Lime water and all soluble lime salts throw down precipitates with oxalic acid; but as these are liable to be mistaken for a precipitate with sulphuric acid, it is better to use sulphate of calcium which is slightly soluble, as the test agent. A good deal of the test solution must be used, and the precipitate takes time to settle. 3. _Sulphate of copper_ gives a faint bluish precipitate with oxalic acid (oxalate of copper), which is not redissolved by a few drops of hydrochloric acid. These tests will not act if the solution contain nitric acid in excess, in which case the liquid must be evaporated to crystallization, and the crystals washed and redissolved in water. These tests for oxalic acid should never be applied without previously separating it from all organic matter. This is best done by first of all acidulating the suspected fluid with acetic acid, and then adding acetate of lead, which combines with the oxalic acid to form a white insoluble salt, which may ordinarily be removed by filtration or subsidence. This filtrate, after being well washed, is to be diffused in water, and into this a current of sulphuretted hydrogen gas is to be passed for some considerable time. This will throw down the lead as sulphide, leaving the oxalic acid in the fluid; any organic matter will also be carried down. Filtration will separate the solids from the liquid containing the acid, which may now be evaporated until crystals are formed, which may be tested in the usual way. ACETIC ACID.—Although this acid, in its concentrated state, is highly corrosive, yet it is very seldom brought under the notice of the toxicologist. In the case of a young woman reported by Orfila, death quickly occurred after several attacks of convulsions. At the subsequent post-mortem examination, the integuments of the dependent parts of the body were found very livid; the tongue and œsophagus were of a dirty brown color, the latter being intersected by a fine net-work of capillary vessels; and the interior of the stomach was interspersed with black elevations caused by the presence of coagulated blood in the sub-mucous areolar tissue. The mucous membrane was entire. As regards the _treatment_, it is only necessary to administer draughts containing magnesia or its carbonate, followed by mucilaginous or demulcent drinks. TARTARIC ACID, though not a corrosive, may be here placed along with the other vegetable acids. Strange as it may seem, tartaric acid has destroyed life in at least one instance in this country; an ounce having been given in mistake for an aperient salt. The deceased swallowed the whole at once, and immediately called out that he had been poisoned. He complained of intense pain in the throat and stomach, as if he had swallowed oil of vitriol, or was on fire. Soda and magnesia were administered without avail; and after death, at the end of nine days’ suffering, the stomach and intestines were found much inflamed. CHAPTER VIII.