hillebrand.] MANGANESE, NICKEL, C0I3ALT, COPPER, ZINC. 6] 
cipitate, collected and washed on a small filter with water containing 
ammonium chloride and sulphide, is extracted by hydrogen-sulphide 
water acidified with one-fifth its volume of hydrochloric acid (sp. gr. 
1.11), manganese and zinc, if present, going into solution. 
MANGANESE AM) ZINC. 
The tiltrate is evaporated to dryness, ammonium salts are destroyed 
by evaporation with a few drops of sodium-carbonate solution, hydro- 
chloric and a drop of sulphurous acids arc added to decompose excess 
of carbonate and to dissolve precipitated manganese, and the latter is 
repr^cipitated at boiling heat by sodium carbonate after evaporation of 
the hydrochloric acid. If zinc is present, it can be separated from the 
manganese after weighing. For the small quantities of manganese 
usually found the sodium-carbonate method of precipitation is to be 
preferred to that by bromine or sodium phosphate, as equally accurate 
and a great time saver. 
The precipitation of manganese in alkaline solution by hydrogen 
peroxide, as proposed by Jannasch and Cloedt, 1 a method which 
appeared to be simple and accurate, besides affording a separation 
from zinc, has been shown by Friedheim and Bruhl 2 to lie valueless, 
as also other separation methods of Jannasch based on the use of 
Irydrogen peroxide. 
The employment of ammonium sulphide instead of bromine for the 
separation of manganese from the alkaline earths and magnesia has the 
advantage that, by a single operation, nickel, copper, and zinc are like- 
wise removed if present. There need be no fear of overlooking nickel 
or copper, for under the conditions of the precipitation they are not 
held in solution. Now and then a trace of alumina may be found in 
the precipitate, and magnesia, too, would contaminate it if ammonium 
salts were not present in sufficient quantity. Regard must therefore 
be had to these possibilities, and also to the rather remote possibility 
of the presence of rare earths which were not thrown out by the basic, 
acetate precipitation (see footnote, p. 55). 
NICKEL, COBALT, COPPER. 
The paper containing these is incinerated in porcelain, dissolved in 
a few drops of aqua rcgia, evaporated with hydrochloric acid, the cop- 
per and platinum thrown out warm by hydrogen sulphide, and nickel 
and cobalt thrown down from the ammoniacal filtrate by hydrogen sul- 
phide. This is then rendered faintly acid by acetic acid and allowed 
to stand. The sulphide of nickel is simply burned and weighed as 
1 Zeitsclir. fur anorg. Chemie, Vol. X, \>. 105, 11 
2Zeitschr. Eur anal. Chemie, Vol. XXXVIII, p. 681, L899. 
