THE CHESTNUT TREE (_castanea vesca_) probably provides the next tanning material of importance. This must not be confused with the chestnut oak, an American tree which also yields a very useful tannin. The chestnut is indigenous to the South of France and Italy, where the forests have been considerably reduced in size to meet the great demand for this popular tanning material. The greater part of the denuded forests have not been replanted with the chestnut, as the land has been put under cultivation whenever possible. A further depletion has been caused by the ravages of an insect, which turns the interior of the wood quite black and renders it unfit for tanning purposes. It will, naturally, be several years before the supply is exhausted, even if no reafforestation is undertaken. As it is the most important tanning material grown in France, and the chestnuts are used as a food, steps may be taken to cultivate the trees on areas unsuitable for agriculture. Liquid chestnut extract contains from 30 to 32 per cent. of tannin, and, when decolorised, gives a light brown colour to the leather. It is rarely, if ever, used alone, but generally in conjunction with quebracho, valonia or myrobalan extracts. THE CHESTNUT OAK TREE is indigenous to America and the wood yields a very good tanning extract, containing up to 30 per cent. of tannin. This material is the principal tanning agent used in America, where the tannages are roughly classified in three sections: (1) oak, (2) hemlock, and (3) the union (_i.e._, a mixture of hemlock and oak). American tanners also use other materials to a smaller extent, chiefly for blending with the principal tannins. Quebracho and spruce extracts are specially favoured. QUEBRACHO COLORADO is a tree indigenous to South America, the best wood for tanning purposes being found in the Gran Chaco district in the north of Argentina, and in Uruguay. The wood contains from 17 to 22 per cent. of tannin, and is so hard and heavy that it sinks in water. In fact, its name is derived from two Portuguese words meaning "axe-breaker." After felling the trees, they are cut up into logs about 4 ft. in length and either exported in this state to Hamburg, Havre, and Liverpool, or sent to the numerous factories in close proximity to the forests to be made into extract, in which an enormous trade has of late years been developed. Very little of the natural material is now used, as, even after cutting the wood into chips, the tannin is extracted only with great difficulty, whereas the extract can be treated with sulphites, alkalies, or neradol (the artificial tannin) to render it easily soluble, besides which the concentration of the material raises the percentage of its tannin to 65 or even 70 per cent. Owing, perhaps, to faulty preparation, this tanning extract was not well received at first, but it is now among the principal tannins and increases in importance every year.