416 K. W. CHALLINOR. 



'04 gm. standard. 

 Take of standard Ni solution 3*04 cc. = "0304 gm. Ni 

 „ Co „ 3*2 cc. = '0096 „ Co 



•04 

 '05 gm. standard. 

 Standard Ni solution 3*8 cc. = '038 gm. Ni 

 Co „ 4 cc. = '012 „ Co 



•05 



'00 gm. standard. 

 Standard Ni solution 4'5G cc. = *0456 gm. Ni. 

 Co „ 4*8 cc. = -0144 „ Co. 



•06 

 Dilute each to 50 cc. 



After obtaining the weight of the two metals deposited 

 electrolytically, dissolve in HN0 3 (16 E. HN0 3 diluted with 

 an equal volume of water) by heating gently on hot plate, 

 in a covered beaker. Evaporate nearly to dryness, take 

 up in water and dilute to a known volume, (a) If the 

 solution is green (indicating the presence of more than 76°/° 

 Ni), take an aliquot portion containing from *04 - # 05 gm. 

 of the mixed metals, and add standard Co (N0 3 ) 2 from a 

 burette till the colour (after diluting to 50 cc. mark) 

 matches that of the standard solution containing the nearest 

 total weight of mixed metals, (b) If the solution is pale 

 pink (indicating more than 24 *Co) take about '02 gm., and 

 if decided pink about *01 gm., add a measured excess of 

 standard Ni (N0 3 ) 2 solution till of a faint green colour and 

 then standard Co (NO 3 ) 2 and match with standard solution as 

 before. After calculating the weight of Ni present in this 

 solution, deduct the amount of added Ni and this gives the 

 weight of Ni in the portion of solution taken. The above 

 proportions are for 50 cc. Nessler tubes 10*9 cm. high from 

 to 50 cc. mark. 



