Section III., 1903 [ 45 ] Tbanb. R. S. C. 



V. — The Oxalates of Bismuth. 

 By Dr. F. B. Allan. 



(Communicated by Prof. W. Lash Miller, and read May 19th, 1903.) 



Neutral oxalate of bismuth Bi^Os 3 C^Os 7^ H^O was prepared by 

 Souchay and Lensson (Ann. der Chem., 105, 245), by adding oxalic acid 

 to a solution of bismuth oxide in nitric acid. It was also prepared by 

 Muir (Jour, of the Chem. Soc. 1878, 193), who gave it the formula 

 Bl^Os 3 CgOg 6 H^O. Swartzenburg (Ann. der Chem. 64, 127) boiled 

 bismuth oxide with acid potassium oxalate and the product, dried at 

 100°, had the composition Bi^O^ 3 C^Og 4 H^O. It this neutral 

 oxalate be boiled repeatedly with water, a basic salt is formed to which 

 various formulas have been given — Bi^O^ 2 C^O^ 1^ R^^ (Heintz, 

 Pogg, Ann. 63, 90) Bi^O^ 2 C^O^H^O (Souchay and Lensson) and 

 Bi^O^ 2 C^O^ (Muir). 



Owing to the easy decomposition of the neutral oxalate by water, 

 I have not been able to obtain it entirely free from basic salt. This 

 oxalate was used in a study of the basic oxalates similar to the researches 

 by the author on the nitrates (Amer. Ohem. Jour., 25, 307), and 

 sulphates of bismuth (Amer, Chem. Jour., 27, 284). The salt was 

 stirred with water and with oxalic acid solutions in a constant tem- 

 perature bath. Owing to the length of time required to get 

 equilibrium in monovariant systems, only divariant systems containing 

 a gaseous, a liquid, and one solid phase have been obtained. 



Bi^O^ 

 At 50° a basic salt, in which -^^^=3.23, was found to be in 



C2C3 



equilibrium with oxalic acid solutions up to .085 normal and in 



stronger solutions the solid phase was the neutral salt. This basic 



salt was air-dried and analyzed, the bismuth being determined as the 



sulphide and the oxalic acid in the filtrate by titration with 



Miller and Kenrick (Trans. Eoyal Soc. Canada, 1901), have shown 

 that the number of possible phases in a given system is not changed 

 if a new constituent be added to the liquid phase provided that this 

 new constituent does not pass into the solid phase. This condition is 



