LEATHER 85 



frequently handled, and worked on both sides on the convex beam. The working, 

 joined to the action of the peculiar lixivium, serves to separate the remaining lime, 

 oil, and glutinous matter, and at the same time to render the skin pliant, soft, and 

 ready to imbibe the tanning principle. It is important that great attention should be 

 paid to the process just described, as too short a period would produce a hard and 

 crisp leather, while a few hours more than is necessary makes the article coarse and 

 spongy, both of which conditions should be very carefully guarded against. 



The skins are next removed to a pit containing a weak solution of bark, in which 

 they undergo nearly the same treatment as crop hides, but they are not commonly 

 stratified in the layers. About three months is usually occupied in tanning calf-skins, 

 but of course the stouter the skin the more will be the time required. When dried 

 they are disposed of to the currier, who dresses them for the upper leathers of boots, 

 shoes, and a variety of other purposes. It is not unusual for the lighter cow hides to 

 be treated like calf-skins. 



Horse-hides are also treated like calf-skins ; but as the horse-hide, with the exception 

 of the part on and near the animal's rump, produces a thin leather, it is usual, before 

 subjecting the hide to the action of the bark, to cut out what is called the butt, whicli 

 is tanned separately, and frequently used as an inferior sole leather. It is also to be 

 remarked that horse-hides and kips (the hides of small foreign cattle) are frequently 

 subjected to a process called bate shaving, in which the stout parts are reduced by a 

 currier's knife previous to tanning, the object being to secure the complete infiltration 

 of the animal fibre by the tannin in every part of the hide in the same time. 



Sheepskins are usually pressed after the wool is removed, and before the tanning 

 process is commenced, to get rid of the fatty matter contained in them, and which is 

 not readily removed by ordinary working. 



In all the above processes, as the animal fibres on the surface of the skin absorb 

 most readily the tanning principles, and thereby obstruct, in a certain degree, their 

 passage into the interior fibres, especially of thick hides, it becomes an object of im- 

 portance to contrive some method of overcoming that obstacle, and promoting the 

 penetration of the tan. The first manufacturer who appears to have employed effica- 

 cious mechanical means for favouring the chemical action was Francis G. Spilsbury, 

 who, in April 1823, obtained a patent for the following operation: After the hides 

 are freed from the hairs, &c., in the usual way, they are minutely inspected as to their 

 soundness, and if any holes be found, they are carefully sewed up, so as to be water- 

 tight. Three frames of wood are provided of equal dimensions, fitted to each other, 

 with the edges of the frames held together by screw bolts. A skin about to be tanned 

 is now laid upon the frame, and stretched over its edges, then the second frame is to 

 be placed upon it, so that the edges of the two frames may pinch the skin all round 

 and hold it securely ; another such skin is then stretched over the upper surface of the 

 second frame, in like manner, and a third frame being set upon this, confines the 

 second skin. The three frames are then pinched tightly together by a series of screw 

 bolts, passing through ears set round their outer edges, which fix the skin in a proper 

 manner for being operated upon by the tanning liquor. 



A space has been thus formed between the two skins, into which, when the frames 

 are set upright, the infusion is introduced by means of a pipe from the cistern above, 

 while the air is permitted to escape by a stopcock below. This cock must of course 

 be shut whenever the bag is filled, but the one above is left open to maintain a 

 communication with the liquor cistern, and to allow the hydrostatic pressure 

 to force the liquor through the cutaneous pores by a slow infiltration, and thus 

 to bring the tannin into contact with all the fibres indiscriminately. The action 

 of this pressure is evinced by a constant perspiration on the outer surfaces of the 

 skins. 



When the tanning is completed, the upper stopcock is closed, and the under is 

 opened to run off the liquor. The frames are now removed, the bolts are unscrewed, 

 and the pinched edges of the skins pared off; after which they are to be dried and 

 finished in the usual manner. 



A modification of this ingenious and effectual process was made the subject of a 

 patent, by William Drake, of Bedminster, tanner, in October 1831. The hides, after 

 the usual preparatory processes, are immersed in a weak tan liquor, and by frequent 

 handling or turning over, receive an incipient tanning before being submitted to the 

 infiltration plan. Two hides, as nearly of the same size and shape as possible, are 

 placed grain to grain, when their corresponding edges are sewed firmly together all 

 round by shoemaker's waxed thread, so as to form a bag sufficiently tight to hold tan 

 liquor. This bag must then be suspended by means of loops sewed to its shoulder-end, 

 upon pegs, in such a manner that it may hang within a wooden-barred rack, and be 

 confined laterally into a book form. About an inch of the bag is left unsewed at the 

 upper end, for the purpose of introducing a funnel through which the cold tan liquor 



