The works of the Honourable Robert Boyle, Esq., epitomiz'd by Richard Boulton ... ; illustrated with copper plates.

EXPERIMENT X.

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.

That 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.

Notes

• A coinci∣dent Dispo∣sition be∣twixt the Agent and the Patient requisite to the produ∣ction of their Effects.