Warwick.] 



118 



[Nov. 6, 



The hydrate of iron in the solution disappeared, but adherent crusts 

 still remained on the surface of the cadmium. 



ZINC FKOM IRON. 



Several tentative experiments were made, but as the iron showed the 

 same tendency to separate on the sides of the dish, as in the preceding 

 determinations, they were not continued. 



COPPER FROM COBALT. 



On attempting to prepare a solution of cobaltous formate for the above 

 determinations, it was found that the salt made according to the method 

 already described was not readily soluble in water. The solution was 

 therefore prepared by double decomposition as follows : 500 c.c. of water 

 containing 6.563 grams of sodium formate was mixed with an equal 

 amount of water in which 8.728 grains of cobalt chloride had been dis- 

 solved. 



Of this solution 50 c.c. was taken, containing .1080 grams of cobalt. 

 The distance between the poles was 3.8 cm. except (1) and (4) in which 

 it was 2.8 cm. Both of the latter were spongy ; the others slightly so. 

 As the conditions, otherwise, were similar, the difference in the character 

 of the deposits was apparently due to the separation of the poles. Traces 

 of cobalt were found in all the copper deposits. The copper was all 

 out except in (3), (5) and (6), in which the solutions were colored yellow- 

 ish brown on the addition of hydrogen sulphide. 



The copper deposit was dark in color and adherent, although not very 

 compact on the bottom of the dish. 



COPPER FROM NICKEL. 



OH gas .._- Difference 



per min. from theory, 



c.c. Hours. Percentage. 

 1 20 



(4) ' 



(5) 



(6) 



.1098 

 .1096 

 .1098 



1.2 



1 



17 

 18 

 17 



.54 



.36 



.36 



.27 



.46 



.27 



