MERCURY. This metal is found chiefly in the state of sulphvret, which is decomposed by distillation with iron or lime. It is also found native. Mercury is the only metal which is lipid at com mon temperature ; it is white and very brilliant. It freezes and assumes a crys talline texture at 40° below zero. Its specific gravity is 13.5. It boils at 660°, and its vapour condenses upon cool sur faces in minute brilliant globules. It is not altered by exposure to air at common temperatures, but when kept in vessels to which air has access, at a temperature near its boiling point, it gradually be comes converted into a deep red crystal line substance, which is the peroxide, or red oxide, of mercury. When mercury is dissolved in cold dilute nitric acid, the pure alkalis throw it down in the form of black protozide. The same oxide is also obtained by triturating calomel with so-. lution of caustic potash. These are the only definite oxides of mercury. The equivalent of this metal is about 200, and the oxides, consisting respectively of 1 atom of mercury and 1 of oxygen, and 1 and 2 are represented by 200+8=208, and 200+16=216. Mercury is represent ed in chemical formula by from the Latin hydrargyrum, literally signifying water sil&r. The symbol of the protox ide will then be (hg.+0.), and of the per oxide (hg.+ 2 o.). Each of these oxides combines with the acids, and produces the protosalts and permits of mercury. Mercury and Chlorine.—There are two chlorides of mercury ; a protochloride or calomel, and a perchiorkle or sub limate. Calomel may be obtained by mixing 60 parts (1 equivalent) of com mon salt, or chloride of sodium, with 248 parts (1 equivalent) of protosulphate of mercury, and exposing the mixture in a proper subliming vessel to a red heat ; the chlorine of the salt combines with the mercury of the sulphate to form pro tochloride of mercury (consisting of 200 mercury and 36 chlorine); and the so dium of the salt, uniting with the oxygen of the oxide of mercury, becomes soda, which, with the sulphuric 'acid, forms sulphate of soda. Calomel may also be obtained by mixing 200 parts of mercury with 272 of corrosive sublimate, and sub liming the mixture. When thoroughly
washed and levigated, calomel is a taste less, white powder ; its specific gravity is 7.2. When heated it acquires a yellow color ; and at a temperature below red ness it rises in dense white fumes, which are deposited in the form of a white pow der upon cold surfaces. It is insoluble in water. When hastily sublimed it often becomes a crystalline horny mass, and occasionally forms beautiful prismatic crystals. It is sometimes found native ; forming, however, a very rare ore, called, from its appearance, horn quicksilver.
Perchloride of mercury, or corrosive sublimate, is obtained by sublimation from a mixture of 120 parts of common salt (or 2 equivalents), and for 296 (or 1 equivalent) of persulphate of mercury. It rises in the form of white crystalline substance, of an acrid metallic taste, highly poisonous, soluble in 20 parts of cold and in 2 of boiling water. Its spe cific gravity is 5.2. When heated it eva porates in acrid fumes, at a temperature below that required for the volatilization of calomel. Corrosive sublimate is a compound of 1 equivalent of mercury and 2 of chlorine. In the above process for preparing it, the chlorine is furnished by the chloride of sodium, and sulphate of soda is the other product.
Bisulphuret of Mercury, known also by the name of cinnabar or vermilion, is prepared artificially by beating together 100 parts of mercury with about 20 of sulphur ; they form a black compound, which, when strongly heated, rises In the form of a deep crimson-colored sublim ate; this, reduced by long trituration into a fine powder, acquires a brilliant red color. It is tasteless, and insoluble in water ; it consists of 200 mercury and 32 sulphur, or (hg.± 2 8.) A black pro tosulphuret of mercury (hg.+ 8.) is preci pitated by aulphuretted hydrogen from a solution of the protonitrate. When a mixture of equal weights of finely-pow dered peroxide of mercury and Prussian blue is boiled in water till the blue color disappears, the solution yields, when fil tered and evaporated, a crop of straw colored prismatic crystals, which are bicy anuret of mercury : 2 cy.+ hg.