1833.] Attraction and Repulsion, 511 
prevent their actual contact. Hence they do not form dense masses, 
but atmospheres round all the atoms of bodies, and endow them with 
mutual elasticity, which operating against the cohesion of bodies pre- 
vents the contact of their atoms. 
From this it is manifest, that the mutual repulsion between the 
particles of heat themselves and their attraction for the atoms of all 
other matter, are forces which operate against each other ; the former 
tending to expand heat, and the latter forcing its particles near to 
each other by collecting it around the atoms of bodies in the form of 
atmospheres, the density of which will vary as the force by which 
they are detained round atoms varies. 
Since, then, these two powers of heat are always operating. against 
each other, no opportunity can be afforded of measuring, either of 
them as asimple force. Since also the atmospheres of heat are always 
from other causes subjected to compression, the only force, which can 
be judged of, is a compound repulsion ; namely, the elastic force of 
the particles of heat modified by their other power, attraction, con- 
densing them round atoms. 
The ratio in which this compound repulsion varies, must greatly 
depend on the force with which the atmospheres of heat are detained 
by atoms, and will therefore probably differ in all bodies. 
It is however of great importance to obtain so much knowledge of 
its properties, as may account for the stability of atoms which takes 
place in the formation of bodies, &c. which must arise from an equi- 
librium subsisting between the compound repulsion above-mentioned, 
and the mutual attraction between the atoms themselves. 
This investigation, though essentially necessary to a sound explana- 
tion of the constitution of bodies in their various states, has not hi- 
therto, I believe, ever been carried on. I shall endeavour to effect 
it by pursuing the following inquiries : 
lst. Whether the repulsion from heat varies in a less inverse 
ratio of the distance than the attraction of atoms. 
2ndly. Whether it varies in the same inverse ratio as the attrac- 
tion. 
And, having shewn that neither of these laws can take place in 
nature, I shall proceed in a second division to consider the important 
proposition which remains ; viz. 
That the force of repulsion with which heat endows atoms, varies 
in a greater inverse ratio of the distance than the attraction; and to 
demonstrate that all states and combinations of bodies are satisfactorily 
accounted for by this law. 
