Corrosive Sublimate, Or Stone Mercury. The bichloride of mercury (or quicksilver) is so called on account of its peculiarly pernicious effects upon animal tissues, and the masses in which it is sold. It is used, in small quantities, in lotions for diseases of the skin, and, in a very diluted state, in cosmetics. Taken internally it is powerfully poisonous. The following tests will be found available to discover this substance. 1. If it is in a solid state it may be mixed with potash, and heated in a test tube. If the corrosive sublimate is present, metallic globules will be found to condense on the upper part of the tube. 2. If it is in solution, and mixed with solid matters, the solution should be filtered before any tests are applied. If portions of the suspected fluid be put into test tubes, they will form precipitates of various colours with the reagents indicated: - lime water, brick red; solution of caustic potass, orange ; prussiate of potass, white. 3. The best and readiest test is the following, to which the engraving refers, viz: - Drop the suspected solution on a clean gold or copper coin, and apply a bright key so that it may at the same time touch the edge of the coin and the globule of fluid. A galvanic current is thus produced, which decomposes the corrosive sublimate, leaving a white spot of reduced metallic mercury on the surface of the coin.