GAMBOGE.—­This resinous juice, which is a most important article of commerce, is furnished by some of the plants of Gambogia, natives principally of South America.  It is a powerful irritant, and is employed medicinally as a drastic and hydragogue cathartic.  From its bright yellow color it is also used as a pigment.

Gamboge fetches in the London market from L5 to L11 per cwt.

Some of the species of Stalagmites (Murray), natives of Ceylon and the East, yield a similar yellow viscid juice, hardly distinguishable from gamboge, and used for the same purpose by painters.  They are a genus of fine ornamental trees, thriving well in soils partaking of a mixture of loam and peat.

According to Koenig, the juice is collected by breaking off the leaves or young branches.  From the fracture the gamboge exudes in drops, and is therefore called gum gutta.  It is received on leaves, coco-nut shells, earthen pots, or in bamboos; it gradually hardens by age, and is then wrapped up in leaves prior to sale.

The common gamboge of Ceylon is produced by a plant which Dr. Graham was led to view as a species of a new genus under the name of Hebradendron Gambogoides.  A very different species, the Garcinia Gambogia, of Roxburgh, once supposed to produce gamboge, and indeed actually confounded by Linnaeus with the true gamboge tree of Ceylon, he has proved not to produce gamboge at all.

This substance is also obtained from several other plants, as the Mangostana Gambogia (Gaertner), Hypericwm bacciferum and Cayanense, natives of the East Indies, Siam and Ceylon, whence it is imported in small cakes and rolls or cylindrical twisted masses.  Its composition is as follows:  number 1 being an analysis by Professor Christison of a commercial specimen from Ceylon; number 2 of a fine sample of common ditto:—­

                           1 2
  Resin, or fatty acid 78.84 74.8
  Coloring matter 4.03 3.5
  Gum 12.59 16.5
  Residue 4.54 5.2
                         ----- -----
                        100. 100.

The average imports of gamboge into the port of London, during the past five or six years, have been from 400 to 500 chests of one to two cwt. each.

Gentian.—­The yellow gentian root (Gentiana lutea) is the officinal species, and a native of the Alps of Austria and Switzerland.

The stems and roots of G. amarella and campestris, British species, and G. cruciata, purpurea, punctata, &c., are similar in their effects, having tonic, stomachic, and febrifugal properties.  So has G. kurroo of the Himalayas.  The root is generally taken up in autumn, when the plant is a year old.  It is cut longitudinally into pieces of a foot or a foot and a half long.  They are imported into this country in bales from Havre, Marseilles, &c., and a good deal comes from Germany.  In 1839, 470 cwts. were entered for home consumption.