m a Branch (^Natural Histori/y ^c. 245 



character. This small artificial class will form a connecting link 

 between the artificial class, already mentioned, and the class of 

 the lithoid-like minerals containing oxygen, &c. 



A division which will also be thought rather artificial, because 

 we have yet no true chemical reason to account for the distinc- 

 tion between the bodies which are possessed and those which are 

 deprived of the property of solubility in water, must be intro- 

 duced in the class containing the lithoid oxides, fluorides, and 

 chlorides, on account of the great influence which such property 

 appears to have on many of the physical characters. Such di- 

 visions or subclasses, as well as the introduction of the two in- 

 termediary artificial classes, are quite necessary in the present 

 state of the science, but may be expected to experience great 

 modifications by its future progress. 



§ 51. We can now see, according to the view we have taken 

 of the distinctive characters appropriated to the different divi- 

 sions of the mineral kingdom, how minerals, which are not found 

 in perfect crystals, may nevertheless be made to appear at their 

 proper place as appendices to the classification. For, although 

 such minerals may be deprived of their specific characters, if 

 they are cleavable and have a crystalline structure, their genus 

 may be characterised. Were they even deprived of crystalline 

 structure, and appear in the shape of compact masses or groups 

 of molecular individuals, the manifestation of their electro-nega- 

 tive element by some chemical or physical character, and their 

 other characteristic properties, would afford the means of assign- 

 ing to these otherwise unknown individuals the family, the order, 

 or at least the class, to which they appear to belong. In like 

 manner, when the characters of such imperfect minerals do not 

 agree completely with any of the genera, families, or orders al- 

 ready established, they may be made the types of new genera, 

 families, or orders, in the same way as in zoology or botany, a 

 single insulated organ, or part of an animal or plant, may be 

 often sufficient to establish a new genus, order, or family. 



The new species and genera of fossil animals or plants have 

 had their place assigned in the method, although not a single 

 complete and perfect individual of them has ever been found. 



