160 FORESTRY INVESTIGATIONS U. S. DEPARTMENT OF AGRICULTURE. 



in this system of collection. Xot more than 17.9 per cent of scrape is expected, as against 29 in the American 

 practice. 



Figures 2,3,4 show cross sections of trees bled through several periods of years; also the manner in which 

 chips are distributed, and healed scars. 



MANAGEMENT OF TURPENTINE PINKlilKS. 



When the yield of turpentine falls below a certain minimum, the time has arrived when the 

 growth must be regenerated. All trees are then bled " to death" and cut as they give out, and 

 the openings are seeded with pine seed and the reproduction is completed in four or five years. 

 The young forest grows up uniformly, densely, and quickly, and when 10 or 12 years old it becomes 

 necessary to thin out and to repeat the operation every five or six years, so that at the age of 20 

 the pines are nearly isolated. Then there are about 250 to 280 trees per acre, and bleeding " to 

 death " is commenced at the rate of, say, 80 or 85 trees, which are to be taken out during the next 

 four or five years. At the age of 25 another 80 are subjected to the operation, and at the age of 

 30 there may be left 100 to 125 trees per acre. At this age, when the trees are about 1 foot in 

 diameter, bleeding "alive" is commenced on all trees. At the age of 00 to 80 years this number 

 has dwindled down by casualties to 80 or even 65. If well managed these trees may last 120 to 130 

 years; otherwise, if bled too much, they will succumb in half the time. A rest of a year or more 

 every fifth year is necessary to recuperate the trees. When the circumference of the tree has 

 been all chipped, the old chips may be opened again. 



In order to produce resin abundantly the trees must stand isolated, their crowns well exposed 

 to the sunlight; but it is only necessary that the crowns should just touch, when the trees are 

 sufficiently isolated. 



The best producers are the short, stout trees, with well -developed crown and well set with 

 branches. To endure tapping without injury, they should be at least 14 inches in diameter, with 

 a bole of 20 to 26 feet to the first limb on the dunes and 40 to 50 feet in the landes. There is no 

 definite relation between volume and resin production. In fact, there is but little known as to the 

 conditions and physiological processes which give rise to the formation of resin, except that full, 

 active foliage and heat seem to be essential factors. 



GATHERING OF SPRUCE TURPENTINE. 



The wood of the spruce contains few and rather narrow longitudinal resin ducts, but wider 

 lateral ducts, which are strongly developed in the liber or new wood fibers. It is these that furnish 

 the flow. Hence the methods of extraction used on the pines must be modified. In growths 

 80 to 100 years old the yield is about 127 pounds of scrape and 40 pounds of dip per acre. Here 

 the scrape is the purer material, and, therefore, more expensive, the dip being more or less impure. 

 The operation is harmful to the trees, as it is apt to induce red rot. The pitch known as Burgundy 

 pitch is derived from the resin of this species. 



The resin of the spruce has also the property of hardening very quickly on exposure to the 

 air; therefore it does not flow readily enough from the chip to permit the methods used in the 

 pines. In May or June two chips are made at the same time, 3 to 3 feet in height and only half 

 an inch in breadth, on opposite sides of the tree. They are cut with a specially curved sharp 

 knife, and deep into the sapwood. In order to prevent stagnant water from collecting at the 

 bottom, this is made pointed. The sides of the chip soon form callous, which would prevent the 

 flow, and therefore the sides must be renewed every two or three years, or yearly, gradually 

 widening the chip, so that after a series of years only two small strips of bark remain between the 

 two chips. The renewing of the sides is done in summer, so that they may protect themselves 

 before winter sets in by forming new callous. In some localities alternate chips are made every 

 two years, instead of enlarging the original one. The bleeding is continued for ten to fifteen 

 years, and the yield per tree and year averages 1 pound scrape and 1 pounds of dip. 



GATHERING OK LARCH TURPENTINE. 



The larch contains resin ducts of very large diameter, and the resinous contents are found 

 mainly in the heartwood. The trees very often contain frost splits in the heart, in which the resin 

 collects. The trees are bored into about a foot above the ground in horizontal direction. The 



