TANNlNe. «» 



pulled off. They arc next put into a pit of lime-water, and kept 

 there for some weeks, acconhng to their size, by which the putre- 

 faction is stoi)()ed, and they become much thicker and harder ; and 

 after beini>; deprived of the superfluous matter, by scraping them 

 on the beam, they are placed in a mixture of bran and water, in 

 which they remain for some weeks being occasionally scraped. 

 By these processes, the whole of the lime and slimy matter is re- 

 moved, and the skin is fit for tawing, in which state it is called a 

 pelt. 



Tawing consists mi soaking the !)eUs in a warm solution of alum 

 and common salt, by which they become thick and tough. They 

 are then, after being washed, put into a vat with bran and water, 

 asid allowed to ferment for a short time, so as to remove a great 

 deal of the alum and salt, after which they are stretched on frames, 

 and kept in a heated room to dry. 



By these means, a thin white leather is procured, which is nriade 

 smooth and glossy, by soaking it in water, containing the white of 

 eggs. It is then dried in a heated room, and the gloss given to it 

 by smoothing it with a hot iron. 



In the process of tawing, it is supposed that the skin imbibes 

 something from the saline matter probably aliimine, by which it is 

 converted into leather ; this combining with the substance of the 

 skin, in the same way as tlie astringent matter does in tanning. 



When the leather is to be dyed, as in preparing black morocco, 

 after being tawed, it is soaked in a solution o^ sumach. It is then 

 rubbed over with a solution of green vitriol, by which it becomes 

 black, the same action taking place, as in the preparation of ink ; 

 and after this, it is polished by glazing it with a glass ball, or, if re- 

 quired to have the ribbed appearance of morocco, by using one of 

 boxwood, round which a number of small grooves are cut, and by 

 which the roughness is communicated to the leather. 



Currxjiiig consists in soaking leather in some oily substance, by 

 which it is made more impervious to water. F'or this purpose, 

 the hides, after being tanned, are soaked in water, and then thinned 

 by scraping them with a knife, after which they are rubbed with a 

 polished stone, and well besmeared with oil, or oil and tallow. 

 They are next hung in a rcom to allow the moisture to escape, 

 and the oil to penetrate them thorougiily, being afterwards dried, 

 eithei' in sunshine or by exposures to he;>t. 



Sharaoij leather is merely sheep or doc's skin, prepared as al- 

 ready described, that is, tanned, and then subjected to the process 

 of currying. 



It is of the utmost consequence for tanners, and others using 

 astringent matter, to be able to judge of the quantity of tannin in 

 any article exposed for sale, particularly as it varies so much in 

 ditFerent samples of the same.stdjstance. owing partly to the age of 

 the vegetable, and to adulteration. Diifeient methods have been 

 recommended, but by far the best, is just that followed by tanners, 

 but conducted in such a way as to be quickly finished. It is well 

 known that skins will continue to imbibe the astringent principle 



