after Knowledg with a desire to attain to a more adequate and compleat Apprehension of it so we most eagerly pursue those Parts of it which we hope to understand most clearly and which we expect to make a Progress in with the most considerable Advantage Since then the Microcosm which is as if it were a Type and Epitomy of the Macrocosm lyes much more within the narrow Cope of our Senses since we can dive and search into all and the inmost Recesses of it and come nearer to those Springs and Fountains upon which all the Effects we perceive in it depend we have much more solid and firm Foundations to proceed upon than in any other Parts of Philosophy whatsoever and may much more reasonably hope for Certainty and Truth besides the Pursuit of it must needs be not only more Pleasant but Advantagious And although in a Man's Body some Things are much more apparent clear than others yet the most obscure may easily be so far explained and understood as is necessary and subservient to shew the Use of them and to what Ends they were designed Amongst those that are accounted most obscure the Heat of the Blood is unfortunately one but the Reason why it is so is not that it is less apparent in it self but rather the Inadvertency of those that searched into it If possible such great Men as have writ concerning it may be guilty of so great a Fault which although otherwise no small one is much more excusable in those whose more weighty Concerns take 'em of a deeper Enquiry Since then so many learned Men and those to whom Physick is not least obliged for considerable Improvements have writ on this Subject I think it not only Justice but also Reasonable I should shew upon what Grounds and for what Reasons I have rejected their Opinions before I take leave to propose my own It would be needless to spend time in Informing my Reader that both Antient and Modern Writers have endeavoured to account for it and it would be Information to but a few since none that have made any considerable Progress in Physick can be ignorant of it I shall only as briefly as I can mention the Opinions of the Antients that it may better appear to the more unlearned wherein they are deficient and then I shall consider the most remarkable Opinions of the Moderns that less competent Judges and young Students in Physick may spend less time in convincing themselves how far they come short of explaining the Reason of the Heat of the Blood Amongst the Ancients who wanted those Improvements in Anatomy that have been made of late to direct them in their Judgments some fancied that it proceeded from a Calidum innatum or innate Heat which was fixed and rooted in all the Parts of a Man's Body before his Birth and that This continued Heat by communicating it self successively to the Nourishment of the Parts as soon as it was received by them Which indeed was so weak and superficial an Account of it that it rather served to please the Unlearned then to satisfie the Curious and more Inquisitive Others thought that there was a sort of Flame lodged in the Heart which kindled the Blood as it passed through it But Moderns having learnt by a further and a deeper Insight into Mens Bodies that the former of those was rather the Effect than the Cause and by frequent Dissections that the Heart was altogether incapable of containing such a Flame and also that that which they supposed to be the Pabulum of it to be clotted Blood they have with sufficient Reason rejected them both Wherefore passing by these I shall proceed to consider those Modern Opinions which are thought most worthy our Consideration The first that I shall take Notice of is the Opinion of the most Ingenious Dr. Willis who although in some things he hath had the Fortune to be mistaken with other Learned Men the best being not exempt yet for the most part hath made the greatest Improvements of any of his Predecessors in Theory This Learned Author in the eight Paragraph or thereabouts of his Exercitation concerning the Heat of the Blood takes Notice that there are three Modes or Sorts of Causes by which Liquids grow Hot. First à culido ad moto or by applying them to something that is Hot as when Water boyls over the Fire Secondly when Saline Corrosives mutually act upon one another or on sulphureous Bodies mixed with them by an intense and powerful Agitation Thirdly when a Liquor abounding with much Spirit or Sulphur takes Flame from some other Body And in the next Paragraph
more readily to it's Motion upwards being less compact above then below I shall produce two or three Instances which prove that if it had but less Liberty to ascend by the Opposition of some other Body then to descend it would as naturally fly downwards as it does now upwards when it is otherwise and I shall also prove that if it had but an equal Resistance on each side it would expand orbicularly And First that if Flame had but an equal Resistance from ambient Bodies on each side it would expand Orbicularly will be proved by this Experiment viz. fill a hollow Globe with Gunpowder one side of which is a little thinner than the other and whatever way that thin side is turned whether down upwards or horizon-ward the Gunpowder will expand and break out that way Secondly to prove that if there were but more liberty for the descent than ascent of it Flame would naturally fly downwards we need but shoot a Gun off with the Mouth downwards for the explauded Gunpowder finding an open and easy Passage downwards and being resisted upwards and on each side it naturally descends But some perhaps that do not throughly understand why a Thing is said naturally to ascend or descend may be unwilling to believe that when a Gun is shot downwards the Motion of the Flame is a natural Motion but may rather think it Preternatural But that it may appear that it is as truly a naral Motion in Philosophy as the ascending Motion of it I shall consider why Flame may be said naturally to ascend Flame then is said naturally to ascend because it is the Nature of it for the most Part to do so which is as much as to say the Nature of Flame inclines it to ascend how the Nature of it inclines it to ascend I have already shown and that there are the same Reasons why the descending Motion should be termed Natural will easily be proved for as it is natural for it to ascend as long as it hath only the Air to oppose it's Motion so it is it's Nature to descend when the Order of Opposition is changed and the latter is as much a natural Motion as the former all that diversifies the tendency of Flame being those accidental Circumstances which are about it and as a Ball cast against the bottom of a Room rebounds upwards and when it is thrown against the top of it as naturally flyes down so Flame being in a brisk Motion naturally flyes up or down as the Parts of Matter it striks against resist it and cause it to fly back from them HAving made this short Digression I shall proceed next to examin Diemerbroek's Opinion who thinks that the vital Spirit by reason of it's Volatility always endeavouring to fly away does continually agitate those grosser Particles of the Blood with which it is entangled and detained from flight and is diversly vibrated and beat back and so the whole Mass being kept in a continual fermentative Motion there is a Heat produced in it which in a greater Agitation is greater c. And so differs according to the different Degrees of Agitation All that I shall or need to take Notice of here is that that Agitation of Particles which he says causes the Heat of the Blood rather produces a Sensation of Heat by affecting our Senses in their Motion than produce that which we call Heat in the Blood But to know the true Reason of the Heat of the Blood we must understand how those Particles are put into Motion which by affecting our Sensory cause such a Sensation So that he seems to me to say no more then that that which hath a Power to cause Heat is the Cause of that Power when he ought in order to explain the Heat of the Blood to have shown from whence that Power proceeds the Reason of which I should have taken in some measure for the Reason of the Heat potentially in the Mass of Blood but from what he hath said it appears that he hath not explained the true Reason of the Heat of the Blood so plainly that I need say no more against it Dr. Henshaw thinks that the Dissimilitude betwixt the Chyle and Blood is so great that it becomes immediately the Cause of an extraordinary Ebullition upon their mixture together which is very much increased by the reciprocal Motion of the Lungs whereby the Blood is wrought into a froth by that time it gets into the left Ventricle of the Heart Which sudden Excess of Heat he thinks not unlike what happens upon the mixing of several Chymical Liquors together for the Heat often becomes so great that they often endanger the Vessels that contain them But he might as well have said that there is so great a Dissimilitude betwixt hot Blood and cold Milk that as soon as the Milk is mixed with it it will cause an extraordiary Ebullition and that by exposing them to the Air running them through Pipes the Heat would increase but this is so plainly false that it needs no other Arguments but Reflection to convince the weakest Reason And he might equally as well conclude that Water would kindle a Fire and encrease the Flame of it because Oyl will as that Chyle will put the Blood into a Heat because Oyl of Turpentine and Spirit of Wine will grow hot when mix'd together but the Conclusion being manifestly absurd I shall in the next Place endeavour to show the Reason of the Heat of the Blood as evidently as possibly I can FROM what I have already said in Answer to Dr. Willis's Opinion it sufficiently appears that whether we say the Blood grows hot per admotum Calidi Accension or any other way it is no more then to express the same Thing several ways or to make Words different in Sound to express one and the same thing But as all that have writ on this Subject have made choice of a different Name to signify the Heat of the Blood by whilst some would have it done by Accension others by Attrition c. so they have by that means rather disputed about Names and Words than any real and fundamental Difference in their Opinions I shall not here enter into a dispute whether the Blood when it becomes hot may most properly be said to grow hot or it's Heat expressed by any one of those Titles they have been pleased to signify it by for as in discoursing about the constituent Parts of a Man it is not necessary to fix any Name upon that Man but whether it be Thomas Robert or William the constituent Parts of him if he be a perfect Man will still be the same so in discoursing concerning the Heat of the Blood and considering the principal Cause or Agent and the more remote and accessory Causes it is no matter at all whether the Consequence of these Causes be signified by the word Accension Attrition or Fermentation because the Difference of the
