Already, in the first paper above named (“Methods of Bacteriological Research”), I had called attention to the bacteria of the bate prepared from dogs’ dung, and in a paper entitled “Fermentation in the Leather Industry,”[3] developed this aspect of the subject, and first pointed out the influence of enzymes in bating. I therefore decided to study the phenomena occurring in the bate in the same way as I had studied drenching. [3] Jour. Soc. Chem. Ind., 1894. p. 218. The work was begun in 1895, and, as it was likely to occupy an indefinite time, the first instalment, entitled “Notes on the Constitution and Mode of Action of the Dung Bate in Leather Manufacture,” was published November 30, 1898; while “Further Notes on the Action of the Dung Bate” was published on November 30, 1899. In these papers I indicated the lines on which a culture of bacteria might be practically applied to the bating of skins, and gave the composition of a liquid which, while acting as a nutrient medium for the bacteria, contained at the same time most of the active chemical compounds of dog dung. Meanwhile, Dr. Popp and Dr. Becker, in Frankfort a/M, were investigating independently the bacteria of dog dung, and conceived the idea of employing them commercially. My dear friend Franz Kathreiner, of Worms,[4] put me in communication with these gentlemen, and we were thus enabled to work in conjunction. As a result of our combined labours, an artificial bate, called “Erodin,” was put upon the market. This will be fully treated of in the chapter on Artificial Bates. [4] Died, April 1905. I shall give first a short account of bating, and then sum up as briefly as possible the present state of our knowledge of the process, afterwards giving an account of the more important of the various patents which have been taken out for artificial bates. Although the book is divided into separate sections for convenience, it is obvious that we cannot separate chemistry from physics, nor bacteriology from chemistry, nor enzyme action from all three. My own papers are printed as read. The Bibliography does not profess to be complete, but includes most of the works consulted. No one realizes more than I how incomplete the work is, and how much research still remains to be done in order to complete it. Thanks to the efforts of the Leather Industries Department of the University of Leeds, and the Technical College of the Leather Sellers’ Company, Bermondsey, the era of Rule of Thumb is passing, and there is little doubt that the work that is being done in these institutions will be translated into practical use in the factories by the coming generation.