396 .Dr. E*Jan on the Ajcent of Vapour. 
Monfieur le Roi, and afterwards revived by 
Lord KaimeSy and Dottor Hugh Hamilton. It is 
this—That the air difTolves water, as water 
does faline fubftances : the folution being per¬ 
fect, the air will become tranfparent. 
Objections. 1. Were this theory true, evapo¬ 
ration could not be performed without air ; but 
Mr. Watt, contrary to the theory fupported 
by Lord Kaimes and Dr. Hamilton, has proved, 
that when water in vacuo was boiled with a degree 
of heat very little greater than that of the human 
body, the (team came over, and was condenfed 
in the refrigeratory. But he relates, that the eva¬ 
poration was not quicker than in the open air. 
2. Were the doctrine of folution true, the air 
would be heavier, the more water it contained ; 
and, as clouds contain a great portion of water, 
they ought to float on the furface of the earth, 
and not in the higher regions, as we daily ob- 
ferve. 
3. We never could expeCt any rain, unlefs the 
air were fuperfaturated with water j and it would 
only yield to us, what it coujd not retain in 
folution. 
4. It is univerfally allowed, that heat con¬ 
tributes, very much, towards converting water 
into vapour, which is again condenled by cold f 
In what manner, will the do&rine of folution 
account for the fpontaneous evaporation of water, 
jind its being fufpended in air, in the colded 
weather, 
