142 



KOLLOCK-SMITH — ELECTRO-ANALYSTS. 



[April 13, 



Curve 4. Zinc- 



In 10 minutes 0.3352 gram was deposited. 

 " 15 " 0.4010 " " " 



"20 " 0.4030 " " " 



" 30 " 0.4050 " 



Curve 4 was drawn from these re- 

 sults. A comparison of the third 

 and fourth curves shows the effect of 

 greater dilution upon the quantity of 

 zinc deposited in the first ten minutes. 

 Two experiments were made to learn 

 the effect of different speeds of the 

 anode upon the rate of precipitation. 

 It was found that the amount of zinc 

 deposited under a rotation of 440 revo- 

 lutions per minute, and 1,000 revolu- 

 tions per minute was only .0004, which 

 is within experimental error, showing 

 that between these limits there is no 

 apparent effect. It was also discovered 

 that when more than 1 gram of zinc was 

 present in the mercury, the latter should 

 not be further used if it is desired to 

 -1.5 Amperes, 10 volts, obtain results in the shortest period. 



Zinc. 



