KOLLOCK-SMITH — ELECTRO-ANALYSIS. 



149 



The conditions which gave the most satisfactory results were as 

 follows : 



Volume of solution 5 c.c. containing 0.275 gram of metallic iron, 

 3 drops of concentrated sulphuric 

 acid and a current of 3 to 4 am- 

 peres and 7 volts. The rotation of 

 the anode varied from 520-920 

 revolutions per minute. The iron 

 was completely deposited in seven 

 minutes. The following observa- 

 tions on rate of deposition were 

 made under the conditions just 

 given : 



In 2 minutes o. 1760 gram of iron deposited. 

 "4 " 0.2000 " " " 



(i 5 << 0.2050 " " " 



" 8 " 0.2075 " " " 



In addition to the results just 

 described a solution of ferrous sul- 

 phate containing 0.1945 gram of 

 iron in 10 c.c. was used to get 

 further working conditions. By 

 using a current of 3.5 A. and 

 10-9 volts, with about 900 revolu- 

 tions per minute of the anode, 

 the total iron content was deposited in fifteen minutes. The 

 residue from the decompositon cell when oxidized by nitric acid 

 and tested with potassium sulphocyanide gave no color. The 



Curve 9. 

 volts. 



Iron — 3.5 Amperes, 7 