Title does not at all diversify the Action But if any one would rather signify the Heat of the Blood by any of these different Words I shall be equally pleas'd with them or any of them provided they all meet in the Matter signified by them and do not deny that which seems to be true That the Heat proceeds from a swift intestin Motion of it's Particles Which Motion is the Reason why it affects our Sensory so as to cause a Sensation of Heat But as the Reason why it affects our Sensory so is not sufficiently satisfactory to explain what is the Cause and how it comes by that Power of causing such a Sensation In making an Enquiry into the Cause of that I shall beg leave to make Use of that Word which I think to be most expressive viz. Fermentation For since in every mechanical Action there is an Agent and a Patient and the Agent operates upon the Patient by moving powerfully against the Parts of it And in that Motion the Parts of the one strike against and rub upon the other so far it may be called Attrition And if by the force of the Agent the Motion and consequently Attrition be more violent and the consequence of that Attrition be a Production of a Power to cause a Sensation of Heat so far it may be called Fermentation If then in causing the Heat of the Blood there be such a Motion and Attrition and the consequence of it be Heat we may properly say the Blood grows hot by Attrition and Fermentation But because to signify the Heat of the Blood by Attrition and Fermentation would be needless I would signify all that Action by Fermentation And when I say the Blood grows hot by Fermentation I would be understood to mean and signify both that Attrition of Parts which is the Cause of Fermentation and also Fermentation which is the consequence of Attrition yet if any one would rather say it grows hot by Accension they have my assent provided they mean thereby not so high a degree of Heat as is usually signified by that Word but since it sounds rather too harsh and implies too high a degree of Attrition and Fermentation than that which is commonly in the Blood I more willingly make choice of the former viz. Fermentation And since I have said thus much of the Use of Words applyed to signify the Heat of the Blood I shall here take Notice of what was by way of Discourse told me by one to whom I communicated in some Measure my Notion concerning the Heat of the Blood which was this He said he thought he could prove that it was done by Mixture and Pressure and that he could explain the Heat of the Blood by that Notion I shall here conceal the Authors Name because he hath not made it public upon this account though upon some others to very little purpose and because he told me he intended to publish it I shall for his satisfaction and also the satisfaction of those to whom he hath communicated it say that as I have shewn that in mechanical Actions there is a Motion and by that Motion there must be implyed a Mixture to any one that doth but understand the Circulation of the Humors in a Man's Body and it will consequently follow that where there is a Mixture and a Motion of Humors there must needs be also an Attrition of Parts so moved which Attrition implies a Pressure For there can be no Attrition without a Pressure tho' Pressure does not imply Attrition This is all he told me and consequently all that I can Answer but for as much as I cou'd gather from the remaining Part of his Discourse the most Essential Part of his Notion but from what he said it appearing not what Pressure he meant that is a Pressure of what whether of the Particles of Blood with one another or not and it being plain that he did not believe that Animal Spirits circulated through the Nerves I not only concluded that his Pressure was only of the Particles of Blood because there are none other except Serum to mix with it but also that what he had to say for it was rather about the Use of Words then any thing else and therefore I have shew'd him how far his Words are significant in my Hypothesis But Words whereby we signifie the Heat of the Blood being nothing at all to the Cause of it and to dispute whether it may be called Accension or Fermentation not at all informing what are the Principal or Accessory Causes of it I shall proceed to shew how it is begun and carryed on and by what That is what Humors are Active and what Passive in producing Heat or a Power to Heat and how they are so and after what manner as also where they chiefly operate And that it may appear we are to consider that the material and corruptible Part of a Man in which the immaterial and immortal is lodged is made up of Solid and Liquid Parts the Solid Parts are all those Vessels that make the Body a curious contrived Vascular Engin which are filled with and actuated by Liquids and in which they all circulate And as those Vessels carry different sorts of Liquids so they are called by different Names Veins Arteries Nerves c. Through the Arteries and Veins the Mass of Blood continually circulates and Animal Spirits through the Nerves The Veins and Arteries being as if it were both rooted and springing from the Heart are branched up and down the Body both through the External as well as Internal Parts except those that the Vena Porta supplyes and the Nerves taking their Original from the Brain and spinal Marrow are dispersed through the whole and meeting with the capillary Terminations of the Veins and Arteries they being interwoven one with another terminate all together and as I Metaphorically expressed it in my Treatise of Muscular Motion all terminate in small Glands in the Cavities of which both through the substance of the Muscles as well as the Internal Parts the Arteries lay down Blood and the Nerves either mediately or immediately Animal Spirits and having there also proved that a subtile Liquor made and prepared in these Glands by Formentation was according to the different degrees of Spirits sent there by our Appetite not only subtilized but thrust out by a succession of Matter into the Fibers and circulating through them distends 'em and by that means contracts the Muscles and there also having shewn that the Fermentation was caused by a mutual Conflict of the Blood and Spirits I shall now in this Treatise endeavour to explain from that mutual Conflict the Heat of the Blood And because some as yet doubt whether Animal Spirits circulate through the Nerves or not and others though they are willing and find it necessary to grant that Spirits do really run through them yet profess that they cannot be demonstrated
Animal Spirits are too high and volatile or too much in Quantity they raise this Fermentation so high that the Blood is presently put into a Preter-natural Heat from whence proceeds that Preter-natural Heat in Fevers And the way that Physitians either do or can take in such Cases is either to take down the Animal Spirits by withdrawing Part of their Pabulum and by Acids given internally to harden the Texture of the Blood and make it less subject to grow too Hot by Fermentation or otherwise by cooling and fixing those predominant Spirits and evacuating other accessory Causes by proper Excretories and Emuctories of the Body Lastly That the more any rarified Sulphureous Body is expanded betwixt the more gross and solid Parts of Matter those gross ones are put into a stronger Motion is evident from a Musket charged with Shot which with a small quantity of expanded Matter will scarce be moved but by a greater quantity of exploded Matter are put into so swift a Motion that they fly forcibly a considerable way Having thus far proved what I proposed to be reasonable and likely and nothing but what is consonant to the Practice of most Rational Physitians I proceed to shew that the sharper the Particles of the Blood are they corrode and grind the Spirits into small and minute Particles with a great deal more Violence and by that means cause them to expand more vigorously and by putting them into a strong Motion cause a higher Degree of Heat This is sufficiently proved by the Preter-natural Effects that Scorbutick Salts cause in some People for when the Mass of Blood is impregnated with Acid Acrid Humors these meeting with the Spirits cause Preter natural flushing Heats which appear in several Parts of the Body and sometimes in the whole which are so violent that those that are affected with them complain