OF NATURAL PHILOSOPHY. 305 



primary importance in the economy of nature ; and 

 such as, in any state of science, it would be indis- 

 pensably necessary to be perfectly familiar with. 

 Like particular theorems in geometry, which, 

 though not rising to the highest point of generality, 

 have yet their several scopes and ranges of exten- 

 sive application, they must be well and perfectly 

 understood in all their bearings. Should we ever 

 arrive at an analysis of these bodies, the chemical 

 properties of the new elements which will then 

 come into view will be known only by our know- 

 ledge of these, or of other compounds of the same 

 class, which they may be capable of forming. Not but 

 that such an analysis would be a most important and 

 indeed triumphant achievement, and change the 

 face of chemistry; but it would undo nothing that 

 has been done, and render useless no point of know- 

 ledge which we have yet arrived at. 



(339.) The atomic theory, or the law of definite 

 proportions, which is the same thing presented in a 

 form divested of all hypothesis, after the laws of 

 mechanics, is, perhaps, the most important which 

 the study of nature has yet disclosed. The extreme 

 simplicity which characterizes it, and which is 

 itself an indication, not unequivocal, of its elevated 

 rank in the scale of physical truths, had the effect 

 of causing it to be announced at once by Mr. 

 Dalton, in its most general terms, on the contem- 

 plation of a few instances*, without passing through 

 subordinate stages of painful inductive ascent by 

 the intermedium of subordinate laws, such as, had 

 the contrary course been pursued by him, would 

 * Thomson's First Principles of Chemistry, Introduction. 



