404 MERCURY trate by heat, it has a bright orange color, and is known as the red oxide of mercury. In the state of a finely levigated powder, or as an ointment, this is applied externally in medicine as a stimulant and caustic. The name red precipitate, or precipitate per se, was given to this oxide because of the manner in which it was formerly prepared. Mercury in a matrass (a glass vessel with a long narrow neck) was subjected continuously to the actipn of heat. The mercurial vapor rising in the neck of the matrass was converted into red oxide, which was prevented from escaping ; and as the op- eration went on for weeks, the whole was converted into the same compound. Other mercurial compounds of especial interest are the subchloride and chloride, the one described under CALOMEL and the other under CORRO- SIVE SUBLIMATE. In the arts, mercury is em- ployed in the construction of philosophical in- struments, and is preferred to other fluids for filling thermometers and barometers by reason of the great range of temperature through which it expands or contracts uniformly with equal increase or decrease of heat. Its amal- gam with tin is largely used for coating or " silvering " the backs of mirrors. The paint, vermilion, is its sulphuret, cinnabar. But its principal consumption is in the extraction of silver and gold from their ores in the amalga- mating process. (See AMALGAMATION.) MERCURY, or Hermes, an ancient deity of the Greeks and Romans. According to the Greek legend, he was a son of Jupiter and Maia, a daughter of Atlas. He was born in a cave of Mt. Oyllene, in Arcadia, whence his epithet Cyllenian. Soon after his birth, escaping from his cradle, he went to Pieria, and stole several of Apollo's oxen, which he drove to Pylos, where he slaughtered two for a banquet and sacrifice, and concealed the rest. On re- turning to Cyllene, ho found a tortoise at the entrance of his cave, of whose shell and some of the ox intestines he constructed the first lyre. Apollo, knowing who had stolen his cattle, went to Cyllene to demand restitution ; and when Mercury denied the theft he took him before Jupiter, who obliged him to con- fess. But when Apollo heard Mercury per- form on the lyre, he was so delighted that he permitted the young musician to retain the cattle, and presented to him his golden caduce- us, or pastoral staff, teaching him at the same time the art of prophesying with dice. Jupi- ter appointed him herald general of the gods, in which capacity he was frequently the medi- um of communication between mortals and immortals. It was he who conducted Priam to Achilles, when the venerable monarch went to beg the body of Hector from his conqueror. He bound Ixion to the wheel for boasting of intimacy with Juno, chained Prometheus to the Caucasus, and escorted Juno, Venus, and Minerva to Mt. Ida to submit their charms to the judgment of Paris. Mercury was es- teemed the author of various inventions, and the origin of letters, numbers, astronomy, music, military tactics, gymnastics, weights, and measures was ascribed to him. He was also regarded as the god of eloquence, the pre- siding deity of the gymnasia, and the patron of fraud and perjury. The original seat of his worship was Arcadia, whence it gradually spread over the Grecian world. His festivals were called Hermaia. The most celebrated of his temples was that on Mt. Cyllene. The principal things sacred to him were the palm tree and the tortoise. He is generally repre- sented as a young man with a broad-brimmed hat adorned with wings, in his right hand a herald's staff or a sceptre, and on his feet a pair of winged sandals. In Rome, Mercury was the god of commerce and diplomacy. The etyma of his name, merx and curius, clearly indicate his predominant function. A temple was raised to him in Rome near the Circus Maximus as early as 495 B. C., and an altar of his stood contiguous to the Porta Capena. Under the cognomen of Malevolus, or the " ill-disposed," he had a statue in the vicus sobrius, or Sober street, in which no wine shops were allowed to be kept, and there milk was the sole beverage offered to him. This statue held a purse in one of its hands as a symbol of his commercial functions. The festival of Mercury was cele- brated on the 25th of May, which was regarded as a high day by the Roman merchants. After the various relations of Greece and Rome had become intimate, the Hermes of the former and the Mercurius of the latter were popularly considered identical, though the resemblance between the two divinities was very slight, and was never admitted by the fetiales, or guardians of the public faith of Rome. MERCURY, the planet nearest to the sun, travelling at a mean distance from it of about 35,392,000 in. The eccentricity of the orbit of Mercury is considerable, the centre of the orbit being more than 7,000,000 m. from the centre of the sun. Thus his greatest distance from the sun amounts to about 42,669,000 m., his least to about 28,115,000 m. When nearest to the earth, Mercury's distance from us amounts to about 45,000,000 m. ; but when so situated he is not visible, because, being between us and the sun, his darkened hemisphere is turned toward us. His greatest distance amounts to about 135,500,000 m. When he is at his great- est distance his illuminated face is turned di- rectly toward the earth ; but he cannot then be seen because he lies in the same direction as the sun, and is lost in the superior glory of that lumi- nary. He is seen most favorably when nearly at his greatest elongation ; that is, when two lines drawn to the sun and Mercury include their greatest angle. At such a time he is about 85,000,000 m. from us, and appears as a half disk. As he is illuminated with great brilliancy on account of his nearness to the sun, he is a difficult object of telescopic study, the more so that when most favorably situated the illumi- nated portions of his disk are seen obliquely.
