CONCLUDING REMARKS. 



I HAVE now gone through the affections of matter to which 

 distinct names have been given in our received nomenclature : 

 that other forces may be detected, differing as much from 

 them as they differ from each other, is highly probable, and 

 that when discovered, and their modes of action fully traced 

 out, they will be found to be related inter se, and to these 

 forces as these are to each other, I believe to be as far certain 

 as certainty can be predicted of any future event. 



It may in many cases be a difficult question to determine 

 what constitutes a distinct affection of matter or mode of 

 force. It is highly probable that different lines of demarca- 

 tion would have been drawn between the forces already known, 

 had they been discovered in a different manner, or first 

 observed at different points of the chain which connects them. 

 Thus, radiant heat and light are mainly distinguished by the 

 manner in which they affect our senses : were they viewed 

 according to the way in which they affect inorganic matter, 

 very different notions would possibly be entertained of their 

 character and relation. Electricity, again, was named from 

 the substance in which, and magnetism from the district 

 where, they first happened to be observed, and a chain of inter- 

 mediate phenomena has so connected electricity with gal- 

 vanism that they are now regarded as the same force, differing 

 only in the degree of its intensity and quantity, though for a 

 long time they were regarded as distinct. 



The phenomenon of attraction and repulsion by amber, . 

 which originated the term electricity, is as unlike that of the 

 decomposition of water by the voltaic pile, as any two natural 

 phenomena can well be. It is only because the historical 

 sequence of scientific discoveries has associated them by a 

 number of intermediate links, that they are classed within the 



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