mixture was applied to the hair by means of a brush, the skins let lie for some time, then dried, brushed and beaten. Many applications were usually necessary to sufficiently degrease the hair. Inasmuch as the killing paste was prepared by mixing the constituents together, and then was brushed on at the comparatively low temperatures which the proper protection of the hair required, it is questionable whether some of the metal compounds were even enabled to act as described above as mordant or dye. In spite of the trouble and considerable time required in working with such a killing formula to obtain the hair in the desired condition for dyeing, the use of such a mixture nevertheless possessed the advantage that the hair was only very slowly and gradually acted upon, and so the gloss was preserved. The action of strong alkaline substances acting quickly is more or less detrimental to keeping the gloss of the hair, while the slow action of the weak alkaline paste of the old formulas, and the gradual formation of a protective metal film on the surface of the hair, rendered the hair suitably receptive to the dye which was subsequently applied, without in any measure affecting the lustre of the hair. It would be needless to describe or discuss any more of the old killing formulas, for the principle involved was the same in all cases, there being usually a slight variation in the content of metallic salts, beechwood ashes and unslaked lime being constituents of the great majority of the mixtures used. Modern killing processes employ substances quite similar to those of the old formulas, the operations, however, being much less laborious and less time-consuming, and the cheap, pure products which chemical science has been able to develop being used in place of the crude products crudely obtained from natural sources. The chemicals used at the present time for killing furs, are chiefly ammonia, soda ash, caustic soda, and caustic lime. The choice of the killing agent depends upon the nature of the fur, the hair of some furs being sufficiently killed by treatment with weak alkalies, while in other furs the hair may require stronger treatment. The ability of the hair of a particular fur to withstand the action of the different alkaline substances must be taken into consideration, there being a great divergence in this regard among the different classes of furs. Raccoon, for example, is not appreciably affected by a solution of caustic soda of 5 degrees Beaumé, while some wolf hair cannot withstand the action of a solution of soda ash of less than 1 degree Beaumé. Frequently much stronger alkalies are necessary to kill the top-hair than the under-hair, so this accomplished by treating the skins in a solution which is suited to kill the under-hair, and subsequently the top-hair is treated with a stronger solution, this being applied by the brush method.