This is prepared by soaking wheaten bran in cold water, diluting with warm water, and straining the extract through a fine hair-sieve. Sufficient of the liquid must be employed to well cover the skins, and the temperature may range from 50° F. (10° C.) to 68° F. (20° C.). These conditions are favourable to bacterial activity, which comes into play, and, on the one hand, evolves formic, acetic, lactic, and butyric acids, which dissolve any remaining traces of lime, and on the other, loosens and differentiates the hide tissue, so as to fit it to absorb the tawing solution (_Gare_). Much care is required in the management of the bran drench, especially in summer, since the lactic readily passes into the butyric fermentation (see also p. 186). The tawing mixture is composed (like that employed in the fabrication of calf-kid, q. v.) of alum, salt, flour, and egg-yolks, in a quite thin paste. The skins are either trodden in it with the feet, or put into a tumbler-drum with it (Fig. 48). Kathreiner pointed out, some years since (in vol. i. of 'Der Gerber'), that a mixture of olive-oil and glycerine might be partially substituted for the egg-yolks, in both the tanning and dyeing of glove-kid leather. The tawed skins are now dried by hanging on poles, grain inwards. Rapid drying in well-ventilated, but only moderately-heated, rooms is essential to the manufacture of a satisfactory product. [Illustration: Fig. 59.] [Illustration: Fig. 60.] The dry leather is rapidly passed through tepid water, and after being hung for a very short time, to allow the water to drain off, is trodden tightly into chests, and allowed to remain in them for about 12 hours, so that the moisture may be uniformly distributed. It is then trodden on hurdles (_Horden_), composed of square bars of wood, joined corner to corner, so as to make a floor of sharply angular ridges, Fig. 59. The next operation is stretching over a circular knife, called the _Stollmond_ (_stollen_, Eng. "staking"), shown in Fig. 60; then the leather is dried nearly completely, and staked again. Dyeing.