All these materials are of course readily putrescible and must be put "into work" without much loss of time. When it is impossible to convey them from the tannery to the gelatine factory quickly enough, _e.g._ foreign material, the "glue stock" is dried out completely and sold in that condition. In the manufacture of pickers from limed pelt there is some superfluous material, and this is cut into shavings and dried. This "picker waste" also forms a useful source of raw material. Skin gelatine material is not very strong in gelatine-substance. The fleshings, pieces, etc., contain much water, even up to 80 per cent. This, however, is very variable, and only a practical test or a hide substance determination can indicate the commercial value of any particular material. This value, moreover, is determined not only by the yield and quality of the gelatine which can be obtained, but also by the yield of grease, the valuable bye-product. The preliminary treatment of material for skin gelatine consists essentially of liming and of washing. The object of each process is to purify. Liming has much the same action on hide pieces, etc., as on hides, and indeed the liming treatment is somewhat superfluous on cuttings from well-limed hides. The material is plumped up and the partially hydrolyzed products are taken into solution. Lime also acts as mild antiseptic, stops any putrefaction and liberates ammonia formed by fermentation in transit to the factory. When plumping is particularly wanted (as in wetting in dry stock) caustic soda is sometimes used as an assistant (_cf._ dried hides). Sodium sulphide has also been used for this purpose. The liming is in brick pits, an excess of undissolved lime being always used. It is advantageous frequently to disturb or agitate the goods in the lime pits. Up to ten weeks liming has sometimes been given, but about three weeks is now generally considered sufficient, and the tendency is to shorten the time. The lime and soda have also a detergent action on soiled stock, and they probably assist in hydrolyzing the pigments of the hair roots and sheaths. They also saponify and emulsify the grease, and it is obvious, therefore, that liming can be carried too far. Slaked lime, of course, must always be used.