164 ANIMAL PROTEINS 



The soaking process is quite similar to that before describe d 

 for the production of goatskin moroccos (q.v.) and need 

 not be here repeated. The liming is similar in many 

 respects also, but from what was said in Section II. about 

 the undesirability of excessive plumping of pelt for chrome 

 leather, it will be clear that caustic soda should be omitted 

 from the limes. The liming should also be shorter for 

 glace than for moroccos, and this is attained both by using 

 a greater proportion of sulphide and by using mellower 

 lime liquors, preferably the latter, as soft pelts are better 

 ensured. Calcium chloride has sometimes been added to 

 the limes : this reacts with the soda from the sulphide, 

 yielding salt and probably precipitating lime, and has its 

 own lyotrope influence, thus reducing the plumping effect 

 possibly in two ways. To obtain either effect it is 

 necessary to use considerable amounts of calcium 

 chloride. As goatskins are so tight fibred, a longer 

 liming and a greater loss of collagen is permissible than 

 with most pelts for chrome. The deliming operations 

 should be' exceedingly thorough in order to obtain the 

 desired softness and the smooth grain. Puering is largely 

 used to the full extent, i.e. the goods are thoroughly pulled 

 down at 85-90 F., and are carefully delimed in the 

 puer liquor. After puering it is common to give a low 

 temperature drench (6o-65 F.), which of course acts 

 slowly over a day or two. The skins must be well scudded 

 after puering or after drenching ; sometimes after both. 

 The drenching is often substituted for purely deliming 

 processes, of which may be mentioned the use of boric 

 acid and also the use of warm solutions of the commercial 

 organic acids (lactic, formic, acetic, butyric, etc.), together 

 with calcium chloride. In place of the chloride, a salt 

 of the acid may be employed, and the deliming bath may 

 be regenerated by oxalic acid and used repeatedly. Some- 

 times puering is omitted and the desired result obtained by 

 washing in warm water, nearly deliming with warm solu- 

 tions of organic acid, washing again and drenching. Skins 

 are also washed often after drenching. 



