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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 be precipitated, in summer 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, I 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