I have the honour to be, Sir, &c.
BENJ. FRANKLIN.
P. S. I have heard, that chymists can by their art decompose stone and wood, extracting a considerable quantity of water from the one, and air from the other. It seems natural to conclude from this, that water and air were ingredients in their original composition: for men cannot make new matter of any kind. In the same manner may we not suppose, that when we consume combustibles of all kinds, and produce heat or light, we do not create that heat or light; but only decompose a substance, which received it originally as a part of its composition? Heat may be thus considered as originally in a fluid state; but, attracted by organized bodies in their growth, becomes a part of the solid. Besides this, I can conceive, that in the first assemblage of the particles of which this earth is composed, each brought its portion of the loose heat that had been connected with it, and the whole, when pressed together, produced the internal fire that still subsists.
FOOTNOTE:
[21] In an American periodical publication, this paper is said to have been so endorsed in Dr. Franklin's hand. We extract the paper itself, from the Transactions of the American Philosophical Society, where it was read Nov. 21, 1788. The two papers that follow it are from the same work, and were read in the Society the preceding day, and the other Jan. 15, 1790. Editor.
TO DAVID RITTENHOUSE, ESQ.
[New and curious Theory of Light and Heat.]
[No date.]
Universal space, as far as we know of it, seems to be filled with a subtle fluid, whose motion, or vibration, is called light.
This fluid may possibly be the same with that, which, being attracted by, and entering into other more solid matter, dilates the substance by separating the constituent particles, and so rendering some solids fluid, and maintaining the fluidity of others; of which fluid, when our bodies are totally deprived, they are said to be frozen; when they have a proper quantity, they are in health, and fit to perform all their functions; it is then called natural heat; when too much, it is called fever; and when forced into the body in too great a quantity from without, it gives pain, by separating and destroying the flesh, and is then called burning, and the fluid so entering and acting is called fire.