216 METALS AND THEIR COMBINATIONS. 



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, NaSb0 2 , are 

 formed when antimonous sulphide is boiled with sodium hydroxide. 



Sb 2 S 3 + 4NaOH = Na 3 SbS 3 -f NaSbO 2 -f 2H 2 O. 



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

 is formed, and antimonous sulphide is precipitated : 



Na 3 SbS 3 + NaSbO 2 + 2H 2 SO 4 = Sb 2 S 3 + 2Na 2 SO 4 + 2H 2 O. 



While the above is the principal reaction, there is formed also some anti- 

 mony oxide. 



Experiment 37. Boil about 2 grammes of finely powdered black antimony 

 with a solution of 2 grammes of sodium hydroxide in 80 c.c. of water for about 

 one hour, stirring frequently and occasionally adding water to preserve the 

 same volume. Filter the warm liquid through paper or muslin and add dilute 

 sulphuric acid so long as it produces a precipitate. Collect, wash, and dry the 

 precipitated red powder, which is chiefly amorphous antimonous sulphide with 

 oxide. 



Antimony pentasulphide, Sb 2 S 5 (Golden sulphuret of antimony). 

 A red powder, which, like antimonous sulphide, forms sulpho-salts. 

 It may be obtained by precipitation of acid solutions of antimonic 

 acid by hydrosulphuric acid. 



Antimonous chloride, SbCl 3 (Antimony terchloride, Suiter of anti- 

 mony). Obtained by boiling the native sulphide with hydrochloric 



acid: 



Sb 2 S 3 + 6HC1 = 3H 2 S + 2SbCl 3 . 



The clear solution is evaporated and the remaining chloride dis- 

 tilled, when it is obtained as a white, crystalline, semi-transparent 

 mass. 



By passing chlorine over antimonous chloride it is converted into 

 antimonic chloride, SbCl 5 , which is a fuming liquid. 



Experiment 38. Boil about 2 grammes of black antimony with 10 c.c. of 

 hydrochloric acid until most of the sulphide is dissolved. Set aside for sub- 

 sidence, pour off the clear solution of antimonous chloride, evaporate to about 

 half its volume and use solution for next experiment. 



Antimonous oxide, Antimonii oxidum, Sb 2 O 3 = 287.2 (Anti- 

 mony trioxide). When antimonous chloride is added to water, decom- 

 position takes place, and an oxychloride of antimony, 2SbCl 3 5Sb 2 O 3 , 

 is precipitated : 



12SbCl 3 + 15H 2 O = 2SbCl 3 .5Sb 2 3 4- 30HC1. 



This white precipitate was formerly known as powder of Algaroth. 



