in manufacturino; leather for some particular uses, the employment 

 of lime is carefully avoided. Hides may, indeed, be cleansed by 

 subjecting them to an incipient fermentation, which may be pro- 

 duced in a variety of ways. But in whatever manner the first 

 part of the operation has been conducted, as soon as it is perceived 

 that the hair is in a fit state to be removed, it is scraped oft, on a 

 wooden horse, by means of a crooked knife, which is not so sharp 

 in any part of its edge as to injure the hide, or, by a whetstone. 

 This operation is not only intended to remove the hair, but like- 

 wise the scurf and filth which collects on the skin at the root of the 

 hair. 



After removing the hair and filth, the next object is to free the 

 hides from the adhesion of any part of the muscle, or fat, and to 

 render them soft and pliant. Those which are intended for par- 

 ticular kinds of work, such as calves' skins for the upper leather of 

 shoes, and neats' leather for shoulder-belts, do not require to be 

 raised or swelled. As soon, therefore, as they are cleansed and 

 freed from the flesh, &c. they are laid in a pit. The hides intended 

 for the soles of shoes, and other strong leathers, are afterwards 

 raised by means of processes which vary in different countries. 

 When lime is employed, the operation is commenced by putting 

 the cleansed skins into the weakest of the lime pits, and another 

 in the strongest. During this operation care is taken to withdraw 

 them, and pile them up in a heap, every two or three days, putting 

 them again into the pit after it has been well stirred. Lime hardens 

 the skin, and in those tanneries where it is used, the hides are put 

 into a ley of pigeons' dung in order to soften them, and this process 

 is termed graining. They are daily withdrawn from the ley, and 

 laid up in a heap for half an hour. This operation is usually con- 

 tinued for ten or fifteen days. Sometimes also acid compositions 

 are employed for raising the hides; and this operation is greatly 

 accelerated by using the acids warm, as well as by the method prac- 

 tised in this country, of removing them from a weaker liquor into 

 a stronger, until they be properly raised or swelled. 



The skin being thus prepared, is next subjected to the operation 

 of tanning; and to this purpose vegetable astringents are employed. 

 Those vegetables answer best which contain the greatest portion 

 of the astringent principle, now known under the name of tannin. 

 Mr. Davy has demonstrated that caoutchouc or Japan earth, 

 contains more of this principle than any other vegetable with 

 which we are acquainted, but oak bark is the substance most 

 commonly employed in our climates; for it is not only very abun- 



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