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TO make it appear, That Heat and Cold,* 1.1 which are generally esteemed two of the most active Qualities, may be me∣chanically produced or destroyed by a bare change of Texture, or by Alterations otherwise mechanically brought on, without the assistance of the Peripatetick Doctrine of Sub∣stantial Forms, or the Hypostatical Principles of the Chymists; I shall subjoin the following Experiments.
* 1.2Having dissolv'd Sal-Armoniack in four times its quantity of Water, whilst the Mixture was a stirring, and the Salt dissolving, the Water ac∣quir'd such a degree of Coldness as to congeal Water, with which the Bottle was wet on the outside, into Ice; but after a Dissolution of that Salt, the Coldness gradually declin'd.
To try whether the Coldness which the for∣mer Mixture acquir'd, did not rather proceed from the Effect which the Water had on the saline Parts than on the Dispersion of those Sa∣line Parts through the Water; I immerg'd a Thermoscope in Water, which was so warm as to make the Spirit of Wine ascend; but the same Thermoscope being removed into Powder of Sal-Armoniac warm, it ascended much faster; yet the Weather-glass being conveyed into the Liquor again, and the Salt poured into it, it speedily began to subside, and sunk a Division and ¼ below the Mark it stood at in cold Wa∣ter, remaining at that Station a considerable time. And the same Experiment succeeded when tryed a second time.
Having immersed a Thermoscope in Spirit of Salt, I pour'd Spirit of fermented Urine leisure∣ly upon it, and observ'd, that the Mixture by a
mutual Conflict growing hot,* 1.3 sensibly raised the Spirit of Wine; which being done, and a Salt obtained from the evaporated Mixture, not much unlike Sal-Armoniack, it was carefully dri∣ed, and being put into Water, in which a Ther∣moscope was placed, upon its dissolution, whilst it was stirred about, the Spirit of Wine in the Weather-glass gradually subsided.
* 1.4Having poured as much rectify'd Spirit of Roch Allom into a wide mouth'd Glass, as was sufficient to cover the globulous part of a Thermoscope, when the Spirit of Wine was equally cooled with the Air about it; we poured into it a vo∣latil Salt, obtain'd by Sublimation from Sal-Ar∣moniack, and a fixt Alcali; and tho' upon the joint Action of these two Bodies, a considerable Noise was raised, with Bubbles and Froth; yet the Spirit of Wine began to subside, and conti∣nued to do so, 'till the Spirit of Allom was wholly glutted with the volatil Salt, the whole Descent being the length of an Inch.
From this Experiment and the foregoing it appears, That when Alcalies and Acids produce Heat, upon a mutual Conflict which ensues their Mixture, they have not that Effect precisely consider'd as such; since it is evident, that an urinous Salt mixed with an acid Spirit, viz. of Roch Allom, produces Coldness; and not a true Effervescence.
* 1.5One part of Oyl of Vitriol being shaken toge∣ther with twelve parts of Water, the Mixture acquir'd a little Warmth; but when it was cool, being poured into a wide-mouth'd Glass, and a Thermometer immersed in it, when the Liquor in the Thermoscope was equally cool with the external, we poured in a sufficient quantity of Sal-Armoniack to glut the Acid: The effect of which Mixture was, that upon a cold Ebullition the Spirit of Wine descended an Inch.
* 1.6Tho' Salt-Peter usually produces a Coldness in Liquors, yet eight Ounces of it being mixed with six of Oil of Vitriol, the Mixture acquired a considerable degree of Heat, emitting Fumes copiously.
* 1.7Though Gun-powder be a Body so inflamma∣ble, yet it evidently imparts a Coldness, if mixed with Water. If a small quantity of Oil of Vi∣triol be mixed with the Salt formerly made use of, before the Oil hath been mixed with Water, it acquires a considerable degree of Coldness.
