ins 



A. The Silver Method. 

 Definite volumes of solutions of NiSO< and ( 'oKO, of known concentration 



were measured from burets into a casserole, K('X added until the precipitate 

 just dissolved, and the solution heated and rotated until complete oxidation 

 was effected. The solution was then diluted with water at 85° to 50 cc., 

 1 ee. of dimethylglyoxime solution added, and then AgX0 3 dropwise with 

 vigorous stirring until a permanent precipitate was produced. The time 

 required for the pink color of nickel glyoximine to appear was observed. 

 In cases where the time exceeded one hour, observations were made at the 

 end of 24 hours. The results are given below. 



TABLE IV. 

 In each expt. 10 cc. CoSd 0.0921 molar, equivalent to 54.31 mg. Co, was used. 



NiSO-4 



Mg. Ni. 



Ratio 



Ni : Co. 



Ratio 

 Ni : H2O 





Vol. 



Cone. molar 



Results. 



2 cc. . 

 1.5 cc. . 

 1.0 cc. . 

 4.5 CC. . 

 4.0 cc. . 



3 5 cc. . 

 3.0 cc. . 

 2.5 CC. . 



. 0005 

 0.0005 

 . 0005 

 .0001 

 .0001 

 .0001 

 .0001 

 .0001 



. 0587 

 .0440 

 .0293 

 .0264 

 .0235 

 .0205 

 .0176 

 .0137 



1 : 925 

 1 : 1234 

 1 : 1851 

 1 : 2054 

 1 : 2314 

 1 : 2644 

 1 : 3085 

 1 : 3702 



1 : 852,000 

 1 : 1,140,000 

 1 : 1,707,000 

 1 : 1,894,000 



1 : 2,440,000 



1 : 3,650,000 



Ppt. pink immediate. 

 Ppt. pink 4 min. 

 Ppt. pink 6 min. 

 Ppt. pink 10 min. 

 Ppt. pink 20 min. 

 Ppt. pink 30 min. 

 Ppt. pink 24 hours. 

 Ppt. pink 24 hours. 



Taking the minimum amount of nickel that could be detected in cobalt 

 in 30 minutes, 0.0205 mg., Ave observed the effect of larger proportions of 

 cobalt. The procedure and final total volume of solution were the same as 

 in the preceding experiments. 



TABLE V. 



C0SO4 0.0921 molar 



Mg. Co. 



Ratio Ni : Co 



Results. 



15 cc 



20 cc 



81.47 

 108.62 

 135.78 

 162.93 



1 : 3966 

 1 : 5288 

 1 : 6610 

 1 : 7932 



Ppt. pink 30 min. 

 Ppt. pink 30 min. 



25 CC 



Ppt. pink 30 min. 