that they feel themselves as Hot as if they were in a Stew or a Bagnio That this Preter-natural Heat proceeds from Corrosive Salt Humours fermenting with the Spirits is very manifest since these Symptoms are only curred by such Medicines as correct the Acidity and Acrimony of the Blood viz. When it most partakes of Acrimony by sweet diaphoretick Decoctions or some sort of Acids which dull and take off their corroding Edges or when they are more Acid by volatile Salts that carry them off by Sweat or Urine or by Acid Absorbers which by correcting the Acidities of the Pancreatick Juice leave the Ferment of the Liver more predominant and the bitter Choler being by that means bred a great deal more plentifully digests and carries off those crude Humors which by the aforesaid means being made thin enough to go off by Urin and insensible Transpiration are dispersed and carry'd off those ways and the Mass of Blood being cleansed of those sharp Humors is reduced to a healthful State If then by considering the Nature of those Medicines that correct vitious Humors we may learn to know what is the Nature of those Humors we must conclude that whatever is corrected by Medicines directly contrary to Acrimony the nature of that Humor is Acrid and when by the Use of volatile Salts the distempered Humors of our Bodies are attenuated and disposed to Evacuation and at the same time we know that volatile Salts by volatizing and preparing the superfluous fixed Acid Acrid Humors of the Mass of Blood dispose them to be carried off we have all the Reason imaginable to conclude that when we find those Medicines carry off such Symptoms that they are caused by such Humors And that these flushing Heats in the Scurvey proceed from Acrid Acid Humors is plain because all Salt Meat that abounds with Acids and all sharp Acrid Bear that hath an Acrid Fluid Salt predominant in it as also Vinegar and such like make those Symptoms more violent If then both from the Method of Cure and the Cause it self augmented by such Sorts of Juices we gather they proceed from sharp Acrid Acid Humors we may be certain that those Symptoms are caused by such Humors grinding and corroding the Animal Spirits and that by putting them into a Preter-natural Motion they are the Causes of such Sensations And that those Sensations only proceed from thence we may easily conceive for since as long as those Humors circulate with the Mass of Blood and forcibly meet with the Animal Spirits they can only affect them by moving amongst them they must needs put them into a more swift Motion and an unusual Expansion by corroding and grinding them more powerfully betwixt their Particles which is evident from the cause of those flushing Heats I just now mentioned and from the Reason I have before given of Heat But that the sharper the Mass of Blood is the more the Animal Spirits are ground and expanded betwixt the Particles of it is evident from Reason it self for it being proved before that the Heat of the Blood proceeds from a swift intestin Motion of the Particles of the Blood and Spirits caused by Attrition nothing is more Reasonable than that the more solid the Mass of Blood is the stronger the Attrition is and consequently the Motion of Particles which upon our sensory cause heat must be more violent and as in striking of a Flint with a peice of Steel the more firm and hard the Steel is the more powerfully it loosneth the Texture of the Flint and strongly expanding it's Sulphureous Particles puts them into that Motion which constitutes Flame so by Parity of Reason we may expect that the Particles of Blood will cause the Sulphureous volatile Parts of the Spirits to expand more powerfully the more solid and compact they are And that the Texture and Constitution of Saline Humors is more Solid and their Parts more Corroding than of a sweet Balsamick Liquor I think none can deny who compares Vinegar and Spirit of Vitriol with Tincture of Sulphur and although in Fevers where the Blood abounds with too much exalted Sulphur Spirit of Vitriol and other Acids cool the Blood by fixing the Spirits and Coagulating the Sulphur yet when the Blood is impregnated with Scorbutick Salts Acidity joyning with Acrimony causes Heat by corroding the Spirits when they want a Mixture of crude Sulphur to dull their Edges of which it would be no difficulty to convince those that are considerably troubled with scorbutic Symptoms But furthermore I shall prove that the Mass of Blood the more it abounds with volatile Salts and Sulphurs is more easily put into a violent Heat and that it's Particles being more easily put into Motion readily joyn with the Animal Spirits and encrease theirs and that on the contrary the more dull and phlegmatic any Body is the less apt are it's Particles to be put in Motion And as it is commonly taken notice of in all Bodies so it is not less observable in the Mass of Blood for we always find that the least quantity of any volatile Liquor
the Heart and from the Heart to the Extremities of the Vessels again being very short before there can be any sensible or considerable Decay of it the Blood is anew fermented in the Glands and so by a continual Circulation the Heat of the Blood is preserved and because by this time the Animal Spirits mixed in the first Fermentation with the Blood are almost spent being incorporated with it and because Part of it is continually separated in the Brain it meets a second time with new Supplies and also by repeated Fermentations is more impregnated with Spirits as well as digested and ripen'd to a higher Degree of Maturity Thus I have given an Account how the Heat of the Blood is carried on in the Vessels that it might more clearly appear how the Original Cause of Heat is principally in the Glands That the Animal Spirits are put into an elastick Motion in the Glands I have before proved by the grosser Particles of the Blood and that the Blood so fermented is successively cast out into the Veins is plain enough to any one that does but understand Circulation to prove then that the Blood being thrust out of the Glands does by a further Expansion of those Spirits for a while increase the Fermentation and that when the Vigour of the Spirits is spent it will gradually decay we need but take Notice how Fermentation is begun and carried on in other Liquors for when oyl of Vitriol and Spirit of Armoniac Salt are mix'd together the Parts of each being in some measure mixed and put into Motion by dropping the one into the other they presently begin to ferment which fermentation is gradually exalted till by a frequent Collision and Attrition the most Fermentative Parts fly away or their Vigour is lost and then Fermentation gradually decreaseth and in like manner all other Liquors that for a time ferment with a sensible Heat But if possible it will further appear that the Original Principal Cause of Fermentation is in the Glands if we do but consider how Fermentation is carried on in a dying Body For in a Body that is about to die the Vigour as well as Quantity of Animal Spirits being diminished and those too being less vigorously grund betwixt the Parts of the Arterial Blood expand so weakly that they scarce agitate the Mass of Blood sufficiently to preserve it's Heat but as soon as the Blood and Spirits cease to circulate the Heat of the Blood presently grows milder till at last it is quite extinguished Now if when the Fermentation is weak the Heat of the Blood is more remiss and depressed and when Circulation is stoped it consequently ceaseth it must needs follow that the Animal Spirits are the Cause of that Fermentation and that it is promoted by driving those two Liquors forcibly together and that the Fermentation is chiefly caused in the Glands is plain because when the Spirits and Blood cease to be driven together and there fermented the Heat of the Blood decreaseth and that it is not in the Vessels is evident because after Circulation is stoped it presently declines whereas if it were caused in the Vessels it would continue after Death as well as before since it then hath the same Matter though it wants Circulation and a forcible Mixture and what I have shewed to be the Consequences of it I shall only bring one Argument more to prove that the Heat of the Blood depends upon the Attrition and Fermentation in the Glandules which may be inferr'd from this common Observation that the Heat of the Blood is encreased by all violent Motion For upon all violent Motion a larger Quantity of Animal Spirits being sent to the Parts to be moved in order to prepare a greater Quantity of subtile Liquor to distend and dilate the Fibres the Fermentation is not only raised higher in the Glandules but the Motion of the Heart being thus accidentally increased quickens the Circulation of the Blood so much that before the vigorous Motion of it's Parts which was raised in the precedent Fermentation is spent it is again renued But the Circulation of the Blood is not only quickened by the Contractions of the Heart but also by the frequently repeated Contractions of the Muscles For the Heart contracting sends it out into the musculous Parts and again those Muscles drive it sooner and more forcibly back upon the Heart from whence it appears that both the Heat of the Blood is encreased by being often fermented in those Glandules and consequently that it depends on the Mixture and Fermentation of the Animal Spirits and Arterial Blood From hence it is manifest how far Circulation is beneficial in carrying on the Heat of the Blood and if we consider the Reason which I have given of Muscular Motion we shall see that as Fermentation depends on Muscular Motion so Muscular Motion