PHYSICAL THEORIES OF HEAT. 593 



those of chemistry ; properties and laws depend- 

 ing upon a new system of notions and relations, 

 among which clear and substantial general princi- 

 ples are far more difficult to lay hold of, and with 

 which the future progress of human knowledge 

 appears to be far more concerned. To these notions 

 and relations we must now proceed; but we shall 

 find an intermediate stage, in certain subjects which 

 I shall call the mechanico-chemical sciences ; viz., 

 those which have to do with Magnetism, Electricity, 

 and Galvanism. 



VOL. II. 



QQ 



