The strong odour yielded by the body on dissection, will furnish a satisfactory proof of the presence of this poison. Instances may occur, when the practitioner will be called before a tribunal to answer, from his professional knowledge, whether a particular case of death can have happened from the action of the hydro-cyanic acid, or any of the compounds in which it may enter as an ingredient; it therefore becomes an object of great importance to inquire whether any farther tests might be made subservient to our purpose. _Dr. Granville_, who has directed a great share of his attention to the history of this poison, has given some directions upon this point, which appear to us to be useful and judicious; we shall, therefore, present them to our readers. “After collecting the blood contained in the ventricles of the heart, a portion of the contents of the stomach, and of the superior intestines, together with a certain quantity of any fluid which may chance to be present within the cavity of the head, chest, or abdomen; and having agitated the mixture for some time in distilled water, and filtered the liquid, taking care to keep the whole at a low temperature, proceed to the following experiments. A. To a small quantity of the liquid add a few drops of a solution of caustic potass in alcohol. B. To this, a few drops of a solution of sulphate of iron must be added, when a cloudy and reddish precipitate, of the colour of burnt _Terra-Sienna_ will fall down. C. Some sulphuric acid is now to be introduced into the tube, when the colour of the precipitate will instantly change to that of a bluish-green, which by a permanent contact with the atmosphere, becomes gradually of a beautiful blue, assuming at the same time a pulverulent aspect. OR A. Treat the filtered liquid with carbonate of potass. B. Add a solution of sulphate of iron with a small quantity of alum: a precipitate, as in the former method, will fall down, which if treated by free sulphuric acid, will also become blue and pulverulent. During this latter part of the experiment, there is a disengagement of carbonic acid. Evidence may be pushed still farther, and the existence of the Prussic acid proved in a most positive manner by decomposing the precipitate, above described, and which is a true Prussian blue, so as to separate the acid. For this purpose, heat the precipitate with an equal quantity of tartaric acid, in a glass retort, at the temperature of 150°, when the hydro-cyanic vapours will soon exhale from the mixture, and may be received in water.”[442] Cl. V. NARCOTICO-ACRID POISONS. We have already stated our objections to this division, and our apology for adopting it. _See page_ 205. DEADLY NIGHTSHADE. _Atropa Belladonna._ (Pentandria Monogynia. _Nat. Ord._ Luridæ _Linn._ Solanaceæ. _Juss._)