SECTION II. RAW MATERIALS AND PRE- 

 LIMINARY 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. , 

 p. 22), 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 " flesh- 

 ings " 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., Section IX. ; Part II., 

 Sections II., III. and IV.), and the " flesh split/' though 

 sometimes made into leather, is also used in making gelatine, 

 a high quality being obtained from such material. Minor 

 sources of material are tendons and cartilages, and also hides 

 and skins which have been too much damaged by partial 

 putrefaction or by accidents to make sound leather. Of 

 course the material from the hides for heavy leathers form 



