INTRODUCTION. 9 



mixtures of terpenes and related heavier oils and as such may possess 

 the peculiar properties which are commercial assets of turpentine 

 and which distinguish it sharply from unrelated oils which are often 

 substituted wholly for it or employed in its sophistication. In the 

 one case the product is a natural result of aging, while in the other it 

 may properly be said to be adulterated, and such oils will be so dis- 

 tinguished in this publication. 



SOURCES AND METHODS OF PRODUCTION. 



Oil or spirits of turpentine, commonly known as " turpentine," or 

 in the paint trade simply as "turps," is obtained chiefly from the 

 longleaf pine (Pinus palustris), though a portion is also obtained 

 from Cuban (P. Tieterophylla) and a little from loblolly pine (P. 

 tseda). The Forest Service has found that loblolly, shortleaf, and 

 Virginia pines yield naval stores equal in quantity to the longleaf 

 yellow pines, and as the former occur in large quantities in the South 

 their utilization would add largely to the turpentine resources of the 

 country. 



During the winter months before the sap begins to rise a pocket or 

 "box" is cut in the tree near the ground, and at intervals during the 

 succeeding spring and summer the bark and a portion of the sap 

 wood are removed from the trunk above the box. This cutting 

 greatly shortens the life of the tree and renders it more liable to 

 destruction by wind, storm, and fire. The injury to standing timber 

 caused by turpentining may be largely avoided by collecting in cups, 

 the gum being directed into them by strips of zinc or heavily gal- 

 vanized iron set in the face of the tree. This system, used exclu- 

 sively in France, is now being extensively introduced in a modified 

 form into this country and not only protects the tree but, as has 

 been shown by the Forest Service, yields a higher grade of rosin and 

 more turpentine. 



In the spring the crude gum begins to flow from the "face," as that 

 portion of the tree from which the bark and a part of the sapwood 

 have been removed is called, and collects in the box or cup near the 

 base, from which it is removed by dipping from time to time during 

 the flowing season, which lasts from March to October or later. The 

 thick, resinous mass, which usually contains water, chips, bark, pine 

 needles, earth, and charred wood, is taken to the still, which is a 

 large copper kettle with an outlet in the bottom by means of which it 

 may be emptied and a cap connecting with a condensing coil. The 

 kettle is bricked around in order that it may be safely heated by a 

 fire underneath. 



The crude gum is poured into the kettle until it is from one-third 

 to one-half full and then slowly heated. A portion of the chips, 

 bark, and pine needles is skimmed out after the contents of the kettle 

 72457 Bull. 13511 2 



