140 



KOLLOCK-SM1TH — ELECTRO-ANALYSIS. 



|April 13, 



were conducted in order to ascertain the rate of deposition with 

 varying concentration, current strength, electromotive force, speed 

 of anode' and how the quantity of metal in the mercury affected the 

 subsequent rate of deposition. The solution for the first experi- 

 ments contained 0.2025 gram of metallic zinc in 10 cc. This was 

 determined by the electrolytic method, depositing it upon a plati- 

 num dish from an ammonium acetate electrolyte. The speed of 

 the anode was 400 revolutions per minute. The current strength 



was one ampere and the 

 E.M.F. was 5 volts. The 

 volume of the zinc sulphate 

 solution equaled 15 cc, the 

 current acted thirty minutes. 

 The solution siphoned from 

 the tube showed no trace of 

 zinc Consecutive experi- 

 ments so conducted gave the 

 following results in 25 min- 

 utes: .2027, .2030, .2025, 

 .2025, .2021, .2027, .2025 

 grams. Two trials were made 

 with the same conditions but 

 using a volume of 10 cc in- 

 stead of 15c c. It was found 

 that the zinc was completely 

 separated in twenty minutes. 

 Experiments were then 

 made to determine the rate 

 of deposition in successive 

 periods of time and the curve constructed from the data thus obtained, 

 using periods of time for abscissas and masses for ordinates. The 

 conditions employed were those given above. The results were as 

 follows : 



In 5 minutes o.ll96gram. 



" 10 " 0.1774 " 



" 15 " 0.1897 " 



"20 " 0.2002 " 



" 25 " 0.2027 " 



Upon employing a current of 2 amperes, adding sulphuric acid 

 to increase the conductivity, the entire amount was deposited in 



Curve i. Zinc — 1 Ampere, 5 volts. 



