148 



KOLLOCK-SMITH — ELECTRO-ANALYSIS. 



[Apri! 



ner previously described, but after the cell was removed anhydrous 

 alcohol was poured in as quickly as possible and the operation re- 

 peated twice and followed by two washings with ether in order to 

 prevent, if possible, oxidation of the chromium. Oxidation, if it 

 occurred, was but slight, for the error never exceeded 0.0007 gram. 

 Curve 8 was constructed from the results given below : 



In 2 minutes 0.048 gram of chromium was deposited. 



Chromium. 



Iron. 

 In experimenting with salts of this metal it was soon discovered 

 that sulphuric acid in large amount retarded its precipitation. It 

 was also noticed when higher currents were used that the solution 

 became very hot and assumed a decidedly pink color, 1 which dis- 

 appeared on the addition of cold water or when the cover glasses 

 were removed, allowing the steam to escape rapidly and thus decreas- 

 ing the pressure and consequently the temperature of the boiling 

 solution. The color reappeared a few seconds after the cover glasses 

 were replaced. 



1 Due to traces of manganese. 



