1. It may be identified by boiling with black oxide of manganese; chlorine being given off, which is known by its odor, color, and bleaching properties. 2. When diluted, its presence is ascertained by nitrate of silver causing a dense white precipitate (chloride of silver). The chloride is distinguished from other salts of silver by (_a_,) its insolubility in nitric acid, and in caustic potass; (_b_,) by its being soluble in ammonia; (_c_,) by its melting and forming a horny mass when dried and heated. MIXED ACIDS.—These acids being used for commercial purposes when mixed—_the nitro-muriatic_ (aqua regia) to dissolve gold, and the _nitro-sulphuric_ (aqua reginæ) to dissolve silver—might occasion their being employed as poisons. _Sulphate of indigo_, which consists of a solution of indigo in strong sulphuric acid, has proved fatal in cases where it has been accidentally taken. _Symptoms, Treatment, &c._—The _symptoms_ produced by the mineral acids are much the same in all cases. There is violent, burning pain in the mouth, œsophagus, and stomach, commencing _immediately_. The burning is followed by retching and vomiting of a dark colored liquid with shreds of mucus, and portions of the mucous membrane of the œsophagus or stomach. The inside of the mouth is shrivelled and more or less corroded unless the agent has been given in a spoon or otherwise passed over the tongue to the back of the fauces. The outside of the lips and mouth will probably present the stains characteristic of the acid used. There is great thirst, difficulty of swallowing, and impeded respiration. The bowels are confined; the urine scanty or suppressed. Next succeeds great exhaustion, the pulse becomes quick and feeble, and the skin gets cold and clammy. The countenance is anxious and expressive of great suffering; death speedily occurs, the intellectual faculties remaining clear to the last. These acids may prove fatal without entering the stomach by causing asphyxia, the chink of the glottis becoming closed by swelling of the fauces, &c. They have sometimes been administered by the vagina, rectum, &c., and been poured into the ear during sleep. Where recovery takes place from their immediate effects there is always fear of death resulting at the end of one or two years from stricture of the œsophagus, and even at an earlier period, unless proper treatment is adopted. Occasionally one of the secondary effects of sulphuric acid has been profuse salivation.