ASTRINGENTS.

501

The nuts, when bought whole, are often found mixed with earth, sand,mica, nux vomica, betel-nuts, &c.

Ground myrobalans are sometimes contaminated with divi-divi, spoiledSumac, and wild galls. To dete# such impurities a little of the powder isthinly sprinkled over a sheet of white paper, and examined with a lens. Ifdivi-divi has been added, fragments of its bright brown flat seeds are sure tobe found. The outer skin of a myrobalan may occasionally resemble a divi-seed in colour, but the minutest portion of the former shows a wrinkledsurface, whilst divi-seeds are smooth. The leaf-stalks and midribs of sumacmay also be distinguished, by the aid of a lens, from the torn and jagged fibreof the myrobalan.

Myrobalans, being cheaper than galls and stronger than sumac, have, to avery great extent, superseded both. Along with salts of iron, they dye cottona fuller black than can be obtained with sumac. They are likewise preferredto sumac for fixing the coal-tar colours upon cotton, owing possibly to the fa#that they contain, along with tannin, certain oily and glutinous matters.Gall-nuts and commercial tannin are, however, still preferable.

M. Muratore, of Algeria, has recently made a series of experiments withthe leaves and fruit of Pistacia lentiscus , a tree found in various parts ofAfrica. He finds that the deco&ion gives, with salts of iron, good solid blacksupon cotton, similar to those produced by gall-nuts. With other mordants,salts, and acids, a variety of shades are obtained. The astringent principle isfound also in the twigs and wood, though less abundantly than in the leavesand fruit. As to the economy of the lentiscus extra#, as compared with otherastringents, details are still wanting.

Sumac, known also as sumach and shumach, consists of the ground leaves,foot-stalks, and young twigs of several varieties of plants, technically knownas sumacs, but botanically belonging to the genus Rhus, of the family of theTerebinthaceas. The sumac of commerce is chiefly obtained from the Rhuscoriaria in the following manner:—A short time before the blooming of theplant, in June or July, the younger twigs are cut off, dried in the sun, nextbeaten, so as to detach the leaves and flower panicles, which are next coarselyground up by means of mill-stones. The shrub just named is a native ofAsia, but is cultivated in many parts of Europe, more especially in Sicily,Spain, Southern France, and Hungary.

in the South of France a peculiar kind of sumac is prepared, and knownlocally as redout or redou. It is derived from the Coriaria myrtifolia , ortanner’s herb, which, according to the researches of M. Ribau, contains aviolently poisonous substance known as coriamyrtin.

The leaves of the Arbutus Uva-Ursi , better known in pharmacy than intechnology, are used as sumac in Dalecarlia (Sweden).

The following are the chief varieties of sumac known in the trade :—

Sicilian Sumac. —The most esteemed article, fetching always a high priceSpanish Sumacs. —Exported from Malaga, Priego, or Molina-Valladolid.Portuguese Sumacs. —From Oporto.

Italian Siwiacs.

Prench Sumacs.

The articles are classified here according to their amount of tannin.