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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 presently into flame capable of promoting the deflagration of the Charcoal, 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 assured me.

This and the foregoing Experiment do readily suggest an Inquiry into the nature of the Coldness, which Philosophers are wont to oppose to that which immediately and upon the first contact affect the organs of sense, and which therefore they call Actual or Formal.