38 Prof. Naumann 07i Mineralogical Classification. 



chemical investigation may prove to us a perfect idtntily, 

 where the entire morphological and physical properties 

 irresistibly demand the recognition of the most decided 

 diversity. 



A classification founded on identity of composition, un- 

 doubtedly approaches its object much more nearly when the 

 arrangement is based on the electro -negative elements, than 

 when it is founded on the electro-positive, because the former 

 have generally a much more decided influence on the internal 

 nature and external physiognomy of the combinations than 

 the latter. This method, however, is also so unsatisfactory 

 in its results, that we are necessarily induced to consider 

 chemical resemblance from a somewhat diff"erent and more 

 general point of view, constant regard being paid to the 

 physical resemblance of the mass. 



It is obvious that we must, in the first place, place apart and 

 arrange as much as possible together, all the elements them- 

 selves which are presented to us as free products of nature in 

 the mineral kingdom ; for it is, indeed, the elementary condi- 

 tion which gives rise to their general chemical resemblance. 

 These elements, however, have partly a metallic and partly a 

 now-metallic habitus, and hence require to be arranged in dif- 

 ferent regions of the minei'al kingdom. The metals claim the 

 centre of the whole series ; while the non-metallic elements, 

 such as carbon and sulphur, must be placed elsewhere. Some 

 metallic combinations must be placed close to the metals, 

 and must, therefore, be arranged along with them in a proper 

 manner. 



The natural metallic oxides and some of their combinations 

 are in part provided with the metallic habitus ; they have a 

 considei*able specific gravity, are generally coloured sub- 

 stances, and must accordingly be placed near the metals ; 

 we assign them a place before the latter, and thus, proceed- 

 ing backwards, we obtain a point of junction for many of 

 those combinations, partaking of the nature of salts, in which 

 the same metallic oxides occur as bases, or at least, are fre- 

 quently substituted for other isomorphous bases» On the 

 other side of the metals, we place the sulphur, tellurium, 

 arsenic, and selenium combinations, which may be grouped 



