BOTANICAL ASPECTS OF PAPER-PULP AND TANNING INDUSTRIES 53 1 



land, England, and Canada; and by 1892 there was production of a semi-solid, 

 48 per cent tannic acid, extract at Deming, New Mexico, more than two 

 million pounds of which was sold on American markets. 



In more recent years extensive investigations have been pursued * regarding 

 the agronomy and processing of canaigre, but whether commercial production 

 of tannin from the roots is feasible is still unknown. Problems of production, 

 harvesting, and extraction must still be solved. 



Perhaps more promising as a native source of tannin is the abundant growth 

 of wild sumac in the United States, especially the three species, dwarf or 

 winged {Rhus copallina), smooth {R. glabra) and staghorn {R. typhina). 

 Sicilian sumac {R. coriaria) of southern Italy, as already mentioned, has 

 long been important in southern Europe and has been imported into the 

 United States except for interruption in wartime. American tanners have pre- 

 ferred it to native species, but proper procedures in harvesting and drying 

 the domestic growth allegedly produce tannin satisfactory in both yield and 

 ciuality. Up to 1920 considerable quantities of the native leaves were harvested 

 each year in Virginia and manufactured into extract for dyeing as well as 

 tanning. Accurate data on the sources and amounts harvested are not avail- 

 able, but it has been reported that in 1933 sumac dealers purchased more 

 than 640 tons of domestic sumac and that from 1937 to 1944, consumption of 

 the leaves by five leading manufacturers of extract averaged 1,100 short tons 

 annually. 



Several investigations of this domestic source have been conducted, the 

 latest of which concluded that: 



a. Of the eight species growing wild in the eastern and southern parts of 

 the United States, Rhus copallina, R. glabra, and R. typhina are the most 

 promising for commercial development and that R. trilobata might prove of 

 value under certain circumstances. The remaining four species {R. aromatica, 

 R. lanceolata, R. microphylla, R. virens) have certain objectionable features. 



b. Tannin from any of the species except R. aromatica and R. virens 

 seemingly would produce leather of satisfactory color. 



c. The average tannin content of moisture-free leaves of all the species 

 varied from 19.32 to 39.14 per cent. 



d. Tannin content in some cases varies according to sex, shading, and 

 height of the plants. 



e. Over an area of about 12,000 square miles in southern Virginia alone, 

 approximately 43,000 long tons of dry sumac leaves would be available 

 annually. 



* By the Eastern Regional Research Laboratory of the Bureau of Agricultural 

 and Industrial Chemistry of the U.S. Department of Agriculture and by the Di- 

 vision of Drug and Related Plants. 



