220 METALS. 



]0. BISMUTH. 



Bismuth occurs native, and also in combination with sul- 

 phur, tellurium, oxygen, carbonic acid and silica. The ores 

 fuse easily before the blowpipe, and an oxyd is produced 

 which stains the charcoal brownish or yellow, without rising 

 in fumes.* Specific gravity of the ores, between 4*3 and 

 9-5. 



\^. NATIVE BISMUTH. \)j© . 3^~ 



Rhombohedral. Cleavage rhombohedral, perfect. In 

 rhombohedrons, near cubes in form, R : R=87° 40' ; gen- 

 erally massive, with distinct cleavage : sometimes granular. 



Color and streak silver white, with a slight tinge of red. 

 Subject to tarnish. Brittle when cold, but somewhat mal- 

 leable when heated. H=2 — 2-5. Gr=9'7 — 9-8. Fuses 

 at a temperature of 476° F. 



Composition : pure bismuth, with sometimes a trace of 

 arsenic. Evaporates before the blowpipe, and leaves ayel 

 low coating on charcoal. 



Obs. •Bismutlf-fs abundant with the opes of silver and co- 

 balt of Saxony and Bohemia, and occurs also in Cornwall 

 and Cumberland, England. At Schneeberg, it forms arbo- 

 rescent delineations in brown jasper. 



In the United States, it has been found at Lane's mine, 

 Monroe, where it occurs with tungsten, galena and pyrites, 

 but is not abundant ; also at Brewer's mine, in Chesterfield 

 district, South Carolina. 



There are other ores of bismuth, but none of them are common. 

 Sulphuret of bismuth. Massive and in acicular crystals, of a lead- 

 gray color. H=2 — 2 5. Gr=6'55. Contains bismuth 81, sulphur 



What are the color and physical characters generally of native bis- 

 muth ] What is its temperature of fusion 1 With what ores is it usually 

 associated ? 



* Tellurium produces a similar stain on charcoal, but on directing 

 the inner flame on the coating, it colors the flame strongly green, while 

 with bismuth no color is obtained. Antimony gives white fumes, pro- 

 ducing a white coating on charcoal, and the flame diiected on it ia 

 colored greenish- blue. * 





