TART H.

Materia Medica.

301

top: the strobiles or cones are about an inch long, obtuse, andpurplish at the apex, with the scales smooth on the surface,lacerated at the edges, and concealing under each two wingedseeds.

The larch tree grows to very great perfection in the forestsof Baye in Provence, where a very large proportion of the Ve-nice turpentine of commerce is procured. It is obtained byboring a hole with an auger into the heart of the tree, at abouttwo feet from the ground, and fitting into it a small pipe,through which the turpentine flows slowly into vessels placedfor its reception. This process is begun in May, and conti-nued till September; when the different quantities collectedare put together, and purified by straining through cloths orhair sieves. No trees under twelve inches in diameter aretapped; but vigorous trees will yield annually seven or eightpounds for forty or fifty successive years, or during the term oftheir life. 1 Much of the Venice turpentine of the shops isbrought from America; and is perhaps procured from a diffe-rent species of fir.

The essential oil is separated from it by distillation in the samemanner as from the common turpentine.

3. Balsam or Balm-oj-gilead Fir.Officinal. Terebinthina canadensis. Lond. Balsamum Cana-dense.* Bub. Canada Turpentine. Canada Balsam.

Syn. Kanadischer balsam [G.)

This tree is a native of North America, flowering in May.It is a straight elegant tree, covered with a smooth whitish-graybark. The leaves are in double rows like a comb, short, andlinear, but broader than the former two species, and less pointed;of a dark green colour on the upper surface, marked withwhitish lines underneath, and fragrant: the cones, which ripenin October, stand erect on the branches, are large, of a beauti-ful deep glossy purple colour, inclining to black; and exude agreat quantity of transparent resin, which gives them a veryrich, beautiful appearance.

The manner in which the Canada balsam, or fine turpentine,yielded by this tree is collected, is not well known in this coun-try : but it is probably by simple incisions, as it exists in greatquantity in vesicles between the wood and the bark. Canada

« Besides turpentine the larch tree exudes a specie3 of manna, which is named Brian-cjn manna. It is in little white concrete drops, which adhere to the leaves, and tastessweet like new honey ; but it has the flavour of turpentine, which it contains. The innerptrtof the tree yields also a gum similar in its properties to acacia gum, of a reddishcolour, with a slight resinous taste. In Russia it is officinal, and sold, as Pallas observes,under the improper name of Orenberg gum, being obtained from the Uralian Forest.-FVora Rosst'ca, i. p. 2, 3.

* The Dublin college have erred in retaining this name ; for, as this substance doesnot alford benzoic acid, it cannot be ranked as a balsam,11