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[[right corner]] (160 [[/right corner]] [[left margin]] [[underline]] Air,[[/underline]] and not [[underline]] heat, [[/underline]] the [[underline]] principal [[/underline]] cause of evaporation. Sec II. p. 105. [[/left margin]] Hugh Hamilton D.D. F.R.S. Professor of Philosophy in the University of Doublin, in his 2. [[superscript]] d [[/superscript]] Edit. of his [[underline]] Philosophical Essays, [[/underline]] 12. [[superscript]] mo [[/superscript]] 2.[[superscript]] s [[/superscript]] 6.[[superscript]] d [[/superscript]] 1769. has the following. [[strikethrough]] experiment: [[/strikethrough]] It is generally allowed that heat or fire keeps bodies fluid, by causing their particles to repel each other; and he shews that all degrees of heat, above that which is necessary to keep them fluid will separate from their surface (except mercury and those which are viscid) some kind of vapour or steam, which for the sake of distin [[strikethrough]] ction [[/strikethrough]] guishing it from that raised by the solvent power of the air, he calls an [[underline]] effluvium. [[/underline]] As this [[underline]] effluvium [[/underline]] visibly rises in great abundance from hot liquors, when ever the pressure of the atmosphere is taken off, he thinks there is reason to suppose that it will rise more copiously from colder liquors, under the same circumstance, and to prove it he brings this experiment. Having placed four equal quantities of spirits of wine, in a large room without a fire, where they remained 24 hours; the first under a receiver full of air: the second, under one only half full of air: the third, in air rarified 42 times: and the fourth, in open air, he found that the spirit, inclosed in the receiver full of [[strikethrough]] air [[/strikethrough]] confined air, had lost a quantity expressed by the number 1; that the spirit, inclosed in air rarified one half, had lost 1 5/7 such parts; that in air rarified 42 times 6 parts; and that in the open air, 48 parts. [[strikethrough]] Now,[[/strikethrough]] Hence it appears, that the last-mentioned quantity, or that lost by common evaporation, in the open air, was eight times greater than that lost by [[strikethrough]] mere [[/strikethrough]] the mere operation of heat, or the [[underline]] effluvium [[/underline]] raised by it alone, in air rarified 42 times; & he thence infers that the cause of common evaporation must be a much more powerful one than that which raised the [[underline]] effluvium [[/underline]] in the exhausted receiver. It appears further, that the quantity, lost by evaporation in the open air, was 48 times greater than that which was lost, [[strikethrough]] by[[/strikethrough]] [[insertion]] in [[/insertion]] the same time, by the [[underline]] effluvium [[/underline]] raised by heat, in the receiver full of air; so that supposing the same quantity of [[underline]] effluvium [[/underline]] to have risen in both cases, the loss only of one part in 48 can be attributed to [[insertion]] the [[/insertion]] mere operation of heat, and that consequently the other 47 parts must have been carried off from the fluid by some very powerful action of the air, at large, who