Chapter XXXVIII: Section II: Raw Materials and Preliminary Treatment

The raw materials for the manufacture of gelatine and glue may be classified according to their origin. The preliminary treatment, which comprises chiefly purifying and cleansing operations, is varied according to type of manufacturing process for which it is a preparation.

In the case of hide or =skin gelatine=, the raw material is a bye-product of the leather industry. After the hides or skins have passed through the preparatory processes which convert them into "pelt" (see Part I., Section II.), they are so trimmed that all that is left will make a useful leather. These "trimmings" or "roundings" include ears and noses, the udders of cows and heifers, and also include parts from the butt, belly and shanks which are collectively termed "pieces." The operation of fleshing (Part I., Section II.), in which fat and flesh are cut from that side of the hides and skins which was next the flesh, also involves cutting into the collagen to some extent, and these "fleshings" comprise another very large class of raw material. The fleshings obtained by hand labour contain distinctly more hide substances than those obtained by machine work, and their commercial value to the gelatine manufacturer is of course proportionate to the collagen content. Some hides and skins are split in the pelt (Part I.,