730 OTHER MINOR PRODUCE FROM TREES. 



of European trees and of other foreign trees yield a brown 

 extract. The husks of the fruits of Rhamnus Frangida and 

 other species yield useful dyes ; the former are imported from 

 Turkey and Persia as Yellow or Persian berries. [From the 

 bark of lihamnus chlorophorus and R. utilis, the Chinese pre- 

 pare a very beautiful green dye called Chinese green indigo, 

 used also for dyeing silks at Lyons, and a similar dye has 

 been extracted from R. catharticus. Tr.] The green chloro- 

 phyll and the red erythrophyll of plants are used but rarely 

 as dyes. The fact, that many vegetable dyes are more per- 

 manent than dyes prepared from coal-tar, alone enables them 

 still to compete with the latter. 



Gums are widespread in the wood of many species, being 

 components of their cell-walls, but only when contained in 

 bark are they of commercial value, as they then exude through 

 wounds in the bark of trees. Gum in the bark is suspended 

 as latex in the sap. 



[The chief kinds of gum* are gum-arabic, gum-tragacanth, 

 gum-resins, copals, oleo-resins, and elastic gums. It is of 

 great importance that the gums collected from different species 

 should not be mixed, and that they should be free from bark, 

 earth and other impurities. 



Gum-arabic is a clear, white or yellowish gum, very soluble 

 in water ; it is produced by Acacia Senegal of N. Africa and 

 also growing in Sind, the Punjab and Kajputana. Other 

 acacias yield inferior gums, and so does Bauhinia retusa, a 

 small tree of N. India, and many others, including the cherry- 

 tree and other species of Prunus, the gum being of pathological 

 origin. These gums are used in calico-printing, in medicine, 

 in giving lustre to silk and for many other purposes. 



Gum-tragacanth is insoluble in water, but swells up ; it is 

 produced by species of Astragalus and Stcrculia. Gum-resins 

 are partially soluble in water, and a type of these is gamboge, 

 the produce of Garcinia Morella, a tree of Eastern India and 

 Ceylon. A thin slice of bark is cut off of the size of the palm 

 of one's hand, the gamboge collects there and is scraped off, 

 when sufficiently dried. Gum-kino, a bright red, astringent 



* "Indian Forest Utilization," R. S. Troup, Supt. of Govt. Printing, Calcutta, 

 1907. 



