THE SCIENTIFIC ASPECTS OF TANNING. 89 



The high price of most tanning agents is stimulating the search 

 for other and new forms in which it may be found. Three or 

 four new materials have been discovered, such as Bran or African 

 Bark, which will retire into obscurity as the price of Valonia 

 lowers. Another is a small gall-nut of the Tamarix tribe, growing 

 in Morocco and India, giving 40 per cent, tannin. Remark- 

 able for its purity, larger quantities will, we hope, be produced as 

 its value becomes known. Another, — the pod of a leguminous 

 plant, called "Balsamic Carbon,'" — has this peculiarity^ that it is 

 a tanning gum of great strength. When pure the bean yields 80 

 per cent, of tannic acid. Efforts are being made to cultivate it 

 largely in climates suitable, as in South America. The heavy 

 showers dissolve the fruit, which is found in masses at the roots 

 of the plant. 



Having thus glanced at the tanning materials, we next come to 

 the '' Process of Tanning."^ First, the raising and swelling of the 

 hide J secondly, the tanning proper. ; 



Hydrate of lime is generally the agent by which the hide is 

 swollen in substance, so as to to affect two purposes, namely, 

 removing all grease and albumen, and separate the cuticle from the 

 corium, which also removes the hair. When the skin is thus 

 distended, after a little washing in water, it is ready for the tanning 

 process. 



Lime from time immemorial has been employed for the purpose, 

 and notwithstanding our better knowledge of alkalies than our 

 forefathers, lime still holds its ground. Compounds of soda and 

 potash have been tried with varying success. The rapid action of 

 both, combined with their costHness, prevent their adoption. 

 With the use of all alkaline solutions must ever arise the question, 

 how to prevent so great a destruction of the gelatinous constituents 

 of the pelt ? The quantity which is lost yearly in the form of 

 ammonia, from all the tanyards in Bristol, would represent a large 

 amount. We read in old treatises on tanning that our pred« 



