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The organic materials are treated with an equal weight of pure hydrochloric acid, and water added, so as to form a clear pulp. This being accomplished, two grammes of chlorate of potassa are added to the mixture at intervals of about five minutes. The fluid is next filtered, and the insoluble residue remaining on the filter washed until the wash-water ceases to exhibit an acid reaction. The filtrate is then evaporated, an aqueous solution of sulphurous acid added, until the odor of this reagent remains distinctly perceptible, and the excess of the acid removed by boiling the solution for about an hour. The fluid is now adapted to further examination for arsenic, or other metallic poisons.

This method is one of the best in use, both chlorate of potassa and hydrochloric acid being reagents easily procured in a state of great purity; their use, however, is liable to the objection that they convert silver and lead into insoluble chlorides.