6 THE MECHANICO-CHEMICAL SCIENCES. 



galvanic agency ; but in galvanism, decomposition, 

 or some action of that kind, universally appears; 

 and these appearances lead to very general laws. 

 Now composition and decomposition are the sub- 

 jects of Chemistry ; and thus we find that we are 

 insensibly but irresistibly led into the domain of 

 that science. The highest generalizations to which 

 we can look, in advancing from the elementary 

 facts of electricity and galvanism, must involve 

 chemical notions ; we must therefore, in laying out 

 the platform of these sciences, make provision for 

 that convergence of mechanical and chemical theory, 

 which they are to exhibit as we ascend. 



We must begin, however, with stating the me- 

 chanical phenomena of these sciences, and the 

 reduction of such phenomena to laws. In this point 

 of view, the phenomena of which we have to speak 

 are those in which bodies exhibit attractions and 

 repulsions, peculiarly determined by their nature 

 and circumstances; as the magnet, and a piece of 

 amber when rubbed. Such results are altogether 

 different from the universal attraction which, ac- 

 cording to Newton's discovery, prevails among all 

 particles of matter, and to which cosmical pheno- 

 mena are owing. But yet the difference of these 

 special attractions and of cosmical attraction, was 

 at first so far from being recognized, that the only 

 way in which men could be led to conceive or 

 assent to an action of one body upon another at a 

 distance, in cosmical cases, was by likening it to 

 magnetic attraction, as we have seen in the history 



