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[ 55 ] ber) 17 degrees less than it was in the months of August and September.

108. I hope this paradox will be explained, and that the principles which may clear it up will draw useful consequences along with them. Those phi- losphers who look upon evaporation as a dissolution of water by air in the manner of menstrua, that is, by affinity, will easily apply their principle to the solution of part of these phaenomena The disso- lution is greater when the menstruum is warmer, and consequently the air must keep a greater quantity of water in dissolution, and suffere a less part of it to beprecipitated, in fummcr than in winter. I can- not but allow that this system is extremely specious, and that many phznomena are very happily ex- plained by means of it. This is what Mr le Roy has shewn us in the memoir I have already quoted ; in which, without contending that ai r really acts as a menstruum with respect to water, he demonstrates, by a parallel very well kept up, that all the chemi- cal expressions concerning dissolutions may with propriety be applied to describe the several phae nomena be examines, relative to the elevation and suspension of water in air, as well as to its precipi≠ tation under different forms 109. If it was not too common a practice, to conclude things from words, 1 should in fact think these chemical expressions very conveniently adapted to explain a number of these phaenomena. But I have rejected them here, on account of this consi≠ deration; that when I took in a greater number of phaenomena, I found them no longer accurate, any more than the general idea of the dissolu≠ tion