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already been mentioned, and this success led to the foundation of Bing & Gröndhal of Copenhagen, who largely follow the styles of decoration initiated at the Royal works. In Sweden there are two important factories at Rörstrand and Gustafsberg. Under the accomplished director of the Rörstrand factory, Mr Robert Almström, a great variety of products have been successfully manufactured, including hard-paste porcelain, English bone china, earthenware, majolica and stoves. Italy, Spain and Belgium have also important modern pottery works.

In the United States of America there are large establishments for the manufacture of earthenware, bone china and tiles, all after the English fashion, while in addition there are a number of experimental kilns at work producing artistic pottery. The Rookwood factory has already been mentioned, but the wares produced at the Grueby factory and by Mrs Robineau and T. Brouwer are also worthy of note. (See “Report on American Art Pottery,” pp. 922-935 of Special Reports of the U.S. Census Office, Manufactures, pt. iii., 1905.)

Technical Pottery Works.—It is only possible to give a selection of the best of the modern standard works dealing with the technical side of pottery production. Brongniart, Traité des arts céramiques (3rd ed., Paris, 1877), with notes and additions by Salvétat; E. Bourry, Traité des industries céramiques (Paris, 1897); Théodore Deck, La Faïence (Paris, 1887); A. Granger, La Céramique industrielle (Paris, 1905); E. S. Auscher, La Céramique cuisant à haute température (Paris, 1899); Technologie de la Céramique (Paris, 1901); Les Industries céramiques (Paris, 1901); Seger, Gesammelte Schriften (Berlin, 1896; Eng. trans., Eastern, Pa., U.S.A., 1902); Langenbeck, The Chemistry of Pottery (Easton, Pa., U.S.A., 1895); William Burton, Porcelain (London, 1906).  (W. B.*) 

CERARGYRITE, a mineral species consisting of silver chloride; an important ore of silver. The name cerargyrite is a Greek form (from κέρας, horn, and ἄργυρος, silver) of the older name hornsilver, which was used by K. Gesner as far back as 1565. The chloro-bromide and bromide of silver were also included under this term until they were distinguished chemically in 1841 and 1842, and described under the names embolite and bromargyrite (or bromyrite) respectively; the chloride then came to be distinguished as chlorargyrite, though the name cerargyrite is often now applied to this alone. Chloro-bromo-iodide of silver has also been recognized as a mineral and called iodembolite. All these are strikingly alike in appearance and general characters, differing essentially only in chemical composition, and it would seem better to reserve the name cerargyrite for the whole group, using the names chlorargyrite (AgCl), embolite (Ag(Cl, Bl)), bromargyrite (AgBr) and iodembolite (Ag(Cl, Br, I)) for the different isomorphous members of the group. They are cubic in crystallization, with the cube and the octahedron as prominent forms, but crystals are small and usually indistinct; there is no cleavage. They are soft (H = 2½) and sectile to a high degree, being readily cut with a knife like horn. With their resinous to adamantine lustre and their translucency they also present somewhat the appearance of horn; hence the name hornsilver. The colour varies somewhat with the chemical composition, being grey or colourless in chlorargyrite, greenish-grey in embolite and bromargyrite, and greenish-yellow to orange-yellow in iodembolite. On exposure to light the colour quickly darkens. The specific gravity also varies with the composition: for the pure chloride it is 5.55, and the highest recorded for an iodembolite is 6.3.

The hornsilvers all occur under similar conditions and are often associated together; they are found in metalliferous veins with native silver and ores of silver, and are usually confined to the upper oxidized parts of the lodes. They are important ores of silver (the pure chloride contains 75.3% of silver), and have been extensively mined at several places in Chile, also in Mexico, and at Broken Hill in New South Wales. The chloride and chloro-bromide have been found in several Cornish mines, but never in very large amounts.  (L. J. S.) 

CERBERUS, in Greek mythology, the dog who guarded the entrance to the lower world. He allowed all to enter, but seized those who attempted to escape. According to Hesiod (Theog. 311), he was a fifty-headed monster with a fearful bark, the offspring of Typhon and Echidna. He was variously represented with one, two or (usually) three heads, often with the tail of a snake or with snakes growing from his head or twined round his body. One of the tasks imposed upon Heracles was to fetch Cerberus from below to the upper world, a favourite subject of ancient vase-paintings.

