596 BISMUTH. 



separation was discovered by Mr. Pattenson of Newcastle. To 

 separate the remaining lead, much of it is converted into massicot, 

 by the action of air upon its surface, in the shallow furnace used 

 for that preparation ; and the last portions of lead are removed 

 by continuing the oxidation upon a porous bason or cupel of 

 bone-earth, which imbibes the fused oxide of lead, while the 

 melted silver is found in a state of purity upon the surface of 

 the cupel, not being oxidable at a high temperature. 



SECTION XI. 



BISMUTH. 

 Eq. 886.907- 71.07; Bi. 



Bismuth generally occurs in the metallic state, and is sepa- 

 rated from the gangue or accompanying rock by fusion. It may 

 be prepared in a state of purity, for chemical purposes, by re- 

 ducing, with charcoal, the oxide of bismuth obtained by igniting 

 the subnitrate. 



Bismuth is a white metal of a reddish shade, and highly cry- 

 stallizable. Its density is 9.53, which may be increased by 

 cautious hammering to 9.8827. It is more fusible than lead, 

 melting at 497, according to Crichton, and at 507, according 

 to Rudberg. This metal, like water, expands considerably in 

 crystallizing. It is volatile at a full red heat, and burns in air 

 at a high temperature with a pale blue flame, and the formation 

 of copious fumes of oxide of bismuth. This metal does not ox- 

 idate in air ; it dissolves with difficulty in boiling hydrochloric 

 or diluted sulphuric acid, by substitution for hydrogen, but is 

 readily oxidised and dissolved by nitric acid. Bismuth resem- 

 bles several of the magnesian metals, in forming, besides a pro- 

 toxide, a suboxide of which the composition is unknown, and a 

 peroxide Bi O 2 , which does not combine with acids. 



Suboxide of bismuth is formed when the subnitrate is digested 

 in a solution of protochloride of tin, and appears as a black 

 powder, which is soluble with heat in hydrochloric acid, (Vogel). 

 When bismuth is oxidated and fused with metaphosphate of 

 soda upon charcoal, by the blow pipe, and the bead afterwards 

 held in the reducing flame, a colourless glass is obtained, which 

 assumes a black colour on cooling. This is analogous to what 



