114 THE ROYAL SOCIETY OF CANADA 



The electrolyte varied from day to day; its composition was 

 approximately : 



ZnSO^ 5 • 0% per cent. 



Manganese 0-11 " 



Lead 0-001 



Copper 0-000075 " 



Cadmium 0-004 



Iron 0-02—0-003 per cent. 



In these experiments, about 2,500cc. of a solution containing 

 4-0-5-0% of zinc was electrolysed between lead anodes and an alum- 

 inum cathode with a current density of 20-30 amperes per square 

 foot. In general the electrolysis was continued until the zinc had 

 been brought to about 0-5 per cent, the acid having increased to 6-7 

 per cent. Various inpurities were added to the solutions before 

 electrolysis, and the effect of these can be seen from the photographs. 



Series 1. 



Electrolyte 4-4% Zn. 



0-009% Fe. 



Current Density, 22 Amps, per square foot. 



Addition. Deposit. 



1. 0-01% Cu (as CuSOO Very bad. 



2. 0-04% Pb (N03)2 



4. Electrolyte Very good. 



5. Pure zinc sulphate " 



7. 0-008% AS2O3 Bad. 



Series 2. 



4-5% Zn. 

 0-009% Fe. 

 Current Density, 29 Amps, per square foot. 

 A ddition . Deposit . 



10. 0-02% Nitric Acid • Very bad. 



11. 0-02% Hydrochloric acid Very good; bright. 



12. 0-005% Cu Very bad. 



13. 0-0025% Ag. (as Ag2S04) 



14. 0-1% Fe (as Fe2(S04)3 Bad. Re-solution of zinc. 



15. " " (asFeS04) 



16. P^lectrolyte Very good. 



