POISONS.

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Por arsenic no specific antidote is yet known. Fat, oil, vinegar,charcoal powder, lime of sulphur, and vegetable decoctions, whichhave been recommended, are not to be relied on.

Tests. — To ascertain when arsenic is present in any fluid, a solu-tion of the ammoniacal sulphate of copper added to it, produces,generally, a beautiful grass green precipitate ; but if added to wine,the precipitate would be a dark-coloured blue. Sulphureted hydro-gen precipitates arsenic from tea of a beautiful yellow colour, andchanges a solution of arsenic in water of a yellow colour, with-out any precipitate. From albumen, gelatine and bile, contain-ing arsenic in solution, nitrate of silver produces a white pre-cipitate. The ammoniaco-nitrate of silver produces a yellow pre-cipitate, soluble in nitric acid and ammonia ; but the presence ofmuriates or phosphates, or their acids, renders this a fallacious:test.

Make with the suspected fluid a broad streak on writing paper,then draw a piece of lunar caustic several times over the moisten-ed part, which will become yellow if arsenic or alkaline phosphatebe present. If it be arsenic, the streak will be rough, curdy, andflocculent, as if done with a crayon ; if a phosphate, homogeneousand uniform. In a few minutes the phosphoric yellow fades intoa dull green, becomes darker, and ultimately black. The arsen-ical yellow remains permanent, or nearly so, for some time, whenit becomes brown. These distinctions are to be viewed by reflect-ed, not transmitted light, the.test being made in the shade.

The most certain test to detect the presence of arsenic, is to re-duce it to its metallic state, by calcining the dried suspected mat-ter in a glass tube, with equal parts of charcoal and potash ; when,if arsenic be present, in however minute a quantity, it will be sub-limed and stick to the inside of the tube, in the form of a shiningmetallic coating, consisting of cubic crystals.

Antimony, and its Preparations.

Emetic Tartar, &c. — When an excess of emetic tartar, or anyother of the preparations of antimony have been taken, we mayremark the following

Symptoms, viz. Those occasioned by acids, with copious andobstinate vomitings, abundant stools, constrictions of the throat,cramps, symptoms of intoxication, and prostration of strength.

Treatment. — Emetic tartar generally defeats itself by the vomit-ing it soon occasions after it is taken ; but when this does not takeplace, it should be excited by tickling the throat with a feather orthe finger ; and encouraged by copious draughts of mild fluids ; orwhen too severe, to be allayed by opium according to the effectspreviously produced by the poison.

The best antidotes are, decoction of astringent vegetables, suchas oak or willow bark, gall nuts, strong green tea, &c, whichshould be given freely for the purpose of diluting and decomposingthe poison.

Tests. — Sulphureted hydrogen, and the bydrosulphurets, precip-itate tartarized antimony from its solution of an orange or deepbrownish red colour ; white, by sulphuric acid, alkalies, barytes or

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