636 UTILIZATION OF BARK AND ITS CONSTITUENTS. 



German galls (on leaves) .... 4 per cent. 



Bark of Q. C err is . . . . . . 4 



Birch 4 



Horse-chestnut . . . . 3*5 ,, 



Ash 3-3 



Beech . . . . 2 



Larch ...... 1*6 ,, 



The contents of tannin in the bark of Pinus halepensis, that 

 is used for tanning, is unknown. 



[Besides the above substances mentioned by Gayer, Mimosa 

 bark from various Australian acacias chiefly (A. harpophylla) 

 from Queensland, the black wattle (A. mollissima), the gold 

 wattle (A Pycnantha), the Tasmanian silver wattle (.4. leuco- 

 phylla) and (A. cyanophylla) is largely imported into the 

 United Kingdom. Sumach, powdered leaves of Rhus coriaria 

 from Mediterranean countries, used for Morocco leather. 

 At Cape Town, the bark of Acacia saligna, a naturalised 

 W. Australian species, is the mainstay of the tanneries. Hem- 

 lock bark (Tsuga canadensis) is the most important tanning 

 material in N. America. Mathey states that Quebracho wood 

 imported into Europe from Argentina tends to oust oak-bark. 

 The Director of the Kew Gardens says that Quebrachia Lorentzii, 

 Griseb. (Anacardiaceae) is " Quebracho Colorado," Quebracho 

 Blanco is Aspidosperuta Quebracho-bianco, Schlecht (Apocy- 

 naceae), but is not used for tanning. The decrease in the 

 annual export of oak-bark from France to the rest of Europe 

 has fallen off since 1893 from 55,000 tons to 40,000 tons, but 

 the extract of chestnut wood from Corsica and French factories 

 besides supplying French tanneries is sufficient to leave 38,000 

 tons over for annual export. Tr.] 



B. Tannin from Young Oak-Bark.* 



Tans prepared from the bark of young oak-trees form the 

 best possible tanning materials. Extensive forest tracts 



* 14 cwt. of Oak-bark, Containing 1 owt. <>)' tannin, are required to convert. 

 into leather 2 cwt. of fresh skins. 2 tons of spruce-bark will produce the same 

 effect. Boppe, />. fit. p. 101). 



Kr. .Jentsch, " Dcr Deutsche Kirlienseh:il\vald u. seine Xukiint't." 



