Fraudulent dealers often substitute the cheaper tartareous acid, for citric acid. The negus and lemonade made by the pastry-cooks, and the liquor called punch, sold at taverns in this metropolis, is usually made with tartareous acid.
To discriminate citric acid from tartareous acid, it is only necessary to add a concentrated solution of the suspected acid, to a concentrated solution of muriate of potash, taking care that the solution of the acid is in excess. If a precipitate ensues, the fraud is obvious, because citric acid does not produce a precipitate with a solution of muriate or potash.
Or, by adding to a saturated solution of tartrate of potash, a saturated solution of the suspected acid, in excess, which produces with it an almost insoluble precipitate in minute granular crystals. Pure citric acid produces no such effect when added in excess to tartrate of potash.
Poisonous Mushrooms.
Mushrooms have been long used in sauces and other culinary preparations; yet there are numerous instances on record of the deleterious effects of some species of these fungi, almost all of which are fraught with poison.[114] Pliny already exclaims against the luxury of his countrymen in this article, and wonders what extraordinary pleasure there can be in eating such dangerous food.[115]
But if the palate must be indulged with these treacherous luxuries, or, as Seneca calls them, "voluptuous poison,"[116] it is highly necessary that the mild eatable mushrooms, should be gathered by persons skilful enough to distinguish the good from the false, or poisonous, which is not always the case; nor are the characters which distinguish them strongly marked.
The following statement is published by Mr. Glen, surgeon, of Knightsbridge:
"A poor man, residing in Knightsbridge, took a walk in Hyde Park, with the intention of gathering some mushrooms. He collected a considerable number, and, after stewing them, began to eat them. He had finished the whole, with the exception of about six or eight, when, about eight or ten minutes from the commencement of his meal, he was suddenly seized with a dimness, or mist before his eyes, a giddiness of the head, with a general trembling and sudden loss of power;—so much so, that he nearly fell off the chair; to this succeeded loss of recollection: he forgot where he was, and all the circumstances of his case. This deprivation soon went off, and he so far rallied as to be able, though with difficulty, to get up, with the intention of going to Mr. Glen for assistance—a distance of about five hundred yards: he had not proceeded more than half way, when his memory again failed him; he lost his road, although previously well acquainted with it. He was met by a friend, who with difficulty learned his state, and conducted him to Mr. Glen's house. His countenance betrayed great anxiety: he reeled about, like a drunken man, and was greatly inclined to sleep; his pulse was low and feeble. Mr. Glen immediately gave him an emetic draught. The poison had so diminished the sensibility of the stomach, that vomiting did not take place for near twenty minutes, although another draught had been exhibited. During this interval his drowsiness increased to such a degree, that he was only kept awake by obliging him to walk round the room with assistance; he also, at this time, complained of distressing pains in the calves of his legs.—Full vomiting was at length produced. After the operation of the emetic, he expressed himself generally better, but still continued drowsy. In the evening Mr. Glen found him doing well."