of 212°, we may infer from the residuary sal ammoniac, the quantity of muriatic acid present. ANTIDOTES. To counteract the poisonous effect of prussic acid, Orfila recommends, after full vomiting has been excited, the exhibition of three or four spoonsful of oil of turpentine, in the infusion of coffee, at intervals of half an hour. M. Virey conceives that sulphate of iron in solution is the best antidote, he having observed that the salt restored a cow that was nearly killed by the essential oil of bitter almonds. When an overdose has been taken, hot brandy and water, and the ammoniated tincture of iron are recommended by Mr. Thomson; on the former I should rely with much greater confidence than upon the latter antidote, or, in other words, it is from vital agents, counteracting its sedative influence, rather than from chemical substances, changing its composition, that we can expect any benefit upon such an occasion. For the chemical processes by which the presence of this acid may be ascertained, the reader may consult my work on Medical Jurisprudence, vol. 2, p. 408. ACIDUM MURIATICUM. L.E.D. _Muriatic Acid._ QUALITIES. _Form_, a liquid of the specific gravity 1·16, a fluid-ounce of which weighs about 527 grains, and according to Dr. Powell ought, when diluted, to dissolve 220 grains of limestone. _Odour_, strong and pungent; if exposed to the air it emits white fumes. _Taste_, intensely sour and caustic; it is however the weakest of the three mineral acids; and no remarkable elevation of temperature is produced by dilution. CHEMICAL COMPOSITION. The liquid acid is a solution of muriatic acid gas in water; when of the specific gravity 1·16, according to Davy, it contains 32·32 per cent of the gas, which recent experiments have shewn to be a compound of _Chlorine_ (_Oxy-muriatic acid)_ and hydrogen in equal volumes. It has therefore received a name expressive of its composition, and is called _Hydro-chloric[348] acid_. We accordingly find that the former element is disengaged from muriatic acid by adding any substance capable of uniting with its hydrogen. For the purpose of obtaining _Chlorine_, we may take three parts of common salt, one of black oxide of manganese, and rather less than three of strong sulphuric acid.[349] Accounts have been received from Spain, that in the midst of the dreadful contagion which reigned in that country, the inhabitants always escaped in those houses where fumigations of chlorine had been used. In our own country, the Penitentiary has lately undergone fumigation by this gas, under the superintendance of Mr. Faraday.[350] Muriatic acid gas has also been strongly recommended for the same purpose; it may be easily evolved by pouring sulphuric acid on common salt. If nitric and muriatic acids be mixed, a mutual decomposition takes place, of which water, chlorine, and nitrous acid are the results;