Lawrence Scientific School. 63 
fact even strong chlorhydric acid scarcely exerts upon them an 
appreciable action. This process has been applied to the separa- 
tion of cobalt and nickel from zinc and manganese by my excel- 
lent assistant, Mr. Maurice Perkins, and gives results which are 
very satisfactory, especially for qualitative purposes, the sulphids 
manganese and zinc precipitated under the same circum- 
stances being readily soluble, even in dilute acid. The process 
is now substituted in this laboratory for that given in most of the 
recent works on qualitative analysis, and has been repeatedly 
tested with satisfactory results. 
Se4, 
ge aa from the double cyanid of cobalt and potassium. 
r. W, ill, who has repeatedly employed this method and 
mined by difference, when, as is always possible, the two metals 
have been weighed together as sulphates. I am not prepared to 
say that this modification of Liebig’s method of separating nick- 
el and cobalt gives better results than Stromeyer’s process by _ 
* Ann. der Chemie und Pharmacie, Ixv, 244. 
* Berzelius, Lehrbuch der Chemie, iii, 872. 
