434 SCIENCE PROGRESS. 



places these minerals in different classes, is certainly not in 

 harmony with modern ideas. 



At Freibero- no doubt the characters of minerals are 

 studied almost entirely with a view to their practical deter- 

 mination ; this was certainly to a large extent also the 

 consideration which influenced the School of Mohs in 

 relegating the chemical characters to a secondary place ; 

 for a chemical analysis is rarely either possible or con- 

 venient if a mineral may be recognised by other means, 

 while the external characters are mostly a matter of easy 

 observation. Hence it is natural that among practical 

 mining- students and those to whom the determination of 

 minerals is the end and object of Mineralogy, the methods, 

 and therefore also the classifications of the Wernerian 

 School, have continued to find favour. 



But an even more serious attempt to raise the Natural 

 System to the rank of a scientific principle has recently 

 been made. 



Thomas Sterry Hunt was always an original and 

 suggestive writer on mineralogical and geological subjects 

 on their more philosophical side, and shortly before his death 

 he published a book entitled Systematic Mineralogy based 

 upon a Natural Classification (1891). Brought up in the tra- 

 ditions of the Natural History System under C. v. Shepard, 

 who was its exponent in America, Sterry Hunt endeavoured 

 to effect a reconciliation between the Natural and the 

 Chemical Systems by developing the former so as to in- 

 clude by implication the latter, and thus to " form a new 

 system of classification which will be at the same time 

 chemical and natural-historical ". 



This extremely curious, and in part fantastic, volume 

 merits somewhat closer attention. The author starts with 

 the conviction, shared probably by most of his readers, that 

 the physical characters of any chemical compound and its 

 composition are dependent each on the other, " and present 

 two aspects of the same problem which can never be solved 

 but by the consideration of both ". Hence the specific 

 gravity and the hardness, so prominently used in the old 

 systems, must give a clue to the chemical composition, and 



