536 » On the two great powers, [Ocr. 
latter must rise into vapor, and so also must those which supply their 
place. And the atoms of water, as they rise, will necessarily become 
intermingled with those of the air, and will be detained among them by 
their attraction for them. But, since the repulsion varies in a greater 
inverse ratio of the distance than the attraction it will form a stable equi- 
librium with it, at a certain point, within which it will prevent the 
atoms of water from approaching those of the air ; that is, prevent an 
intimate combination from ensuing. 
Thus is explained the fact, that an attraction between the air and 
water may favor the transition of the latter into vapor, and yet not 
bring the atoms of water into intimate combination with those of 
the air, a fact, which I do not think can be explained by any other 
doctrine. 
Sixthly.—To the constitution of mixed gases. 
The minute investigation into the various theories proposed to ex- 
plain the nature of a gaseous mixture, which I have endeavoured to 
pursue, has shewn, that each of them is liable to one or more insuper- 
able objections. 
It appears to me that this phenomenon also, may be explained by 
the application of the present doctrine. 
Having first stated the theorem, I shall endeavour to demonstrate it. 
If a cylindrical vessel, of any given length, be filled with hydrogen 
gas, and inverted (so as to fit closely) over a similar vessel filled with 
carbonic acid gas ; part of the former gas, although of far less speci- 
fic gravity than the latter, will descend, and part of the latter will as- 
cend, until the atoms of hydrogen gas, are perfectly mixed with those 
of carbonic acid gas, and, when mixed, they will not enter into com- 
bination. 
This may be demonstrated in the following manner. 
Since the repulsive force, operating from the atoms of the one gas 
towards those of the other, varies in a greater inverse ratio of the 
distance, than their attraction, it must form with this force, at a certain 
point, a stable equilibrium. Since when the hydrogen gas is placed 
on the carbonic acid gas, the lowermost atoms, of the former, press 
upon the upper stratum, of the latter, these contiguous strata, of the 
two gases, must be brought within the point of equilibrium, between 
their attraction and mutual elasticity; and must therefore have an 
effective repulsion for each other. 
But, excepting the contiguous strata, all the atoms of the one fluid 
must be farther from those of the other, than the point of stable equi- 
librium, and must therefore, exert an effective attraction for them. 
