- 1833.) Attraction and Repulsion. 537 
If then their mutual effective attraction be superior to their differ- 
ence of gravity, atoms of hydrogen gas must descend, and of carbonic 
acid ascend until the mixture is complete. When mixed however, no 
atom of the former can approach nearer to one of the latter gas, 
than the distance at which the forces, operating between them, form a 
stable equilibrium : for within that distance an effective repulsion ex- 
ists. This distance, owing to the great quantity of heat round gaseous 
atoms, will be so considerable, that the atoms of the two fluids cannot 
produce on each other those changes, attendant on combination. 
From which, the gases must be considered, as merely having their 
atoms detained approximate to each other, by their mutual attrac- 
tion. 
Tn like manner, may the constitution of the atmosphere be elucidat- 
ed ;—its consisting of gases in a state of mixture, though of different 
specific gravities, and yet not entering into intimate combination with 
each other. 
ConcLusIon. 
The inquiry into the law of the repulsive force, with which heat en- 
dows atoms, namely, of that compound repulsion resulting from the op- 
posed action of the two ultimate powers of heat, themselves, which it 
has been my endeavour to pursue with such minuteness, as the length 
of this essay would permit, has, I trust shewn, that this power must 
vary in a higher inverse ratio of the distance, than the attraction. 
By way of illustration, I have imagined this ratio to be the inverse 
cube, that of attraction being the inverse square of the distance ; 
but I would by no means be understood as intending to enforce this as 
the actual ratio. Since (as has been above remarked) the actual ratio 
of this compound repulsion, it is probable, differs in bodies according 
to the force of their attraction for the particles of heat, it will perhaps 
never be possible to ascertain it exactly in any individual case. But 
the limit, which has been laid down, is of the highest importance, since 
(as I trust) I have deduced from it a simple doctrine, which accounts 
for the stable residence of atoms at various distances from each other, 
constituting in nature, solids and liquids, combinations of solids with 
liquids, liquids with aerial fluids, and mixtures of aerial fluids with each 
other; and without which none of these phenomena can be accounted 
for, but they may even be demonstrated impossible. 
3A 