* 1.8Potential Coldness is usually looked upon to be a Quality so absolute, as not to be explicable without the Doctrine of Substantial Forms: But it will easily appear, That it may, without any great difficulty, be clearly explained by Me∣chanick Principles; if we consider, that the Fi∣gure, Shape and Texture of Bodies may be so contrived as to lessen the usual and natural Agi∣tation of Humors about our Sensory, and con∣sequently, the Perception of this Imminution, may cause such a Sensation as is usually term'd Potential Coldness; which account being allow∣ed, it will follow, That Potential Coldness is only a relative Quality, depending on the dispersion of the Agents through the Bodies to be cooled by them: According to which Notion, the cold Fitts in Agues may easily be conceived to arise from an Intermixture of the Parts of some clam∣my Matter, which before a Dissolution, were unable to cause any considerable Effect in the Mass of Blood; but presently after being mixed with the Blood, produce such a change in the Motion of its Parts, as affects the Sensory with such a Sensation as is usually esteemed Potential Coldness; which Sensation may not only be so produced in Agues, but by a like Cause in other Distempers, and in several Parts of the Body, as in Hypochondriack and Hysterical Cases. To render which Account more probable, I shall subjoyn, That I have learnt by the Effects of Poysons, that the small Parts of them being in∣terpersed
through the Parts of Humors previ∣ously disposed, may cause a notable Refrigeration: And I my self have prepar'd a penetrating Chy∣mical Liquor, a Drop of which being given to an Animal, would cast him into a seeming Sleep; and a little larger Quantity, being by Mischance applyed to an akeing Tooth, gave the Person a sort of trembling, and almost an universal Re∣frigeration. And that Coldness may be produ∣ced by the Mixture of some subtile Parts of Mat∣ter with the Mass of Blood, appears from the following Histories. Famulum habui (says Be∣nivenius, Cap. 56. Abditorum apud Schenk. Lib. 7. de Venen. Obs. 24.) qui a Scorpione ictus, tam subito ac tam frigido Sudore toto Corpore perfusus est, ut algentissima Nive atque Glacie sese opprimi quere∣retur, verum cum algenti illi solam Theriacam, ex Vino potentiore exhibuissem, illico curatus est. And to this I shall add another, related by A∣matus Lusitanus, Cent. 6. Obs. Vir qui a Scorpi∣one in Manus digito punctus fuit, multum dolebat, & refrigeratus totus, contremebat & per Corpus dolores, Cute tota quasi aut puncta, formicantes pa∣tiebatur, &c.
* 1.9Whether such Refrigeration depends on a sort of Coagulation of the minute Parts of the Blood, or whether it may be produced by a dif∣ferent Determination of the motion of the Parts of those Liquors as to the Lines they move in, I shall not now examine; but shall rather offer it to be considered, since the internal Constituti∣ons of several Parts of the Body are different from each other, and since the Size and Textures of seve∣ral Agents are also various, whether they may not upon that account have different Effects upon
distinct Parts of the Body, for all the Qualities of such Agents do not wholly depend on the Acti∣on of the Corpuscles of the Medicine only; but depend on some adventitious Qualities, which they acquire by being mixed with particular Hu∣mors and which they may dispose to be more or less worked upon, by the other Efficients of Heat or Cold.
And these Conjectures may not be render'd a little probable, by observing, That tho' Spirit of Wine inwardly taken causes Heat; yet exter∣nally it abates the Heat of inflamed Parts; but hath different Effects on a tender Eye: And though internally five Grains of Camphire may diffuse Heat through the whole Body, yet ex∣ternally it is used in refrigerating Medicines.
How far these Observations may be of Service in determining whether Camphire, &c. be hot or cold, I shall leave to Physicians to consider, and shall here only offer in Proof, That Potential Coldness is only a relative Quality, the follow∣ing particulars, viz. That from the VI. and VII. Experiments it appears, that according to the Dispositions of Bodies to be worked on, the Agent may have different Qualities: As Fumes of Lead may coagulate Mercury, tho' it hath not a like Effect on other Liquors: And further, al∣though Sal-Armoniack and Nitre be, when sepa∣rate, cool, and tho' the latter melted in a Cru∣cible takes not Fire of it self, yet upon an addi∣tion of Sal-Armoniack it flashes vehemently. But I shall leave this Digression, and proceed to Ex∣periments about Cold.
