CHEMICAL ATTRACTION. 20-3 



sulphuric acids are decomposed by the pile, 

 sulphur goes to the negative pole ; but that 

 when sulphuretted hydrogen is decomposed, 

 sulphur goes to the opposite pole that when 

 carbon, selenium, arsenic, and tellurium are 

 united with oxygen, they are positive, but ne- 

 gative with hydrogen proving that bodies are 

 neither essentially positive nor negative, and that 

 they vary in this respect according to circum- 

 stancesconsequently, that all classifications of 

 bodies founded on their electric polarities are 

 fallacious. 



Dr. Thomson observes, that " if chemical affi- 

 nity were merely the result of different states 

 of electricity, bodies could not remain united 

 unless these different electrical states were per- 

 manent. But if the positive and negative elec- 

 tricities combine and fly off in the form of fire, 

 there must be an end of the different electrical 

 states which caused them to unite, and of course 

 the union must cease, which is contrary to 

 matter of fact. (Thomson on Heat and Elec- 

 tricity, p. 335.) 



3. A still more fatal objection to the electro- 

 chemical theory is, that it affords no explana- 

 tion whatever of cohesion or simple aggrega- 

 tion ; whereas I have demonstrated that the 

 particles of homogeneous bodies are held to- 

 gether by the same cause which maintains the 

 chemical union of heterogeneous elements that 



