1818.] Crystalline Form and Chemical Composition. 269 



definite proportions in which most of the elements of minerals 

 combine. Of the earths particularly we are ignorant, and yet 

 nearly half the minerals known contain proportions of these. It 

 is impossible, therefore, in the greater number of the minerals, 

 which we are led by analysis to regard as mixtures, to determine 

 the nature of the compounds of which the mixture consists; and 

 we must, consequently, renounce, as respects these, the double 

 classification above proposed. , 



There are, notwithstanding, some mineral species, to which 

 the foregoing reasonings may be applied. Let us take grey 

 copper as an example ; in the analysis of which, Klaproth has 

 obtained the following results : 



In separating successively from these elements the proportions 

 required to constitute the known compounds, copper pyrites, 

 sulphuret of antimony, &c. we shall distribute the results of these 

 analyses as follows : * 



* The proportions here assumed are deduced from the following analyses: 



Copper Pyrites, by Gueniveau. 



Copper 3035 



Iron 32-65 



Sulphur 3600 



Loss ; 100 



100 



Sulphuret of Copper, by the Same. 



Copper 74-5 



Sulphur 20-5 



Oxide of iron 1-5 



Loss 3 - 5 



100 



Sulphuret of Antimony, by Jltrgman. 



Antimony 71 00 



Snlphur 26 00 



Sulphuret of Silver, by Klaproth. 



Silver 8500 



Sulphur 1500 



100 



Antimonlated Sulphuret of Silver, by 

 Thenard. 



Silver 58-00 



Antimony 23 50 



Sulphur." 1600 



Loss.. '-2-30 



100 



100 