depends on Fermentation so that as I said before there is a continual Chain and Circulation of Causes as well as Humors in a Man's Body To proceed therefore to the second Objection I supposed some might raise viz. Whether this Fermentation can be carried on in so short a time as a continual and quick Circulation will admit This does not only appear Possible from evident Matter of Fact but also if we consider that in much less Time than what is allowed for Fermentation in the Glandules if a Spark of Fire be put to Gun-powder it immediately puts it's Parts into an Explosion and that the Blood not only ferments in so short a time but that it may prepare that subtile Matter which circulates through the Muscular Fibres we may with a great deal of Reason believe if we do but take notice that warm Milk if it be but forcibly milked into Vinegar it presently is separated into two Parts viz. Curd and Whey If then by mixing these two Liquors they cause so great a Change on one another I cannot conceive any Reason why Part of the Animal Spirits fermenting with the Blood may not as soon be mixed with some Part of the rarified Succus Nutritius and forced forward into the Fibres But from what I have said it appearing that the Heat of the Blood Is caused in the Glandules by Fermentation and how it is continued in the Musculous Parts I shall in the next Place consider in what Parts it is most vigorously fermented which will appear only by considering where the Spirits are most plentifully laid down for if Fermentation depends on and is chiefly caused by the Animal Spirits as I have shewn then it must needs follow that the Heat of the Blood is most promoted in those Parts where Animal Spirits are most predominant And having proved that in order to prepare that subtile Liquor which causes Contractions of the Muscles a greater Quantity of Animal Spirits is sent there it will follow that the Blood grows hotest being most vigorously fermented in those Parts that are in Motion and
then it will follow that the Heart being a Part in constant Motion and that Motion proceeding from a successive Supply of Spirits the Blood must needs acquire the most considerable Degree of Heat in the Substance of it But although I say that the Blood for these Reasons acquires a greater Heat in the Heart then in any other Part I would not be thought to mean that it grows hot so in the Ventricles of the Heart For the Use of the Heart being only to force the Blood out of it and by dilating to receive it in again for another Expulsion and so to keep it in Circulation it can get no great Heat there since it wants Spirits to ferment with it but I only mean that considering the Substance and Dimensions of the Muscular Part of the Heart and that small Portion of Blood contained in the Arteries dispersed through it that that Blood acquires a greater Heat than that Quantity of Blood does in another Part that is not in Motion But there being besides Muscular Parts many considerable Internal Parts in a Man's Body in which a great Number of Blood Vessels are distributed it perhaps will be asked whether Fermentation be carried on in these too To which I answer that Animal Spirits and Arterial Blood being either mediately or immediately laid down in them all there must needs be a Fermentation which being proved upon such Premises by what I have already said there is no need I should repeat it again But since Anatomists have not as yet discovered Nerves to be distributed through the Liver although Blood be communicated to it by the Vena Porta which supplies the Office of an Artery to the Liver it perhaps may be doubted whether Fermentation is carried on after the same Manner there and consequently whether the Office of the Liver be performed by Fermentation or not that it is I shall shew hereafter and also how the Glands in that Part are supply'd with Spirits From what I have hitherto said it appears what are necessary to continue the Heat of the Blood and also what is the Cause of it For First It is necessary that the Animal Spirits and Blood should be in a continual Circulation that being forcibly driven together their Particles might be intimarely mixed one with another And Secondly That the Animal Spirits should be grund betwixt the Parts of the Mass of Blood that they may be thereby rarified and expanded and their Particles put into a swift Motion And Thirdly It is requisite that the Animal Spirits should be of an oyly Sulphureous volatile Temper that being more easily rarified and expanded they may be presently put into Motion and cause the whole Mass to ferment Having then explained the Heat of the Blood and proved it agreeable to these Circumstances I am for the Reasons before mentioned perswaded to believe that the Heat of the Blood thus proceeds from Fermentation OF THE USE OF THE LUNGS FOR as much as appears from the Books of several Learned Men the Use of the Lungs hath not been hitherto indisputable no more than the Use of other Parts For as there are several Opinions concerning others so there are no less Disputes about this whilst some would have it to be only a sort of Fan to cool and air the Blood And others that it was designed to kindle and put the Blood into a Flame by continually supplying it with Nitre Whether of these is most probable may easily be gathered by considering the Effects that Air hath upon us For since the Air is continually drawn in and thrust out again in Respiration any one that does but know what Effects it hath upon himself cannot be ignorant of the Use of the Lungs in respect of the Heat of the Blood evidently finding himself cooled by it and if any one that by daily Experience finds that it cools him can conclude thence that it kindles and promotes the Heat of the Blood he may be pleased with his Notion but no Body else will with such as contradict self-evident Truth But that it may appear how far the Lungs may be said to be a Fan or Ventilabrum to the Blood and whether the Air promotes the Heat of it or not I shall take this Method First consider the Use of the Lungs with respect to the Rational Soul and Secondly with respect to the Body The Use of the Lungs with a more immediate Respect to the Soul appears to be nothing else but as a large capacious Vessel endued with a Cavity to contain a great Quantity of Air so that it performs the same Office in the Body as a Pair of Bellows to Organs For as in Organs the Bellows supply Pipes of different sizes with Air and that being driven through them produces different Sounds so the Lungs dilated and extended by the Motion of the Thorax and being full of Air contract and accordingly as the Pharinx and it's Parts are differently modulated so the Air forcibly driven through them causes different Voices In which Action the Lungs seem chiefly to be an Organ made on purpose to be serviceable to the rational Soul to express all it's Conceptions and Reasons and to form Voices or Articulate Sounds to signifie those Notions contained in and apprehended by it that those Things which must otherwise remain in silence might be communicated to promote a mutual Commerce and Conversation amongst Men. But here some may ask if it be chiefly designed to form articulate Sounds as it really seems to be why do we take our Breath continually Or why are our Spirits constantly consumed by keeping the Part in a perpetual Motion Since sometimes we use it very little for a long time to express any Thing by one half of our Lives and the larger too being passed away in Silence To which it may be answered that it is necessary the Lungs should be in a constant and continual Motion that they might be kept in readiness to express what and whenever we have a Mind Another Reason is that since the Cavities of the Lungs are constantly supplyed with a serous Lympha to moisten their Coats and to moderate the Acrimony of the Air it is necessary there should be a constant and continual Respiration to carry that serous Lympha off which would otherwise stuff up the Bladders of the Lungs that they would be incapable of receiving Air but every Inspiration that superfluous Moisture being mixed and incorporated with the Air is by every Expiration carried off which prevents those ill Consequences which would otherwise follow Another Reason why the Lungs ought to be always in Motion is least they should Preter-naturally affect and disturb the Constitution of our Bodies when put in Motion as we have a mind to express our selves for if the Lungs were at other times quiet and still our Bodies would be put into such Disorder by violent and sudden Motions that we should be as unfit to discourse of
