The balsam ie a light-brown, viecid or fluid resin, gradually hardening to brittlenesa, but readily softened by warmth ; of ep. gr. 1.2, agreeable odour, and alight aromatic flavour. It is soluble in alcohol and chloroform completely, and in ether partially ; but is very slightly dissolved by eseential oils and carbon bisulphide, whence the detection of such adulterants as rosin ie rendered easy. The use of liquid etorax (see p. 1682) as an adulterant is eaid to occur in the United States, It is employed allghtly in medicine, but more in perfumery. Its London market value is about 3-4s. a lb. It is exported from Colombian (New Granada) porta:—The shipments from Santa Marta were 2002 lb. in 1870, 2183 in 1871, and 1206 in 1872 ; and from Savanilla, 27,180 kilo. in 1876.
the term " tragacanth " in a generic sense, the species to be described are :—(1) Tregacanth proper, (2) Indian traga.canth, or kuteera, (3) African tregacanth, (4) Hog tragacanth, or simply " hog gum," which must be disting-uished from the gura bearing the same nanie described on p. 1051.
1. Traga, a uth proper (Fa., Adragante ; GER., Traganth).—True tragacanth is a gummy exudation afforded by the stems of several species of Astragalus, of which the principal are the following:— A. gummifer, occurring on Lebanon and Hermon in Syria, Beryt Dagh in Catalonia, Arjish Dagb (Argteus) in Central Asia Minor, and in Armenia and N. Kurdistan : A. microcephalus, extending from S.-W. Asia Minor to Turkish and Russian Armenia ; A. adecendens, a native of the mountains of S.-W. Persia at 9000-10,000 ft. ; A. brachycalyx, on the mountains of Persian Kurdistau ; A. pycnoclado,, on the high mountains of Avroman and Stahn, Persia; A. kurdicus, on the mountains of Cilicia and Cappadocia, extending thence into Kurdistan ; A. stromatodes, at 5000 ft. on the Akker Dagh range, N. Syria; A. vents, in N.-W. Persia and Asia Minor ; A. Parnassi, var. cylleneus, on the northern mountaina of the Mores ; and A. leioclados.
The mode of secretion of tragacanth has been discussed under the generalities commencing this article (see p. 1620). Reference must here be made to Giraud's researches, quoted in the Bibliography at p. 1695, which throw quite a new light upon the subject ; according to his analysis, tragacanth contains only 8-10 per cent. of soluble gum, and about 60 of pectinous prineiple, apparently identical with Fremy's pectose. The collection of the gum in Asia Minor and Armenia. is described Ity Tozer, Maltase, Hamilton, Von Scherzer, and others. The principal localities for it are the district of Angora ; Isbarta, Buldur, and Yalavatz, north of the Gulf of Adalia ; the Ali Dagh range between Tarsous and Kaisarieh, and the hilly country eaatward as far as the Euphrates valley ; the elevated Bingol Dagh range, aouth of Erzeroum ; and throughout Kurdistan, from Mush for 500 miles in a S.-E. direction to the Persian province of Luristan. About
the first week in August, the gum is seen adhering to the stems and branches, looking from a distance almost like down, but later in the season it usually has fallen off, so that the ground below is strewn with it. The common way of obtaining it, however, is to cut the plant and leave it to bleed ; after some days, when the gum has exuded and hardened, the oolleetors return and gather it. The ground is often swept cleau to receive the droppiugs. The incisions are sometimes cute made into the hark, soinetimes simply punctures with a knife-point. lu Persia, the production of the gum is spread over an area of 300 miles long by 100-150 broad, between Gilpaigon and Kashan, southward to the Mahomed Suma range, N.-E. of Shiraz. The tragaeanth collected in Persia and Kurdistan is inostly of spontaneous exudation.
The eonuposition of tragacanth has already been stated. The best samples are dull-white, translucent, lustreless, flexible, strong, odourless, and almost flavourless. It oceurs in two prin cipal forms, distinguished as " leaf " and " vermicelli." The latter consists of vermiform pieces ; the former, of flattish stripe, 1-3 in. long and .1-1 in. wide. Immersed in water, it swells up and finally disintegrates. It is readily aoluhle in alkaline liquids. Its chief use is for im parting firmnesa to lozenges and pill-masses, and in other pharmaceutical preparations ; the oommoner kinds are employed in a mucilage for " marbling" books. The approximate London market values are 10-201. a cwt. for leaf, and 2-101. for low to good sorts, the price depeuding upon the purity and whiteness. One of the chief export marts is Smyrna, whither it is brought from the interior (Kaisarieh, Konieb, &e.) in s. very erude state in bags of about 2 quintals, in August, and where it is largely assorted by Spanish Jews for the European market. The annual export from Smyrna is stated at about 4500 quintals (of 100 lb.), value 65,0001. It is also shipped from Conatantinople and the Persian Gulf. The Persian and Kurdistan article is de,spat,ched from Bagdad, which sent 555 ewt., yalue 2259/., to India and Europe in 1878. This article is erroneously terraed " Syrian " in English drug sales. Mersine [Musyna] exported 245 tons, value 31,8001., in 1880.