io8 ANIMAL PROTEINS 



the symbiotic bacteria discovered by Wood. It is equally 

 possible that the acids produced are also different, in relative 

 proportion, if not in nature, and that consequently there is 

 a real difference in the practical effect. In the Author's 

 opinion, the great probability is that in the drench are several 

 fermentations, and that if the action be reduced by lowering 

 the temperature, but intensified by adding peameal to the 

 bran, some of these fermentations are encouraged at the 

 expense of others. 



The tannage of sealskins depends upon the size of the 

 skins, the purpose for which they are intended, and whether 

 they have been split or not in the limed state. The largest 

 and coarsest skins intended for boot uppers, and those 

 which have been heavily scratched on the grain and are 

 only suitable for enamels, are given a tannage which may 

 last about 5 weeks. The liquors are made from oak bark 

 and mimosa bark, and are made up to 35 with gambier and 

 possibly myrabolans extract. For fancy work also heavy 

 skins are used, but a softer tannage is needed. If for blacks 

 the tannage is with gambier and chestnut extract. Two 

 sets of handlers are given (io-i5 and I5-20), using 

 only gambier in the green sets. They are well sumached 

 after tanning to bleach and to mordant. If for colours, 

 only sumach and oak bark are employed. The skins are 

 first paddled for 3-4 days in sumach liquors, in which they 

 are coloured through. The liquors may be warmed ; this 

 quickens the tannage and also leaches the sumach. The 

 skins are then split, and the grains pass through a handler 

 set with liquors made from oak bark (8-24). The skins 

 are in this set for 3 weeks, in the first half of which they 

 are very frequently handled. They are finished off by 

 paddling for i or 2 days in a fresh liquor containing much 

 sumach, which mordants the skins and bleaches the bark 

 tannage. The flesh splits are given a drum tannage in 

 chestnut and quebracho extracts. If small skins are being 

 tanned for bookbinding purposes, sumach only is employed, 

 and usually the tannage is entirely in paddles. 



In finishing many types of grain may be obtained, in 



