BOTANICAL ASPECTS OF PAPER-PULP AND TANNING INDUSTRIES 527 



extract has lost favor in very recent years. The tannin content in the long- 

 dead trees was manufactured 25 to 40 years ago, and after a quarter century 

 or more, without any replenishment, it has deteriorated in industrial use- 

 fulness. In addition, the paper-pulpmaking quality of the spent wood has 

 been lowered, and the remaining stands of dead trees are less accessible than 

 previously harvested material was. For these reasons chestnut lumber is 

 scarcely obtainable ; paper-pulp manufacturers no longer want the wood ; and 

 if they could use it, first extracting the tannin, there would no longer be a 

 market for the by-product. The last commercial extraction of chestnut wood 

 tannin was carried out in February, 1956. 



These latest developments mean that the tanning industry in the United 

 States, as will be shown, is desperately more dependent upon imported stock 

 than ever before, so far as vegetable agents are concerned. And a conspicuous 

 example of integrated industrial plant utilization, feasible as a result of favor- 

 able economic factors and technological development, has been brought to 

 a close by wholly natural forces. 



Foreign materials. At the beginning of the American tanning industry, 

 domestic wages and the consequent price of tannin were sufficiently low so 

 that importation of foreign tanning materials held no attraction. As wages 

 and prices increased, however, and as the requirements of the leather indus- 

 try grew beyond the domestic supply of tannin, a demand for foreign tannins 

 developed. The demand began shortly before the year 1900; by the time of 

 World War II foreign tannins were meeting about 60 per cent of the domestic 

 needs. 



WOOD. The most important of foreign botanical sources has always been 

 the heartwood of quebracho {Schinopsis balansae and 5". lorentzii), forest 

 trees 20 to 40 feet in height, covering some 300,000 square miles along the 

 watercourses and on the plains of central South America, embracing southern 

 Brazil, southeastern Bolivia, Paraguay, and northern Argentina. The name 

 "quebracho," signifying "axe breaker" in Spanish, is applied to several 

 South American trees in allusion to the hardness of their wood. That of 

 Schinopsis is one of the hardest and heaviest known, having a specific gravity 

 of 1.35 and a weight of 75 pounds per cubic foot. It has extensive use for 

 railway ties in Argentina, and in this service is said to resist decay for more 

 than half a century. 



Excepting chestnut, quebracho is the only wood that has been commercially 

 used as a source of tannin. The heartwood contains 20 per cent to 28 per 

 cent, the bark 5 per cent to 15 per cent, but the sapwood only 3.5 per cent. 



The first importation of the wood came to this country in 1897. In 1909 

 quebracho furnished 38 per cent of all tannin extract used in the United 

 States. In the year ending June 30, 1914, it constituted 87 per cent of the 

 total value ($3,864,000) of all tanning agents brought to this country. In the 

 last normal year prior to World War II and during the prewar depression, 



