These enzymes were prepared from dung, and it now remained to prepare them in the laboratory by the action of bacteria alone. For this purpose 200 c.c. of a mixed culture of dung bacteria in the solution above described, seven days old, was mixed with 200 c.c. of dilute alcohol (alcohol 65, water 100) and well shaken. Gelatin and albuminoid bodies are by this means precipitated. The liquid was filtered and poured into eight times its volume of 98 per cent. alcohol. The precipitate which came down was washed with absolute alcohol and dried in the usual way. The enzymes thus obtained were redissolved in water and the former experiment with skin repeated with this solution. The same effect was produced, showing conclusively that it is the enzymes produced by the bacteria, acting in conjunction with the amines, which bate the skin. It would seem that the special action of the enzymes is aided by the presence of amine compounds, in addition to the chemical action which these latter have upon the skin. The action is shown to be interdependent, i.e., bacterial action alone is insufficient, and chemical action alone is insufficient, the true bating action being a combination of the two. In conclusion the author has pleasure in acknowledging the valuable assistance of Mr. H. S. Shrewsbury in carrying out some of the experiments. III. FURTHER NOTES ON THE ACTION OF THE DUNG BATE.[126] [126] Reprinted from the Journal of the Society of Chemical Industry, November 30, 1899, No. 11, vol. xviii. The present notes are a continuation of those published in 1898. It has been impossible for me to follow up the subject except in a desultory manner, but I think it desirable to put further results, however meagre, before you with the object of throwing more light on the complex process of bating hides and skins. Since the previous notes were written, Dr. Th. Körner[127] has called attention to the physics of the process, a matter which I had not previously mentioned. He explains part of the action by differences of osmotic pressure. The ammonium salts and salts of organic bases contained in the dung, possess a smaller osmotic pressure than the solution of calcium hydrate contained in the skins. The ammonium ion endeavours to unite with the hydroxyl ion of the calcium hydrate to form undissociated ammonium hydroxide. In consequence of the osmotic pressure and the electrostatic attraction of the oppositely charged ions, the calcium hydrate solution is withdrawn from the skin and the latter falls. [127] 10 Jahresber. d. Deutsch. Gerberschule zu Freiberg, 1898–99: Beiträge zur Kentniss der wissenschaftlichen Grundlagen der Gerberei, p. 32. _Experiments with Bacteria on a Large Scale._