In the leather trades by far the most important and valuable bye-products are obtained from the hides and skins themselves, and all these are obtained before the tannage proper is commenced. The leather trades use only the dermis (corium) or true skin for the manufacture of leather, and as we have noted (Part I., Section II.) this prepared and purified dermis is called "pelt." The cuttings and trimmings from the pelt form the most valuable bye-product of the leather trades, and are the raw material of the gelatine and glue industries (Part V., Section II.). Many portions of the pelt, indeed, such as ears, noses, and cows' udders, are quite useless for any other purposes. Other portions, such as cheeks, faces, and even bellies, may be made either into glue or leather according to the state of trade. Hardly less important to the same industry are the cuttings of adipose tissue removed in "fleshing" the hides and skins. These, though yielding less protein, yield also, however, the valuable animal greases (Part V., Section II.). To obtain both these products in a purer condition the removal of "flesh" after "soaking," but before "liming" (Part I., Section II.), has been favoured by some, especially in America. Amongst the epithelial structures of the hides and skins, we have several protein bye-products which have some commercial value. The horns of cattle are now almost invariably removed before reaching the leather manufacturer, but have some little value. This part of the epidermis is not solid keratin. A "pith" is easily removed after boiling in water. The outer parts, too, are often coarse and somewhat damaged, but if removed by scraping reveal often a rather beautiful structure of varying colour. There is some opening for this product in the manufacture of small articles of horn, but much of it, together with hoofs, is roasted and crushed for making fertilizers. The hair of cattle, goat, etc., has also a commercial value. This is removed after liming, and needs subsequent purification (Part I., Section II.). The hair is well washed with water, using either repeated changes or a continuous supply, the operation being carried out in paddles or similar machines which stir up the hair in the water. When clean, the hair is transferred to a centrifugal machine or "spinner," in which much adhering water is removed. This is a great assistance in drying out, which is the next and final operation. In drying, the hair is laid upon steam-heated boxes or pipes, and a current of warmed air passed over or through it by means of a fan. It is better to have the hair "turned" occasionally. This ensures quicker as well as more even drying. The product is made up into large bales and sold for the manufacture of felts, mattresses, etc. White hair is usually kept separate and commands a larger price. The power consumed in driving the washing machinery, the centrifuges and the drying fan, together with the fuel required for the