The varieties of sandal-wood are not classified by the few persons who deal in the article in London, and we are unable to point out characters by which they may be distinguished. In the price-currents of commercial houses in China three sorts of sandal-wood are enumerated, namely, South Sea Island, Timor, and Malabar; the last fetches three or four times as high a price as either of the others. Even the Indian sandal-wood may vary in an important manner. Beddome,[2264] conservator of forests in Madras, and an excellent observer, remarks that the finest sandal-wood is that which has grown slowly on rocky, dry and poor land; and that the trees found in a rich alluvial soil, though of very fine growth, produce no heartwood and are consequently valueless. A variety of the tree with more lanceolate leaves (var. β myrtifolium DC.), native of the eastern mountains of the Madras Presidency, affords a sandal-wood which is nearly inodorous.
Microscopic Structure—The woody rays or wedges show a breadth varying from 35 to 420 mkm., the primary being frequently divided by secondary medullary rays. These latter rays consist of one, often of two, rows of cells of the usual form. The woody tissue which they enclose is chiefly made up of small ligneous fibres with pointed ends, some larger parenchymatous cells, and thick-walled vessels. The resin and essential oil reside chiefly in the medullary rays, as shown by the darker colour of these latter.
Chemical Composition—The most important constituent is the essential oil, which the wood yields to the extent of from 2 to 5 per cent.[2265] In India, with imperfect stills, 2·5 per cent. of the oil are obtained; the roots yield the largest amount and the finest quality of it.[2266] It is a light yellow, thick liquid, possessing the characteristic odour of sandal; that which we examined had a sp. gr. of 0·963. We did not succeed in finding a fixed boiling point of the oil; it began to boil at 214° C., but the temperature quickly rose to 255°, the oil acquiring a darker hue. Oil of sandal-wood varies much in the strength and character of its aroma, according to the sort of wood from which it is produced.
The oil as largely prepared by Messrs. Schimmel & Co., in a column 100 millimetres long, deviates the plane of polarization 18·6° to the left. Oil of Venezuela sandal-wood, from the same distillers, examined in the same manner, deviates 6°·75 to the right.
From the wood, treated with boiling alcohol, we obtained about 7 per cent. of a blackish extract, from which a tannate was precipitated by alcoholic solution of acetate of lead. Decomposed by sulphuretted hydrogen, the tannate yielded a tannic acid having but little colour, and striking a greenish hue with a ferric salt. The extract also contained a dark resin.
Commerce—The greatest trade in sandal-wood is in China, which country in the year 1866 imported at the fourteen treaty ports then open 87,321 peculs, equivalent to 5,197 tons; of this vast quantity the city of Hankow on the river Yangtsze, received no less than 61,414 peculs, or more than seven times as much as any other port.[2267] The imports into Hankow have recently been much smaller, namely, 14,989 peculs in 1871 and 12,798 peculs in 1872.[2268] On the other hand, Shanghai lying near the mouth of the same great river, imported in 1872, 59,485 peculs of sandal-wood, the estimated value of which was about £100,000. In 1877 the imports of all China were 72,934 peculs.
A considerable trade in sandal-wood is done in Bombay, the quantity imported thither annually being about 650 tons, and the animal export about 400 tons.[2269]
Oil of sandal-wood is largely manufactured on the ghats between Mangalore and Mysore, where fuel for the stills is abundant. Official returns[2270] represent the quantity of the oil imported into Bombay in the year 1872-73 as 10,348 lbs., value £8,374; 4,500 lbs. were re-exported by sea.
Uses—The essential oil has of late been prescribed as a substitute for copaiba, otherwise sandal-wood has hardly any uses in modern European medicine. It is employed as a perfume and for the fabrication of small articles of ornament. Among the natives of India it is largely consumed in the celebration of sepulchral rites, wealthy Hindus showing their respect for a departed relative by adding sticks of sandal-wood to the funereal pile. The powder of the wood made into a paste with water is used for making the caste mark, and also for medicinal purposes. The consumption of sandal-wood in China appears to be principally for the incense used in the temples.