168 CAUSE OF COHESION. 



many and diversified effects ; that chemistry and 

 natural philosophy are only different branches 

 of one great science, which cannot be studied 

 apart from each other, without departing from 

 the unity and simplicity of nature, every ope- 

 ration of which is governed by the same code of 

 physical laws, from the aggregation of a crystal 

 to that of suns, planets, and their satellites. 



It is still a problem with philosophers, whether 

 the particles of bodies are drawn together, or 

 pressed together. Newton supposed, that the 

 aBther, which I have shewn to be identical with 

 the cause of heat, was more rare within the sub- 

 stance of dense than light bodies ; and more 

 dense in the spaces beyond them, than around 

 their particles, by which they are pressed to- 

 gether. (See page 28, chap. 1.) But I have 

 shewn the reverse of this to be the fact ; that a 

 cubic inch of carburetted hydrogen, which is 

 eight times the specific gravity of simple hydro- 

 gen, contains a greater amount of aethereal matter 

 around its particles, because they are larger, and 

 have a stronger attraction for it. For the same 

 reason, equal volumes of olefiant gas contain 

 more of the igneous ther around its atoms than 

 light carburetted hydrogen, while the vapours of 

 alcohol, aether, naphthalin, setherine, and many 

 other gaseous bodies, attract and retain around 

 their particles still larger quantities, correspond- 

 ing with their greater size. 