about them But though there were no such Contraction upon Inspiration yet the Dilation of the Thorax is not so long continued but that the Lungs renue the vigorous Contractions of the Heart before they are sensibly decreased as I have before explained it From what I have said of the Use of the Lungs with respect to the Rational Soul as well as the Motion of the Heart it appears that the Lungs perform a Sort of a mixed Action partly voluntary and partly involuntary with respect to the Body it is involuntary being carry'd on whether we will or not and when we are able to take no notice of it and with respect to the Soul voluntary it being in our Power to quicken or remit the Motion of them differently to modulate our Voices as occasion and necessity require or our own Will inclines us But besides these extraordinary Offices it performs in promoting both a Circulation of Humors and of Discourse since there is such a great Quantity of Air drawn in by every Inspiration it must needs produce some Effects in the Mass of Blood and those Humors that circulate along with it and since it is so minutely mixed with it by the small and circular Windings of the Blood Vessels about the Bladders of the Trachea the Blood must needs be sufficiently impregnated with Nitrous Particles But it being a Question how the Nitre of the Air comes to be mixed with the Blood and whether the Air it self be mixed with it also before I proceed to shew how the Mass of Blood is affected by it I shall endeavour to solve these two Questions And First That the Air it self is no otherwise mixed with the Mass of Blood but as I have shew'd viz. by the Mediation of the distinct Vessels in which each run is plain because we don't perceive the Effects of it in that Mass and also we may probably guess so because Air would hinder Circulation and much disturb it Air being always unapt to mix with Liquids and to fly from their Embraces there being therefore these Reasons why it ought not to be mixed with the Blood and none that it shou'd nor any Sign of it being so we have Reason to conclude that it is not But Secondly That those Nitrous Particles which swim in the Air are mixed with it we see manifestly by the Effects which are caused by them there being the same Alterations in some Measure made in the Blood as it passes through th Lungs as when exposed to the open Air. But the Question then will be how the Nitre of the Air is mixed with the Mass of Blood and by what means To which it may be answered that if we consider what fine and subtile Bodies those Particles of Nitre are which we draw in by Inspiration and through what minute and small Pores they are capable of passing so that they penetrate the most solid Bodies in Nature well may we suppose that they can find Pores fine enough to pass through the Coats of the Vessels That they pass through the most compact and solid Bodies Bodies that are much more close and less Porous than the Vessels of the Lungs are is certain for otherwise hot Water contained in a brazen Vessel would never grow cold and that the substance of Brass is less porous than the Substance of the Lungs no thing is less dubious Moreover since that the Nitrous Particles of the Air are conveighed into the Blood is so plain from the Effects that are there caused by them they must needs be conveighed through those Pores there being no other ways at all for them to pass by But Another Question which may perhaps be asked will be how the Nitrous Particles of the Air are forced through those Pores which will be easily understood by taking notice that when the Thorax is violently contracted the Air contained in the Bronchia being violently pressed together in order to an Expulsion of it a considerable Number of those Particles of Nitre must needs be pressed through those Pores that are wide enough to receive them and that there are Pores wide enough is visible from what I have said It appearing hence how the Nitre of the Air is mixed with the Blood I shall next consider how it affects it and what Effects it produces in respect of Heat To understand then the Effects that it hath upon all that Mass of Humors that circulates through the Veins and Arteries to wit Blood and serous Lympha we are to consider them both together and apart together that it may appear how they influence each other and a part that we may know for what end each is impregnated with those Nitrous Particles and because when we are acquainted how it alters each singly it will better appear how they influence each other I shall first consider them apart The Effects then which we perceive the Nitre of the Air hath upon our Blood and the Alterations we are sensible it produces are either in respect of it's Colour or Heat That the Air alters the Colour of the Blood and makes it more florid is very plain in extravasated Blood and is so commonly known that I need not take any further Notice of it but shall shew what other Effects it causes in the Blood and how Having therefore explained the Heat of the Blood in the foregoing Treatise and it appearing that it is caused by a swift and violent Agitation of the Particles of the Spirits and Mass of Blood the way to understand how Nitre affects the Heat of the Blood is to consider how it promotes or hinders the Motion of those Parts of Matter which cause Heat which as I conceive and as Reason seems to evince is performed after this Manner The Nitre of the Air consisting of Particles not at all inclined to Motion but on the contrary disposing those Bodies they are mixed with to rest except by accident when they are too powerfully resisted and opposed These I say being mixed with the Mass of Blood inviscate and fetter up the most subtile Spirituous Parts and hinder them from Motion by which means the more gross ones are moved more slow and the Heat of the Blood consequently abated but when the Mass of Blood is so Elastick and the Parts of it move so strong that the Nitre cannot depress them sufficiently and check them the Heat of the Blood is increased the Motion of those Parts being inverted That the Nitre of the Air inclines those Bodies to rest with which it is mixed and consequently the Blood is not evident only by exposing hot Water to a cold freezing Air but even Blood and nothing is less dubious than that excessive Cold extinguishes a moderate Heat But that Nitre when it is not powerful enough to check and extinguish the Heat of the Blood does increase it I have before explained and the manner how it does it and also that it hath never those Accidental Effects upon Liquids
A TREATISE Concerning the HEAT OF THE BLOOD And also of the USE OF THE LUNGS By RICHARD BOULTON of Brazen-Nose College in OXFORD LONDON Printed for A. and J. Churchill at the Black Swan in Pater-Noster-Row 1698. IMPRIMATUR JO. MEARE Vice-Can Oxon. Jan. 24. 1697. HUNC Librum cui Titulus A Treatise of the Heat of the Blood c. dignum Censemus quî Imprimatur Thomas Millington PRAESES Samuel Collins Edward Hulse Richard Morton Charles Goodall CENSORS Martij 5. 1697 8. TO THE Reverend Dr. JO. MEARE PRINCIPAL OF Brazen-Nose College AND VICE-CHANCELLOR OF THE University of Oxford SIR IT is not any great Opinion I have of my present Performance though there are some who would perswade me that it is not altogether despicable that makes me presume to prefix your Name before it Indeed amongst Men of Sense and Learning Truth for the most Part brings it's own Recommendation along with it and finds that Candid and ready Reception which it deserves But the Generality of Mankind will not relish any thing that bears not in the Front some great and eminent Name And for this Reason it is that I have made bold to make this Dedication Your real Worth which hath deservedly placed you in two Eminent Stations to both which you do more Honour than you receive from them And the Encouragement and Favour you shew to all Persons of Industry Vertue and good Learning under your Government soon determined me in the Choice of such a Patron though my small Share of each of the latter could merit neither of the former And here according to the usual Mode of Dedications I might easily enlarge upon so fair a Character But as it is your peculiar Delight to oblige do good with all the ease and sweetness imaginable so with as little Noise and Ostentation possible And I should sooner hope for your Pardon for this Presumption and the Faults of my Book than for such an Attempt upon your Modesty I shall therefore only add that you would be pleased to accept this as a Testimony of my Duty and Gratitude and that I shall always remain Reverend SIR Your Ever Obedient and Obliged Servant R. BOULTON To the very LEARNED AND JUDICIOUS Dr. R. ANGELL Resident in the CITY of CHESTER Learned Sir SIXTEEN Years Education in a University and a great many more improved in succesful and judicious Practice hath sufficiently qualified You for a Judge and Patron when I consider the former and withal my own Weakness I confess I have less Reason to desire the latter But sinoe it usually happens that those that are least subject to Faults are commonly candid Criticks and most ready to forgive others I am bolder to beg your Patronage yet not for it's Faults since that is below your Judgment but whatever Truth is contained in it which will scarce be deny'd by One that is so much an Encourager of Learning But perhaps I ought to make an Apology to You as well as the World for deviating from the Opinions of some Learned Men especiatly of that never too much Honoured Dr. Willis who was One of the Greatest Physitians of his and preceding Ages And truly all that I can say for my self is That as it would be below the Character of so Great a Man to write any Thing upon any other Consideration than an Improvement of Knowledg and Truth so undoubtedly he would not desire any Thing he writ should be believed except it seemed so That then which I hope will be an Apology for such an Attempt is That I have considered his Opinion with no other Design than an Endeavour after Truth and have offered nothing against his Opinion but plain and unprejudiced Reasons and though I have given Reason enough to prove he was mistaken in this Point yet I must ever have the greatest Veneration and Esteem for all such Men of unparallelled Worth and Learning and so candidly Ingenuous But whether this little BOOK may pretend to any Reason for what it offers or not I am more encouraged to ask Your Patronage it being approved by Men of noted Learning and eminently Judicious the President and Censors of the College of Physitians of which Number that your Self is not a Member no other Reason can be given but that Your own Choice of a more retired Life hath fixed you in that CITY where