A similar process, by the same author (_U.S. Pat._ 798,293), is described by Dr. Allen Rogers[144] in which 5 per cent. of glucose syrup and 10 per cent. of sulphur, computed on the weight of the skins, is fermented with yeast for twenty-four hours, after which it is used as a bate. From a chemical point of view, it is difficult to express the reactions taking place. [144] J.S.C.I. 1906, p. 103. When the bath is first prepared, it is neutral in reaction, but, after standing, gradually assumes a slight acid reaction. On introducing the skins, it becomes alkaline, owing to diffusion of the lime. After a short time, it becomes neutral again, and remains thus until the skins are in a perfect condition, when a slight acid reaction is observed. These changes are caused by the fermentation of the glucose, carbon dioxide and alcohol being generated. Owing to the presence of sulphur, a quantity of hydrogen sulphide is produced, which, in its nascent condition, combines with the alcohol to form mercaptans, which in their turn are slowly oxidized to thioacids. These mercaptans and thioacids, being of weak acid character, act in conjunction with any excess of hydrogen sulphide upon the lime, converting it into soluble compounds, which are readily removed by diffusion. *Lederer, L.* (_French Pat. No._ 404,926 _of_ 1909).--Method of Preparing a Substitute for Animal Excrement (dog dung) in Puering Skins for Glacé Leather. In this process a mixture of 10 parts finely powdered bone meal, and 1 part of crushed lupin seeds or beans is formed into a paste with water and allowed to undergo spontaneous fermentation from 3–4 weeks. The mixture is said to form a perfect culture medium for the micro-organisms indispensable in bating. The removal of the lime is facilitated by the addition of 2 per cent. of fat, 0·75 per cent. sodium polysulphide and 1-1/2 per cent. common salt reckoned on the weight of the bone meal. In this patent the researches of Wood, Andreasch and Eitner are referred to, and also Benker’s process of bating with Peruvian guano to which soda has been added.