1833.] Attraction and Repulsion. 533 
direct ratio of the distance, its attraction might be made to vary in any 
less ratio than the inverse square. 
The reader will perceive, that the ratio of the attraction of the pla- 
net, in the one case, and the doctrine I have laid down, of the ratio of 
the repulsion in the other, were both disturbed by the absolute forces 
varying. Inthe former case, by the quantity of matter in the planet, 
in the latter by the quantity of heat in the air subjected to experiment 
being constantly changed. 
And moreover, I may observe, it would appear from later experi- 
ments than Mr. Boytn’s, as is well known, that the elasticity of the 
air varies in a somewhat greater rativ, than the density, and there- 
fore that the effective repulsion varies in a higher inverse ratio, than 
inversely as the distance. 
The following quotation from an author in Dr. Rrzs’s Cyclopzdia* 
will strongly corroborate the views I have taken of the constitution of 
gases. After some former remarks he observes ;: ‘‘ Thus also in high de- 
grees of rarefaction, the elasticity is decreased rather more than in ex- 
act proportion to the weight or density of the air ; whence it may be 
concluded, that there is a limit to its rarefaction, or expansion, so 
that it cannot be expanded to infinity.” 
This observation, which is founded on actual experiments of philo- 
sophers (and which appears to me a just one) is exactly conformable to 
the doctrine I have laiddown. This doctrine therefore (that the force 
of repulsion, from heat, varies in a greater inverse ratio of the distance 
“than the attraction) which must be admitted to explain the situation of 
of atoms, in other states of bodies also, I think, elucidates clearly the 
nature of gaseous elasticity. 
Fourthly.—To the solution of solids in liquids. 
In applying this law to the solution of a solid in a liquid, it is pro- 
per to take into consideration all the forces, which can operate either 
for, or against the combination. 
In a saline, or any other solution, of a solid in a liquid, there are at 
least, five forces, which must greatly affect the solution. Two of 
these operate in favor of the solution, and three against it ; and in pro- 
portion as the former forces exceed the latter so will the combination 
be the more intimate. 
When a salt is immersed in water, it is true, that the cohesion and 
greater specific gravity of the salt are opposed to the affinity between 
the water and salt, but these (which as far as I am aware are alone 
* Article Air, 
