Online Encyclopedia

Search over 40,000 articles from the original, classic Encyclopedia Britannica, 11th Edition.

CATECHU

Online Encyclopedia
Originally appearing in Volume V05, Page 507 of the 1911 Encyclopedia Britannica.
» Make a correction to this article.
» Add information or comments to this article.
Spread the word: del.icio.us del.icio.us it!

CATECHU , or CUTCx (See also:

Malay, kachu), an See also:extract obtained from several See also:plants, its See also:chief See also:sources being the See also:wood of two See also:species of See also:acacia (A. catechu and A. suma), both natives of See also:India. This extract is known as See also:black catechu. A similar extract, known in See also:pharmacy as See also:pale catechu (Catechu pallidum), and in See also:general See also:commerce as gambir, or terra japonica, is produced from the leaves of Uncaria gambir and U. acida, cinchonaceous plants growing in the See also:East See also:Indian See also:Archipelago. A third product to which the name catechu is also applied, is obtained from the fruits of the areca or betel See also:palm, Areca catechu. See also:Ordinary black catechu is usually imported in three different forms. The first and best quality, known as See also:Pegu catechu, is obtained in blocks externally covered with large leaves; the second and Iess pure variety is in masses, which have been moulded in See also:sand; and the third consists of large cubes packed in coarse bags. The wood of the two species of Acacia yielding catechu is taken for the manufacture when the trees have attained a See also:diameter of about 1 ft. The bark is stripped off and used for tanning, and the See also:trunk is split up into small fragments, which are covered with See also:water and boiled. When the extract has be-come sufficiently thick it is See also:cast into the forms in which the catechu is found in commerce. Catechu so prepared is a dark See also:brown, or, in See also:mass, almost black, substance, brittle, and having generally a shining lustre. It is astringent, with a sweetish See also:taste. In See also:cold water it disintegrates, and in boiling water, See also:alcohol, acetic See also:acid and strong See also:caustic See also:alkali it is completely dissolved.

Chemically it consists of a mixture of a See also:

peculiar variety of See also:tannin termed catechu-tannic acid with catechin or catechuic acid, and a brown substance due to the alteration of both these principles. Catechu-tannic acid is an amorphous See also:body soluble in cold water, while catechin occurs in See also:minute, See also:white, silky, See also:needle-shaped crystals, which do not dissolve in cold water. A very minute proportion of quercetin, a principle yielded by See also:quercitron bark, has been obtained from catechu. Gambir, which is similar in chemical See also:composition to ordinary catechu, occurs in commerce in the See also:form of cubes of about an See also:inch in See also:size, with a pale brown or yellow See also:colour, and an even earthy fracture. For the preparation of this extract the plants above mentioned are stripped of their leaves and See also:young twigs, and these are boiled down in shallow pans. The juice is strained off, evaporated, and when sufficiently concentrated is cast into shallow boxes, where, as it hardens and dries, it is cut into small cubes. Gambir and catechu are extensively employed in See also:dyeing and tanning. For dyeing they have been in use in India from the most remote See also:period, but it was only during the 19th See also:century that they were placed on the See also:list of See also:European dyeing substances. Catechu is fixed by oxidation of the colouring principle, catechin, on the See also:cloth after dyeing or See also:printing; and treated thus it yields a variety of durable tints of drabs, browns and See also:olives with different mordants (see DYEING). The See also:principal See also:consumption of catechu occurs in the preparation of fibrous substances exposed to water, such as fishing-lines and nets, and for colouring stout See also:canvas used for covering boxes and portmanteaus under the name of tanned canvas. Black catechu is See also:official in most pharmacopoeias except that of See also:Great See also:Britain, in which pale catechu is the official See also:drug. The actions and uses of the two are similar, but black catechu is the more powerful.

The dose is from five to twenty grains. The pulvis catechu compositus contains catechu and kino, and may be given in doses twice as large as those named. The drug has the actions and uses of tannic acid, but owing to the relative insolubility of catechu-tannic acid, it is more valuable than ordinary tannic acid in See also:

diarrhoea, See also:dysentery and intestinal See also:haemorrhage.

End of Article: CATECHU

Additional information and Comments

There are no comments yet for this article.
» Add information or comments to this article.
Please link directly to this article:
Highlight the code below, right click, and select "copy." Then paste it into your website, email, or other HTML.
Site content, images, and layout Copyright © 2006 - Net Industries, worldwide.
Do not copy, download, transfer, or otherwise replicate the site content in whole or in part.

Links to articles and home page are always encouraged.

[back]
CATECHISM (from Gr. Karnxeiv, teach by word of mout... 		[next]
CATECHUMEN (Lat. catechumenus, Gr. KarnXouµevos, i...

Site © 2006 - Net Industries