146 FORESTRY INVESTIGATIONS u. s. DEPARTMENT OF AGRICULTURE. 



a mixture of hydrocarbons of tlio formula CiHi 6 ; but the impure product from the slill contains also other hydro- 

 carbons :md acids. To rectify it, it is mixed with limewater and again distilled; yet, according to the source from 

 which derived, the oil of turpentine possesses different qualities. Freshly prepared oil of turpentine, especially 

 that from virgin trees worked for the first time, is colorless, tasteless, a thin fluid, of peculiar smell, of low specific 

 weight (0.855-0.875), and its boiling point at 300-340 F. Most of the oils of turpentine of the trade polarize light 

 to the left, but the American oil polarizes it to the right, and may thereby be recognized. 



The oil evaporates very readily in ordinary temperature, and by oxidation thickens until hard, becomes yellow, 

 and shows sour reaction. It burns with a strongly sooty flame: it is insoluble in water, but soluble in alcohol. It 

 is a good solvent for many resins, wax, fats, caoutchouc, sulphur, and phosphorus. In the arts it is used mainly for 

 the preparation of varnishes, in paints, and in the rubber industry. It is also used for illuminating purposes as pine 

 oil, or mixed with alcohol as camphene, and under other names. It has a wide use in medicine internally and 

 externally. It is often used in the adulteration or imitation of various essential oils. 



(3) Rosin or colophony. This is the residue remaining from the distillation of the crude turpentine or resin. 

 According to the nature of the crude turpentine, which depends on the number of seasons the tree has been worked 

 it shows different properties. It is either perfectly transparent, translucent, or almost opaque; in color, from pale 

 yellow, golden or reddish yellow, through all shades to deep dark brown, almost black; and of different degrees of 

 hardness; some soft enough to take the impression of a finger nail, and some so hard that only iron will make an 

 impression. 



The hard colophony or rosin is almost without- smell or taste, of glassy gloss, very brittle, easily powdered. It 

 becomes soft at about 176 F. and melts between 194 and 212 F. It is soluble in the same solvents as the crude 

 resin; its specific weight is 1.07. Rosin is used in the manufacture of varnish, sealing wax, putty, soap, paper, etc. 



In the American market the following grades are distinguished: \V<; window glass; WW water white, the 

 lightest colored grade, obtained from virgin dippings and under special care at the distillery ; N extra pale; M 

 pale; K low pale; I good No. 1; H No. 1; F good No. 2; E No. 2; D good strain; C strain; B common 

 strain ; A black. 



By dry distillation of the rosin are obtained the following three products: 



(a) Light rosin oil, which is used in the fabrication of varnishes. 



(ft) Heavy rosiu oil, which is used in the manufacture of printers' ink, machine oil, axle grease, etc. 



These oils, known in commerce as pale oil, pine oil, ink oil, etc., are of a light reddish or brown color, more or 

 less fluorescent, with a specific gravity of 0.98 to 1; of slight odor but characteristic taste. The distillation is 

 carried on at a dull, red heat, yielding about 85 per cent of rosin oil. They are composed of a mixture of several 

 hydrocarbons of indefinite nature (colopheue, heptin, etc.), and contain from to over 15 per cent of resinous acids. 

 They are insoluble in water, slightly so in alcohol, can not be saponified, hut form unstable compounds with slaked 

 lime and other bases. The rosin grease made by stirring slaked lime finely suspended in water is an excellent lubri- 

 cant, adapted especially for metal bearings in machinery and wagons. Mixed with sweet oil, rape oil, or the denser 

 mineral oils, it is used for the preparation of lubricating oils. These oils are also used in the manufacture of varnish, 

 in the preparation of cheap paints used to cover metal, roofs, etc. 



(c) Common pitch. This is the residue from the dry distillation of rosin; a glossy, black, brittle body, which 

 is used in the manufacture of the common ship-chandlers' pitch, used for calking of vessels, shoemakers' pitch, and 

 black pigments. Pitch is also obtained by boiling tar down until it has lost about one-third or more of its weight. 

 The navy pitch of commerce has more or less rosin of lowest grades added to it. It commands a price of about 

 $1.50 per barrel. 



(4) liretven' pitch, -This is used for pitching beer kegs and barrels, and is obtained when the distillation of the 

 crude turpentine is stopped, before all the oil has been distilled. It, therefore contains a certain quantity of oil of 

 turpentine; if too much, the pitch foams when melted and imparts a disagreeable, sharp taste to the beer, while 

 with too little oil the pitch becomes brittle and does not adhere to the barrel. The best quality of this product is 

 obtained from the larch, and is produced mostly in Tyrol, but there is quite an amount of brewers' pitch made in 

 the Southern pineries. 



(5) Tar. This is not exactly a by-product, of the turpentine orchard, but is mostly a product of destructive 

 distillation of the wood itself. Most of the tar in the United States is made in North Carolina, where the industry 

 has been largely carried on from earliest colonial times. In other parts of the Southern coast pine belt it is only 

 produced for home consumption. Perfectly dry wood of the longleaf pine dead limbs and trunks perfectly seasoned 

 on the stump, from which the sapwood has rotted are cut into suitable billets, piled into a conical stack in a 

 circular pit lined with clay, the center communicating by a depressed channel with a receptacle a hole in the 

 ground at a distance of 3 or 4 feet from the pile. The pile is covered with sod and earth, and otherwise treated 

 and managed like a charcoal pit, being fired from apertures at the base, giving only enough draft to maintain slow 

 smoldering combustion. After the ninth or tenth day the flow of tar begins, and continues for several weeks. It is 

 dipped from the pit into barrels of 320 pounds net, standard weight, mostly made by the tar burner himself from the 

 same pine. From one cord of dry " fat'' wood or "lightwood" from 40 to 50 gallons of tar are obtained. 



There is but little profit in the business, except that it employs labor in remote districts at a season (winter) 

 when there is but little else to do. The price of tar, at present quoted as low as $1.05 per barrel at Wilmington, 

 N. C., has been depressed, especially since considerable quantities of tar are produced incidentally in the destructive 

 distillation of wood in iron retorts for charcoal purposes. 



(6) Oil of tar. This is obtained by distillation of the tar. It is a complex mixture of hydrocarbons with some 

 wood alcohol and a small quantity of creosote, often more or less covered by einpyreumatic substances, with adeiisily 

 of 0.841 to 0.877. It is used as an insecticide and for various external applications in domestic and veterinary practice. 



