THEORTofRAIN. 45 



will have neither excefs nor deficiency of the diffolved fubftance. 

 This, however, is not the cafe in the other two rates of folu- 

 tion ; for, as in thofe two cafes the ordinates of heat and folu- 

 tion are not the fame, the medium of heat will not exprefs a 

 folution faturated with humidity, or a mixture in which there 

 is not fuperfluity of the diffolved fubftance. Let us now con- 

 fider thefe more particxilarly. 



IN the curve m d efr, which reprefents the increasing rate of 

 folution, let equal portions of the folution in 40. and in 10. be 

 mixed, then the medium of heat in 25. will have for the ordi- 

 nate of mixture, that is to fay, the quantity of water contain- 

 ed in this mixture o p, whilft o e is the ordinate of folution, 

 that is to fay, the quantity of water that may be diffolved in 

 this degree of heat, confequently, e p is the quantity of water 

 that cannot be retained in folution, in this medium temperature 

 produced by the mixture. 



IF two parts of the folution in 40. be mixed with one of that 

 in 10. the medium temperature will be 30. ; and, if two parts 

 of the laft be mixed with one of the other, the medium tempe- 

 rature produced will be 20. In thofe two cafes, fq and dn are 

 the quantities which will be feparated from the folution. 



IN like manner, may be found the effect of any mixture of 

 two portions in different temperatures, and the quantity of wa- 

 ter that would be feparated on thefe occafions afcertained, if 

 the actual curve of evaporation were known, or that rate in. 

 which the folution of water in air proceeded. 



THE progrefs of folution, inftead of being in an increaung 

 rate, may be in one that decreafes, in relation to the progrefs of 

 heat. In that cafe, the mixture of two portions of the folution 

 in different degrees of heat, inftead of producing a feparation 

 of fuperfluous moifture in the medium temperature, by reafon 

 of the fuperiaturatioii, as in the former cafe, will be followed 

 by an increafed power for the evaporation of water, by having 

 an underfaturation in the mixed mafs. 



THIS 



