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
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
sulphureous oyly Matter is farther manifest by exposing the Brains of any Animal to the Air because they presently grow rancid and fetid It appearing then that the Animal Spirits are an oyly mucilaginous Substance abounding with the most volatile Salts and Sulphurs of the Blood and that they are in a continual Circulation from the Brain and spinal Marrow through the Branches of the Nerves and that being forcibly laid down in the Glands there meet with the Arterial Blood I shall next endeavour to shew how the Heat of the Blood is carried on and continued which I conceive to be after this Manner These oyly Salino-Sulphureous Spirits being violently driven through the Nerves meet with the Arterial Blood in the Glandules and these two Liquors being forcibly driven one against another the Particles of them are intimately mixed together by which means the Animal Spirits are as if it were ground and rubbed betwixt the fixed and more solid Particles of the Blood whereby they are minutely dissolv'd and being put into a swift intestin Motion they endavour powerfully to expand themselves and to fly away but being held in and reverberated by those grosser Particles their Motion is by that means inverted and that Force which if they had but Liberty would be lost in a further Expansion being inverted and driven forcibly upon the other Particles they mutually increase and promote one anothers Motion by which Motion the Blood when it affects our Sensory causes us to perceive Heat In carrying on of which it is to be observ'd that the Animal Spirits being thus accidentally expanded and put into Motion by the grosser Parts of the Blood and being thus held in and struck back by them does not only by that Means fly back and increase each others Motion but also hurry the grosser Particles of the Blood along with them and so increase their Motion and by striking against them and knoking them together break them as if it were into smaller Parts and consequently ratify and expand Them also It is further to be observed that as these Spirits are more or less in quantity so the gross Parts of the Blood grinding them together and putting them in Motion they more powerfully or less vigorously expand and moving accordingly digest and rarify the Mass of Blood to a higher or lower Degree and consequently put the Parts of it into a stronger or weaker Motion We may further take Notice also that the sharper the Particles of the Blood are so they corrode and grind the Spirits into Parts with greater Violence and consequently sharpen their Motion Again when the Mass of Blood is very full of and plentifully abounds with volatile Salts Sulphur the Particles of it are with less difficulty put into Motion by the Spirits and joyning with them encrease their Motion and on the contrary when the Mass of Blood is more dull and phlegmatic it neither so powerfully grinds the Animal Spirits nor is so easily put into Motion it self Furthermore The Animal Spirits do not only according to their different Quantities differently exagitate the Mass of Blood but also according to their different Degrees of Activity whence the more volatile and stronger the Spirits are the more conspicuous are their Effects Lastly we may take Notice that neither the Animal Spirits nor the Mass of Blood are altogether Active or Passive in producing these Effects but mutually both of them and by Turns Having premised this short Account of the Heat of the Blood without any manner of Proof to the end that we might have a more clear and entire View how it was caused without the Interruptions it would have made to prove every Paragraph as I proposed it I shall now proceed to a Proof of what I have proposed collectively for the Material Formal and Efficient Causes of it And First That the Animal Spirits and Arterial Blood are both forcibly laid down in the Glandules I have given sufficient Reasons to evince in my Treatise of Muscular Motion and have given further Proof of it here To prove then that the Heat of the Blood does proceed from that Fermentation it being necessary to explain the mechanical Motion of the Parts of those Liquors that work mutually one upon another I shall in the next Place shew that the Heat of the Blood is caused by such a mechanical Motion of Parts as I have before mentioned That the Animal Spirits then are forcibly driven against the Arterial Blood is so self evident that it needs no Proof and if so it must needs follow that the Particles of the one will be intimately mixed with the other and it is undeniably True that the Animal Spirits will by that means be ground and rubbed betwixt the Particles of the Blood which are in Motion and amongst which they are mixed and the Animal Spirits being of an oyly Salino-Sulphureous Nature will consequently be expanded and rarified and put by that means into a swifter degree of Motion is evident whether we consider the Effects that solid or liquid Substances have on one another when in Motion for Amber by a violent Attrition of it's Parts against a woollen Cloath feels hot the Sulphureous fat Effluviums being by that Attrition encreased and caused to fly out in greater Quantities It is