TANNING MATERIALS 61 



it was easier to transport the lighter hides to the centers of tannin pro- 

 duction, rather than the heavy barks. 



For several years past it has been customary to use tanning materials 

 containing not less than 8 to 10 per cent of tannin, but a method has been 

 devised whereby chestnut wood which has a very variable content of 

 3 to 1 1 per cent can be utilized. This method consists of extracting the 

 soluble matter from the wood and concentrating the extract in a vacuum 

 to a very dense liquid or dry powder. This extract may contain, as a 

 result of this process, as much as 30 to 70 per cent of tannin. 



With the exception of this wood and quebracho, tannin is a prod- 

 uct found chiefly in the portions of a tree which are of little com- 

 mercial importance otherwise, namely: in the bark, portions of the 

 roots, the heartwood (only in case of quebracho and chestnut), the 

 husk of the fruit and in a few other cases in the leaves and twigs. 

 The tannins found in the various sources are not precisely the same 

 in their chemical constituents. Two acids are formed, namely; gallic 

 and pyrogallic. 



At the present time there are at least 600 consumers of tannin in the 

 United States and aside from foreign materials, they use about 625,000 

 cords of hemlock bark, 290,000 cords of oak bark and 380,000 cords of 

 chestnut wood. 



HISTORICAL 



Records of early civilization indicate that the tanning of leather 

 to preserve it was practiced by the Chinese over 3000 years ago. It is 

 said the Romans tanned their animal skins with oil and alum and occa- 

 sionally with oak bark. The Indians of this country were found using 

 bark to preserve buffalo skins. It is reported that the first tannery 

 erected in this country was built in Virginia in the year 1630 but the 

 industry developed most widely and successfully in Massachusetts. 

 There were 51 tanneries in Xew England in 1650. Oak bark was used 

 principally at first and was generally preferred to hemlock. The abun- 

 dant supply of hemlock, however, brought it into early and prominent 

 use. At this time, there was a strong demand for the export of skins 

 and hides to Europe, and it is said by the year 1810 the value of the 

 product of American tanneries was about $200,000,000. Salem and 

 Peabody in Massachusetts became great centers of industry and Boston 

 became the great leather market of the United States. About 40 to 50 

 years ago. owing to the rapid cutting of available oak and hemlock forests, 

 the center of the production of tanning materials moved toward the 



