1591.] 



119 



[Warwick. 



The same trouble was experienced in preparing a satisfactory solution 

 of pure nickel formate as with cobalt and it was found advisable to pre- 

 pare the solution by double decomposition in the same way as the latter 

 salt, 500 c.c. of this solution contained 8.3077 grams of nickel chloride and 

 6.2469 grams of sodium formate. In both cases a slight excess of sodium 

 formate was used. The copper contained traces of nickel and slightly 

 colored the solution when tested with hydrogen sulphide. The condi- 

 tions were similar to those given under cobalt and the results were quite 

 as satisfactory. The copper was bright and compact. 



CADMIUM FROM COBALT. 



H,0. 



OH gas 



Time. 



Difference 



per min. " from theory, 

 c.c. c.c. Hours. Percentage. 

 100 .5 22 

 150 .8 45 ..... 

 1.5 18 



It was naturally expected that cadmium would be completely precipi- 

 tated from cobalt and nickel by employing a weak current, but from an. 

 examination of the above results, it will be seen that a separation was not 

 accomplished. 



Even with a current of 1.5 c.c. OH gas per minute, the cadmium failed 

 to deposit completely and was contaminated with cobalt (3). (1) was 

 very spongy and the solution still contained cadmium at the expiration of 

 22 hours. The current was then increased and allowed to act for 45 hours 

 (2). Cadmium was found in the solution, cobalt in the deposit. The dis- 

 tance between the electrodes was 2.8 cm. 



CADMIUM FROM NICKEL. 



Cadmium Nickel Cadmium Free TT o OH gas T - Difference 



taken. taken. found. add. 2U- per min. '* from theory. 



Grams. Grams. Grams. c.c. c c. c.c. Hours. Percentage. 



(1) .0984 .1028 .0758 35 .150 .5 19 



(2) " " .1645 " " 1.5 21 



(3) " " .1348 50 125 1.5 17 



The results were quite as unsatisfactory as with cobalt. Cadmium was 

 found in all three solutions, and more or less nickel was found in the 

 deposits. In (3) the nickel came out as a gray deposit on the 

 cadmium. The deposit was firm and adherent, although dark in color. 

 The distance between the electrodes was 2.5 cm., except (3), in which 

 the pole separation was 2.8 cm. 



ZINC FROM COBALT. 



