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See also:LOGWOOD (so called from the See also:form in which it is imported) , the See also:heart-See also:wood of a leguminous See also:tree, Haematoxylon campechianum, native of Central See also:America, and grown also in the See also:West See also:Indian Islands . The tree attains a height not exceeding 40 ft., and is said to be ready for See also:felling when about ten years old . The wood, deprived of its bark and the See also:sap-wood, is sent into the See also:market in the See also:form of large blocks and billets . It is very hard and dense, and externally has a dark brownish-red See also:colour; but it is less deeply coloured within . The best qualities come from Campeachy, but it is obtained there only in small quantity . See also:Logwood is used in See also:dyeing (q.v.), in microscopy, in the preparation of See also:ink, and to a small extent in See also:medicine on See also:account of the tannic See also:acid it contains, though it has no See also:special medicinal value, being much inferior to kino and See also:catechu . The wood was introduced into See also:Europe as a dyeing substance soon after the See also:discovery of America, but from 1581 to 166a its use in See also:England was prohibited by legislative enactment on account of the inferior dyes which at first were produced by its employment . The colouring principle of logwood exists in the See also:timber in the form of a See also:glucoside, from which it is liberated as haematoxylin by See also:fermentation . Hacmatoxylin, C16H,406, was isolated by M . E . See also:Chevreul in 181o . It fonns a crystalline See also:hydrate, C,6l-11406+3H20, which is a colourless See also:body very sparingly soluble in See also:cold See also:water, but dissolving freely in hot water and in See also:alcohol . By exposure to the See also:air, especially in alkaline solutions, haematoxylin is rapidly oxidized into haematcin, C16H12O6, with the development of a See also:fine See also:purple colour . This re-See also:action of haematoxylin is exceedingly rapid and delicate, rendering that body a laboratory test for alkalis . By the action of See also:hydrogen and sulphurous acid, haematcin is easily reduced to haematoxylin . It is chemically related to brazilin, found in See also:brazil-wood . Haematoxylin and brazilin, and also their oxidation products, haematin and brazilin, have been elucidated by W . H . See also:Perkin and his pupils (see Jour . Chem . See also:Soc., 1908, 1909) . LOBAR%, a native See also:state of See also:India, in the See also:south-See also:east corner of the See also:Punjab, between See also:Hissar See also:district and See also:Rajputana . See also:Area, 222 sq. m.; pop . (1901) 15,229; estimated See also:gross See also:revenue, 4800 . The See also:chief, whose See also:title is See also:nawab, is a See also:Mahommedan, of Afghan descent . The nawab See also:Sir See also:Amir-ud-din-Ahmad See also:Khan, K.C.I.E., who is a member of the See also:viceroy's legislative See also:council, was until 1905 See also:administrator and adviser of the state of Malec Kotla . The See also:town of Loharu had a See also:population in See also:tool of 2175 . |
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[back] LOGROSCINO (or Lo GRoscINo), NICOLA (1700?–1763 ?... |
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