170 



METALS AND THEIR COMBINATIONS. 



Bismuth is trivalent, as shown in the chloride, BiCl 3 , or 

 oxide, Bi 2 3 . A characteristic property of this metal is the 

 decomposition of the concentrated solution of any of its normal 

 salts hy the addition of much water, with the formation and 

 precipitation of so-called oxy-salts or subsalts of bismuth, while 

 some bismuth with a large quantity of acid remains in solution. 



The true constitution of these subsalts is as yet doubtful, but 

 a comparison of them has led to the assumption of a radical 

 Bismuthyl) BiO, which behaves like an atom of a univalent 

 metal. 



The relation between the normal or bismuth salts and the 

 subsalts or bismuthyl salts will be shown by the composition of 

 the following compounds: 



Bismuth chloride, BiCl 3 . 

 bromide, BiBr 3 . 

 iodide, BiI 3 . 

 nitrate, Bi3NO 3 . 

 sulphate, Bi 2 3SO 4 . 

 ite, Bi 2 3C0 3 

 not known. 



Bismuthyl chloride, (BiO)Cl. 

 bromide, (BiO)Br. 

 " iodide, (BiO)I. 



nitrate, (BiO)NO 3 . 

 " sulphate, (BiO) 2 SO 4 . 



" carbonate, (BiO 2 C0 3 . 



Bismuthyl nitrate, Subnitrate of bismuth, Bismuthi subnitras, 

 BiON0 3 .H 2 = 306 (Oxynitrate of bismuth}. By dissolving metallic 

 bismuth in nitric acid, a solution of bismuth nitrate is obtained, 

 nitrogen dioxide escaping : 



Bi 



4HN0 = Bi3N0 



NO -- 2H0. 



Upon evaporation of the solution, colorless crystals of bismuth 

 nitrate (Bi3N0 3 .5H 2 0) are obtained. 



If, however, the solution (or the dissolved crystals) be poured 

 into a large quantity of water, the salt is decomposed with the 

 formation of bismuthyl nitrate, some bismuth and the larger 

 quantity of nitric acid remaining in solution : 



5(Bi3NO 3 ) + 8H 2 = 4(BiONO 3 .H 2 O) + Bi3N0 3 ; 8HNO 8 . 



As bismuth frequently contains arsenic, tests should be ap- 

 plied for this metal before using the bismuth. 



Subnitrate of bismuth is a heavy, white, tasteless powder, 

 insoluble in water, soluble in most acids. 



Bismuthyl carbonate, Subcarbonate of bismuth, Bismuthi subcar- 

 bonas, (BiO) 2 C0 3 .H 2 (Oxy carbonate of bismuth, Pearl-white). Made 



