134 ECONOMIC GEOLOGY 



94.5; Rose's metal, fusing at about 100. The range of the 

 melting point of these alloys between 60 and 100 renders them 

 capable of industrial application, as on passenger and freight 

 trains where gas is used for lighting and as safety fuses for elec- 

 trical apparatus. Britannia metal is an alloy which carries 1.8 

 per cent, of bismuth. One variety of type metal carries 7.6, per 

 cent, of bismuth. With zinc the alloys of bismuth are always 

 of definite composition. 



The alloys of bismuth expand upon cooling, therefore they 

 make fine, hard, sharp castings and are used for safety plugs 

 to fill blow holes in boilers. These alloys are used also in the 

 production of wood cuts. Some of the alloys known as bis- 

 muth solders have so low a melting point that they can be used 

 directly under hot water. Bismuth is used also in the manu- 

 facture of clique metals. It is utilized in the preparation of 

 glass of high refractive power. Bismuth unites with mercury 

 in the formation of dental amalgams. Bismuth is used quite 

 extensively in medicine, the subnitrate being the most important 

 compound. It is used in cosmetics, in calico printing and several 

 of its salts in the chemical trade. Bismuth is one of the 

 most objectionable constituents in brass. 



The world's supply of bismuth has long been controlled by 

 Johnson, Mathey & Co. of England, who have regulated abso- 

 lutely the production of bismuth, the price of the metal, and the 

 supply of its ores. An attempt has been made to establish a 

 price that would be renumerative to both the mine owners and 

 the producers. The price of bismuth ores in London depends 

 upon the bismuth content. With the metal at $1.25 per pound 

 the following values would be attached to the ores: 10 per cent, 

 ore would be worth $150 per ton; 15 per cent., $200; 20 per cent., 

 $350; 30 per cent., $550; 35 per cent., $650; 40 per cent., $750; 

 45 per cent., $850; 50 per cent., $1000. 



The small amount of bismuth ore produced in the United 

 States was formerly sent abroad for reduction. Plants have 

 recently been established 'at St. Louis, Missouri and Grasselli, 

 Indiana, for the recovery of bismuth from lead ores. Bismuth, as 

 already noted, is contained in other ores than lead, but most of 

 the bismuth passes into the atmosphere through the smelter 

 flues unrecovered. It is estimated that 880 Ib. of bismuth are 

 thrown oft in every 24 hours in the smoke and gases of the 

 Washoe smelter. 



