Читать книгу Treatise on Poisons - Robert Sir Christison - Страница 41

In all its forms acetic acid is easily known by its very peculiar odour, together with its acid reaction on litmus. But if farther evidence of its nature be required, it will be requisite to neutralise the fluid suspected to contain it with carbonate of potass, and then to procure the acetate of potass by evaporation. This salt is known by its extreme tendency to deliquesce, and by a concentrated solution in water, yielding, when distilled with sulphuric acid, a fluid possessing the peculiar odour and pungency of concentrated acetic acid.

When in a state of compound admixture with organic substances, such as the contents of the stomach, it has been proved by late researches of Orfila,^[378] that this acid may be present in considerable proportion without distinctly reddening litmus. For such mixtures the following process of analysis, devised by the Parisian professor, will be found convenient and effectual. The fluid being put into a retort with a receiver attached, the retort is to be heated in a muriate of lime bath till the residuum be dry. The distilled fluid may then be tested tentatively for sulphuric and muriatic acids; and these being proved to be absent, the acidity and peculiar smell of the liquid will supply strong presumption of the presence of acetic acid. This presumption may be turned to certainty by forming acetate of potass, as already directed for the pure diluted acetic acid.

Orfila has omitted in his paper a serious fallacy to which this, as well as every process for the detection of acetic acid in the contents of the stomach is exposed,—namely, that the natural secretions of the stomach, according to the researches of many physiologists, but more especially in recent times those of Tiedemann and Gmelin in Germany, and those of Leuret and Lassaigne in Paris, frequently contain a small proportion of acetic acid. Hence, the inference in favour of the introduction of acetic acid into the stomach from without, founded on the process related above, is only legitimate when the quantity discovered is considerable.—The medical jurist ought also to keep in mind that vinegar is a common remedy with the vulgar for many diseases, and especially for poisoning.