ts of the
ingredients--potassium chlorate, antimony sulphide, and mercury fulminate,
and to estimate these substances in the presence of each other by ordinary
analytical methods is a difficult process. Since the separation of
antimony sulphide and mercury fulminate in the presence of potassium
chlorate necessitates the treatment of the mixture with hydrochloric acid,
and this produces an evolution of hydrogen sulphide from the sulphide, and
a consequent precipitation of sulphur; and potassium chlorate cannot be
separated from the other ingredients by treatment with water, owing to the
appreciable solubility of mercury fulminate in cold water.

In the course of some experiments on the solubility of mercury fulminate
Messrs Jones and Willcox observed that this body was readily soluble in
acetone and other ethereal solvents when they were saturated with ammonia
gas, and that chlorate of potash and sulphide of antimony were insoluble
in pure acetone saturated with ammonia; these observations at once
afforded a simple method of separating the three ingredients of cap
composition. By employing this solution of acetone and ammonia an analysis
can be made in a comparatively short time, and yields results of
sufficient accuracy for all technical purposes. The following are the
details of the process:--

A tared filter paper is placed in a funnel to the neck of which has been
fitted a piece of rubber tubing provided with a clip. The paper is
moistened with a solution of acetone and ammonia, the cap composition is
weighed off directly on to the filter paper and is then covered with the
solution of acetone and ammonia and allowed to stand thirty-four hours. It
is then washed repeatedly with the same solution until the washings give
no coloration with ammonium sulphide, and afterwards washed with acetone
until washings give no residue on evaporation dried and weighed. The paper
is again put in the funnel and washed with water until free from potassium
chlorate, dried and weighed.

If _c_ = weight of composition taken,
_d_ = " " filter paper,
_a_ = " after first extraction,
_b_ = " " second extraction,
then _c+d-a_ = weight of fulminate,
_c+d-a-b_ = " " KClO_{3},
_b-d_ = " " sulphide of antimony.

The composition should be finely ground in an agate mortar.

The results of the analysis by this method of two mixtures of known
composition are given below--

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