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. 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. 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. Drenching usually follows bating. Scudding sometimes follows deliming. The theory of the volume and elasticity changes of pelt during preparation will be better understood after considering the behaviour of gelatine gels. The determining factors are the _nett_ charge of hydroxyl ions on the disperse phase, resulting from ionic adsorptions, and the lyotrope influence of dissolved substances on the continuous phase. In softening dried hides the swelling may be due to either influence, but the latter tends to loss of hide substance and the production of soft leather. In liming, the nett adsorption of hydroxyl ions is the principal factor, but the lyotrope influence of the alkali cations and of the impurities is important. Plump pelts are those in which the contained water is in a relatively greater average state of compression. Few substances can assist plumping, but many can hinder it. In plumping all lyotrope influence is objectionable, and "sharp" (pure) alkali solutions are required. Mellow limes reduce elasticity and plumpness by lyotrope influence. In bating and puering the essential change is that before the process the swelling is due chiefly to adsorption of hydroxyl ions, whereas afterwards it is due chiefly to a composite lyotrope influence. REFERENCES. "Principles of Leather Manufacture," Procter, pp. 108-184. "The Manufacture of Leather," Bennett, pp. 49-113. "Lyotrope Influence and Adsorption in the Theory of Wetwork," Bennett, _J.S.L.T.C._, 1920, pp. 75-86.