28 



AMERICAN HOMES AND GARDENS 



January, 1910 



Two views of the pergola of Mr. Rhoade's fiouse with its vines showing the purpose for which they are intended 



The Quebracho Tree of South America 



THE quebracho is a tree of South America (Argentine 

 Republic), where it forms entire forests, but never- 

 theless has been, until now, almost completely un- 

 known. Its use is now beginning to spread among tan- 

 neries, and for two reasons: First, its high content of 

 tannin, which amounts to 18 to 20 per 100 pounds weight 

 of wood and bark; second, the discovery of chemical 

 methods of treating the extracts, which facilitate the em- 

 ployment thereof. It was a German tanner of Buenos 

 Ayres who was the first to find that extracts of quebracho 

 wood were able to tan hides; but the first sample of the 

 wood was carried into Europe bv way of Havre in April, 

 1875, by Dubosc, who undertook the industrial manufac- 

 ture of the extract. The employment of the extract de- 

 veloped difficulties consequent upon the peculiar property 

 of the tannin. When one extracts the tannin from the bark 

 by boiling water, the solution deposits on cooling the insolu- 

 ble tannin, while there remain in solution soluble tannins 

 and the glucosides, or non-tannins. These three compon- 

 ents operate during the tanning, the soluble tannins com- 

 bining with the fundamental substance of the skin, the non- 

 tannin fermenting and giving the acids, which are neces- 

 sary for "plumping" the hides, and which facilitate the 

 absorption of the tannin; the insoluble tannins finally pene- 



trate uniformly into the pores and render the hide imper- 

 meable. The quebracho is composed of 20 parts of soluble 

 tannins in 100 parts, and only 2.5 of non-tannins per 100, 

 while it does not contain any glucosides; it is therefore not 

 able to furnish enough acid by fermentation. But if one 

 adds thereto acid liquors resulting from other extracts, 

 there is produced a precipitation of soluble tannin, which 

 renders the tannin process very difficult. 



Attempts have been made from the first to eliminate the 

 insoluble tannins by addition of lead acetate, alum, albu- 

 men, etc., and to thus obtain a clarified and decolorized ex- 

 tract, but these attempts have not solved the problem. After 

 that endeavors were made to render the insoluble tannins 

 soluble; two Italian chemists, Leptit and Tagliani, found 

 that by a treatment with alkaline bisulphites, the non-soluble 

 compounds were able to remain In solution and also In the 

 acid liquors. This process, patented in all countries, has 

 made feasible the universal employment of quebracho. In 

 the United States there was employed In 1901 not more 

 than 5,000 tons of extracts; In 1907, six years after the 

 discovery of the bisulphite process, 50,000 tons were con- 

 sumed, in 1909, 70,000 tons. The extraction Is effected 

 /'// situ; on the Parana River is found a plant producing 

 50,000 tons per year. 



