A N T I M O N Y : ITS HISTORY, CHEMISTRY, MINERALOGY ...
A N T I M O N Y : ITS HISTORY, CHEMISTRY, MINERALOGY ...
A N T I M O N Y : ITS HISTORY, CHEMISTRY, MINERALOGY ...
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THE ANALYSIS OF ANTIMONY COMPOUNDS.<br />
"With a view to remove the necessity of consuming so much valuable<br />
time over the certain identification of antimony, Alexander<br />
Johnstone proposes the following exceedingly simple test, which he<br />
discovered and successfully applied while working among the various<br />
metallic ores of antimony.<br />
" To the white coat which will invariably form on the charcoal if<br />
the mineral containing antimony be properly treated and heated<br />
before the blowpipe, add, by means of a narrow glass tube, a single<br />
drop of ammonium sulphide. If the white sublimate is composed of<br />
antimonious oxide, then the portion touched by the drop (or the part<br />
touched by the edge of the drop) will immediately become converted<br />
into the well-known and highly characteristic reddish or orange<br />
antimony sulphide.<br />
" As no other white coat producible on charcoal by heating a mineral<br />
in the blowpipe flame becomes reddish or distinctly orange in colour<br />
when treated as above with ammonium sulphide, the value of this<br />
easily applied test must at once be apparent.<br />
" (/?) In the examination of mineral bodies for antimony the test<br />
substance is often roasted in an open tube for the production of a<br />
white sublimate. Dr E. Chapman, Professor of Mineralogy at<br />
Toronto, recommends for the detection of antimony in this substance<br />
the following process—a method more especially available when the<br />
operator has* only a portable blowpipe-case at his command :—The<br />
portion of the tube to which the chief part of the sublimate is attached<br />
is to be cut off by a triangular file, and dropped into a test-tube<br />
containing some tartaric acid dissolved in water. This being warmed<br />
or gently boiled, a part at least of the sublimate will be dissolved.<br />
Some potassium bisulphate—either alone, or mixed with some sodium<br />
carbonate and a little borax, the latter to prevent absorption—is then<br />
to be fused on charcoal in a reducing flame; and the alkaline sulphide<br />
thus produced is to be removed by the point of the knife-blade and<br />
placed in a small porcelain capsule. The hepatic mass is most easily<br />
separated from the charcoal by removing it before it has time to<br />
solidify. Some of the tartaric acid solution is then to be dropped<br />
upon it, when the well-known orange-coloured precipitate of antimony<br />
sulphide will at once result.<br />
" In performing this test, it is as well to employ a somewhat large<br />
fragment of the test substance, so as to obtain a thick deposit in the<br />
tube. It is advisable also to hold the tube in not too inclined a<br />
position, in order to allow but a moderate current of air to pass<br />
through it; and care should be taken not to expose the sublimate to<br />
the action of the flame, otherwise it might be converted almost wholly