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—­

_______________________________________________________

_________________
|                    |                         |                         |
|                    |            A            |            B            |
|                    |                         |                         |
|                    | Percentage | Percentage | Percentage | Percentage |
|                    |   Taken.   |   Found.   |   Taken.   |   Found.   |
|____________________|____________|____________|____________

|____________|
|                    |            |            |            |            |
| Antimony Sulphide  |   36.47    |   36.25    |   37.34    |   37.22    |
| Potassium Chlorate |   33.25    |   33.71    |   46.03    |   46.43    |
| Mercury Fulminate  |   30.27    |   30.02    |   16.61    |   16.34    |
|____________________|____________|____________|____________

|____________|

Dr. H.W.  Brownsdon’s (Jour.  Soc.  Chem.  Ind., xxiv., April 1905) process is as follows:—­The cap composition is removed by squeezing the cap with pliers, while held over