CHROME LEATHER MANUFACTURE 141 



practice, but sometimes a 3-4 days' process with more 

 sulphide is also found satisfactory. 



It would seem probable that the real solution of the 

 problem would be found by a different process altogether. 

 In this connection it is interesting to note that a Continental 

 proposal to unhair by enzyme action only has been found 

 most practicable with goods for chrome, and, in the author's 

 opinion, some development on these lines, in which a 

 lipolytic enzyme is used in addition to a proteolytic, might 

 solve the difficulty, and give a rapid depilation which 

 dispenses with liming, plumping and deliming with the 

 consequent loss of valuable hide substance. 



In the usual short, mellow, sulphide liming it is clear 

 that there is not much advantage in a " round " or " set " 

 of pits. Hence the one-pit system is popular on account 

 of the less labour involved. 



The above remarks are less applicable in the case of 

 chrome sole leather. In this case weight is a great con- 

 sideration and plumping is necessary. In such leather 

 the chrome tannage is supplemented by the use of 

 waxes, which fill up the spaces between the fibres and 

 give solidity and waterproof ness to the finished article. 

 With this leather an ordinary sole leather liming in 

 sharp liquors is not unsuitable, handling the goods from 

 " mellow to fresh," but there is, on the whole, a tendency to 

 shorten the process to about a week by using more sulphide. 



Processes for deliming pelt for chrome leather should 

 also be chosen by our guiding principle of hide substance 

 conservation. Here again short processes involving little 

 change in swelling should be preferred. Now, the ordinary 

 bating and puering processes give (i) neutralization of 

 lime by organic acids combined with weak bases ; (2) the 

 solation of some hide substance ; and (3) a " pulling 

 down " effect on the swollen pelt. Now, neutralization is 

 quite superfluous, as the acids of the chrome liquor (one- 

 bath or two-bath) can quite well accomplish this ; the 

 solvent effect is undesirable altogether ; and the " pulling 

 down " effect is also unnecessary if the goods are not 



