422 JVf, Rose on the Compounds of Antimony , 8^c, [Dec. 



There is, however, a combination of sulphuret of antimony with 

 oxide of antimony in definite proportion, and that is the native 

 kermes of mineralogists (rothspiesglanzerz). The result of my 

 analysis of that substance differs very much from that obtained 

 by Klaproth, in consequence of his having supposed that the 

 whole of the antimony was both oxidated and sulphuretted, and 

 of his not having determined the quantity of the antimony. 

 According to him, its composition is, 



Antimony 67*8 



Oxygen 10-8 



Sulphur 19-7 



98-3 



1 analyzed the rothspiesglanzerz from Braunsdorf, near Frei- 

 "berg, in Saxony, which M. Weiss had the goodness to send me 

 for the purpose. The analysis was made by hydrogen in the 

 same manner as those of the different sulphurets of antimony. 

 I added, however, to the apparatus a weighed tube containing 

 chloride of calcium, to absorb the water formed. In one expe- 

 riment I obtained 0*676 gramme (10*4 grs.) of antimony and 

 0'054 gramme (0*84 grs.) of water from 0*908 gramme (14 grs.) 

 of the mineral, or 74*45 per cent, of antimony and 5*29 of oxy- 

 gen; and in another, from 0*978 gramme (15*1 grs.) of the mine- 

 ral, 0*74 gramme (II '4 grs.) of antimony, and 0*047 gramme 

 (0*73 gr.) of water, or 75*66 per cent, of antimony and 4*27 

 oxygen. 1 then dissolved 0*34 gramme (5*24 grs.) of the mineral 

 in aqua regia, added tartaric acid to the solution, and precii)itated 

 by muriate of barytes. I obtained 0*517 gramme^ (8 gi^s.) of 

 sulphate of barytes, equivalent to 20*47 per cent, of sulphur. 



If we take the mean of the oxygen in the two first analyses, 

 viz. 4*78 per cent, and add to it as much antimony as is neces- 

 sary to form the oxide, the remaining quantity of metal is suffi- 

 cient, neglecting shght errors of obseiTation, to form with the 

 sulphur, the sulphuret of antimony with 3 atoms of sulphur. 

 We shall find besides that the quantity of oxide of antimony is 

 to the quantity of sulphuret as the weight.of an atom of the first 

 is to the weight of two atoms of the second, so that the native 

 kermes consists of 1 atom of oxide of antimony and 2 atoms of 

 sulphuret of antimony, or per cent, of 



Sulphuret of antimony 69*86 



Oxide of antimony 30*14 



100*00 



This composition accords with that which M. Berzelius had 

 already assigned to the native kermes. This compound is 

 remarkable as presenting the only instance of a native crystal- 

 lized oxisulphuret that has hitherto been discovered. 



