_Fatal Period._--From two to five minutes after a large dose, but may be less.
_Method of Extraction from the Stomach._--Having previously carefully fitted a watchglass to a wide-mouthed bottle, nearly fill the bottle with the contents of the stomach, blood, secretions, etc. Place a few drops of a solution of nitrate of silver on the concave surface of the watchglass, and cover the mouth of the bottle with it. The vapour of hydrocyanic acid, if present, will form a white precipitate which may be tested. Other watchglasses, treated with sulphide of ammonium or sulphate of iron and liquor potassæ, will give the reactions of the acid with appropriate tests. This method removes all objections as to foreign admixture. If the acid is not at first detected, gentle warming of the bottle in a water-bath will assist the evolution of the vapour. The vapour may be obtained by distillation, but this process is open to objections to which the other is not. In some cases it becomes changed in the body into formic acid, which should therefore be sought for.
_Tests._--With nitrate of silver a white precipitate, insoluble in cold, but soluble in boiling, nitric acid. The precipitate heated, evolves cyanogen, having an odour of peach-blossoms, and burning, when lighted, with a pink flame. Liquor potassæ and sulphate of iron give a brownish-green precipitate, which turns to Prussian blue with hydrochloric acid. Liquor potassæ and sulphate of copper give a greenish-white precipitate, becoming white with hydrochloric acid. Sulphide of ammonium gives sulpho-cyanide of ammonium. This develops a blood-red colour with perchloride of iron, bleached by corrosive sublimate.
=Aconite= (_Aconitum Napellus_, monkshood).--Root and leaves. Poisonous property depends upon an alkaloid, aconitine. Aconite is one of the constituents of St. Jacob's Oil.
_Symptoms._--Numbness and tingling in mouth, throat, and stomach, giddiness, loss of sensation, deafness, dimness of sight, paralysis, first of the lower and then of the upper extremities, vomiting, and shallow respiration. Pupils dilated. Pulse small, irregular, finally imperceptible. The mind remains unaffected. Death often sudden.
_Post-Mortem Appearances._--Venous congestion, engorgement of brain and membranes.