known. Nitrates of cerium have been described, as have also phosphates, carbonates and a carbide.
Cerium compounds may be recognized by the red precipitate of ceric hydroxide, which is formed when sodium hypochlorite is added to a colourless cerous salt. For the quantitative determination of the metal, the salts are precipitated by caustic potash, the precipitate washed, dried and heated, and finally weighed as the dioxide.
The atomic weight of cerium has been determined by B. Brauner (Chem. News, 1895, lxxi. 283) from the analysis of the oxalate; the values obtained varying from 140.07 to 140.35.
CERNUSCHI, HENRI (1821–1896), Italian politician and economist, was born of wealthy parents at Milan in 1821, and was destined for the legal profession. During his studies he became involved in the revolutionary movement. He played a conspicuous part in the insurrection at Milan in 1848, and also at Rome in 1849, where he had a seat in the National Assembly. On the collapse of the revolutionary government he was arrested (1850), but managed to escape to France, where he engaged in commerce and banking, became naturalized, and acquired a large fortune. He took a prominent part in opposing the Socialist movement, and in April 1870, having subscribed a large sum to the funds of a committee formed to combat the Napoleonic plebiscite, had to leave the country. In September the formation of the Third Republic enabled him to return, but he soon left Paris to travel in the East, whence he returned with a fine art collection, particularly of Japanese objects. Cernuschi is best known for his publications on financial questions, more especially bimetallism. Of the latter he was an ardent champion, and the word itself is commonly supposed to have originated with him—at least in its English form it is first found in his Silver Vindicated (1876). Among his other works may be mentioned: Mécanique de l’échange (1861); Illusion des sociétés coopératives (1886); Le Bimétallisme en Angleterre (1879); Le Grand Procès de l’Union latine (1884). He died at Mentone on the 12th of May 1896.
CEROGRAPHY (from the Gr. κηρός, wax, and γράφειν, to write), the art of painting in wax. (See Encaustic Painting.)
CERRO DE PASCO, or Pasco, a mining town of Peru, capital of the department of Junin, 107 m. (221 m. by rail, via Oroya) N.E. of Lima. Pop. (1907 est.) 10,000. It is situated on the plateau of Bombon, 14,280 ft. above sea-level, and in the midst of one of the oldest and richest silver-mining districts of Peru. There were 342 silver mines in this district in 1890, and at the end of the 19th century the average annual output since the discovery of the mines in 1630 was estimated at 1,600,000 oz. A decline in the silver production having set in, the American company which had become owners of three-fourths of the mining properties in the district turned its attention to the extensive copper deposits there, built a railway to Oroya 83 m. distant, another, 25 m. long, to the coal-fields of Gollarisquisga, north of Pasco, and then erected large smelting works (in which 2500 men were regularly employed in 1907) 8 m. out of town and 4 m. from limestone beds. The railway to Oroya was completed in 1903, the coal mine branch and smelter later on, and in 1907 the copper output was 20,152,000 ℔ The town of Pasco is badly built and unattractive, and is inhabited chiefly by mining labourers and their families. Its population is increased 50% in times of great mining activity. The name Cerro de Pasco is that of a “knot” of mountains uniting the two great ranges of the Andes at this point.
CERTALDO, a town of Tuscany, Italy, in the province of Florence, 35 m. S.S.W. by rail and 18 m. direct from the town of Florence. Pop. (1901) town, 4552; commune, 9120. It was the home of the family of Giovanni Boccaccio, who died and was buried here in 1375. His house (of red brick, like the other old houses of the town) was restored in 1823 and fitted up with old furniture. A statue of him was erected in the principal square in 1875. The Palazzo Pretorio, or Vicariale, the residence of the Florentine governors, recently restored to its original condition, has a picturesque facade and court adorned with coats of arms, and in the interior are various frescoes dating from the 13th to the 16th century. The town as a whole is picturesque, and lies on a hill 426 ft. above sea-level.
See R. Pantini, S. Gimignano e Certaldo (Bergamo, 1904), p. 101 seq.
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Fig. 1. |
CERUSSITE, a mineral consisting of lead carbonate (PbCO3), and an important ore of lead. The name (sometimes erroneously spelt cerusite) is from the Lat. cerussa, “white lead.” “Cerussa nativa” was mentioned by K. Gesner in 1565, and in 1832 F. S. Beudant applied the name céruse to the mineral, whilst the present form, cerussite, is due to W. Haidinger (1845). Popular names in early use were lead-spar and white-lead-ore.
Cerussite crystallizes in the orthorhombic system and is isomorphous with aragonite. Like aragonite it is very frequently twinned, the compound crystals being pseudo-hexagonal in form. Three crystals are usually twinned together on two faces of the prism m{110}, producing six-rayed stellate groups (figs, 1 and 2) with the individual crystals intercrossing at angles of nearly 60°. Twinning on the faces of the prism r{130}, the angles of which are also nearly 60°, produces a similar kind of grouping, but is much less common. Crystals are of frequent occurrence, and they usually have very bright and smooth faces. The mineral also occurs in compact granular masses, and sometimes in fibrous forms. It is usually colourless or white, sometimes grey or greenish in tint; it varies from transparent to translucent, and has an adamantine lustre. It is very brittle, and has a conchoidal fracture. Hardness 3-312; sp. gr. 6.5. A variety containing 7% of zinc carbonate, replacing lead carbonate, is known as iglesiasite, from Iglesias in Sardinia, where it is found.
The mineral may be readily recognized by its characteristic twinning, in conjunction with the adamantine lustre and high specific gravity. It dissolves with effervescence in dilute nitric acid. Before the blow-pipe it fuses very readily, and gives reactions for lead. Cerussite occurs in metalliferous veins in association with galena, and has been formed by the action of carbonated waters on the galena; it is therefore found in the upper parts of the lodes together with other secondary minerals, such as limonite. Finely crystallized specimens have been obtained from the Friedrichssegen mine near Ems in Nassau, Johanngeorgenstadt in Saxony, Mies in Bohemia, Phenixville in Pennsylvania, Broken Hill in New South Wales, and several other localities. Delicate acicular crystals of considerable length were found long ago in the Pentire Glaze mine near St Minver in Cornwall. It is often found in considerable quantities, and contains as much as 7712% of lead. (L. J. S.)
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Fig. 2. |
CERUTTI, GIUSEPPE ANTONIO GIACHIMO (1738–1792), French author and politician, was born at Turin on the 13th of June 1738. He joined the Society of Jesus and became professor at the Jesuit college at Lyons. In 1762, in reply to the attacks on his order, he published an Apologie générale de l’institut et de la doctrine des Jésuites, which won him much fame and some exalted patronage; notably that of the ex-king Stanislaus of Poland and of his grandson the dauphin. During the agitations that preceded the Revolution Cerutti took the popular side, and in 1788 published a pamphlet, Mémoire pour le peuple français, in which in a clear and trenchant style he advocated the claims of the tiers état. In May 1789 he presided over the electors of Paris, by whom in January 1791 he was chosen member of the administration of the department and afterwards deputy to the Legislative Assembly. He was a friend of Mirabeau, whose policy he supported and whose funeral oration he pronounced. He himself died on the 3rd of February 1792. Of Cerutti's literary enterprises the most interesting, and probably the most influential, was the popular newspaper founded by him, on the 30th of September 1790, in collaboration with Rabaut Saint-Étienne and Philippe Antoine Grouvelle. Its character and
