ANTIMONY. 193 



Antimony is used in a number of important alloys, for in- 

 stance, in type-metal, an alloy of lead, tin, and antimony. 



Antimony trisulphide, Antimonii sulphidum, Sb 2 S 3 = 336 (Antl- 

 monious sulphide, Sulphide of antimony). The above-mentioned 

 native sulphide, the black antimony, is purified by fusion ; it 

 forms steel-gray masses of a metallic lustre, and a striated, crys- 

 talline fracture, forming a grayish-black, lustreless powder, 

 which is insoluble in water, but soluble in hydrochloric acid 

 with liberation of hydrosulphuric acid. 



When finely powdered antimonious sulphide is treated with 

 water of ammonia to remove any traces of arsenic (which is fre- 

 quently found in this ore) and the washed sulphide dried, the 

 purified sulphide of antimony of the U. S. P. is obtained. 



Antimonious sulphide found in nature is crystallized and 

 steel-gray, but it may also be obtained in an amorphous condition 

 as an orange-red powder, by passing hydrosulphuric acid gas 

 through an antimouious solution. By heating the orange-red 

 sulphide, it is converted into the black variety. 



Sulphurated antimony, Antimonium sulphuratum ( Oxysulphide of 

 antimony), chiefly antimonious sulphide with some antimonious 

 oxide. This preparation is made by boiling purified antimonious 

 sulphide with solution of sodium hydrate, and adding to the hot 

 solution sulphuric acid as long as a precipitate is formed, which 

 is collected and dried. 



The sulphides and oxides of antimony, like those of arsenic, 

 combine with many metallic sulphides or oxides to form sulpho- 

 salts or oxy-salts. Thus, the sodium sulph-antimonite, Na 3 SbS 3 , 

 and the sodium antimonite, Na 3 Sb0 3 , are formed, when anti- 

 monious sulphide is boiled with sodium hydrate : 



Sb,S, + 6NaHO = Na 3 SbS 3 + Na 3 SbO 3 + 3H 2 O. 



By the addition of sulphuric acid, both salts are decomposed, 

 sodium sulphate is formed, and antimonious sulphide and oxide 

 are precipitated: 



2Na 3 SbS 3 + 3H 2 SO 4 = 3Na 2 SO 4 + Sb 2 S 3 + 3H 2 S ; 

 2Na 3 SbO 3 + 3H 2 SO 4 = 3Na 2 SO 4 + Sb,O, + 3H 2 O. 

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