258 CHEMISTRY. 



ing, because they shrink in becoming solid, instead of swell- 

 ing as they do when mixed in alloy. The metal plates on 

 which music is sometimes engraved is an alloy of tin and 

 antimony. The Britannia Metal, which has taken the place 

 of the old-fashioned pewter, is composed of one hundred 

 parts of best block-tin, eight of the metal antimony, and 

 either two and a half parts each of copper and brass, or 

 two of copper and bismuth. Antimony is obtained chiefly 

 from its sulphide, which is quite an abundant ore. It is 

 associated commonly with ores of silver, copper, lead, 

 zinc, etc. 



363. Compounds of Antimony. Antimony forms two 

 chlorides, one of them, SbCl 3 , has long been known under 

 the name of butter of antimony. It forms also two oxides, 

 Sb 2 O 3 and Sb 2 O 5 , and two sulphides of corresponding com- 

 position. Tartar emetic is a double tartrate of antimony 

 and potassium, K(SbO)C 4 H 4 O 6 . It is obtained by boiling 

 antimonious oxide with cream of tartar (hydro-potassium 

 tartrate), and evaporating the solution. Nearly all the 

 salts of antimonious oxide are decomposed on adding wa- 

 ter to their acid solutions. Antimonetted hydrogen has 

 been mentioned in 360. 



364. Bismuth. This metal is found in but few localities, 

 and mostly in the metallic state. By far the largest part 

 of it comes from one locality, Schneeberg, in Saxony. It is 

 obtained from the rocks in which it is present by reducing 

 them to a coarse powder, which is burned in a sort of kiln. 

 The bismuth, which is quite fusible, is thus melted out, and 

 is collected in a trough at the bottom of the kiln. It is a 

 white metal with a peculiar reddish tint, and a remarkable 

 crystalline structure. It is used chiefly in forming certain 

 alloys, as one kind of type-metal, and the metal for stereo- 

 type plates. 



365. Nitrate of Bismuth. If a solution of this salt be 



