1G6 HIS'I"!: 1 ! OF THERMOTICS. 



tlic supporters of the doctrine, though tlicy must be far more complex 

 than the hydrostatical law l>y which a hollow sphere floats. 



Xewton's opinion was hardly more satisfactory ; he 5 explained eva- 

 poration by the repulsive power ofJic.it; the parts of vapors, accord 

 ing to him, being small, are easily affected by this force, and thus 

 ome lighter than the atmosphere. 



Muschenbroek still adhered to the theory of globules, as the expla- 

 nation of evaporation ; but he was manifestly discontented with it ; and 

 reasonably apprehended that the pressure of the air would destroy the 

 trail texture of these bubbles. He called to his aid a rotation of the 

 globules (which Descartes also had assumed) ; and, not satisfied with 

 this, threw himself on electrical action as a reserve. Electricity, 

 indeed, was now in favor, as hydrostatics had been before ; and was 

 naturally called in, in all cases of difficulty. Desaguliers, also, uses 

 this agent to account for the ascent of vapor, introducing it into a kind 

 of sexual system of clouds ; according to him, the male fire (heat) 

 does a part, and the female fire (electricity) performs the rest. These 

 are speculations of small merit and no value. 



In the mean time, Chemistry made great progress in the estimation 

 of philosophers, and had its turn in the explanation of the important 

 tacts of evaporation. Bouillet, who, in 1742, placed the particles of 

 water in the interstices of those of air, may be considered as approach- 

 ing to the chemical theory. In 1743, the Academy of Sciences of 

 Bourdeaux proposed the ascent of vapors as the subject of a prize ; 

 which was adjudged in a manner very impartial as to the choice of a 

 theory ; for it was divided between Kratzenstein, who advocated the 

 bubbles, (the coat of which he determined to be 1 -50,000th of an inch 

 thick,) and llamberger, who maintained the truth to be the adhesion 

 of particles of water to those of air and fire. The latter doctrine had 

 become much more distinct in the author's mind when seven years 

 afterwards (1750) he published his Elcmoifn PJnifticcs. He then gave 

 the explanation of evaporation in a phrase which has since been 

 adopted, the solution of walcr in cur ; which he conceived to be of 

 the same kind as other chemical solutions. 



This theory of solution was further advocated and developed by Le 

 Roi; 6 and in his hands assumed a form which has been extensively 

 adopted up to our times, and has, in many instances, tinged the 

 language commonly used. He conceived that air, like other solvents, 



Opticks, Qu. 31. c Ac. Pi. Sc. Paris. 1750. 



