1921.] Wright.—Chemical Technology of Meat Industry. 
159 
The process of fleshing is usually carried out by machines operating 
a right-and-left spiral knife-cylinder, the pelts being fed into the machine 
by being thrown upon an apron beam, flesh side to the knife-cylinder. 
A process similar to fleshing is also carried out in order to remove as much 
as possible of the hair root-sheaths and fat-glands upon the grain side of the 
pelt. This process is known as “ scudding," the skins being fed into the 
machine, grain side to the knife-cylinder. 
The lime, having served its useful purpose in loosening the hair and 
fatty and other tissues and in swelling the pelt-fibre, must now be re¬ 
moved from the skins, as it would interfere with the tanning processes to 
which the pelts are ultimately subjected. Much of the treatment to which 
the pelts are exposed prior to curing or pickling for export has for its 
object the removal of the lime. 
As the lime and other alkalis used in the depilatory processes and for 
the loosening of the adhering tissues are all more or less soluble in water, 
it might be thought that simple washing would suffice in order to remove 
them. Skin or hide substance is, however, “ amphoteric "—that is to say, 
it is capable of acting either as a weak base or as a weak acid, and is just 
as ready to combine with acids as with alkalis. Hide substance therefore 
forms definite chemical compounds with lime, which are only very slowly 
decomposed or “ hydrolysed ” by the action of water. In any case, how¬ 
ever, a certain amount of loose lime can be removed by washing, and with 
this in view the fleshed pelts are placed in washing “ dollies in order to 
remove as much as possible of the free lime. 
The precaution noted previously in regard to waters containing carbon 
dioxide should be taken into consideration here, and, if necessary, lime-water 
should be added to the water before its utilization in the pelt-washing, so 
as to eliminate the possibility of 41 blasting ” of the grain of the pelt. 
While lime and alkalis are retained by the constituents of the pelt sub¬ 
stance, their neutral salts are buf loosely held, and in consequence suitable 
treatment with acids capable of forming soluble salts with lime is adopted 
to aid in removing the latter. Difficulties in this connection arise, however, 
for, as has been shown, hide substance is just as ready to combine with 
acids as with alkalis, and acids, equally with lime, produce results pre¬ 
judicial to the tanning process. It is necessary, therefore, to use either 
the exact quantity of acid needed to form a neutral salt or to take other 
means to prevent the skin from absorbing acid in excess. It is in order to 
thoroughly delime the pelt without subjecting it to injury that the processes 
of chemical deliming are carried out with the utmost care and attention 
to detail. 
The pelts are usually placed in an infusion of bran and allowed to remain 
there during the process of bacterial fermentation, which results in the 
production principally of lactic and acetic acids, the lime salts of these 
acids being soluble in water and easily removed from the pelt. The fer¬ 
mentation of the bran infusion is brought about mainly by two species 
of lactic bacteria. These bacteria find their food-supply only in the carbo¬ 
hydrates of the bran, and do not attack the pelt substance, so that if no other 
bacteria were present the operation could be carried out without destruction 
of the pelt. It is, however, not practicable under manufacturing condi¬ 
tions to secure absolute freedom from other bacteria, and the bran drench 
under ordinary working-conditions always contains other species, some of 
them capable of injuring the skin. In order to prevent these from caus¬ 
ing serious injury to the skin, the only way is to make the conditions so 
