Note 257 — MINERAL POISONS.

This explanation applies equally to the objection lately advanced by Dr. Porter, of the University of South Carolina, who, in his observations on the tests of arsenic, remarks, that an appearance similar to “Scheele’s Green,” is produced by the carbonate of potass, when added to a solution of the sulphate of copper in coffee, but without arsenic, more striking than if even a weak solution of arsenic were used. Silliman’s Journal, iii. 865.

Fodere reports a case, in which an erroneous conclusion respecting the presence of arsenic was drawn, evidently owing to the same source of fallacy. The Society of Medicine at Marseilles, in consequence of a girl having been poisoned by a quack medicine, appointed a scientific person to examine the composition of the Nostrum; this person, strongly prepossessed with the opinion that it contained arsenic, applied the copper test above described, and having obtained by means of it, a green precipitate, reported, without any further inquiry, that the medicine in question was an arsenical solution. Foderé, however, suspected the correctness of the conclusion, in consequence of the residue not yielding by combustion, any alliaceous odour; a new analysis was therefore made, which proved the nostrum to be nothing more than a very strong alcoholic tincture of colocynth. Médecine Légale, tom. iv. p. 137.