1833.] Attraction and Repulsion. 531 
force, it collects several atoms into a drop, under favorable circum- 
stances. 
The gradual expansions and contractions of liquids can also be 
explained by this law. The distance of the equilibrium is gradually 
increased, or lessened, by an addition, or abstraction of heat; and 
whatever difference should exist between the forces at any one dis- 
tance, a stable equilibrium would be formed at some other, where the 
atoms would be fixed. The doctrine then, that the force of repulsion 
from heat, varies in a greater inverse ratio of the distance, than the 
attraction, affords a happy explanation of the nature and constitution 
of liquids, and also of their gradual contractions and expansions, with 
variations of temperature. 
Thirdly.—To the constitution of simple gaseous fluids. 
It has been above remarked, that the pressure of the atmosphere is the 
chief force opposing the repulsion, in a gaseous fluid. But it has also 
been shewn, under a former head*, that atoms in a gaseous state at- 
tract each other. And this force, though certainly much inferior to 
the pressure, must aid the operation of the latter. 
Let all the forces operating from any atom A towards any other 
atom B, of a simple gas be represented by the following diagram : 
MR 8 AS Ge 7 BG 10. IN 12, 1S 1a IG 17 1B 9 90 
Pr. 1 4 9 16 25 36 49 64 81100 121 144 169 196 225 256 289 324 361 400 
Att. 648 162 72 40,526 18 13,4 10,1 86,4 5,3 4,4 3,8 3,3 2,8 2,52 2,24 2 1,8 1,62 
Be OOP n Rite Hy Bu? 38 Dera ey oq) 10 i Daeg le glog 
Rep. 11664 1458 432 182 93,3 54 34 28,8 16 11,6°9,64 6,7 5,3 4,2 3,4 2,9 2,37 2 1,7 1,45 
In this case, the atoms of the gaseous fluid will be stationary at dis- 
tance 6, where the repulsion, being 54, is equal to the united attrac- 
tion and pressure, (18-36) which are also 54. On removing the at- 
mospheric pressure there being a powerful effective repulsion, the 
atoms must separate greatly, unto that point at which, from the re- 
pulsion varying in a higher ratio than the attraction, a stable equi- 
librium is established. In the above instance, this is at distance 18, 
where the attraction and repulsion being each 2, the gaseous fluid will 
expand no further, although all external pressure is removed. 
To this, I am aware, it may be objected, that the air in the receiver 
of an air pump expands without limit, as long as a portion is removed, 
and, therefore, that the attraction cannot be equal'to the repulsive force 
at any distance of the atoms. 
This however it will be easy to shew is no objection. In proportion 
as the air expands in the receiver, so does its tendency to part with 
* The distance to which attraction is exerted. 
2 pe 
