claims that this prepares the hide for rapid and heavy tanning, but the swelling and subsequent reduction almost certainly entail loss of weight and quality, and to get good results the bate should at most only be allowed to have a superficial effect. Professor Lufkin proposed the use of a mixture of various sulphides of lime and soda, formed by mixing 10 lb. each of soda ash and sulphur, kneading to a paste with a little moist slaked and then mixing _warm_ in a cask with 80 lb. stone lime slaked to a paste. This quantity will unhair 50 hides in the same way and in about the same time as an ordinary lime. The pelt is not much plumped and is easily reduced by a few minutes' wheeling in warm water. (J. S. Schultz.) Various other depilatories have been proposed, but as they have not come into general use, brief mention of the most important will suffice. Anderson, in 1871, patented the use of wood-charcoal, applied in a similar manner to lime in the ordinary process. The hair is probably loosened simply by putrefaction, as in sweating, while the charcoal acts as a deodoriser, very little smell being produced, and the action proceeding with considerable uniformity. John Palmer has patented a process for unhairing, in which the hides are alternately steeped in water and exposed to the air till the hair loosens. In this, very similar principles to those of the charcoal method are involved. Caustic potash and soda will loosen hair, but seem to have no decided advantage over lime, though it is quite possible that in skilful hands good results might be obtained. They are more costly, and their corroding action on the hide-substance is more powerful, but they form soluble soaps with the grease of the hide. Unless used in very dilute solution, the pelt is so swollen as to fix the hair, and the leather is dark-coloured and spongy. Soda-ash or crystals (sodic carbonate) may be used to strengthen ordinary limes, in which caustic soda is formed. The time of liming is shortened, the hides are more swollen, and the grease is better "killed" than when lime alone is used. The patent for Moret's "Inoffensive" claimed the use of the carbonate or caustic potash formed from calcined wool-washings, for unhairing. This is more costly than, and has no advantage over soda. I am not aware whether "Inoffensive," as now sold, has other constituents. Whatever method of loosening the hair may be adopted, the next step is to remove it by mechanical means. This is usually accomplished by throwing the hide over a sloping beam, and scraping it with a blunt two-handled knife (Fig. 25), the workman pushing the hair downwards and away from him. The beam is now usually made of metal. The knife employed is also shown at C, Fig. 26.