you are now resident to the Satisfaction and Good of those that commit themselves to your Care But Learned Sir That I may not press too much upon your Patience That Patronage which you were pleased to Give my Last when I was a Stranger to You both encourages me to hope for it now You have been pleased to take me into Your Favour and also that You 'll Pardon me for taking this Liberty since it is only designed to testify my Gratitude for those Favours You have already been pleased to Confer on Your very Humble and Obliged Servant R. BOULTON THE CONTENTS THE Introduction Page 1 Our Knowledg is very short ibid. And Imperfect p. 3 The Pursuit of Knowledg very desirable p. 4 Where most easily attained p. 5 The Heat of the Blood not obscure in respect of it's Cause p. 6 The Opinion of the Antients very Superficial p. 9 Dr. Willis's Opinion answered p. 11 But one Way by which Bodies grow hot p. 13 Fire is rarified Matter in Motion p. 16 Heat not actually in the Body that causes it p. 19 Heat only a Sensation p. 20 Heat only produced one Way proved further in Answer to Dr. Willis p. 23 An Objection answered p. 27 His comparison of the Blood 's Accension with Flame answered p. 28 Several Degrees of Heat without Flame p. 29 Nitre makes no Part of the Flame p. 32 How Nitre promotes Flame p. 33 Why a Candle in a Glass-Globe is extinguished by extracting Air. p. 36 Whether Nitre promotes the Heat of the Blood p. 39 Liquids fetter up Heat without Nitre p. 41 Blood may grow hot without a Sulphureous Pabulum p. 42 His Comparison of the Recrements of Flame and Blood answered p. 43 A Digression why Flame usually ascends p. 50 Why it sometimes descends p. 60 Diemerbroek's Opinion answered p. 62 Dr. Henshaw's Opinion answered p. 65 Of the true Reason of the Heat of the Blood p. 67 Animal Spirits Demonstrated p. 80 That they are in Motion through the Nerves p. 89 The Nature of them p. 91 The Reason of the Heat of the Blood explained p. 94 That Reason of it's Heat prov'd p. 100 By Attrition p. 103 How the Animal Spirits rarify the Blood p. 111 Why the Heat varies p. 112 How Sp. of C. C. raises the Pulse p. 116 The Reason of flushing Heats p. 120 How far the Blood and Spirits are Active and Passive p. 131 How the Heat of the Blood is continued p. 132 Some Objections answered p. 134 Why it's Heat declines p. 139 Of the Use of the Lungs p. 159 In Respect of the Soul p. 162 Why they
he says that there are other ways of Calefaction as Fermentation Putrefaction and Attrition but the seare only observable in solid Bodies The Design of which is to prove that since the Blood hath not any other Body applied to communicate Heat to it and since it is not impregnated with Saline Corrosives but is sufficiently stocked with Sulphureous Particles and since Fermentation Putrefaction and Attrition are only the Causes of Heat in solid Bodies It must needs be preserved in a continual Heat by Accension of it's Sulphureous Pabulum But if we do but duly consider how Heat is promoted in all these several sorts of Substances it will presently appear that in Philosophy there is but one way by which all whether Liquid or Solid grow Hot and if so then it will follow that whether we say the Blood grows Hot by applying of a hot Thing to it or Saline Corrosives whether by Fermentation Accension or Attrition it will be equivalently the same To make it evident then that there is but one way by which all Bodies grow Hot and that to say that the Heat of it proceeds from the Application of other hot Bodies Saline Corrosives Accension Fermentation or Attrition is but to express the same thing several ways since they are all equivalently performed the same way we are to consider what is the Nature of hot Bodies and wherein their Power consists either to cause Heat themselves or to communicate that Power to others And because several remiss Degrees of Heat differ only in Proportion from Fire which is the most intense and because That is free from those Masks and Clouds which intervene it and our Senses when it is in more remiss Degrees the best way to understand the Reasons of Heat will be to consider wherein the essential Nature of Fire consists Amongst Philosophers although it is very dubious what it is that causes Fire to differ so much from all other Substances yet it is by the Consent of most Moderns and evident from Flame it self and the manner that it destroys other Bodies by that it is made up of rarified Matter whose Particles are in a swift and powerful intestine Agitation and of a peculiar Figure and Size And if Fire be nothing else but Matter rarified and in a swift Motion and from that swift and intense Motion of Matter affecting our Organs of Sence we perceive Heat we must needs conclude that whatever rarifies Matter and puts it's Parts into a brisk Motion is the cause of Heat And although according to the Diversity of Subjects that Heat is dispersed through it hath different Appearances to our Senses and in most it 's Light which when it exists seperately is always joyned with it 't is obscured by the Interposition and Mixture of other Matter yet if Heat depends Essentially upon the Effects that rarified Matter in Motion hath upon our Senses it is undeniably true that Heat is caused only one way Remotely and Proximately with respect to Matter in Motion and the Effect it then hath upon us viz. By puting the Parts of Matter into a brisk Motion to affect our Senses with Violence enough to cause such a Sensation But before I proceed to a further Proof of what I have asserted viz. That there is but one Way in Philosophy by which all Things grow hot it being a Controversy whether Heat be actually in the Body that causes it or whether Matter in Motion only produceth such an Effect as the Sense of Heat upon our Sensory although it is not requisite I should here Publish my Opinion of it yet it is necessary I should explain what I mean when I say that Heat is only produced one Way or that Heat is caused by putting the Parts of Matter into a swift Motion or that Heat depends on the Effects which rarified Matter hath upon our Senses when it is in Motion But if I were here to declare my Opinion of this Point which is so differently held by various Philosophers I should say that as far as I can conceive of it Heat is not actually in the Body that causes it to be perceived by our Senses but potentially in as much as that Body hath a Power to cause such a Sensation And although a great many may wonder that Fire which causes Heat should not be hot it self yet there is as much Reason to believe that it is not as that a Sword which will cause Pain is not Pain it self For those who think that Fire which causes Heat is Heat it self take the Cause for the Effect and affirm it to be so Besides Heat being only a Sensation and it being impossible there should be a Sensation where there is no Sense it is impossible there should be Heat where there is only Fire and no Sense for it to work upon For Heat is not a Mode of Matter rarified and in Motion but an Effect of Matter so modified But say they it is impossible for us to think so truly if we are not directed in our Thoughts by Reason we may irrationally think that Matter in Motion which only causes Heat is Heat but if our Reason proceeds upon those Mediums which our Senses furnish us with and certainly we can on no other we shall easily be induced to believe that the Cause is not the Effect there being a great deal of Reason for us to believe so though none to the contrary When then I say that Heat is only produced one Way I mean that there is but one Way to modify Bodies so as to make them capable of causing Heat when they affect our Sensory And when I say that Heat is caused by putting the Parts of Matter into Motion I mean that a Power of producing Heat is caused so And when I say that Heat depends on the Effect that rarified Matter hath upon our Senses I mean it is caused by those affecting our Senses And because always when I have occasion to mention the Cause of Heat it would be too much Circumlocution to say the Power of causing Heat is produced so or otherwise I shall use the Word Heat sometimes to signify that Motion of rarified Matter which is sufficient to cause Heat and shall call that Motion Heat in respect of the Effects which it causes But to proceed to a further and more evident Proof That Heat or a Power to produce it is only caused one Way we are to consider how the Motion of Particles is carryed on in all those which Dr. Willis calls different Ways of causing Heat viz. per admotum Calidi Saline Corrosives Accension and even Fermentation and Putrefaction And first when Water is put over the Fire and heated per admotum Calidi the fine Particles of Fire penetrating the Vessel are imbibed into the Water and being fettered up and kept from flying away by the Parts of the Liquor put them also into a quick Motion from whence proceeds a sensible Heat In
