GENEKAL ACCOUNT. 485 



Southern Europe, especially the southern provinces of Austria- 

 Hungary, produce certain tanning substances, which are not only 

 locally important, but are exported to other countries ; these are 

 Knoppem-galls, Galls, and Sumach. Knoppem-galls are rough 

 excrescences on acorns of the pedunculate oak, produced by 

 various gall-wasps, chiefly Cynips calycis, Burgod. Galls are 

 more or less round and smooth growths on the twigs and 

 petioles of several species of oak, caused by Cynips r/allae 

 tinctoriac, L. Those from southern countries, such as Aleppo, 

 Turkey, and the Levant, are superior to those from Istria on 

 Quei'CKs Cerris ; Hungarian galls are the worst, and those 

 appearing on the leaves of oaks in Northern Europe have no 

 commercial value. 



[Except the knoppern-galls, galls are too valuable to be used for 

 tanniiif^, containing much gallic acid used for ink and dyes. — Tr.] 



Venetian sumacli is a tanning material prepared from the 

 leaves, young twigs, and bark of the wig-tree {liJiiis Cotinus, L.), 

 which grows abundantly in Transylvania, Hungary, Dalmatia, 

 Venice, South Tyrol, &c., often as coppice, and is cut annually, 

 dried, and ground into tan.* Sicilian sumach is similarly prepared 

 from Rhus Coriaria, pollards of which are grown in Sicily. 



For the quantity of tannic acid in these various substances, 

 special works + should be consulted, the only source of interest 

 here being young oak-bark. The amount of tannic acid this 

 contains varies considerably with the locality, age, mode of 

 growth, &c., and in commercial oak-bark, the extreme limits of 

 the contained tannic acid are 6 and 20 %.t 



From the numerous analyses w^hich have been made of oak- 

 bark from the provinces of South Germany and Austria-Hungary, 

 the best kinds of young bark contain 15 — 20 7o of tannic acid ; 

 middling kinds, 10—15 % ; old bark, 8—10 7„ ; in North 

 Germany, oak-bark gives an average of Gg — 10 7o> ^^^ spruce- 

 bark 6 — 8 7o- "Tlie tanner, however, does not attach much im- 

 portance to analyses of bark, but trusts to appearance, taste, and 



* Ehus Cotiaus also grows in the Himalayas, its wood termed yellow-wood, or 

 false Brazil-wood, is used commercially as a yellow dye. 



+ [Encyc. Brit. Xiiitli edition. Vol. XIV. " Leather."— Tr.] 

 :;: The results of numerous analyses of oak-bark, from the Bavarian Palatinate, 

 are given in the reports of experimental stations of the Bavarian Agiicultural 

 Society, 1861, Vol. 3. Also Theo. Hartig, Gerbstotf der Eiche, 1869. 



