158 T. H. LABY. 
cipitation of the nickel as sulphide and subsequent electro- 
lysis. In this and the previous method the presence of 
much ammonium chloride makes the solution unsuitable 
for the immediate determination of the nickel by electro- 
lysis. The solubility’ of the sulphide in excess of ammonium 
sulphide may make the sulphide precipitation inaccurate. 
3. Basic Acetate. 
Kessler’ uses a solution containing 1 gram of ferric iron 
per 500 ce., and adds 1 gram each of acetic acid and sodium 
acetate. The presence of much of the latter caused the 
iron to carry down manganese. Meineke’ adds a small 
quantity of acetic acid and sodium acetate to a neutral 
solution and gives a short rapid boil. Mackintosh‘ believes 
ammonio-cobalt bases are formed which are peroxidised, 
finding five or six precipitations necessary; and that cobalt 
is more difficult to separate than nickel. Moore’ says four 
precipitations are necessary. Brearley, who has done 
much to elucidate the acetate process, found, for a ratio 
first determined by Kessler, that the solution produced by 
carefully adding sodium or ammonium carbonate to a cool 
ferric chloride solution till incipient precipitation, contains 
then about seven-eights of the ferric chloride as “‘ dissolved 
hydrate.’’ He’ adds sodium or ammonium carbonate to the 
cool ferric and nickel chlorides etc. tilla slight permanent 
precipitate forms, 10 cc. of 5 H.’ acetic acid, water to about 
a litre, then 10—12 cc. of °36 EH. ammonium or sodium 
acetate for each gram of iron present, and raises to the 
boiling point. He showed the separation is for total dissolved 
hydrate solutions most nearly complete when this small 
1 Terril—Chem. Gaz., 1857. 
2 Kessler, Ber. d. Deutsch. Chem., also C.N. xxvit., 14. 
3 Meineke, Zeit. Angew. Chem. 1888, 2, x1x., 232. 
* Mackintosh—School of Mines Quarterly, July, 1887. 
§ Moore—C.N. 1892, p. uxv.. 75. 
6 Brearley—C.N. 1899, pxxrx., 194; C.N. 1897, txxvt., 210. 
7 Or 5 normal. 