sometimes so high a degree of it as actual Flame as when Spirit of Wine and Oyl of Turpentine are mixed together And that Heat proceeds from an Attrition of sulphureous Particles and their violent Motion I have not only brought Instances enough to make it appear but have sufficiently proved it before in my Answer to Dr. Willis's Opinion And now since not only Solid but also Liquid Bodies grow hot by an Attrition of their more volatile and sulphureous Particles betwixt the more gross ones and since there appears from what I have before said but one way by which all Bodies grow hot we must needs conclude that the volatile salino-sulphureous Particles of the Spirits grow hot by being ground betwixt the grosser Particles of Arterial Blood and that those by putting the whole Mass into a more violent Agitation cause the Heat of the Blood But some will perhaps say that in all those Phaenomena I have mentioned these grosser Parts of Matter which grind upon the sulphureous Particles are put into Motion by something else But they do not perceive how the grosser Parts of the Blood are put into Motion first To which I answer that the Particles of the Mass of Blood are put into Motion by that force which is always inseparably joyn'd with Circulation so that in a Man's Body as there is a continual Circulation of Humours so there is of Causes for the Fermentation in the musculous Glands is raised by the Mass of Blood grinding the Animal Spirits betwixt the Parts of it in which Fermentation a subtile Liquor is prepared which being forced into the Fibres of the Heart cause it to contract which Contraction forces the Blood and consequently the Nervous Juice through their distinct Vessels and so causes them again to meet and ferment a second time in the Glandules and as Circulation is preserved and carried on by the subtile Liquor which is continually prepared in this Fermentation so the Particles of the Blood are mixed with the Spirits and preserved in Motion by Circulation Having thus shew'd that the Heat of the Blood may as probably proceed from Attrition as Heat in any other Bodies since Heat is nothing else in respect of that which causes the Sensation than a quick intestin Motion of Parts and since those can be put into Motion no other way but by Attrition I should in the next Place prove that the Particles of refined and rarified Matter always expand and endeavour to fly away but being reverberated by the Opposition of those gross ones with which they swim their Motion is inverted and by that means much increased But it is so evidently True that it needs not for we always observe that where any two Bodies meet together and strike against one another that which is less yields to that which is most solid and makes the strongest Opposition this is manifest in Flame it self as also in the Expansion of Gunpowder for if a Gun be shot against a Wall the Flame of the expanded Gun-powder striking against it presently flyes back again and by mixing with that which immediately follows it encreaseth the force of it and for this Reason a Gun which is charged with a greater weight of Shot more forcibly recoils the Powder not finding free Liberty to expand but flying backward with a greater Force It is also further evident from the Reason which I have given why Nitre is beneficial-in continuing Flame and making it more vigorous The gross Parts of the Blood having thus put the Animal Spirits into a swift Motion and by inverting them in their Motion having caused them to encrease one anothers Motion the Spirits at last set upon the Mass of Blood and by breaking and dissolving the Particles of it rarifie them and cause them to expand also so the Rays of the Sun being in a swift Motion and gathered into a Point by a burning Glass grow more vigorous so as to dissolve and burn even solid Bodies and after the like manner Flame by the force of it subtilizeth and attenuates the Sulphureous Parts of it's Fuel neither does it only rarifie and expand the Sulphureous Matter of it's Fuel but also carries violently the Ashes of the calcined Matter along with it where it may be observed that as the Particles of Animal Spirits are not in so strong a Motion as those of Fire so the Particles of the Blood are moved with a more easie force then Ashes which are far more Solid But for a further Proof that the Mass of Blood grows hot in a Natural state by the Methods and Ways which I have endeavoured to explain I shall in the next place prove that the Animal Spirits being put into Motion according to their different Quantities differently expand themselves and exagitate the Mass of Blood and put it's Parts in a more violent or weaker Motion and consequently encrease or diminish the Heat of it And this is easily manifest if we do but observe that young healthful People whose Nerves as well as the Fountains from whence they spring are full of and abound with Spirits are always of a more brisk and vigorous Heat then People of a declining Age whose Nerves are less plentifully stocked with them But it is not only observable in People of different Ages but also in different Constitutions that as the Pabulum of the Animal Spirits is more plentiful and yields a more constant and large Supply so the Heat of the Blood is more powerful and intense as in cold and Phlegmatick Constitutions where the Mass of Blood abounds with dull Phlegmatick Humours or Acid and Austere Juices of too close and compact Texture and a large Supply of Spirits is denyed the Blood is not of so hot a Temper as in Cholerick Constitutions whence it evidently appears that the Heat of the Blood depends on the Vigour of the Animal Spirits for if when the Vessels are filled with Spirits and plentifully supply the Glands that Fermentation is raised higher and by that means the Heat of the Blood is accordingly encreased it is a most certain Conclusion that the Heat of the Blood depends upon the Effects that the Animal Spirits have in that Fermentation Which is further confirmed by the common and constant Practice of all Physitians for when the Natural Heat as some call it is languid and weak and almost extinguished they give such Medicines as increase the Heat of the Blood by renuing the Vigour of the Spirits whence to People that are almost a dying their Spirits being dulled or exhausted nothing is more usual then to give them Spirits of Harts-horn or of Armonick-salt or some other Saline or Sulphureous Spirits which presently joyning with those in the Nerves encrease the Fermentation in the Glands and by that means put the Mass of Blood into a more swift Exagitation and by raising the Fermentation not only renue Circulation but the Heat of the Blood On the contrary when the
inflames the Blood of those that are of a tender and open Constitution much sooner then phlegmatic and melancholly Peoples and as the former is evident in those that are subject to Fevers so the latter is not less remarkable in those of cold Constitutions for to encrease the natural Heat of their Blood when it is too much depressed it is not only necessary to take away some of those crude Humors which stuff up the Vessels and too much depress the Spirits but also by volatile and spirituous Medicins to encrease the Spirits and at the same time to exalt and spiritualize the Blood by absorbing Acids and exalting the volitile and subtile Parts to render them predominant Moreover that the Animal Spirits do not only according to their different Quantities and the different State of the Blood variously exagitate and encrease the Heat of it but also according to their different Degrees of Activity and Strength is put beyond Dispute by the different Effects that Spirit of Wine or Aqua-mirabilis hath upon us from Sack which any one that does but taste must soon acknowledg It remains in the next Place that I should shew how far the Animal Spirits are Active and how far Passive in causing these Effects as well as the Blood which evidently appears from what I have already said For when the Spirits and Blood are forcibly driven together then they seem to be mutually Active and Passive the Spirits being forced betwixt the Particles of the Blood and vice versâ but the Animal Spirits being ground and rarified betwixt the Particles of the Blood are so far Passive but being by that means expanded by a powerful expansive and elastic Motion exagitate the Mass of Blood and by that means are active so that throughout the whole Process it appears that neither of them singly are altogether Active or Passive but both mutually and by turns From what I have said it appearing how the Heat of the Blood is caused I shall in the next Place proceed to shew how it is continued which will be sufficiently evident if we do but consider that the Animal Humors are in a constant and continual Circulation for since all the Blood in a Man's Body is allowed to circulate through the Heart several times in an hour and that the Blood from thence is continually forced and dispersed through the Parts of the Body and so great a Quantity of Blood is at one Pulsation laid down in the whole Habit of the Body and ferments at the same time with the Animal Spirits there must needs be raised in the Blood a considerable Heat or in other Words the Parts of the Blood and Spirits must of necessity be put into so swift and intense a Degree of Motion as to enable them to produce an extraordinary Heat when they strike upon our Sensory The whole Mass then circulating thus through the Extremities of the Vessels there is not only a great deal of Blood fermented every Pulsation but also by a continual Succession of Pulsations the Blood being forced into a Fermentation by the expansive Motion of the Spirits is by that Means preserved in a constant and continual Heat But I know here will some Difficulties offer themselves and perhaps some may doubt whether the Blood only ferments in the Extremities of the Vessels and not in the Vessels themselves and since it is hot in the Arteries before it be laid down in the Glands as well as in the Veins after Fermentation they may think it reasonable to conclude that where-ever it ferments there it 's Fermentation is caused and because there is a great deal of Blood betwixt their Extremities and the larger Vessels they may think that the Fermentation in the Extremities cannot be the Cause of the Heat of the Blood in the larger Vessels it being an old Maxim that tolle Causam tollitur Effectus which is