46 THEORTofRA IN. 



THIS proportion will be illuftrated in the curve rngklr, 

 which reprefents the decreasing rate of folution. Let equal 

 portions in 40. and 10. be mixed, and let the ordinate be raifed 

 in the medium degree of heat 25. ok will then be the whole, 

 power of folution, or the quantity of water that air is capable 

 of diflblving in this degree of heat ; but o p is the quantity of 

 water that is actually in this mixture ; confequently, the air. is 

 here underfaturated with humidity by the quantity p k. 



IF two parts of 40. {hall be mixed with one in 10. or two of 

 10. with one in 40. the quantities of underfaturation will be 

 changed, and q I and n g will exprefs thofe quantities, in rela- 

 tion to the mixtures in the medium temperatures. 



THUS, in every mixture of folution in this decreafing rate of 

 folution, there will be found an underfaturation of the air, 

 with regard to the difTolved moifture, inflead of a fuperfatura- 

 tion, which is found in all the mixtures of the folution in the 

 increafing rate. 



LET us recapitulate : 



IF the folution of water in air increafes with heat in an equal 

 rate, no mixture can be made of portions, in different degrees 

 of heat, that will produce either fuper or underfaturation j but 

 the mixture, like the conftituent portions, will be always fatu- 

 rated without fuperfluity. 



IF the folution of water in air increafes with heat in a de- 

 creafing rate, the mixture of two faturated portions, in dif- 

 ferent degrees of heat, will produce no condenfation of humi- 

 dity, but, on the contrary, will be capable of difTolving more 

 aqueous fubftance. 



IF, on the other hand, the folution of water in air increafes 

 with heat in an increafing rate, the mixture of two faturated 

 portions, in different degrees of heat, will produce a condenfa- 

 tion of humidity, as being fuperfaturated in the medium tem- 

 perature of heat. 



THIS 



