Burgundy pitch is obtained by making incisions through the bark, so as to lay bare the wood. It concretes in the form of flakes at the incisions, which are detached by an iron instrument, once a fortnight during the summer, and fresh incisions successively made. The flakes after being detached, are put into large boilers with a sufficient quantity of water, melted, and then strained through coarse cloths under a press. The greatest quantity is collected in the neighbourhood of Neufchatel, whence it is brought to this country, packed in casks. A fictitious sort is made in England, and found in the shops under the title of common Burgundy pitch. It may be distinguished by its friability, want of viscidity, and unc-tuosity, and the odour which characterises the genuine sort.

Theophrasti. Die Fichte (G.), Hartsboom (Dutch), Gran (Dan., Swed.), La Pesse (F.), Picea (I., S.), Pence (Port.), Jel(Russ.). This species of fir is cultivated in Britain, but it does not appear to have been introduced before 1739. When grown in Norway it is used for masts; but that which is cultivated in Britain is used only for the coarsest purposes.

2 Like the Scotch fir, it is attacked by the Bostrichus piniperda.

Qualities.-Turpentines.-Although these are produced from different species of the Pine tribe, and one sort from the Pistacia terebinthus, yet all of them possess the same general physical and chymical properties. They have a peculiar, somewhat aromatic odour, and a warm, pungent, bitterish taste; are semifluid, tenacious, translucent, combine readily with fixed oils, and are inflammable, burning with a white flame and much smoke. Alcohol and ether dissolve them entirely, leaving the impurities; but water takes up only their flavour. When distilled with water a volatile oil comes over, and towards the end of the operation succinic acid rises1; resin remains in the retort: the turpentines therefore are compounds of these three substances. But each sort of turpentine has characteristic qualities which require to be noticed. 1. Common Turpentine has a strong, somewhat fragrant odour, and a bitter, disagreeable taste; its consistence is greater than that of honey; its colour is dirty yellow, and it is more opaque than the other sorts. 2. Venice Turpentine is more fluid, having the consistence of new honey, a yellowish colour, and is less unpleasant to the smell and taste than the common.

3. Canadian Balsam (or more correctly Turpentine) has a strong, not disagreeable, odour, and a bitterish taste; is transparent, whitish, and has the consistence of copaiva balsam.

4. Chian or Cyprus Turpentine (see Pistacia) is very fragranr, but almost insipid, nearly transparent, thick, tenacious, and of a whitish colour.

Oil of turpentine has a strong, penetrating, peculiar odour, and a hot, pungent, bitterish taste. It is perfectly limpid and colourless: extremely light, volatile, and inflammable; its boiling point is 312° Fahr.: it dissolves completely in six parts of sulphuric ether; but although hot alcohol readily dissolves it, yet it again separates in drops as the spirit cools, and is very sparingly soluble in the cold in the strongest alcohol: one hundred parts in volume, however, unite with twenty of alcohol, and form a homogeneous solution, which does not become turbid by water.2 In all other respects it agrees with the other volatile oils. It consists of 10 equiv. of carbon = 61.2 + 8 of hydrogen = 8, making the equivalent 69.2. In this state it is named Camphene, When a stream of chlorine is passed through, an artificial camphor is formed: and I found that an imperfect camphor is also formed when a stream of oxygen gas is passed through the pure oil of turpentine.

1 Annates de Chin, xxi.. 328. 2 Ure, Phil. Trans. 1822.

Tar has a strong odour, familiar to every person; a resinous, subacid, bitterish taste; and a coarse, thick consistence, with a deep brown colour, approaching to blackness, derived from the charring of the wood during its formation. It consists principally of empyreumatic oil, resin, and acetic acid; is partially soluble in water; and is inspissated by boiling into pitch.

Yellow and white resin are varieties of the same substance. They are nearly inodorous when cold; but, when heated, emit a slight terebinthinate odour. Their taste is slightly acrid and bitterish; and their colour a dull whitish yellow, or a greenish yellow. The mass of resin is semipellucid, brittle, breaks with a true vitreous fracture, and adheres moderately to the fingers. Its specific gravity is 1.0742. It melts when heated, then inflames, and burns with a yellow flame, giving out much smoke. It is insoluble in water, but entirely soluble in alcohol, ether, the fixed oils, and the alkalies. The mineral and the acetic acids also dissolve resin, and the nitric converts it into artificial tannin. When sulphuric acid is employed, charcoal, in the proportion of forty-three per cent, of the resin acted on, is produced.1 The resin of the Norway Spruce possesses nearly the same properties. It is in the form of solid brittle tears, of a brownish yellow colour on the outside, and internally white; and emits a very agreeable odour when burning.

Burgundy pitch has a terebinthinate odour and taste, is brittle, opaque, and of a light yellow or reddish brown colour. It softens moderately in the heat of the hand, appears unctuous, and has a considerable degree of tenacity.