Fig. 8 shows a mill for grinding sumach-leaves; it consists of a heavy solid circular wooden bed _a_, 15 ft. diam., with a depression around the edge _b_, a few inches deep and 1 ft. wide, for the reception of the ground sumach from the bed, and 2 edge-rollers _c_, weighing about 2500 lb. each, 5-6 ft. diam., and provided with numerous teeth of iron or wood, thickly inserted. Most mills have to be stopped to allow the unloading of the bed, but this delay is obviated by an apparatus consisting of an angular arm _d_, attached to a scraper _e_, and worked by a lever _f_, which passes through the hollow shaft _g_ and extends to the room above, where it terminates in a handle _h_. The scraper carries the ground sumach to the opening _i_, whence it is taken by an elevator to a revolving sieve or screen in a room above. After screening, the sumach is packed in bags, 15 to the ton, being always sold by that weight. The chasers and beds are inclosed in a case or drum, and the grinding is done by the application of power to the upright shaft _g_. The mills are fed from above. The packing is sometimes done by machinery alone. The best mills cost about 600_l._ In Europe, and in some parts of the Southern States, sumach is still ground by stones revolving on a stone bed, and the sifting is often done by hand. E. Coez & Co., St. Denis, near Paris, make a sumach extract. It is concentrated to a syrupy consistence in a vacuum-pan, and keeps well, exhibiting none of the acidity which is manifested by a simple decoction of sumach leaves. Sumach contains 16-24 per cent. of gallotannic acid, and is somewhat similar in tanning properties to myrobalans, but paler in colour. It is principally used for tanning morocco and other fancy leathers. The district of Ancona yields 200 tons per annum of sumach, said to be equal to and cheaper than the Sicilian, but mostly consumed locally. Palermo exported of "ventilated" sumach to the United States 120,043 bags (14 = 1 ton) in 1877, and 50,085 in 1878, the average value being 14_l._ a ton. Trieste exported 7800 cwt. by land in 1877; in 1878, the shipments to England were 16,600 _kilo._ (of 2·2 lb.), value 1328 fl. (of 2_s._), and in 1880, 91,800 _kilo._ 7344 fl. Rustchuk in 1880 exported 1400 tons, chiefly to Roumania and Austria. Our imports in 1880 were 10,573 tons, 133,249_l._ from Italy, and 1047 tons, 12,416_l._, from other countries; total, 11,620 tons, 145,665_l._ The approximate London market value is 15_s._-16_s._ 6_d._ a cwt. for Sicilian, 10-11_s._ for Spanish.