Experimental notes of the mechanical origine or production of fixtness.

EXPER. VII.

THis brings into my mind, that though Gunpowder seems to be of so igneous a nature, that, when 'tis put upon a Coal, it is turn'd pre∣sently into flame capable of promo∣ting the deflagration of the Char∣coal, and kindling divers bodies it meets with in its way; yet if some ounces of Gunpowder reduced to powder be thrown into four or five times as much water, it will very manifestly impart a Coldness to it, as experience made with, as well as without, a seal'd Thermoscope has as∣sured me.

This and the foregoing Experi∣ment do readily suggest an Inquiry into the nature of the Coldness, which Philosophers are wont to op∣pose to that which immediately and upon the first contact affect the or∣gans of sense, and which therefore they call Actual or Formal.

The success of this Experiment upon a second trial serv'd to confirm it, which is the more strange, because I have found, that a small quantity of Oyl of Vitriol, not beforehand mingled with water, would produce a notable heat in its conflict with a small portion of just such Salt as I em∣ployed before (both the parcels ha∣ving been, if I well remember, ta∣ken out of the same Glass.) And this heat did upon trial, made with the former Thermoscope, make the tincted Spirit ascend much further than the lately recited Experiment made it subside.