as much as to say the Cause immediateley goes before the Effect Another Doubt which perhaps may arise will be that since I affirm that there is such a mutual Action and Passion in the Attrition of these Humors in order to a Fermentation whether Fermentation can be carried on in such a manner in so short a Time as the quick Circulation and consequently Protrusion of the Blood from the Extremities of the Vessels admits As to the First To wit whether the Fermentation of the Blood be caused in the Extremities of the Vessels or the large ones I affirm that it is chiefly and originally caused in the Extremities of the Vessels just where the Nerves and Arteries meet and where their contents are first mixed together and that the Fermentation in the larger Vessels is but a Continuation of the Effects of the same Original Cause and as when Water is heated over a Fire that Part of the Water which is at the top of the Vessel that contains it is as truly said to receive it's Heat from the Fire as that in the Bottom so that Blood which is in the Body of the Vena Cava is as really put into a Fermentation by a Mixture of Spirits as that in the Extremities for the Animal Spirits being mixed with the Arterial Blood in the Glands and ground betwixt their Particles and being by that means put into an elastick and expansive Motion they powerfully ferment and exagitate the whole Mass This Blood then so fermented is thrust out of the Glands by a Succession of Matter forced in the next Pulsation and so forwards by the next successively till it be driven into the Vena Cava Now as soon as it is thrust out of the Glands those Spirits which did so powerfully expand before and the remaining Part of them which are not mixed with that subtile Liquor that circulates through the Fibres being yet further corroded and exagitated by Pulsation still continue to expand themselves and by that means keep the Blood in a continual Heat And the Animal Spirits being yet more expanded do not only continue but in a great Measure encrease the Heat of it But these Spirits being frequently opposed in their Expansion by striking against the Blood loose in a short time a great deal of their Vigor the Particles that before grund the Animal Spirits betwixt them obstructing their Motion and the Animal Spirits not being able any longer to keep them in a just Motion sufficient to continue the Heat which is Natural to human Blood they are as if it were linked and fettered up betwixt those grosser Parts are incorporated into one Substance with them which is the Reason that the Blood by frequent Circulations is ripened and digested and for this Reason the flesh of a Hare grows tenderer by being coursed along time The Blood being thus impregnated with Animal Spirits and by that means wanting Spirits in a free and strong Motion would by degrees grow cold but the Intervals of time while the Blood moves from the Extremities of the Vessels to
except by hindring the fierce volatile Parts which ought to be dissipated from flying away through the Pores of the Skin which being increased thereby to too great a Quantity exagitate the Mass of Blood too much From hence it breifly yet plainly appears that the Nitre of the Air alters the Colour of the Blood and also serves to temper the Heat of it I shall now consider what Effects it hath upon the serous Lympha and if we may but compare it to Milk which differs only from Chyle by being less impregnated with Oyl it will be manifest that it precipitates the Watry Parts of the Serum which joyning with the fixed Salts of the Blood dispose them to be separated and carryed off by the Urinary Passages This is so strongly proved both by Non-Naturals and Medicine that to deny it would be to contradict Reason and plead Ignorance of those Things it is almost impossible for us not to take notice of for if we sit by a Fire in a close warm Room and drink a good Quantity of Beer which is not very strong it presently if we go into the cold Air runs off by Urin besides nothing in Medicine is a more known and common Diuretick than Sal. Prunel which is purified Nitre concentered and condensed and it is no less observable in an Experimental Observation of the Famous Dr. Lower's who in his Book de Corde takes notice that as much Serum is precipitated in a short time after we rise from Bed as in the whole night when we are less affected with the ambient Air. How Beneficial Nitre is in Precipitating the Serum of the Blood and what Advantages the Animal Oeconomy receives thereby I shall not now enquire yet how inconsiderable a Part of it's Office soever it may seem yet if it be duly weighed it will appear very useful From what I have said concerning the Alterations made on the Blood and it 's Serum I should now proceed to consider how they influence each other but since as much as is sufficient for our present Purpose may be gathered from what hath gone before it being plain that the cool Serum will help to temper the Heat of the Blood and vice versa I shall wave a further Notice of it here and should rather shew That The Lungs perform many more and considerable Offices in respect of each Part But to explain them would not only be to treat of the Lungs but the whole Body and the Use of all the Parts which being not my present Design I shall omit giving an imperfect Account of them because they are so interwoven mutually with one another that they cannot truly be understood without an Account of the whole FINIS Our Knowledg in Philosophy is limited to a small Part of the Creation Which is furnished with Objects too copious for our Senses Of which at the best we have but an imperfect Knowledg The Pursuit of Knowledg very desirable Especially of that which is most Advantagious There is more Reason to expect Truth and Certainty in the Microcosm than the Macrocosm Where it is easily attained The Heat of the Blood not obscure in respect of it's Cause Both Antients and Moderns have differed as to the Cause of it The Opinions of the Antients very Superficial and Insatisfactory Dr. Willis ' s Opinion considered Who asserts that there are three ways by which Liquids grow hot And that the Blood grows Hot by Accension To which it is answered that there is but one way in Philosophy by which all things grow hot Several degrees of Heat differ only in Degrees of a peculiar Power to cause Heat And Fire which is the highest is rarified Matter in a swift Motion which Masked in different Subjects affects not our Sight Heat is not actually in the Body that causes it but potentially because that Body hath a power to cause such a Sensation Heat is only a Sensation which is actually where there is Sense to perceive it That Heat is only produced one way further proved Viz. by putting the Parts of Matter into Motion A seeming Objection answered His Comparison of the Bloods Accension with Flame considered There are several degrees of Heat produced without visible Flame Nitre makes up no part of the Flame The Nitrous parts of the Air promote Flame by keeping i'ts Matter from dispersing too soon Wherefore Fire burns better in the Winter than in the Summer Why a Candle in a Glass Globe is extinguished by extracting the Air. His Comparison of extinguished Flame compared with the Death of an Animal considered Nitre does not promote the Heat of the Blood but rather depresses For in Liquids the volatile Parts are sufficiently opposed by the Parts of the Blood and kept from flying away Blood may grow hot without a Sulphureous Pabulum His Comparison of the Recrements of Flame and of Blood considered Which appears widely inconsistent First because that Juice that sweats through the Coats of the Trachea and the Skin is not Recrementitious And the Fuliginous Effluviums of Fire are Recrements Secondly because the former if not carried of encrease it But Smoak extinguishes Fire Smoak is not altogether an Effluvium of Flame Smoak thus compounded A Digression in which is given the Reason why Flame Ascends rather then Descends Which is because it hath less Opposition in it's Motion that way Because the Air the nearer to the Center makes stronger Opposition than that above Which is proved by these Experiments It is also proved by the Expansion of Gunpowder The Motion of Flame downwards is a natural Motion in Philosophy Diemerbroek's Opinion examined Dr. Henshaw ' s Opinion considered Antient and Modern Writers have rather disputed about the Vse of Words than much difference observable in their Opinions The Reason why Heat affects our Sensory does not shew how it comes by that Power The Blood grows hot by Attrition the Consequence of which is Fermentation Attrition and the consequence of it both to be signified by the Word Fermentation How far the Heat of the Blood proceeds from Pressure and Mixture To dispute about Words is not material in an Enquity after the causes of Things The whole Body is made up of Vessels and Humors contained in them By what means the Spirits and Blood are mixed in order â—o a Fermentation Animal Spirits demonstrated In the substance of the Brain Viz. that Mucilaginous oily Moisture which we call Brains An Objection Answered That it is the most spirituous Part of the Blood and consequently Animal Spirits proved That oyly Substance is capable of performing all those Actions which we can suppose the Animal Spirits do Another Objection answered That these Spirits are in a constant Motion proved The Nature of the Animal Spirits considered The Reason of the Heat of the Blood explained How it's Heat is promoted The Heat of the Blood varies according to the different Quantities of them It varies also according to the sharpness of those Humors that put the Animal Spirits