OF NATURAL PHILOSOPHY. 293 



by chemical analysis stamped them with a scientific 

 and decided character which they have retained ever 

 since. 



(329.) Meanwhile the progress made in chemical 

 analysis had led to the important conclusion that 

 every chemical compound susceptible of assuming 

 the solid state assumed with it a determinate crys- 

 talline form ; and the progress of optical science 

 had shown that the fundamental crystalline form, in 

 the case at least of transparent bodies, drew with it 

 a series of optical properties no less curious than im- 

 portant in relation to the affections of light in its pass- 

 age through such substances. Thus, in every point 

 of view, additional importance became added to this 

 character ; and the study of the crystalline forms 

 of bodies in general assumed the form of a separate 

 and independent branch of science, of which the 

 geometrical forms of the mineral world constituted 

 only a particular case. Mineralogy, however, as a 

 branch of natural history, remains still distinct either 

 from optics or crystallography. The mineralogist 

 is content, and thinks he has performed his task, if 

 not as a natural historian at least as a classifier 

 and arranger, if he only gives such a characteristic 

 description of a mineral as shall effectually distin- 

 guish it from every other, and shall enable any one 

 who may encounter such a body in any part of the 

 world to impose on it its name, assign it a place in 

 his system, and turn to his books for a further de- 

 scription of all that the chemist, the optician, the 

 lapidary, or the artist, may require to know. Still 

 this is no easy matter : the laborious researches of 

 the most eminent mineralogists can hardly yet be 

 u 3 



