GALLS, or GAta.-NuTs, are of various shapes, hut the oak galls chiefly used in com merce are nearly globular, with'slightly pointed excrescences sparingly placed on their surface. They are remarkable for containing a peculiar acid called gallic, which is only an altered condition of tannic acid, and their value is entirely due to the great accumu lation of this principle in the diseased condition of the vegetable tissue 'which constitutes the gall. This gallic acid (q.v.) is easily separated in the form of beautiful white acicu lar crystals, which, after a little exposure, become pale yellow. It is in extensive demand as a fixing agent for photographic pictures. Until this demand was created, , only three or four kindsof G. were known in commerce, and these were almost wholly employed for dyeing purposes, a small quantity of the common Turkish G. being also used medicinally; now, several others arc imported in considerable quantities. The fol lowingare the chief: 1. The Turkish .G., of two kinds, blue and white; these are by far the most com mon in use. They are chiefly imported from Constantinople and' .Strtyrna, from which.
places the average annual imports amount to 300 tons—an enormous quantity when we consider how they arc produced, and the industry necessary to collect so vast a quan tity. They are each about the size of a round nutmeg, and the which are the best, are entire, being gathered before the escape of the insect: The so called white G. are of a yellowish-brown color, and each is perforated with a small round hole, about the sixteenth of an inch in diameter, whence the insect has escaped. These G. are produced by a species of cynips (C. quercus-galli) on the dyer's oak (quercus Wee toria), a native of Asia Minor, from the Bosphorus to Syria, and from the Grecian archi pelago to the frontiers of Persia. Of this kind of gall, several varieties are known in commerce, as the Aleppo G. the Syrian or Mosul G., which are the best known; the Tripoli Taraplus or Tarablous G., obtained from Constantinople, and the Smyrna galls.
2. The small Aleppo or coriander gall, which is generally about the size of a large pea. They are always perforated or empty G., and are of a brownish-yellow color, round, and with small blunt spines. The quantity used in this country is not very large.
3. The large Bassorab, Bnssorah, or Mecca G., which are the largest G. known in commerce; they areas large as an Orleans plum, smooth, except a ring of curious slightly raised excrescences sometimes foundiround the middle, dividing the gall into two hemi spheres. They are reddish brown, and are said, when on the trees (quercus infectorta), to be colored as brightly as apples. These are the apples of Sodom. or the Dead sea
apples. bright to the eye, but filled with a gritty astringent matter, which is likened to ashes; it is formed on the quercus infectoria by egnips insana. These are not extensively imported.
4. The acorn gall, Knoppern, Knobben, Hungarian, or German gall. This is found chiefly in Hungary, and is much used by the German dyers; it is also occasionally used in this country. It is a curious irregular-shaped brown gall, deeply furrowed, and cov ered with angular excrescences. It is produced on the common oak (quercus penduncu lata) by cynips quercus calycis.
5. The small East Indian G. called Mabee, and Sumrut-ool-toorfa, are obtained from the Indian tamarisk (tamarir Indica). They are very small, about the size and color of tares, and are so rough and irregular in form, that they look rather like little lumps of dried garden soil.
6. The Chinese G., or woo-pei-tsze. These very curious vegetable excrescences were regarded only as curiosities some years since, but they now form regular articles of com merce. They are of a very irregular shape, branching out sometimes like fingers. Their length seldom exceeds 2 in.; they are vilely more than I in. in diameter at the base, where they spring from the tree, but they spread out as much sometimes as Li to 2 inches. When broken, they•are found to consist of a thin shell, not thicker than a walnut shell, of a dark-yellowish or reddish-brown color internally, and semi-trans parent; hut externally they are covered with very fine down, and consequently look like the young horns of a stag when just budding. They are produced on the rites semi (data (see SumAen), by an insect not yet known to science. Since the Japanese ports have been opened to British commerce, considerable imports of these curious G. have been received from that country. They are rather more branched, the branches or lobes being smaller than in the Chinese variety, but in all other respects they are iden tical.
A very great many G. are known in most parts of the world, and in our own country the oaks yield numerous species, but those above enumerated are the G. of commerce: few others have. ever been found to 'pay the expense of collecting. G. are extensively used in dyeing, chiefly for the production of black colors, with logwood and the salts of iron, either for dyeing in the piece, or printing patterns; in each case, the material is first submitted to the action of a solution of the G., and afterwards to another of the dye-wood and iron salt. They are also an important constituent in writ ing ink (see INK), and are used in tanning the finer kinds of fancy leathers.