MEBCIEB 193 MEBCURY boundary S. to the Thames, and Ethel- bald (716-755) spread his conquests round all the neighboring states. But the mightiest kings of Mercia were Offa (757-795) and Cenwulf (796-819), and after their time its power rapidly de- clined before the invasions of the Danes on the one side, and the spread of the West Saxon kingdom on the other. At length it became one of the great earl-, doms, and Elfgar, Leofric, Edwin, and Morcar retained at least the shadow of past power. MERCIER, DESIRE JOSEPH, Car- dinal; bom Nov. 22, 1851, at Braine I'Al- leud, Belgium. After studying at St. Rombaud's College, Malines, was raised to the priesthood in 1874. Appointed to the chair of Philosophy of the Seminary of Malines in 1877. In 1886 Pope Leo CARDINAL MERCIER XIII. appointed him a domestic prelate. He was next appointed to the chair of Neo-Scholastic Philosophy at the Univer- sity of Louvain, where in a few years he built up the world-known "Higher Insti- tute of Philosophy." Made cardinal, Feb. 21, 1906. During the German occupation of Belgium in the World War HU- 1918, Mercier stood firmly for the rights of his oppressed countrymen, maintaining a correct, but uncompromising attitude toward the conquerors. His indomitable courage was effective in maintaining un- shaken the patriotic spirit of the people of Belgium. His pastoral letter on "Pa- tinotism and Endurance," distributed in spite of German opposition (Christmas, 1914), gained a world-wide fame and is regarded as one of the greatest utter- ances of the World War. Cardinal Mercier visited America in 1919 to ex- press his gratitude for American services to Belgium in the war and was every- where received with enthusiasm. MERCURIC CHLORIDE (Corrosive sublimate; Mercury bichloride) Hg CI;. A heavy, white crystalline powder, spe- cific gravity 5.32, melting point 265 C, boiling point BOS'" C. Prepared by heat- ing a mixture of mercuric sulphate and sodium chloride, with a little manganese peroxide, and collecting the sublimate. Soluble in water, alcohol, and ether. Very poisonous and an extremely pow- erful antiseptic. For general use, a solution of one part in 1,000 of water is an efficient disinfectant, but one part in a million of water will prevent the growth of most bacteria. Medicinally it is used both externally and internally. In the form of ointment it is used in all parasit- ic skin diseases, and to reduce swellings. Its principal use is in the treatment of syphilis, when it is given either by the mouth, in the form of ointment, injection, or by hypodermic. The symptons of mercurial poisoning are salivation, fetid breath, virulent gas- tro-enteritis, and collapse. In acute cases death follows in a few hours. The best antidote is raw white of egg, and emetics should be given and the stomach pump employed. Other uses of mercuric chloride are as a wood preservative, in the tanning in- dustry, for embalming, and in textile printing. MERCUROUS CHLORIDE. See CAL- OMEL. MERCURY, in astronomy, the planet nearest the sun. Its stationary points are from 15 to 20 degrees of longitude from the sun, hence it rises and sets not far from the time when the sun does so. The light of the sun and the haze of the horizon combine to render observation of the planet difficult. It varies in bright- ness from 15" to 12" of the celestial circle or vault. Hence it is sometimes telescopic, and at other times visible to the naked eye, being as bright as a star of the second magnitude. It was known to the ancients. Its diameter is about 3,- 200 miles; its mass about 1-19 that of the earth; its sidereal period is 88 terrestrial days. It is seen at its greatest bright- ness as an evening star, at average inter- vals of about 116 days. Its average dis-
