the solvent has been added. When the solution contains iron and manganese,
it is separated by decantation from the sediment and oxidized with bromine
(according to the method of Nic-Wolff) until a flocculent precipitate of
iron sesquioxide and manganese dioxide becomes visible; it is united with
the original residue and filtered.

The filtrate is diluted till it appears cloudy, boiled to expel ammonia,
tested with sodium sulphide upon the presence of zinc, and, when freed of
all zinc, decanted. The precipitate of zinc carbonate is filtered,
exhausted with water, transferred into zinc oxide by ignition, and
weighed. The gravimetric method can be substituted by the volumetric by
introducing a solution of sodium sulphide of known strength into the
ammoniacal filtrate. On dividing the filtered liquid into various equal
portions other substances, arsenic and sulphuric acid, can be determined
from the same sample. For this purpose the filtrate is concentrated;
divided into two equal portions, one of which is acidified and treated
with hydrogen sulphide for the determination of arsenic, the other is
acidified and used for the estimation of sulphuric acid by means of barium
chloride. The original residue is dissolved in muriatic or acetic acid and
filtered. The lead of the filtered liquid is thrown down by sulphuric
acid, and alcohol, and cadmium, after dissipation of alcohol into gas,
precipitated by hydrogen sulphide. Iron, manganese, alumina, and other
substances present in the solution are determined by known methods.

It is manifest that the determination of substances--zinc, lead, and
sulphuric acid--which are of importance in technical analysis of zinc ash,
can be executed by this method within a comparatively short time. The
application of ammonium carbonate as solvent has the advantage, over the
application of ammonia, that it is a far better solvent, that it
decomposes insoluble basic sulphates, and that the remaining carbonates