The different kinds of starch do not take the same tint with the same
quantity of (solid) iodine. That from the potato _arum_ gives a blue, and
that from wheat and rice a violet tint; while the filtrate from starch
paste, from whatever source, always gives a blue color.
* * * * *
THE AMALGAMATION OF SILVER ORES.
DESCRIPTION OF THE FRANCKE "TINA" OR VAT PROCESS FOR THE AMALGAMATION OF
SILVER ORES.
[Footnote: Paper read before the Institution of Mechanical Engineers at
the Cardiff meeting.--_Engineering_.]
By Mr. EDGAR P. RATHBONE, of London.
In the year 1882, while on a visit to some of the great silver mines in
Bolivia, an opportunity was afforded the writer of inspecting a new and
successful process for the treatment of silver ores, the invention of Herr
Francke, a German gentleman long resident in Bolivia, whose acquaintance
the writer had also the pleasure of making. After many years of tedious
working devoted to experiments bearing on the metallurgical treatment of
rich but refractory silver ores, the inventor has successfully introduced
the process of which it is proposed in this paper to give a description,
and which has, by its satisfactory working, entirely eclipsed all other
plans hitherto tried in Bolivia, Peru, and Chili.
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