THE PREPARATION OF PELT 25 



heralds the approach of a putrefactive action, which if 

 allowed to continue for even a short time will ruin the 

 hides. Bating is consequently a risky process, and needs 

 experienced oversight. For goods which need only a mild 

 bating, there is the alternative of giving a longer liming in 

 older limes. This of course involves more bacterial 

 hydrolysis, and perhaps does it in a safer, more economical 

 and certainly in a less offensive manner. Bating is often 

 followed by a further deliming by acids. Boric, lactic, 

 acetic, formic and butyric acids are all used, and with care 

 even hydrochloric and sulphuric acids may be employed. 

 Innumerable " artificial " bates have been put on the market, 

 but most are merely weak acids, acid salts or salts of strong 

 acids with weak bases. An American " bacterial bate " 

 consists of a lactic fermentation of glucose in the presence 

 of glue. 



Closely similar to bating is "puering," investigated by 

 Wood (see p. 94). 



Drenching is another fermentive deliming process. In 

 this the goods are inserted into an infusion of bran. This 

 is made by scalding the bran with hot water, and allowing 

 it to stand until it is about 70-90 F. The infusion is then 

 " inoculated " with a few gallons of old drench liquor, 

 and the goods are immersed. This fermentation has been 

 examined carefully by J. T. Wood. First the enzyme 

 cerealin converts bran starch into glucose, which is then 

 fermented by the drench bacteria with the production of 

 lactic acid, some acetic acid and small amounts of formic and 

 butyric acids. The butyric fermentation is liable to become 

 too violent. These acids, as they are formed, neutralize the 

 lime in the hides and plump the pelt slightly (see pp. 

 107-109). 



Various gases (carbon dioxide, hydrogen, nitrogen, 

 methane and sulphuretted hydrogen) are involved, and the 

 proportion produced in the pelt itself has a peculiar opening 

 effect on the hide fibres. The activity of the drench can be 

 decreased by dilution and by using a less starchy bran, 

 and can be increased by adding pea meal or rye meal. 



