FRANKINCENSE. 277 
the juice flows forthwith in a copious stream (frequently covering 
the entire stem), until the wounds are closed by the desiccation of 
the fluid into a gum. In this state the trees glisten in their rich 
investiture, and, as if vexed at being prevented from pouring forth 
all their store, the bark distends from the abundance of the sap 
within. After the juice is inspissated and dried by the action of 
the atmosphere and the sun, it is scraped off the trees and the 
ground beneath and collected by the natives, who store it in large 
loose heaps at particular places on the sea-coast. It is then 
packed in sheep and goat skins and transported on camels to the 
great fair held in Berbera, from whence it is shipped in native 
vessels to Aden and other parts on the Arabian coast. It is, 
however, sometimes purchased by the Banians and sent direct to 
the Bombay market. The olibanum of commerce appears in 
oblong, pear-shaped, or rounded tears, of a yellow or reddish 
colour; always covered externally with a fine white dust, and even 
where that is wiped off the tears appear translucent, milky, and 
semi-opaque, but the finest quality is almost colourless and of a 
greenish tint. When rubbed in a mortar with water it forms a 
white emulsion. It softens between the teeth, producing an 
aromatic, slightly rough taste. Its odour is agreeably aromatic, 
but is only developed by exposing the substance to a high temper - 
ature. It is but partially soluble in water and alcohol. It melts 
with difficulty and imperfectly when heated. At 100° C. it 
softens without melting, and on the temperature being raised it 
begins to decompose. It burns with a bright white flame on the 
approach of a taper.” 
According to Braconnet * it contains 56 per cent. resin soluble 
in alcohol (but insoluble in alkalies), and 8 per cent. of essential 
oil. The chemical constitution of the resin agrees nearly with the 
formula C,H 3,0. The residue, about 33 per cent., was found by 
Hekmejer + to consist of a gum identical with gum arabic. 
By distillmg this gum resin with water in a cast-iron retort, an 
oul is obtained constituting about 7 per cent. of the resin taken 
alcohol extracts from the residue about 72 per cent. of resin, and 
the remainder is gum. The crude oily distillate boils between 
160° and 170°, and contains oxygen, as Stenhouse previously 
* Ann. Chim. Phys, [2] lviii. p. 60. 
+ Jahresb. 1858, p. 482. 
