into a tough, flexible, and quite white leather; but to give them a 

 glossy finish, and to take off the harshness of the feel still remain- 

 ing, they are again soaked in water and put into a large pail 

 containing the yolks of eggs beat with water. Here the skins are 

 trodden for a long time, by which they so imbibe the substance of 

 the egg that the liquor above them is rendered almost perfectly 

 limpid, after which they are hung up in a lott to dry, and finished 

 by glossing, with a warm iron. 



The essential difference, therefore, between tanning and tawing 

 is, that in the former case the pelt is combined with tan and 

 other vegetable matter, and in the latter with something that it 

 imbibes from the alum and salt (possibly alumine), and which is 

 never again extracted by the subsequent washing and branning. 



The Morocco leather, as it is called, prepared from sheepskins 

 chiefly, and used so largely for coach-lining, pocketbooks, and the 

 best kind of book-binding, is thus made: the skin, cleansed and 

 worked in the way already described, is taken from the lime-water, 

 and the thickening brought down, not by bran liquor as in tawing, 

 but by a bath of dogs' or pigeons' dung diffused in water, where it 

 remains till suppled, and till the lime is quite got out and it becomes 

 a perfectly white clean pelt. If intended to be dyed red it is then 

 sewed up very tight in the form of a sack with the grain side out- 

 wards, and is immersed in a cochineal bath of a warmth just equal 

 to what the hand can support, and is worked about for a sufficient 

 time till it is uniformly dyed. The sack is then put into a large vat 

 containing sumach infused in warm water, and kept for some hours 

 till it is sufficiently tanned. 



The skins intended to be black, or any colour but red, are merely 

 sumached without any previous dyeing. After some further prepa- 

 ration, the colour of the red skins being finished with a weak bath 

 of saffron, the skins when dry are grained and polished in the follow- 

 ing way; they are stretched very tight upon a smooth inclined 

 board, and rubbed over with a little oil. Those intended for black 

 leather are previously rubbed over with an iron liquor, which uniting 

 with the gallic acid of the sumach, instantly strikes a deep and 

 uniform black. They are then rubbed by hand with a ball of glass 

 with much manual labour, which polishes them and makes them 

 very firm and compact. Lastly, the graining or ribbed surface 

 by which this kind of leather is distinguished is given by rubbing 

 the leather very strongly with a ball of box-wood, round the centre 

 of which a number of small equidistant parallel grooves are cut. 



S5 



