214 W. Gibbs—Contributions to Chemistry. 
The filtrate is perfectly free from copper if the process has been 
well conducted. 
e ignited oxyd is in a state of great subdivision, and the 
ignition must therefore be conducted with much care to avoid 
A small portion of the oxyd or basic carbonate usually 
adheres to the sides of the vessel in which the boiling takes place. 
This is to be re-dissolved, and again precipitated, but great care 
must be taken not to add a large excess of the alkaline carbo- 
nate, which gives a solution from which the copper is not pre 
cipitated by boiling. 
Nickel may be completely precipitated from’ its solutions by 
precisely the same process. The green basic carbonate may be 
washed much more readily than the oxyd precipitated by caus- 
tic alkali; it is to be ignited and wuighed as oxyd. In two 
analyses Mr. Taylor obtained the following results. 
1-9808 gr. anhydrous sulphate of nickel gave 0°9551 gr. Ni0—37'79 p. c 
14601 gr.“ - « —“€ —0°7008 gr. NiO=37°64 © 
‘ The formula ¥iS©, requires 87°69 (Ni=58). Dr. F. A. Genth 
informs me that he has also used the alkaline carbonates in pre 
cipitating nickel, and with most satisfactory results. 
‘The precipitation of cobalt by an alkaline carbonate can only 
with much difficulty and by long boiling be made complete. 
As a means of determining cobalt it is not to be recommended. 
On the other hand Mr. F. W. Clarke has found that cobalt 1s 
completely and easily precipitated by the process. of oxydation 
first given by Popp,* which consists in neutralizing the solution 
with carbonate of sodium, adding acetate of sodium and thet 
boiling with an excess of an alkaline hypochlorite, taking care 
to keep the solution*alkaline. The hydrated sesquioxyd (?) ° 
cobalt thrown down may be readily washed. After reduction 
in hydrogen the metal is found to be free from alkali. Nickel 
may, as Popp has also shown, be precipitated in the same manne! 
but the process given above seems to me preferable. 
: An this connection I may be permitted to state that the method 
of separating cobalt from nickel by means of peroxyd of lead 
tributed to myself in the new edition of oust H 
Analytischen Chemie and also ascribed to me by Gauhet w% 
never even proposed by me. : 
par ae nickel may be precipitated from neutral solutions 
of one se nitrates and chlorids by adding first an exces 
nes GF Hou the concentrated solution and then a large & 
ra : cohol. After standing a few hours the alee 
Lviiga’ from metal. The oxalates are very eas! 
wash method is, however, rarely available for analyt 
* Fei ay . 
f Zeitechens Rey analytisehe Chemie. -‘ Sechate Auflage, Bd. i, p48 
* 
