3/echvay — Further Wor~k with the Rotating Cathode. 57 



Cadmium 



Cadmium 











taken 



found 



Error 



Current 



N. D. 



Time 



grm. 



grm. 



grm. 



Amp. 



100. 



min 



0-1088 



0-1083 



— 0-0005 



2 



6-6 



15 



0-1088 



0-1085 



— 0-0003 



2 



6-6 



15 



0-1088 



0-1092 



+ 0-0004 



1-5 



5- 



15 



0-1088 



0-1090 



+ 0-0002 



2 



6-6 



15 



0-1088 



0-1093 



+ 0-0005 



1-5 



5- 



12 



0-1088 



0-1093 



+ 0-0005 



2 



66 



10 



0-1088 



0-1087 



-o-oooi 



2 



6*6 



10 



Tin. 



For the purpose of trying the electrolytic deposition of tin, 

 a solution of stannous ammonium chloride was prepared of 

 about 20 cm 3 volume. To this was added a cold saturated 

 solution of ammonium oxalate amounting to 100 cm 3 . The 

 electrolysis then proceeded in the usual way. 



Results are below: 





Tin 



Tin 













taken 



found 



Error 



Current 



N. D. 



Time 





grm. 



grm. 



grm. 



Amp. 



100. 



min 



1) 



0-0804 



0-0802 



— 0-0002 



2-5 



8-3 



20 



2) 



0-0804 



0-0800 



— 0-0004 



2 



6-6 



20 



3) 



0-1607 



0-1610 



+ 0-0003 



2-5 



8-3 



20 



4) 



0-1607 



0-1603 



— 0-0004 



2-5 



8-3 



20 



5) 



0-1607 



0-1607 



±0-0000 



3-5 



11-6 



15 



An alkaline oxalate was also used in the case of zinc — the 

 next metal whose precipitation was attempted, but it was found 

 expedient to use potassium oxalate instead of ammonium 

 oxalate, since the presence of ammonium salts appeared to re- 

 tard the complete deposition of the metal. Therefore, the fol- 

 lowing procedure was adopted : The zinc salt — preferably the 

 sulphate — was dissolved in 50 cm 3 of water and 4 grms. of 

 potassium oxalate were added. The solution was then sub- 

 mitted to electrolysis. 



The results follow: 





Zinc 



Zinc 













taken 



found 



Error 



Current 



N. D. 



Time 





grm. 



grm. 



grm. 



Amp. 



100. 



min 



1) 



0-0553 



0-0556 



+ 0-0003 



2-5 



8-3 



25 



2) 



0*0553 



0-0553 



±0-0000 



2-5 



8-3 



25 



3) 



0-0553 



0-0552 



—o-oooi 



2-5 



8-3 



25 



4) 



0-0993 



0-0995 



+ 0-0002 



2'5 



8-3 



30 



5) 



0-0993 



0-0994 



+ 0-0001 



2- 



6-6 



25 



6) 



0-0993 



0-0991 



— 0-0002 



2- 



6-6 



25 



