176 ECONOMIC GEOLOGY 



used as a pigment. The crude ore was crushed and used by the 

 ancients for coloring the hair, eyebrows, eye lashes so as to 

 increase the apparent size of the eyes. 



Antimony plays an important part in the refining of gold. 

 It is also used in the manufacture of matches and percussion caps. 

 Antimony pentasulphide is a bright red pigment used in the manu- 

 facture of vulcanized rubber and in many forms of fireworks. 

 Antimony trisulphide is a fiery red pigment used in certain paints. 

 Antimony is used in the lining of lead chambers for the manu- 

 facture of sulphuric acid. It is also used in the manufacture of 

 toys and in coffin trimmings. The soluble salts of antimony are 

 powerful irritant poisons, and 0.092 of a gram has proven fatal. 



Economics. Antimony for the consumption in the United 

 States is largely derived from four sources. (1) Hard lead ob- 

 tained in the smelting of foreign and domestic ores; (2) imported 

 regulus or metal; (3) imported antimony ores, and (4) domestic 

 ores. Considerable quantities of antimony are also recovered 

 from the drosses of old type metal and similar sources by firms 

 making a speciality of this branch of metallurgy. 



The reasons for the small production of antimony in the United 

 States are: (1) The low price of the metal; (2) the low cost of 

 production in foreign countries ; (3) the distance of known Amer- 

 ican deposits from market; (4) extensive foreign deposits; (5) 

 the difficulty in smelting the ores; (6) low ocean freight rates, 

 and (7) the low duty on crude antimony. 



Tin: Its Properties, Occurrence and Uses 



Properties. Tin, symbol Sn, is a white metal remaining untar- 

 nished in either dry or moist atmosphere. It is soft enough to 

 cut with a knife, malleable enough to be beaten out into a leaf, 

 and ductile enough to be drawn out into a fine wire. At a tem- 

 perature a little below its melting-point it becomes brittle and can 

 be powdered. The "tin cry" is emitted whenever the metal is 

 bent. No other metal cries so distinctly. It results from the 

 friction of the crystalline particles moving upon each other. This 

 friction perceptibly evolves heat. Tin is insoluble in the 

 strongest nitric acid, but ordinary concentrated nitric acid oxi- 

 dizes tin to metastanic acid, H 2 SnOs. The metal is readily sol- 

 uble in concentrated HC1. Its specific gravity is 7.3, melting 

 point, 232 C., and its atomic weight, 119. 



