78 farmers' and mechanics' journal. 



ed it becomes liquid, the water is driven off, and it is thus procured 

 in a state of purity. 



When gelatin is put into cold water, it softens and swells, but is 

 not dissolved ; it is not necessary to heat it, by which a solution \s 

 formed, differing in consistence according to its strength. By far 

 the most important action of gelatin, is with the astringent matter 

 of vegetables. When an infusion of nutgalls, oak bark, or willow 

 bark, is added to the solution of gelatin, a powder is precipitated, 

 or if the solution be strong, a tough matter is formed, which is a 

 compound of the vegetable and animal principles, and which be- 

 comes hard on being kept, (^^n this depends the art o[ tanning, or 

 the making of leather, which is merely the union of the astringent 

 matter m vegetables, with the gelatinous principle existing in the 

 skins, by which they are gradually converted to a substance inso- 

 luble in water, and not liable to undergo decay. 



The previous steps, in preparing skins for converting them into 

 leather, consist in removing the hair, fat, and other impurities, 

 after which they are subjected to different processes, according to 

 their nature, and the kind of leather required, as tanning, or caus- 

 ing them to unite with astringent vegetable matter, tawing, or 

 making them imi)ibe alum and olher salts, with some animal sub- 

 stance, and currying, or soaking them in oil to make the leather 

 soft, and impervious to water. These processes are often perform- 

 ed on the same skin, by which the leather is fitted for more pur- 

 poses. The thick hides of which the soles of shoes are made, 

 are merely tanned, while the white kid glove leather is tawed. 

 That for the upper leather of boots and shoes, is both tanned and 

 curried, and the fine Turkey leather is first tawed, and afterwards 

 tanned. 



AVhen the skin is to be tanned, it is allowed to lie in water for a 

 day or two, to remove any dirt, and to wash out the blood, after 

 which it is laid on a round piece of stone or wood, called a beam, 

 and deprived of the fat and flesh. It is then put into a pit with lime- 

 water, and allowed to remain there for some days, by which the 

 hair is loosened, and is easily removed, by placing it on the beam, 

 and scraping it with a blunt knife. As the lime employed in this 

 part of the process hardens the skin, it is necessary again to soften 

 it. For this purpose, it is put in what is called the mastering pit, 

 which contains water and dung, chiefly of pigeons or fowls, where 

 it continues for some days, the time depending on the thickness of 

 the hide. Great care must, however, be taken, not to allow it to 

 remain too long, otherwise, owing to putrefaction, its texture is 

 completely destroyed, so that it is torn by the slightest effort. 

 After this, it is again cleaned on the beam. 



When the skins are very thick, they are sometimes submitted to 

 another process. After being deprived of the dirt and blood by 

 washing, a number of them are heaped together in a warm place, 

 so as to c\ e a slight putrefaction, after which the hair is remov- 

 ed, in general without immersing them in the lime pit, as this 

 would harden them too much, and render the leather liable to 



