HYDRARGYRUM - MERCURY - QUICKSILVER, Hg,=200.

Mercury is most frequently found in combination with sulphur, as native sulphide or cinnabar, in mines in Almaden, Ydria, China, Peru, Japan, and California. It is obtained from the ore by fusion with lime, which combines with the sulphur, while the mercury distils over. It occurs, also, as a natural amalgam with silver - "argental mercury" - combined with chlorine in small gray crystals, known as "horn mercury;" also more rarely as an iodide, and sometimes in a pure state - "virgin mercury."

Characters And Tests

Mercury is a silvery-white metal, with bluish lustre, and is fluid at ordinary temperatures. When pure, it has neither taste nor smell; it readidly oxidizes on exposure to the air, but does not tarnish. Should tarnishing occur, it implies the presence of other metals, as lead, zinc, or bismuth; it is susceptible of such division, that it may be squeezed in minute globules through chamois leather. On agitation with alcohol, ether, or turpentine, or on trituration with sulphur or unctuous substances, it loses its fluid character. With other metals, and even with hydrogen, it forms soft compounds termed amalgams, and a mere trace of it will leave a white stain on silver or gold. It has a sp. gr. of 13.59, which is exceeded only by that of gold and platinum, is slightly volatile at ordinary temperatures, boils at 662° F., and freezes at 39° F., becoming crystalline, tough, malleable, and sonorous. Its specific heat is low, but it is a good conductor, and has a regular rate of expansion and contraction, hence it is well suited for thermometric and barometric purposes: from its power of combining readily with silver and gold, and yet afterward quickly volatilizing on being heated, it is valuable in the arts of gilding and silvering, and alloyed with tinfoil it forms the reflecting surface of mirrors.

Hydrochloric acid has no action on mercury, and hence the chlorides cannot be prepared in a direct manner. Sulphuric acid, when boiling, and nitric acid, whether cold or hot, form respectively salts of different degrees of saturation - proto- or sub-salts which are known as mercurous, and per-salts, known as mercuric, and which have much more active powers than the former.

The per-salts of mercury are many of them (as the perchloride and red iodide) soluble in ether when the sub-salts are not, so that by this agent they may be separated from each other.

If any salt of mercury be heated in a test tube with sodic carbonate, the pure metal will sublime, and it may be obtained from its various combinations by distillation. With sulphuretted hydrogen in excess, mercurial compounds give a black precipitate of sulphide; but the best general test is the deposition of metallic mercury upon bright copper. It may be applied by heating any mercurial salt with a strip of copper and a few drops of hydrochloric acid, and, if the copper be afterward heated, small globules of quicksilver may be obtained as a sublimate.