On comparing 2 and 3 it will be seen that apparently 1·61 grm. of the insoluble matter has passed into solution. This is not entirely the case, for part of the additional soluble matter is lime and hide substance from the skins, while part of the insoluble at the same time adheres to the skins and is not estimated.
In conclusion, it will be seen that it is now quite possible to produce an artificial dung bate, or rather a bate having the essential properties of a dung bate, by producing the required enzymes by fermentation and then adding to them the amine compounds. Such a bate I am able to show you here. The chief difficulty in its practical application in the tannery is the question of cost. If this can be overcome, and efforts are being made to overcome it, there is no doubt that the tanners of the next generation will be supplied with a bate which will do the same work as the dung bate, and which will have a definite and uniform composition and properties, and a regular and certain action. The tannery will become cleaner and healthier, and what is perhaps of equal importance, the sewage effluents will be comparatively harmless.
CHAPTER VII.
ARTIFICIAL BATES.
As may be supposed, inventors have from very early times turned their attention to the substitution of some other material in place of the unappetizing one so long in use. But as I pointed out in a short article entitled “Rationale of Bating”[133] many of them looked upon bating and puering as a process for removing lime from the skins, and nothing more; whereas we have seen that it is a very complicated process in which, not only is lime removed more or less effectively, but the skin fibres are acted upon, and portions of them rendered soluble, and the skin thus got into the necessary condition.
This misconception of the object of bating or puering prevented the success of most inventions of artificial bates up to quite recent times. Procter states that the use of ammonium chloride as a bate was patented by Zollikoffer in 1838. Such agents as this, and various acids, which have been proposed are merely chemical deliming agents, and, as such, we do not propose to discuss their use as artificial bates. Procter[134] gives an excellent account of these processes, including one of his own, in which ammonium chloride is used in conjunction with metabisulphite of soda, and for successive packs sufficient sulphuric acid is added to neutralize the ammonia formed.
The same author[135] also mentions an American invention for bating by the use of old lime liquors neutralized with sulphuric acid. This method is much more scientific than would at first sight appear, and more nearly approximates to the conditions of the dung bate than any of the early inventions. Old lime liquors contain much ammonia and weak organic acids, such as caproic, amido-caproic (leucin) and tyrosin. On adding sulphuric acid, the lime forms an inert sulphate, and the sulphate of ammonia and the weak organic acids which remain dissolved are just what are required in a chemical bate. The author has used this bate with success on certain classes of goods.
Tiffany’s bate, which is used in America, is composed of glucose and glue, and bates of this composition are also in use in England. As an example, 10 lb. glucose and 1/2 lb. of glue dissolved in 1000 gallons water, at a temperature of 75° F., and allowed to ferment for a few hours, may be used for the bating of bellies, and if used in a paddle or latticed drum will bring them “down” very rapidly.