The so-called " pine barrens " of the United States extend from Virginia to the Mexican Gulf, especially through N. and S. Carolina, Georgia, and Alabama, but the extraction of turpentine is an industry mainly developed in N. Carolina. In wiuter (November-March), the " boxing " is carried on. This consists in cutting cavities in the tree, at 6-12 in. above the ground, aud shaped like a distended waistcoat-pocket, the lower lip being out horizontally, the upper one arched, and the bottom of the box being about 4 in. below the former, and 8-10 in. below the latter. The capacity of each " box" is about 2-3 pints, and its purpose is to form a receptacle for the exudation. The boxes are cut by means of a specially-shaped axe, and considerable skill is required to wield it properly, a chief object being to attain the desired capacity while approaching as little as possible the heart of the tree, and thereby endangering its life. An expert may make a box in 10 minutes, or about 50-60 in a day. The box being made and carefully cleaned of all chips, the exudation is induced by removing with the axe a thin slice from the upper lip of the box, including the bark and about 2 or 3 rings of the wood. There are commonly 3 boxes in a tree of 18 in. diam., it being a good rule to have at least 6 in. of face between the boxes. Some authorities are of opinion that it is beneficial to restrict operations to the northern face of the tree, the turpentine thereby retaining more of the volatile constituent, and the boxes being leas exposed to the dust and leaves blown about hy the southerly winds of summer. From the pared upper lip of the box, the sap begins to flow about the middle of March. From that time, the surface of the wound requires to he renewed every 7-10 days, which is effected by slicing off about in. from its faoe, the object being merely to expose fresh tissue as fast as it becomes clogged by the exudation. The latter mainly colleots in the box, and is dipped out at intervals by special ladles, and barrelled. By the repeated slicing of the upper lip of the box, the wound ascends the, tree t,o a height of 12-15 ft., ladders being used in the later years during which the operation Is prolonged. The higher the wound haa been carried, the greater the surface passed over by the exudation on its way to the box, and the greater the proportion whioh solidifies prematurely on the wound. This is the portion which is t,ermed " scrape " in America (see Thus, p. 1684). The liquid portion which collects in the boxes is called " in contradistinction. The scrape is removed about once a year ; by allowing it to accumulate excessively, the yield of dip is much reduced. The 1st year'a flow of a newly-boxed tree is known as " virgin dip," and is separately barrelled, being of superior quality. All leaves and chips should be cleared away from around the base of tbe trees, to avoid the outbreak of flre, and afford no harbour for insects.
The crude turpentine has to undergo a process of distillation, to separate the " rosin " from the " spirit," " oil," or " essence " of turpentine. This distillation is carried on mainly on the strearns near the localities of production. During the Civil War, large quantities of the crude oleo-resin were shipped to England for distillation, hut thia has long since ceased to he the case. The little sent into the N. States undistilled is used for making printing-ink. The production in the United States in 1876 was stated at 300,000 casks turpentine-spirit, and 1,500,000 barrels (of 280 lb.) of rosin.
Both rosin and turpentine-spirit were made in Canada, during the American Civil War, from the common red pine (Pinus resinosa), which grows abundantly in the N. counties of Ontario. The turpentine obtained from it ia not identical in its qualities with that of the S. States, but forms a convenient substitute. Since the suppliea of the southern article have resumed their normal condition, this manufacture has been abandoned.
In the French departments of Landes and Gironde, the extraction (gemmage) of the crude oleo-resin is conducted in a much more rational manner. Towards the end of February or begin ning of March, preparations are oommenced by thinning down the rough hark till only the last cortical layers rernain covering the sap-wood, thua presenting a smooth even surface. The thinning is confined to the space which will be operated on during the current season, allowing a margin of 4 in. in height and 1-11 in. in width, ao as to prevent bark fragments from falling into the reoeptacle placed to catch the exudation, and avoid tbe blunting of the edge of the inatrument used in making the incision. The next operation, generally performed about 1st-10th March, consists in cutting the resiniferous ducts by means of the abchotte. The workman cuts into the foot of the tree an incision with a convex top, termed a carre, measuring 1 in. wide, 1-1 in. high, and in. deep. The orude turpentine (gemme) escapes in viscous transparent drops, thickening by exposure to the air, a portion adhering to the carre, while the more liquid remainder flows into receptacle. This latter was formerly a hole made in the earth at the foot of the tree, and named crot ; but since 1860, little earthenware dishes have come into general use, the oleo-resin being conducted into them by strips of zinc, called crampons. The renewal of the wound (piquage) is performed every 5-7 days. When the dishes are suffioiently full, their contents are emptied into ft wooden basket termed an escouarte, the dishes are replaced, and the oleo-resin is conveyed to large reservoirs known as barcous, built of wood or bricks here and there in the forest, where it remains till required for manufacture. By the pigu,age, the carre constantly increases in height, but never exceeds certain dimensions. These have been recently fixed at the following figures:— Height : 1st year, 32 in.; 2nd, 51 in.; 3rcl, 80 in.; 4tL, 109 in. ; 5th, 148 in.; width, 31- in. ; depth, in., measured from a line parallel with the red part of the bark.
There are two modes of gemmage : mort and 'it vie. The former is applied only to trees xvhich are to be felled, in which case, it is desired to extract the greatest possible quantity of turpentine in the shortest time, and with this object, a number (2-6) carres are made simultaneously. The latter system (a vie) is adopted with trees which are to remain growing (called pins de place), and in which never more than one carre is opened at a time. When the first, at the end of 5 yeare, has n height of 148 in., the tree is allowed to rest for several years; a fresh one may then be made at a distance of not less than 6-8 in. from the last. The old-fasbioned plan of collecting the turpentine in a hole in the ground is termed gemmage au crot ; the modern plan of using earthen ware dishea is known as the systeme Huques. By the latter, the yield is increased and the value 10 francs (8.9.) a barrel, while the additional cost is about 5c. (2id.) a tree per annum. The gemmage a mort, on trees which are to be felled, is performed as soon as they are large enough to support a carre, which is when they are 16 in. round, initially attained at an age of 20 years. Until 1877, in the government foresta, the gemmage Me was commenced on reaerved timber at a circumference of 39 in., but this has since been increased to 43 in., when the pines are 30-35 years old. The mean annual yield per hectare (of 2i acres) of turpentine and " thus" varies from 240 kilo. (of 2.2 lb.) in the younger forests, to 450 kilo. in those where the trees are mostly 40-70 years of age. The yield, however, fluc tuates greatly both in quality and quantity, according to the mason and other varying conditions.