SLANG. 226 SLATER. for 'bitch.' Centre slang is more elaborate. Tlie middle vowel of the vord to be turned into slang is taken as the initial letter, followed by the lat- ter part of the original word. To this the first part of the word is added, often with extra let- ters to give it a finished sound, as 'ockler' for 'lock.' In rhyming slang, a phrase which rhymes with the word to be disguised is substituted, as 'apples and pears' for 'stairs.' The linguistic ne- cessity of slang is shown by its universality. Not only is it current in all modern languages, but it reaches its acme in the most highly de- veloped tongues, as English, French, and Ger- man, and is used by the most cultured society, despite puristic attempt to suppress it. Further- more, it is not a characteristic of modern lan- guages alone, but of ancient ones as well. Slang aboimds in the more popular literature of Greece and Rome, as in the comedies of Aristophanes and Plautus, or in the Satyria of Petronius. Consult: Hotten, l^lang Dictionary (2d ed., London, 1885) ; Barr&re, Argot and Slang (ib., 1887) ; Farmer and Henly, Slang and Its Ana- logues (ib., 1800-96) ; Jlaitland, American Slang Dictionary (Chicago, 1891) ; Barrfere and Le- land. Dictionary of Slang, Jargon, and Cant (New York. 1893) : Kluge, Deutsche Stud-eytten- sprache (Strassburg, 1895); Francisque-Michel, Etudes rfe philologie comparce sur I'argot et sitr les idiomes analogues paries en Europe et en Asie (Paris, 1855) : Eigaud, Dietionnaire de I'argot moderne (ib., 1885) ; Delvan, Dietionnaire de la langiie verte (ib., 1889) : Larchey, Dietionnaire liistorique de I'argot (10th ed., "ib., 1887-89); Tinmiermans, L'argot parisien (ib., 1893). SLATE (OF. esclat, Fr. iclat, splinter, frag- ment, from OHG. silicon, Ger. scMeissen. AS. sl'itan, Eng. slit). A hard, fissile rock which has been produced from shale or clay by metamorpli- ism. This process by means of heat and pressure consolidates the original rock and obliterates the original stratification, developing new lines of parting or cleavage planes along which slate splits easily and in thin layers. Many fine- grained shales which split readily along the bed- ding planes are erroneously called slate, but true slate is a very liard and compact rock, little likely to be acted on by the weathering agencies. Owing to its origin, slate is found only in regions of metamorphic rocks, and therefore its geo- graphical distribution is somewhat restricted. Its geological range extends from the Cambrian to the Jurassic. Slate is commonly bluish black or gray black in color, but red, green, purple, and variegated varieties are known. In the United States the most important slate quarries are in Maine, Vermont, New York, Pennsylvania, Maryland, and Georgia. A small production is also made in California and Minnesota. The sup- ply of slate in Europe is derived mostly from Wales and France. Slate was formerly quarried by blasting, but at present it is generally extracted in large blocks by means of a channeling machine, simi- lar to that used in quarrying marble. The rock splits best when it is green or freshly taken from the quarry. Slate is extensively employed as a roofing material and for sinks, washtubs, bil- liard-table tops, electrical switchboards, floor- ing, mantels, blackboards, school slates, pencils, and in acid towers. In roofing it is necessary to lay the slates in two thicknesses, so that the slop- ing joints may be covered by the overlap of the course above, and the third course must al.so cover the first by an inch or two, to prevent rain from penetrating. Slate for interior decoration is sul>jeeted to a process called marbling, which consists in coating it with materials which give the surface a veined appearance like marble. The value of the slate produced in the United States in 1901 was $4,787,525. Most of this product was used for roofing purposes. The ex- ports amounted to $898,262, a large part being shipped to Great Britain. Bibliography. Merrill, Stones for Building and Decoration (New York) and "The Strength and Weathering Qualities of Roofing Slates," Transactions of American Society of Civil Engi- neers, September, 1892, and December, 1894; Dale, "The Slate Belt of Eastern New York and Western Vermont," in 'Nineteenth Annual Report of United States Geological Suri^ey, pt. iii. For statistics, see volumes on Mineral Resources is- sued annually by United States Geological Survey. See Metamoephism ; Shale; Building Stone. SLATER, John Fox (1815-84). An Ameri- can manufacturer and philanthropist, the nephew of Samuel Slater (who introduced in this country the business of cotton-spinning) , and grandson of William Slater, of Belper, Derbyshire, England. John F. Slater (son of .John Slater) was born at Slatersville, R. I., and after a good academic training took charge of his father's woolen mill, at Hopeville, Conn., and of a cotton mill near by, at Jewett City. In 1842 lie removed to Norwich, Conn, (still retaining with his brother William S. the business of a cotton manufacturer), and there he remained till his death. He was a liberal benefactor of local institutions, and as his years advanced he determined to set apart $1,000,000 for the edu- cation of "the freedmen." (See Slater Fund.) Congress voted thanks to Mr. Slater for his beneficence, and caused a gold medal to be struck in commemoration of it. Consult the "Mem- orial." privately printed in Norwich, Conn. (1S85). SLATER, Samuel (1768-1835). An American manufacturer, founder of the cotton-spinning industry in the United States. He was born in Derbyshire, England. He acquired a thorough knowledge of cotton-spinning under Jedediah Strutt, the partner of Richard Arkwright, and in 1789 emigrated to the United States for the purpose of introdvicing the industry there. He left England secretly for fear attempts would be made to prevent him from carrying his knowledge and skill to a foreign country. In .January, 1790. he proceeded to Pawtucket. R. I., where he entered into a contract to build and equip a mill with spinning machinery modeled on the Arkwright system. After great labor and sev- eral failures the machinery was completed and the spindles were set to work on December 21, 1790. In 1806. in conjunction with his brother, .Tohn, he constructed extensive cotton mills on the site of the present town of Slatersville. R. T., and there accumulated a large fortune. By 1810 there were in the United States 100 mills in operation, all constructed on the Arkwright system after the Slater models. In 1812 Slater constructed mills at Oxford, Mass., and