evident also by striking of a piece of Flint against Steel that the sulphureous Particles of the Flint being as if it were disyok'd from the Embraces of the more firm and solid Particles of the Stone and being rubbed and ground betwixt them are put into a violent Motion which causes them so much to rarify and expand that whenever they affect our Sensory they cause that Sensation we call Heat which is accordingly violent as their degrees of Motion are more or less intense and so Amber by a mild Attrition is moderately warm and by a violenter more sensible Again It is observable in the turning of any large and weighty Wheel where the extraordinary Weight makes such a forcible Pressure of those Parts that lie about the Axle-tree that by strong and frequent Attritions of the Parts together the crude Sulphur which is fettered up in the Substance of the Wood is by degrees loosned and dissolved and being put into Motion is rarified and expanded which being still ground betwixt the solider Parts of the Wood it's Parts are yet put into so strong a Motion that they break and dissolve that solid Substance and by creating a Flame consume and burn it In like manner the Particles of Fire being applyed to Gunpowder by dissolving and grinding of it's Parts in Pieces and putting them into a violent Motion cause them to expand and explode But not only solid Bodies cause Heat by grinding of volatile sulphureous Particles betwixt them and so by putting them into Motion but also the Patticles of Liquids by grinding one upon another put themselves into so violent a Motion as not only to cause Heat but
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
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
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
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
into Motion The volatile Salts and Sulphurs in the Mass of Blood make it more apt to be fermented Which is more or less promoted according to the different Degrees of the Activity of the Spirits Neither the Animal Spirits nor Arterial Blood are wholy Active or Passive That the Heat of the Blood proceeds from Fermentation proved That Heat proceeds from Attrition further proved Not only solid Bodies but also Liquids grow hot by an Attrition of their Particles The Particles of 〈◊〉 of these Humours are first put into Motion by Circulation That the Particles of refined and rarified Matter are by an Inversion of their Motion put into a higher degree of it proved How the Animal Spirits rarifie the Blood That the Animal Spirits according to their different quantities differently exagitate the Mass of Blood prov'd By the observation of People of different Ages As also by different Constitutions And the Practical Part of Physick How Spirit of Harts-horn raises the Pulse That the Spirits according to their different Degrees of Activity variously exagitate the Mass of Blood The sharper the Particles of Blood are the more they corrode the Spirits and put them into Motion The Keason of flushing heats in the Scurvy Proved by comparing the Nature of the Medicines that oppose it and correct it That as the Blood as more or less Volatile it's Parts are put more or less easily into Motion proved And that it is differently promoted according to teir different Degrees of Activity of the Spirits How far the Blood and Spirits are Active or Passive How the Heat of the Blood is continued Some Objections considered and answered The first Objection answered viz. whether the Heat of the Blood be chiefly caused in the Extremities of the Vessels The Reason why the Heat of the Blood in time decays And that Reason proved How Fermentation is carried on in a dying Body and the Reason why it ceaseth when it is quite dead Another Argument to prove that the Heat of the Blood depends on and is caused by Attrition Fermentation Circulation mutually depend on one another The second Objection answered viz. That Fermentation may be performed in so short a time as the Circulation of the Blood admits The Blood is more powerfully fermented in the substance of the Heart than in any proportionable Part of the Body besides Fermentation is not only promoted in the Muscular Parts but also in the internal Bowels Three things requisite to continue the Heat of the Blood The Vse of the Lungs in Respect of the Soul Is to express all it's Conceptions and Reasoning Why the Lungs ought to be in a continual Motion is because It carries off that Superfluous Moisture that supplies them And that their voluntary Motion might less Preternaturally affect our Bodies What Effects it causes when too thick and also why thick foggy Air is troublesom to some People The Vse of the Lungs in respect of the Body Seems to be to perform the Office of another Heart By helping the Blood to force violently enough into the Cavities to distend them against the next Contraction How stopping the Breath of an Animal kills it Why by permitting it to breath again the Circulation of the Blood is renued How the Motion of the Heart is promoted in an Infant unborn The Office of the Lungs is partly voluntary partly involuntary What Effects the Air hath upon the Mass of Blood In respect of it's Colour Nitre depresses the Heat of the Blood What effects Nitre hath upon the Serum of the Blood