Page:Encyclopædia Britannica, Ninth Edition, v. 6.djvu/175

Rh sixteen years lie was a constant exhibitor; bis fishermen, shrimp-catchers, boats and nets, stretches of coast and sand, and, above all, his rustic children were universally popular. Then, however, he went abroad on the advice of Wilkie, and for two years (183 7-1 838) studied the life, manners, and scenery of Italy. In 1839 he exhibited the first fruits of this journey; and in 1840, in which year he was ap pointed librarian to the Academy, he made his first appear ance as a painter of history. In 1842 he returned to his early manner and choice of subject, and during the last years of life enjoyed greater popularity than ever. As a painter Collins is entitled to high praise. He was a good colourist and an excellent draughtsman ; he was also con scientious exceedingly, and an ardent lover and student of nature. His earlier pictures are deficient in breadth and force, are feeble, in fact, from excess of care and finish ; but his later work, though also carefully executed, is rich in effects of tone and in. broadly painted masses. His biography, Life of William Collins, 11. A., 2 vols., by his son Wilkie Collins, the well-known novelist, appeared in 1848.  COLLODION (from KoXXa, glue), a colourless, viscid fluid, made by dissolving gun-cotton and the other varieties of pyroxylin, or cellulotrinitrin, C H 7 2 (NO. J ). !, in a mix ture of alcohol and ether. It was discovered in 1848 by Maynard in Boston. The quality of collodion differs according to the proportions of alcohol and ether and the nature of the pyroxylin it contains. Collodion in which there is a great excess of ether gives by its evaporation a very tough film ; the film left by collodion containing a large quantity of alcohol is soft and easily torn ; but in hot climates the presence of an excess of alcohol is an advantage, as it prevents the rapid evaporation of the ether. Pyroxylin for the making of collodion for photographic purposes is prepared by immersing cotton-wool ten minutes in a mixture of nitric and sulphuric acids at a temperature of 140 Fahr. When tolerably strong acids at a low temperature are employed, the nitric acid being in by far the larger quantity, the pyroxylin made requires an amount of alcohol equal to only about /th or T th that of the ether in bulk. According to M. Miallie, the most explosive kinds of gun-cotton are not the best adapted for the preparation of collodion ; a pyroxylin very soluble in ether is in his process made from 2 parts by weight of carded cotton to 40 parts of nitre and GO of concentrated sulphuric acid. Under the micro scope, the film produced by collodion of good quality appears translucent and colourless, the cotton being perfectly dissolved ; old collodion that does not give good photo graphic impressions sufficiently quickly exhibits liquid globules of modified ether. The film from collodion which is too alcoholic has the microscopic appearance of cellular tissue ; and when water has been present, the fibrillse of the cotton become apparent as amorphous flocks. To pre serve collodion it should be kept cool, and out of the action of the light ; iodized collodion that has been discoloured by the development of free iodine may be purified by the immersion in it of a strip of silver foil. For the iodizing of collodion, ammonium bromide and iodide and the iodides of calcium and cadmium are the agents employed. The first to suggest the use of collodion in photography was M. le Grey, in Paris ; Mr F. S. Archer, in February 1851, recommended iodized collodion instead of paper for the taking of photographs (The Chemist, New. Ser., vol. ii. No. xix. p. 257, March 1851). In surgery collodion is used in its usual condition, or combined with elastic and other substances, for the protection of inflam-ed surfaces, as in erysipelas and smallpox. When poured upon the skin, it forms a thin film which contracts as it dries. Flexible collodion, which, as it does not crack in drying, is prefer able for surgical purposes to the ordinary preparation, is made from collodion 6 oz., Canada balsam 120 grs., castor- oil one fluid drachm. Vesicating or Blistering Collodion contains cantharidin as one of its constituents. The styptic colloid of Richardson is a strong solution of tannin in gun- cotton collodion. Small balloons are manufactured from collodion by coating the interior of glass-globes with the liquid ; the film when dry is removed from the glass by applying suction to the mouth of the vessel. M. E. Gripon has found (Compt. Iicnd., April 5, 1875) that collodion membranes, like glass, reflect light and polarize it both by transmission and reflection; they also transmit a very much larger proportion of radiant heat, for the study of which they are preferable to mica. See.  COLLOT D'HERBOIS, (1750-179G), a prominent actor in the French Revolution, was a Parisian actor. After figuring for some years at the principal pro vincial theatres of France and Holland, he became director of the playhouse at Geneva. He had from the first a share in the revolutionary tumult ; but it was not until 1791 that he became a figure of importance. Then, however, by the publication of L Almanack du Pere Gerard, a tract designed to set forth, in homely style, the advantages of a constitu tional government, he suddenly acquired great popularity. His renown was soon increased by his active interference on behalf of the Swiss of the Chfiteau-Vieux llegiment, condemned to the galleys for mutiny at Nancy. His efforts resulted in their liberation ; he went himself to Brest in search of them ; and a civic feast was decreed on his behalf and theirs, which gave occasion for one of the few poems published during his life by Andre Chenier. He next endeavoured to obtain the office of minister of justice, but was disappointed. The Tenth, of August, how ever, placed him in the municipality of Paris. There he attached himself to Billaud-Varenne, and had with him a large share in bringing about the September Massacres. Having been elected a deputy for Paris to the Convention, he was among the first to demand the abolition of royalty ; and from Nice, whither he had gone on an embassy, he voted the death of Louis XVI. &quot; sans sursis.&quot; In the struggle between the Mountain and the Girondists he dis played great energy ; and after the coup d etat of May 31 (1793) be made himself conspicuous by his pitiless pursuit of the defeated party. In June he was made president of the Convention ; and in September, with Billaud-Varenne, lie w r as admitted to the Committee of Public Safety. He voted loudly and persistently for all the bloodiest and sternest measures. In November, after the Lyonese insur rection, he was sent with Fouche to punish the rebellious city, where, it is said, he had once been hissed as an actor. This he effected by putting about 1500 persons to death in one day. In May 1794 an attempt was made to assas sinate Collot; but it only increased his popularity. In the struggle for mastery between Robespierre and Tallien, Collot took the part of the latter In spite, however, of his fierce attack on Robespierre he was expelled from the Committee of Public Safety, and was denounced in form by Lecointre. He defended himself, and was acquitted, but only to be denounced anew by Merlin, and to be con demned, with Billaud-Varenne, to transportation to Cayenne, where he died of fever a few months after his arrival.

1em  COLMAN, (1733-1794), essayist and dramatist, usually called the Elder, and sometimes George the First, to distinguish him from his son, was born at Florence, where his father was stationed as resident at the court of the grand duke of Tuscany. After a preliminary 