* 1.10To make it appear, how much Motion and Texture may contribute to the Production of Cold, we gradually added twelve Ounces of Wa∣ter to an equal quantity of Sal-Armoniack; and whilst upon a Dissolution of the Salt, the Wa∣ter became cold, we poured in twelve Ounces of Oyl of Vitriol, upon which the Mixture be∣came hot; where it is not a little strange, that though Sal-Armoniack in either of these Liquors produces Cold, yet a contrary Effect should happen upon its Mixture with both together: The Reason of which could be no other but that the Heat produced by the two Liquors over∣powred the Degree of Cold, which the Salt was able otherwise to produce.
The Effects of the same Mixtures are so un∣certain sometimes, that I have observed, that having placed a Thermometer in eight ounces of Spirit of Verdigrease, and gradually put in two ounces of Salt of Tartar, after some time, the Ingredients having worked upon each other with a copious Froth and a hissing Noise; the Bottle was something warm, and the Liquor in the Thermometer raised: Yet another Salt being mixed with Salt of Tartar, and Spirit of Verdi∣grease prepared without Spirit of Vinegar, and Spirit of Wine poured upon it, instead of an In∣calescence, a considerable degree of Coldness would be produced.
Oyl of Vitriol and Water shaken together, upon an Addition of Sal-Armoniack, acquire a sort of Goolness; but if Oyl of Vitriol and the Salt be first mixed, upon an Affusion of Water they become hot: And tho' Salt of Tartar grows hot in Water, yet the Caput Mortuum of Salt of Tartar and Cinnabar, distill'd in a strong Fire, produces no Heat, notwithstanding a hissing Nolse like that of Quick-lime succeeds its Immersion.
* 1.11That the artificial Production of Cold may be obstructed by an Indisposition in the Pati∣ent, to be acted on by the grand Efficients of Cold, I have learned by several Observati∣ons; and particularly by noting that tho' Oyl of Vitriol be so fiery a Liquor, as in some measure to have the Effects of Fire it self, and to dissolve Ice sooner than Spirit of Wine; yet a Pound of choice rectified Spirit of Wine being put into a Bottle, except a little at the Top, it was wholly coagulated into a consistent Mass like Ice, notwithstanding the Glass stood in an Elaboratory in which that Oyl was never at any other time observed to congeal. And this Phe∣nomenon was the more remarkable, because the Oyl continued in that state, when the Weather was too moderate to be the cause of such an Ef∣fect; on the contrary I have observed, that Oyl of Anniseeds, which usually coagulates with a less degree of Cold than Water, continued undi∣sturb'd and transparent, without the least Coa∣gulation, in a very frosty Season; and the like
we have observ'd in Camphire reduced to an Oyl by some Nitrous Spirits.
But to conclude this Section; If Heat depends on a brisk agitation of the Particles of the Hu∣mours about our Sensory, and if Cold be an Effect of a less degree of Motion than that about our Sensory; it appears that an Imminution of that Motion which is requisite to produce Heat, is sufficient to cause the contrary Quality, viz. Coldness. And tho' Cold seems in such a Sense a privitive Quality, yet in as much as the A∣gent which causes that Imminution acts positive∣ly upon the Parts in motion; it may be esteem∣ed a positive Quality, tho' in respect of our Sensory it is but a relative one, as luke-warm Water will appear hot or cold, as the Hand im∣mersed in it hath either been exposed to an intense degree of Cold or Heat. And indeed the princi∣pal mistakes which sometimes occur in Discourses concerning Cold, happen upon the account of the ambiguity of that Expression, which sometimes is used to signifie the Idea imprinted on the Mind by the advention of an external Object; some∣times for an Imminution of such a Motion as causes Heat, and sometimes for the Object upon a contact of which we perceive Cold.
Experi∣ments con∣cerning the Mechanical Origin of Cold.
A solution of Sal-Ar∣moniac.
A Thermo∣scope im∣mers'd in a Mixture of Spirit of Salt and fermented Urine.
Another immersed in Spirit of Roch Allom, &c.
A Thermo∣scope in a Mixture of Oil of Vi∣triol and Sal Armon.
Heat pro∣duced by a Mixture of Salt-peter and Oyl of Vitriol.
The effect of Gun-pow∣der mixed with Water.
Potential Coldness Mechani∣cally ex∣plained.
What Re∣frigeration depends on.
Oyl of Vi∣triol poured upon a So∣lution of Sal-Armon.
A coinci∣dent Dispo∣sition be∣twixt the Agent and the Patient requisite to the produ∣ction of their Effects.