522 On the two great powers, [Ocr. 
between the atoms of air and water when at a distance, it will also: 
be superior when they are near to each other. Hence this superior at- 
traction would bring the atoms of the two fluids into absolute contact, 
much more then, into intimate combination. 
But hygrometric vapor is in a very weak state of combination. The 
mere solution of liquids in gases cannot then be explained, if the two 
forces are supposed to vary in the same ratio. 
Sixthly. Of the constitution of mixed aerial fluids. The fact that 
all gaseous fluids, however different their specific gravities, mix when 
placed together, has been already noticed in a former part of this es- 
say. I shall now attempt a brief inquiry into the various explanations 
proposed, to account for this phenomenon. These have been applied 
chiefly to the constitution of the atmosphere ; it being a remarkable in- 
stance of a mixture, or solution, of gases in each other. 
When treating of attraction, | endeavoured to prove, that between 
all gaseous fluids an attraction is exerted, with more or less force, at all 
distances. 
That the atmospheres of heat round atoms, must endow them with 
mutual elasticity, is itself evident ; and is proved by ‘the fact, that 
compound atoms are separated by an addition of heat, as is evinced in 
the decomposition of bodies by heat. 
I shall therefore consider both forces, as operating between all atoms 
of gases; and inquire whether the nature of mixed gases, can be ex- 
plained, according to the law, that attraction and the force of repulsion 
vary in the same ratio ; supposing, first, that these two forces are equal 
between gases ; or secondly, that the repulsion is superior ; or thirdly, 
that the attraction is superior. 
1.—If between mixed gases, the attraction and force of repulsion 
are equal. 
Mr. Datton was formerly of opinion, that mixed gases neither at- 
tracted nor repelled each other ; and he explained the mixture of gases, 
by their own elasticity expanding each, which occupied the whole 
space between the atoms of the other, as if it were a void. 
This very ingenious theory, which in many respects would give a 
sufficient mechanical explanation of mixed * gases, has, as is well 
known, been the subject of various discussions. Among others, the fol- 
lowing objections of BertHouier, and Dr. Murray, are doubtless in- 
superable. 
* It has been already shewn under a former head, that this theory cannot afford 
even a mechanical explanation of the solution of water in the atmosphere. 
