The above-described method is most suitable, when the bate has to be kept for a time before being used, or when it is desired to concentrate it for transit or export; but if the bate is to be used immediately, it may be prepared as follows: 100 parts of gelatin are dissolved in 1000 parts of water, and there is then added 50 parts of commercial lactic acid. The mixture is then heated, in a closed vessel, to 100° centigrade, by which operation the gelatin is partially peptonized, and the subsequent bacterial action is hastened. The acid liquid is afterward neutralized with ammonia, or other alkali, and the whole diluted with water to 20,000 parts. The dilution may conveniently take place in the wheel or paddle in which the bating is to be done, and to the liquid thus obtained there is added from 5 to 10 per cent. of the active culture from the Carlsberg vessel, as above described. The liquid is then allowed to stand for 15 to 20 hours at a temperature of 37° centigrade, and is then ready for use.
For bating skins in a practical manner with the improved bate herein set forth, the method of using the same is varied, according to the skins to be treated and the kind of leather it is required to produce, and the strength of the bate is varied in exactly the same manner as the strength of a dung bate, and such variation is made according to the judgment of the tanner, the improved bate acting in the same manner as a dung bate.
For kid-skins, calf-skins, skivers, and other skins for which dog dung has hitherto been used, the skins, after the liming process, are first well washed in water in the usual way, to remove the bulk of the lime. The skins are then placed in a wheel or paddle, with the bate prepared, as above described, with the acid exactly neutralized, or so nearly neutralized, that the alkaline action of the skins will complete the neutralization, all skins being alkaline when introduced into the bate. The bate is maintained at a temperature of 37° centigrade, and the skins are kept in motion until they have “fallen” considerably, i.e., until the swollen condition of the fibres due to the liming has disappeared. The skins are then removed from the wheel or paddle and scudded by hand or machine, preferably on the grain side, and the skins not sufficiently reduced are returned to the paddle, and the bating continued until the action is completed, this being judged in the usual way by the tanner by the feel of the skins. The strength of the bate, when skins are returned thereto, may be varied from the original strength, if desired, and after the bating is completed the skins are treated in the usual manner.