manera 
SCIENCE AND INDUSTRY. 
Wood, of Nottingham, seemed to indicate that pancreatin is the active 
constituent of the dung, and now mixtures of pancreatic enzymes and 
‘aiimonium chloride largely replace the obnoxious dungs. But the 
question as to why we bate at all is still a moot one. Many tanners, 
‘especially those making heavy leathers, do not bate; others claim that 
good leather cannot be made without bating. If the object of bating 
were simply to counteract the alkaline swelling of the hides coming 
from the limes, this could easily be accomplished by reducing the hides 
to a nearly neutral condition, and some tanners claim’ that this does 
produce the desirable effects of bating. Recently, however, evidence 
has been. brought forth to show that, in bating, the elastin fibres of the ” 
papillary layer are digested by the enzymes present. 
The foregoing represent what are known as the “beam house” 
operations, and their prime object to free the hides from everything 
excepting the collagen fibres and hyaline layer of the true skin, which 
‘is then ready to be tanned. 
TANNING. 
There are numerous methods of tanning, of which only the two most 
important will be mentioned: these are vegetable tanning and chrome 
tanning. While the origin of vegetable tanning is lost in antiquity, 
chrome tanning is a product of the last few decades and is often referred 
to as the one big contribution of chemistry to the leather industry. 
These two processes and the materials involved in them have been the 
subject of the great majority of investigations made in the industry, 
and yet it cannot pe said that we have made more than a start in the 
direction of solving the chemistry of tanning. 
CHROME TANNED COWHIDE (x 15). 
662 
