Adulteration—The Cambojans adulterate gamboge with rice flour, sand, or the pulverized bark of the tree,[353] which substances may be easily detected in the residue left after exhausting the drug successively by spirit of wine and cold water.
Other Sources of Gamboge—Although the gamboge of European commerce appears to be exclusively derived from the form of the plant named at the head of this article, Garcinia travancorica Beddome, is capable of yielding a similar drug which may be collected to some small extent for local use, but not for exportation. It is a beautiful tree of the southern forests of Travancore and the Tinnevelly Ghats (3,000 to 4,500 feet). According to its discoverer Lieut. Beddome,[354] it yields an abundance of bright yellow gamboge.
OLEUM GARCINIÆ.
Concrete Oil of Mangosteen, Kokum Butter.
Botanical Origin.—Garcinia indica Choisy (G. purpurea Roxb. Brindonia indica Dup. Th.), an elegant tree with drooping branches and dark green leaves.[355] It bears a smooth round fruit the size of a small apple, containing an acid purple pulp in which are lodged as many as 8 seeds. The tree is a native of the coast region of Western India known as the Concan, lying between Daman and Goa.
History—The fruit is mentioned by Garcia d’Orta(1563) as known to the Portuguese of Goa by the name of Brindones. He states that it has a pleasant taste though very sour, and that it is used in dyeing; and further that the peel serves to make a sort of vinegar. Several succeeding authors (as Bauhin and Ray) have contented themselves with repeating this account.
As to the fruit yielding a fatty oil, we find no reference to such fact till about the year 1830, when it was stated in an Indian newspaper[356] that an oil of the seeds is well known at Goa and often used to adulterate ghee (liquid butter). It was afterwards pointed out as the result of some experiments that the oil was of an agreeable bland taste and well adapted for use in pharmacy. A short article on Kokum Butter was published by Pereira[357] in 1851. With the view of bringing the substance into use for pharmaceutical preparations in India, it has been introduced into the Pharmacopœia of India of 1868.
Preparation—The seeds are reniform, somewhat crescent-shaped or oblong, laterally compressed and wrinkled, ⁶/₁₀ to ⁸/₁₀ of an inch long by about ⁴/₁₀ broad. Each seed weighs on an average about eight grains. The thick cotyledons, which are inseparable,[358] have a mild oily taste. Examination under the microscope shows them to be built up of large reticulated cells containing a considerable proportion of crystalline fat readily soluble in benzol. In addition globular masses of albuminous matter occur which with iodine assume a brownish yellow hue. With perchloride of iron the walls strike a greenish-black.
The process followed by the natives of India (by whom alone the oil is prepared) has been thus described:—The seeds having been dried by exposure for some days to the sun are bruised, and boiled in water. The oil collects on the surface, and concretes when cool into a cake which requires to be purified by melting and straining.
Description—Kokum Butter is found in the Indian bazaars in the form of egg-shaped or oblong lumps about 4 inches long by 2 inches in diameter, and weighing about a quarter of a pound. It is a whitish substance, at ordinary temperatures, firm, dry, and friable, yet greasy to the touch. Scrapings (which are even pulverulent) when examined in glycerin under the microscope show it to be thoroughly crystalline. They have a mild oily taste, yet redden litmus if moistened with alcohol.