HYDROCYANIC ACID.

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face ; and adds, to an irritable face it is very soothing, if employed beforeand after shaving. In cancer of the uterus, lotions containing this acidhave been applied to allay the pain, by Frisch, of Nyborg. Osiander hasalso employed, in the same disease, chcny-laurel water, the active prin-ciple of which is this acid. In gonorrhoea, injections containing hydro-cyanic acid have been employed with benefit. Sclilegel has tried alsothe cherry-laurel water with the same result. Lastly, the dilute acid hasbeen proposed as an effectual and agreeable mode of destroying vermin.

Administration. —The best mode of exhibiting this acid internally isin the form of mixture. I generally give from three to five minims of thedilute acid in about an ounce of some mild vehicle (simple water answersveiy well), and repeated three or four times a day. Gum or syrup andsome flavouring ingredient (as orange-flower water, used on the continent)may be added. Some persons give it in almond emulsion.

As a wash, two fluidrachms of the dilute acid of the shops may beemployed mixed with half a pint of distilled (or rose) water as a lotion inskin diseases. Frequently about half an ounce of rectified sprit is added,and Dr. Thomson recommends, in addition to this, sixteen grains ofacetate of lead. The external use of this acid, in all cases (more espe-cially if there be sores) requires great caution. Its effects on the nervoussystem and on the pulse must be carefully watched. In some cases itcauses giddiness and faintness ; and Mr. Plumbe says, in two instances itproduced intermission of the pulse.

Antidotes. —The most important agents in the treatment of poisoningby hydrocyanic acid, as well as by the substances which contain it (viz.the cherry-laurel, bitter almonds, the volatile oil of these substances, &c.),are chlorine, ammonia, cold affusion, and artificial respiration.

(a.) Chlorine is the most powerful of these. It was first proposed bylliauz in 1822. It has been subsequently strongly recommended byBuchner, Simeon, and Orfila. It should he applied both internally andexternally if possible. If chlorine water ( aqua chlorinii, Ph. D.) be athand, this should be given in doses of one or two tea-spoonfuls properlydiluted with water. In the absence of this, weak solutions of the chlorideof lime or the chloride of soda maybe administered. Nitro-hydrochloricacid largely diluted might be given where none of the above agents couldbe procured. The patient should be allowed to inhale, very cautiously,air impregnated with chlorine gas (developed by the action of dilutehydrochloric acid on chloride of lime). Enemata containing chlorinewater or a solution of chloride of lime should also be employed.

(b.) Ammonia. —The spirit of sal ammoniac was proposed by Mead {Meehan. Account of Poisons, 5tli edit. p. 275, 1756) as an antidote forlaurel water. In 1822, ammonia was recommended by Mr. J. Murray asan antidote lor hydrocyanic acid; and its value has been admitted byBuchner, Orfila, Dupuy, and Herbst: but it is certainly inferior tochlorine; and, therefore, should be used only in the absence of this. Ifthe patient he able to swallow, the liquor ammonia;, diluted with eight orten parts of water, should be exhibited, and the vapour of ammonia or itscarbonate inhaled: the latter practice is most important, and should notbe omitted. Orfila says that ammonia is of no use when introduced intothe stomach, but that the inhalation of the vapour will sometimes preservelife. Great caution is requisite in the employment of it (see p. 169). Inthe absence of ammonia the inhalation of the vapour of burnt feathers