=Quebracho Extract= is made from the wood of the South American tree _Loxopteryngium Lorenzii_, which contains about 20 per cent. of a typical catechol tan. It is associated with a little catechin, much phlobaphene, but practically no sugar. The tannin is very astringent, penetrates quickly and gives a firm red leather which darkens on exposure to light. It is not noted for weight-giving powers. The wood itself, as chips or shavings, has been used in British tanneries, to a limited extent, but the great bulk of the material is made into extract chiefly in South America. The crude "extract," made by evaporating aqueous infusions of the wood, is largely exported for refinement in Europe. It is also refined on the spot to a large extent and converted into solid extract containing 60 per cent. of tannin. The great difficulty with quebracho has been the disposal of the phlobaphenes, and a great variety of quebracho extracts are now available which deal with this problem in different ways. In some the more soluble reds are simply left in the extract under the idea that they are really tannins and may be of some use in some part of the tanning process; in others they have been removed by settling and filtration at appropriate temperatures and concentrations; in most, however, they have been solubilized by treatment with alkalies, in the presence of reducing agents, notably by heating with sodium bisulphite in closed vats. The base combines with the phlobaphenes, which are made completely soluble and available for tanning. Sulphurous acid is evolved, and its reducing powers assist materially in retaining and promoting a good colour in the product. Such "sulphited extracts" are now extensively manufactured in this country from the imported "crude" extract, and sold as liquid extracts containing 30, 35 or 40 per cent. of tan according to the requirements of the buyer; "mixed extracts" which are solubilized quebracho blended with about 15 per cent. of myrabolans, are also used. By solubilizing quebracho with excess of bisulphite an extract is obtained which possesses considerable bleaching powers, and such extracts are also extensively manufactured for the "vatting" or bleaching of heavy leather after tannage. The excess of sulphurous acid not only bleaches the leather, but also swells it up and thus permits a further absorption of strong tan liquor, which is conducive to good weight. These bleaching extracts are usually of 36-38 per cent. strength in tan.