PHYSICAL SCIENCE. 43 



and motions, far removed from all cognisance of the senses, 

 but interpreted to our reason by the closest experimental 

 analogies ? Faraday has given the sanction of his opinion to 

 the molecular view of the phenomena, and Grove and others 

 have done much to strengthen this conclusion. 



We have hitherto been speaking of Matter generally, with- 

 out regard to the various aspects under which it is known to 

 us. For with all the refinements of modern analysis, there 

 still remain more than sixty substances undecomposed, and 

 which must therefore be deemed simple or elementary to our 

 present knowledge. Of these the largest proportion are what 

 we term metallic bodies, and most of the additions recently 

 made to the list of simple substances belong to this class ; 

 with the further curious speciality pertaining to several of 

 them, that, while perfectly distinct from all others in physical 

 characters, they are hitherto known to exist in a few rare 

 specimens only. Almost we might be tempted to surmise 

 that they belong to the number of those materials of which 

 aerolites seem to tell us that other worlds are made ; and 

 that they exist more largely in these worlds than in the 

 feeble representation of their existence on our own globe. 

 Such suggestion, however, must be received simply as illus- 

 trating the manner in which modern science attaches facts 

 already attained to problems yet unresolved ; concentrating 

 them as it were around common foci, towards which they 

 ever more closely converge. 



The great problem regarding these many kinds of matter 

 on our own earth, lies in the question, whether they may not 

 hereafter be lessened in number by reduction to certain ele- 

 ments, common to several or all ? Whether, in other words, 

 bodies simple to our present knowledge, are not actually com- 

 pound in their nature ? Chemistry, it must be owned, has 

 hitherto done little directly towards solving this question; 