CERDIC (d. 534), founder of the West Saxon kingdom, is described as an ealdorman who in 495 landed with his son Cynric in Hampshire, where he was attacked at once by the Britons. Nothing more is heard of him until 508, when he defeated the Britons with great slaughter. Strengthened by fresh arrivals of Saxons, he gained another victory in 519 at Certicesford, a spot which has been identified with the modern Charford, and in this year took the title of king. Turning westward, Cerdic appears to have been defeated by the Britons in 520 at Badbury or Mount Badon, in Dorset, and in 527 yet another fight with the Britons is recorded. His last work was the conquest of the Isle of Wight, probably in the interest of some Jutish allies. All the sovereigns of England, except Canute, Hardicanute, the two Harolds and William the Conqueror, are said to be descended from Cerdic.

See Anglo-Saxon Chronicle, edited by C. Plummer (Oxford, 1892–1899); Gildas, De excidio Britanniae, edited by Th. Mommsen (Berlin, 1898); Nennius, Historia, Brittonum, edited by Th. Mommsen (Berlin, 1898); Bede, Historiae ecclesiasticae gentis Anglorum libri v., ed. C. Plummer (Oxford, 1896); E. Guest, Origines Celticae (London, 1883); J. R. Green, The Making of England (London, 1897).

CERDONIANS, a Gnostic sect, founded by Cerdo, a Syrian, who came to Rome about 137, but concerning whose history little is known. They held that there are two first causes—the perfectly good and the perfectly evil. The latter is also the creator of the world, the god of the Jews, and the author of the Old Testament. Jesus Christ is the son of the good deity; he was sent into the world to oppose the evil; but his incarnation, and therefore his sufferings, were a mere appearance. Regarding the body as the work of the evil deity, the Cerdonians formed a moral system of great severity, prohibiting marriage, wine and the eating of flesh, and advocating fasting and other austerities. Most of what the Fathers narrate of Cerdo’s tenets has probably been transferred to him from his famous pupil Marcion, like whom he is said to have rejected the Old Testament and the New, except part of Luke’s Gospel and of Paul’s Epistles. (See Marcion, and Gnosticism.)

CEREALIS (Cerialis), PETILLIUS (1st century A.D.), Roman general, a near relative of the emperor Vespasian. He is first heard of during the reign of Nero in Britain, where he was completely defeated (A.D. 61) by Boadicea. Eight years later he played an important part in the capture of Rome by the supporters of Vespasian. In 70 he put down the revolt of Civilis (q.v.). In 71, as governor of Britain, where he had as a subordinate the famous Agricola, he inflicted severe defeats upon the Brigantes, the most powerful of the tribes of Britain. Tacitus says that he was a bold soldier rather than a careful general, and preferred to stake everything on the issue of a single engagement. He possessed natural eloquence of a kind that readily appealed to his soldiers. His loyalty towards his superiors was unshakable.

Tacitus, Annals, xiv. 32; Histories, iii. 59, 78, iv. 71, 75, 86, v. 21; Agricola, 8, 17.

CERES, an old Italian goddess of agriculture. The name probably means the “creator” or “created,” connected with crescere and creare. But when Greek deities were introduced into Rome on the advice of the Sibylline books (in 495 B.C., on the occasion of a severe drought), Demeter, the Greek goddess of seed and harvest, whose worship was already common in Sicily and Lower Italy, usurped the place of Ceres in Rome, or rather, to Ceres were added the religious rites which the Greeks paid to Demeter, and the mythological incidents which originated with her. At the same time the cult of Dionysus and Persephone (see Liber and Libera) was introduced. The rites of Ceres were Greek in language and form. Her priestesses were Italian Greeks and her temple was Greek in its architecture and built by Greek artists. She was worshipped almost exclusively by plebeians, and her temple near the Circus Maximus was under the care of the plebeian aediles, one of whose duties was the superintendence