Chap. 25.] [ 139 ] 



CHAP. XXV. 



BISMUTH. 



External Qualities of Bifmuth. A powerful DiJJol-ver ofEarihs.^f 

 Pearl White, a pernicious Co/metic. Curious Experiment. A metal- 

 lif Compaction, which pielts in boiliug Water, Various Uj'es of 

 Bifmuth in the Arts. 



BISMUTH is extremely brittle, fo that it may 

 be eafiiy feparated, and even reduced to powder 

 by the hammer. When broken it exhibits at the 

 place of fracture large mining plates, difpofed in a 

 variety of directions. It is confiderably ponderous, 

 and is of a yellovvifh white colour; when in rhin plates 

 it is in fome degree fonorous. It is very fufible, and 

 melts at a temperature not exceeding 460 of Faren- 

 heit. 



Bifmuth is fcarcely altered by expofure to air and 

 light. In clofed vefiels it fublimes without alteration ; 

 it cryflallizes the mod eafiiy of any metallic fubftance. 

 If bifmuth is kept in fufion in contact with air, its fur- 

 face becomes covered with a pellicle, which changes 

 into an earth-like matter of a greenifh grey or brown, 

 named calx of bifmuth. Nineteen drachms of bifmuth, 

 calcined in a capfule of glafs, afforded M. Baume 

 twenty drachms thirty-four grains of calx. Bifmuth 

 heated to rednefs burns with a fmall blue flame, 

 fcarcely fenfible. Its calx evaporates in the form of a 

 yellowilh fmoke, which condenfes on the furface of 

 cold bodies, into a powder of the fame colour, called 

 flowers of bifmuth. This powder owes its volatiliza- 

 tion only to the rapidity with which the bifmuth 

 burns 3 for if it is expofed in clofe veflels to fire, it melts 

 3 into 



