CHAPTER VI 

 USEFUL METALS CONTINUED (GROUP II, SUBGROUP B) 



ARSENIC, ANTIMONY, TIN 

 Arsenic : Its Properties, Occurrence and Uses 



Properties. Arsenic, symbol As, is a steel gray, brittle metal- 

 loid. It crystallizes in the hexagonal system in regular acicular 

 prisms, and begins to volatilize at 100 with a characteristic 

 garlic odor. It is a good conductor of heat and electricity. In 

 its salts it suggests an acid, and in its alloys a metal. It is 

 seldom that it plays the role of a base. It is soluble in HC1; 

 specific gravity, 5.8, melting point, at red heat, and its atomic 

 weight is 75. 



Ores of Arsenic. Native arsenic, 100 per cent. As. Often al- 

 loyed with gold and silver, sometimes with bismuth and iron. 



Realgar, AsS, 70.1 per cent. As. The only aurora red mineral 

 entirely volatile before the blow pipe. 



Orpiment, As 2 Ss, 61 per cent. As. With honey yellow surfaces 

 on its cleavage face. 



Arsenopyrite, FeAsS, 46 per cent. As. A sulph-arsenide of iron. 



Arsenolite, As 2 O3, 75.8 per cent. As. A white oxidation prod- 

 duct of other ores. 



Lollingite, FeAs2, 72.8 per cent. As. 



Leucopprite, FesAs^ 62.1 per cent. As. 



Smaltite, CoAs2, 71.8 per cent. As. 



Niccolite, NiAs, 76.1 per cent. As. 



Allemontite, SbAs 3 , 65.2 per cent. As. 



There are also many arsenates of the useful and rare metals, 

 also the arsenate of calcium. 



Origin of the Ores. Arsenic is one of the rarer elements, 

 although widely distributed in nature. It has been found in 

 the nails of man, in the horns and hoofs of cattle, in the mane 

 and hoofs of horses, and in the bristles and hoofs of hogs. Ac- 

 cording to F. W. Clarke, traces of arsenic have been observed in 



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