84: RED SILVER ORE. 



mass with water, the residue well washed, the solution 

 acidified slightly with hydrochloric acid, and the sul- 

 phuric acid precipitated by chloride of barium. 



58. BERTHIER1TE. 

 FeS, Sb 2 S 3 . 



The mineral, in the state of fine powder, is oxidized 

 with hydrochloric acid and chlorate of potassa, until 

 the separated sulphur has a pure yellow color. The 

 solution is mixed with tartaric acid, and may then be 

 diluted with water without any precipitation taking 

 place. The separated sulphur is collected upon a dried 

 filter, washed, and dried at 100. The sulphuric acid 

 produced by the oxidation is precipitated from the 

 solution by chloride of barium, and the sulphate of 

 baryta washed with hot water. 



When the excess of baryta has been removed from 

 the filtrate by sulphuric acid, a stream of sulphuretted 

 hydrogen gas is passed through the solution, and the 

 antimony precipitated. (See also No. 55.) 



From the filtered liquid the iron is completely oxi- 

 dized and then precipitated by ammonia. 



59. RED SILVER-ORE.* 

 Pyrargyrite, 3AgS, Sb 2 S 3 . Proustite, 3AgS, As 2 S 3 . 



1. PYRARGYRITE. To determine the amount of sul- 

 phur, a weighed quantity of the mineral is fused in a 



* These compounds may be readily obtained artificially by fus- 

 ing their constituents together. That which contains antimony is 

 prepared by fusing 2'2 parts of sulphide of silver with 1 part of 

 black tersulphide of antimony in a crucible, beneath a layer of 



