Frankincense, or olibanum, occurs in commerce in semi-opaque, round, ovate or oblong tears or irregular lumps, which are covered externally with a white dust, the result of their friction against one another. It has an amorphous internal structure, a dull fracture; is of a yellow to yellowish-brown hue, the purer varieties being almost colourless, or possessing a greenish tinge, and has a somewhat bitter aromatic taste, and a balsamic odour, which is developed by heating. Immersed in alcohol it becomes opaque, and with water it yields an emulsion. It contains about 72% of resin soluble in alcohol (Kurbatow); a large proportion of gum soluble in water, and apparently identical with gum arabic; and a small quantity of a colourless inflammable essential oil, one of the constituents of which is the body oliben, C10H16. Frankincense burns with a bright white flame, leaving an ash consisting mainly of calcium carbonate, the remainder being calcium phosphate, and the sulphate, chloride and carbonate of potassium (Braconnot).[14] Good frankincense, Pliny tells us, is recognized by its whiteness, size, brittleness and ready inflammability. That which occurs in globular drops is, he says, termed "male frankincense"; the most esteemed, he further remarks, is in breast-shaped drops, formed each by the union of two tears.[15] The best frankincense, as we learn from Arrian,[16] was formerly exported from the neighbourhood of Cape Elephant in Africa (the modern Ras Fiel); and A. von Kremer, in his description of the commerce of the Red Sea (_Aegypten_, &c., p. 185, ii. Theil, Leipzig, 1863), observes that the African frankincense, called by the Arabs "asli," is of twice the value of the Arabian "luban." Captain S. B. Miles (_loc. cit._, p. 64) states that the best kind of frankincense, known to the Somali as "bedwi" or "sheheri," comes from the trees "Mohr Add" and "Mohr Madow" (_vide supra_), and from a taller species of _Boswellia_, the "Boido," and is sent to Bombay for exportation to Europe; and that an inferior "mayeti," the produce of the "Yegaar," is exported chiefly to Jeddah and Yemen ports.[17] The latter may possibly be what Niebuhr alludes to as "Indian frankincense."[18] Garcias da Horta, in asserting the Arabian origin of the drug, remarks that the term "Indian" is often applied by the Arabs to a dark-coloured variety.[19] According to Pliny (_Nat. Hist._ xiv. 1; cf. Ovid, _Fasti_ i. 337 sq.), frankincense was not sacrificially employed in Trojan times. It was used by the ancient Egyptians in their religious rites, but, as Herodotus tells us (ii. 86), not in embalming. It constituted a fourth part of the Jewish incense of the sanctuary (Ex. xxx. 34), and is frequently mentioned in the Pentateuch. With other spices it was stored in a great chamber of the house of God at Jerusalem (1 Chron. ix. 29, Neh. xiii. 5-9). On the sacrificial use and import of frankincense and similar substances see INCENSE.