ORES OF ARSENIC. 225 



The sulphuret may be reduced also by heating it wi.h iron filings ; 

 the iron takes the sulphur and liberates the antimony. 



Antimony forms an important part of type metal. The proportions 

 vary in different establishments ; they have been stated at 1 of aitimony 

 to 4 to 12 of lead. A little tin is sometimes used, and also bismuth for 

 the best type. The alloy is specially fitted for this purpose because 

 it expands a little on ' cooling, filling well the mould and making a 

 sharp, clear letter. The Britannia metal, which has superseded the 

 use of pewter, consists of 100 parts of the best block tin, with 8 parts of 

 the metal antimony, and either 2£ parts of each copper and brass, or 

 parts of copper and bismuth. A soft solder is used in the manufacture 

 of Britannia ware, consisting of fine tin alloyed with about 30 per cent, of 

 lead. Antimony with tin, forms the metal on which music is engraved 



The glass of antimony, which is much used for making pharmaceu- 

 tical preparations, is a mixture of the sulphuret and oxyd of antimony 

 usually 85 of the latter to 15 of the former ; it is formed by partially re- 

 ducing the sulphuret to an oxyd by roasting, and then raising the b«*at 

 till the whole melts. 



Antimony in the condition of tartrate of antimony and potassa, is the 

 tartar emetic of the apothecary. 



12. ARSENIC. 

 The metal arsenic occurs native, and united with oxygen 

 or sulphur. It also occurs in combinations with various 

 metals, as iron, cobalt, nickel, silver, copper, manganese, and 

 antimony ; also as an acid in combination with the oxyds of 

 iron, cobalt, nickel, copper, lead, and with lime. Its ores are 

 distinguished readily by giving off an odor like garlic when 

 heated on charcoal before the blowpipe. Its compounds with 

 the metals and bases have already been described. 



NATIVE ARSENIC. 



Rhombohedral. R : R = 185° 41'. Cleavage basal, im- 

 perfect. Also massive, columnar, or granular. 



Color and streak tin-white, but usually dark grayish from 

 tarnish. Brittle. H = 35. Gr=5'65 — 5*95. 



Volatilizes very readily before fusing, with the odor of 

 garlic ; also burns with a pale bluish flame when heated just 

 below redness. 



Obs. Occurs with silver and lead ores. It is found in 

 considerable quantities at the silver mines of Freiberg an 



How is crude antimony reduced? For what is antimony used 

 What is Britannia metal 1 How does arsenic occur in the minera 

 kingdom ? How is it distinguished 1 Describe native arsenic. Wit 

 what is it found ] 



