TIN. 195 



have not occurred, the stomach-pump must be applied. Tannic 

 acid in any form, or recently precipitated ferric hydrate, should 

 be administered. . 



Analytical reactions. 



1. Add hydrosulphuric acid to an acidified solution of anti- 

 mony : an orange-red precipitate of antimonious or antimonic 

 sulphide (Sb 2 S 3 or Sb 2 S 5 ) is produced. 



2. Add ammonium sulphide to the precipitated sulphide of 

 antimony : this is dissolved and may be reprecipitated by neu- 

 tralizing with an acid. 



3. Produce a concentrated solution of antimonious chloride 

 by dissolving the sulphide in hydrochloric acid, and pour it into 

 water : a white precipitate of the oxychloride is formed. (See 

 explanation above.) 



4. Boil a piece of metallic copper in the solution of anti- 

 monious chloride : a black deposit of antimony is formed upon 

 the copper. By heating the latter in a narrow test-tube, the 

 antimony is volatilized and deposited as a white incrustation of 

 antimonious oxide upon the glass. 



5. Use " Marsh's test" as described under analytical reactions 

 for arsenic, and apply tests mentioned there for distinguishing 

 spots of arsenic from those of antimony. 



Tin, Sn = 117.7 (Stannum). This metal is found in nature 

 chiefly as stannic oxide or tin-stone, Sn0 2 , from which the metal 

 is easily obtained by heating with coal : 



Sn0 2 + 2C = Sn + 2CO. 



Tin is an almost silver-white, very malleable metal, fusing at 

 the comparatively low temperature of 228. It is used in many 

 alloys, in the silvering of looking-glasses by tin-amalgam, and 

 chiefly in the manufacture of tin-plate, which is sheet-iron 

 covered with a thin layer of tin. 



Tin is bivalent in some compounds, quadrivalent in others. 

 These combinations are distinguished as stannous and stannic 

 compounds. 



Stannous chloride, SnCl 2 (Protochloride of tin). Obtained by 

 dissolving tin in hydrochloric acid by the aid of heat : 



Sn + 2HG1 = SnCl 8 + 2H. 



