MERCURY, or QUICKSILVER. This metal, which possesses the remarkable pro perty of being fluid at usual temperatures, has been known from the remotest ages. Although it is met with in very largo quantity, yet the mines occur in comparatively few places ; those of Almaden in Spain, and Idria in Carniola, are the most important. There are however mines of this metal in Hungary, Transylvania, and the district of Zweibriicken in Germany. Mercury has been obtained for a very long time in China and Japan, and although the amount of the produce is un known, there is every reason to think it is considerable ; it is also found at Huancavelica in Peru. The average yearly produce is esti mated at about 2000 tons, of which about two-thirds come from Almaden. The quantity brought to England in 1848 was 1,502,663 lbs. and in 1849 it rose to 2,682,592 lbs ; in 1850 it was very much smaller, owing to monopoly arrangements.
Mercury is always obtained from cinnabar, which is a bisuiphuret of the metal ; it is found in the red sandstone associated with coal at Almaden ; sometimes, as in the district of Zweibriicken, the cinnabar occurs in the subordinate porphyries ; and at Idria in the subordinate bituminous schist, but rarely in limestone itself.
Various processes are adopted for the pur pose of separating the mercury from the ore, all of which depend upon the volatility of the metal, its conversion into vapour in distilling or retorts, and its condensation by cold. In order to separate the sulphur from the metal, either iron or lime may be em ployed ; the first forms sulphuret of iron, and the latter of calcium, with the sulphur, and the metal is thus setfree, volatilised, and con densed. The retorts employed are made of
cast or sheet iron or earthenware.
Mercury is fluid at ordinary temperatures, is of a silvery white colour, and possesses a high degree of lustre; it is inodorous, tasteless, unacted upon or very slightly by exposure to air at common temperatures, and not at all by water at any temperature. The specific gravity of mercury is about 13.568. It boils at 670°. At 40° below zero, mercury becomes solid, crystallises in octahedrons, and gives a dull sound like lead ; at the moment of conge lation it contracts considerably ; when in this state it is malleable, and may be cut with a knife. It is only on some few rare occasions that our Arctic explorers have encountered a cold se intense as to freeze mercury ; in such case a spirit thermometer is the only one available, for spirit has never yet been frozen or solidified.
The number of valuable compounds which mercury forms with other substances is very considerable. The binoxide is a dark red crystal used in medicine. The protochloride constitutes calomel, and the bichloride corrosive sublimate. The bi-sulphuret yields cinnabar or vermillion ; and another combination of mer cury and sulphur forms Ethiop's mineral. The sulphate of mercury is Turbeth mineral. The fulminate of mercury forms detonating powder. All the alloys of mercury, or combinations of mercury with other metals, are called amal gams, and are noticed elsewhere. [AmttLeAlr.] The uses of mercury in the arts are most varied and abundant. A few among them will be found briefly noticed under BARO