20 WOOD TURPENTINE. 



PROPERTIES AND COMPOSITION OF WOOD TURPENTINE. 



Ordinary gum turpentine recently prepared by distilling the crude 

 gum may be defined as a mixture of terpenes having the same empirical 

 chemical formula, C 10 H 16 , together with small quantities of certain 

 derivatives of these terpenes, concerning which but little is known. 

 These components differ in specific gravity, optical properties, boiling 

 point, consistency, refractive index, odor, and probably in other 

 physical and chemical properties. The peculiar suitability of gum 

 turpentine as a diluent for paints and varnishes is due apparently to 

 the fact that it evaporates neither too rapidly nor too slowly not so 

 fast as to leave the coated surface full of fine pores through which 

 moisture may enter and destroy the paint or varnish, nor so slowly as 

 to unduly prolong the drying. Further, its oxygen-carrying power 

 hastens the oxidation of the linseed oil, and thus forms the binding 

 coat which holds the paint bases and resins to the surface of the 

 material. 



Crude wood turpentine differs from gum spirits primarily in that it 

 contains additional terpenes and terpene derivatives, together with 

 other nonterpene derivatives. In that obtained by the destructive 

 distillation of long-leaf yellow pine, dipentene, pentane, pentene, 

 toluol, hep tine, etc., have been reported, in addition to pinene. 



After washing with soda to remove phenoloid bodies derived from 

 the breaking up of the wood, fractional distillation, or fractiona- 

 tion alone in the case of the steamed distilled oils, will separate these 

 mixtures into two or more portions, each of which will consist very 

 largely of constituents whose boiling points are very close together. 

 It is impossible, however, by distillation to separate those com- 

 pounds having nearly the same boiling points, and as a matter of fact 

 each fraction will also contain more or less of the heavier oils, depend- 

 ing on how carefully the fractionation has been conducted. Thus, 

 from the destructively distilled oils, fractions distilling at from 80 

 to 155 C., from 155 to 180, from 180 to 220, from 220 to 250, 

 from 250 to 400, or, as a matter of fact, between any desired limits, 

 may be obtained. 



The first fraction distilling between 80 and 154 C. closely resem- 

 bles rosin spirits, and is in fact the lighter portion of rosin spirits con- 

 taminated with small quantities of materials from the nonresinous 

 wood constituents. The portion passing over between 154 and 

 180 C. is destructively distilled wood turpentine. This fraction 

 contains pinene and dipentene, together with smaller quantities of 

 other compounds, at least some of which are normal constituents 

 of rosin spirits. The heavier oils distilling from 180 C. up are pine 

 and rosin oils in indefinite mixtures. They are used in the manu- 

 facture of lubricants, printing inks, solvents, etc. The crude oils 



