This is prepared by soaking wheaten bran in water at about 50° C., and diluting with warm water. Sometimes the mixture is strained, and the bran-water only used, to save the trouble and cost of removing adhering particles of bran from the delicate skins. 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 acetic and lactic 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. 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. 167). 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. A small quantity of olive oil is also generally used. The skins are either trodden in it with the feet, or more generally put into a tumbler-drum with it. Kathreiner pointed out, some years ago,[114] 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. [114] Gerber, i. (1875) p. 170; ii. (1876) p. 664. 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. 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 (German _Horden_) composed of square bars of wood, joined corner to corner, so as to make a floor of sharply angular ridges. The next operation is stretching with the “moon-knife”; after which the leather is dried nearly completely, and staked again.