1833.] Attraction, and Repulsion. 529 
Let us apply this law, 
First.—To the constitution of solids. 
Let there be a liquid between the atoms of which, owing to a loss 
of heat, the attraction has become so far superior to the repulsion, as 
to bring them to that distance, at which solidity naturally subsists. 
And, since the attraction may be conceived to vary as the inverse 
square of the distance, and repulsion varies in a higher inverse ratio, 
let this ratio be the inverse cube of the distance, and let the atoms of 
the liquid be supposed to have been at any distance 4 from each other, 
and let the following diagram represent the opponent forces operating 
between any two atoms, A and B, at different distances. 
Distances. ] 2 3 4 5 6 
Attraction, 576 144 64 36 23 &c. 
Ay . +B xB 
Repulsion, 1728 =. 216 64 27 13.8 &c.* 
Here it is plain, since between the two atoms at distance 4 from 
each other, the attraction is 36, but the repulsion only 27, that these 
atoms must approach, and will come to distance 3, where both forces 
are equal, each being 64. The atoms of the body, which is now a 
solid, cannot come nearer ; as at any distance within this, there is an 
effective repulsion operating, which must keep them at this distance, 
unless, by abstracting or adding more heat, the point of equilibrium 
is transferred to a smaller, or greater distance. Thus will be consti- 
tuted a true mechanical stable equilibrium, and thus the nature of 
solids, and their contraction, and expansion, are at once explained. 
Secondly.—To the constitution of liquids. 
A true explanation of the constitution of liquids, which has hitherto 
never been clearly given, appears to be afforded by this doctrine. 
In applying this law to the constitution of liquids, a third power 
must be taken into consideration, namely, the pressure of the atmos- 
phere. 
Let it be supposed, that these forces have brought the atoms of a 
gaseous fluid into the liquid state ; and let the following represent all 
the forces operating upon any two atoms, A and B, of the liquid 
at various distances. 
* It is evident that these series are not supposed to represent the real forces, 
but are merely intended to illustrate the doctrine more clearly. The diagram re- 
presents the forces acting from one atom only, the relative power being the same, 
as if the forces of both atoms had been represented. 
+ Lest when a vapor is passing to the liquid state, any one should attribute the 
cause solely to atmospheric pressure overpowering the expansive force of the 
vapor, I may instance the condensation of hygrometric vapor in the air, on a fall 
QZ 
