192 METALS AND THEIR COMBINATIONS. 



of bismuthyl nitrate and nitric acid, which latter keeps in solution 

 some bismuth : 



Bi(N0 3 ) 3 + 2H 2 = BiON0 3 .H 2 + 2HNO 3 



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

 insoluble in water, soluble in most acids. 



Experiment 33. Dissolve by the aid of heat about 1 gramme of metallic bis- 

 muth in a mixture of 2 c.c. of nitric acid and 1 c.c. of water. Evaporate the 

 clear solution to about one-half its volume, in order to remove excess of acid, 

 and pour this solution of normal bismuth nitrate into 100 c.c. of water. Col- 

 lect the precipitate of bismuthyl nitrate on a filter, wash and dry it. Prove 

 the presence of bismuth in the filtrate by tests mentioned below. 



Bismuthyl carbonate, Bismuth subcarbonate, Bismuth! sub- 

 carbonas, (BiO) 8 CO 3 .H 2 O (?) (Oxy carbonate of bismuth, Pearl-white). 

 Made by adding sodium carbonate to solution of bismuth nitrate, 

 when the subcarbonate is precipitated, some carbon dioxide escaping: 



2[Bi(NO 3 ) 3 ] -f 3Na 2 CO 3 + H 2 O = 6NaNO 3 + 2CO 2 + (BiO) 2 CO 3 .H 2 O. 



A v/hite, or pale yellowish-white powder, resembling the subnitrate. 

 It readily loses water and carbon dioxide on heating, when the yellow 

 oxide, Bi 2 O 3 , is left. 



Bismuthyl iodide, Bismuth subiodide, BiOI, may be obtained 

 by adding solution of hydriodic acid to freshly precipitated bismuth 



oxide : 



Bi 2 O 3 + 2HI = 2BiOI + H 2 0. 



A better method for making the compound is to pour gradually a 

 solution, made by dissolving 95 grammes of crystallized normal bis- 

 muth nitrate in 125 c.c. of glacial acetic acid, into a solution of 40 

 grammes of potassium iodide, and 55 grammes of sodium acetate in 

 2500 c.c. of water. The precipitate, which has a brick-red color, is 

 well washed and dried at 100 C. (212 F.). The decomposition is 



this : 



2[Bi(N0 3 ) 3 ] + 2H 2 + 2KI + 4NaC 2 H 3 O 2 = 

 2(BiOI) + 4NaNO 3 -f 2KNO 3 + 4C 2 H 4 O 2 - 



Analytical reactions. 

 (Bismuth nitrate, Bi(NO 3 ) 3 , or bismuth chloride, BiCl 3 , may be used.) 



1. Add to solution of bismuth, hydrogen sulphide or ammonium 

 sulphide : a dark-brown (almost black) precipitate of bismuth sul- 

 phide, Bi 2 S 3 , is produced (Plate III., 8): 



2BiCl 3 + 3H 2 S = 6HC1 -f Bi 2 S 3 . 



