ANTIMONY. 215 



31. ANTIMONY TIN-GOLD-PLATINUM MOLYBDENUM. 



Antimony, Sb : = 119.6 (Stibium). This metal is found in nature 

 chiefly as the trisulphide, Sb 2 S 3 , an ore which is known as black anti- 

 mony j crude antimony, or stibnite. 



The metal is obtained from the sulphide by roasting, when it is 

 converted into oxide, which is reduced by charcoal. Antimony is a 

 brittle, bluish-white metal, having a crystalline structure ; it fuses at 

 450 C. (842 F.), and may at a higher temperature be distilled with- 

 out change, provided air is excluded ; heated in air it burns bril- 

 liantly. 



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

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



Antimony trisulphide, Antimonii sulphidum, Sb 2 S 3 = 335.2 

 (Antimonous sulphide, Antimony sulphide). The above-mentioned 

 native sulphide, the black antimony, is found generally associated 

 with other ores or minerals, from which it is freed by heating the 

 masses, when the antimony sulphide fuses and is made to run oif into 

 suitable vessels for cooling. Thus obtained it forms steel-gray masses 

 of a metallic lustre, and a striated, crystalline fracture, forming a 

 grayish-black, lustreless powder, which is insoluble in water, but 

 soluble in hydrochloric acid with liberation of hydrogen sulphide. 



When finely powdered antimonous sulphide is treated with water of ammonia 

 to remove any traces of arsenic (which is frequently found in this ore) and the 

 washed sulphide dried, the purified antimony sulphide of the U. S. P. is obtained. 



Antimonous sulphide found in nature is crystallized and steel-gray 

 (Plate V., 6), but it may be obtained also in an amorphous condition 

 as an orange-red (Plate V., 5) powder by passing hydrogen sulphide 

 through an antimouous solution. By heating the orange-red sul- 

 phide, it is converted into the black variety. 



Sulphurated antimony, Antimonium sulphuratum ( Oxysulphide 

 of antimony, Kermes mineral), chiefly antimony trisulphide with some 

 antimony oxide. This preparation is made by boiling purified anti- 

 monous sulphide with solution of sodium hydroxide, and adding to 

 the hot solution sulphuric acid as long as a precipitate is formed, 

 which is collected and dried. 



It is a reddish-brown amorphous powder, insoluble in water, 

 soluble in hydrochloric acid or sodium hydroxide. 



