1833.] Attraction and Repulsion. 517 
I am ready indeed to acknowledge, that it is not possible to prove 
from the constitution of a simple gas, that the two powers attraction 
and repulsion from heat do not vary in the same ratio ; for the effec- 
tive repulsion, though (according to this law) superior to the attraction 
at every distance, may have its force limited by atmospheric compres- 
sion. 
Yet, however, since both in solids and liquids it has been proved 
that the two forces cannot vary in the same ratio, it may be concluded 
that they neither can, when a body has assumed the gaseous state, 
although from the peculiar nature of a gas, it may not be possible 
directly to prove this fact. 
Fourthly.—Of the solution of solids in liquids. 
Of all combinations none are more frequent, than the solution of solids 
in liquids ; and ofall states no one is more remarkable, than that of many 
bodies in solution. Oftentimes a dense solid is disintegrated by the 
powerful affinity of a liquid ; and yet a very weak combination takes 
place. A combination, in which most of the characters of the bodies 
remain, contrary to a well known law of combination. 
Tt is somewhat remarkable, that even BeRTHOLLET, who has written 
very fully and ably on Chemical Statics, should have said very little 
in explanation of the weakness of the combination in many solutions. 
The two following are the chief passages in his work, which refer to 
this important question. 
«* Solution,’’ he observes, ‘‘ is therefore the effect of a power which 
can overcome the resistance of the force of cohesion, and the differ- 
ence of specifie gravity* : and again, ‘‘in reality it (the solvent) exer- 
cises a force similar to that of the affinity which produces combinations, 
and whose effect is limited, in the solution of a solid, by the force of 
cohesion, &c.¢” The late Dr. Murray, while supporting his doc- 
trine of mixed gases, has written more definitely on this subject, ‘* In 
-_ the solution of a solid,” observes this able author, ‘‘ there are opposed 
the force of affinity between the solid substance and the solvent, and 
the cohesion of the solid retaining the solid particles in aggregation t.” 
And again he writes ; ‘‘ In the solution of salts in water, the attrac- 
tion exerted is merely sufficient to give fluidity to the solid and to coun- 
teract its cohesion and specific gravity ; the properties are not alter- 
ed, &c.§” 
* Chemical Statics, translated by LAMBERT, vol. i. 20, 
+ Ditto, vol. i. 295. 
t System of Chemistry, vol. i. 40. 
§ Ditto, p. 41. 
