COMMERCIAL TURPENTINES. 



INTRODUCTION. 

 NATURE AND GENERAL PROPERTIES. 



Commercial spirits of turpentine is a mixture of similar and closely 

 related terpenes having the general composition expressed by the 

 formula C 10 H 16 , with varying quantities of oxidized and hyd rated 

 derivatives of terpenes, usually present only in small amounts when 

 first distilled from the gum. 



These terpenes differ both in their physical and chemical prop- 

 Arties, and consequently commercial turpentine may distill at from 

 154 to 215 C. (309 to 419 F.). The fractions obtained on dis- 

 tillation have specific gravities ranging from 0.8580 to 0.9500 or more, 

 with refractive indices of from 1.462 to 1.520, respectively. 



The pinenes, several of which, differing slightly from one another 

 in boiling point, specific gravity, and refractive index, have been 

 recognized, are among the chief constituents of spirits of turpen- 

 tine freshly distilled from the gum. Dipentene l has also been 

 reported as occurring in American turpentine, but as dipentene 

 distills alone at about 178 C., it is probably present in but small 

 quantities in those turpentines which distill completely below this 

 temperature. The above-mentioned terpenes boil between 155 C. 

 (311 F.) and 178 C. (352 F.); their specific gravities lie between 

 0.845 and 0.866, and their refractive indices between 1.46 and i.472. 

 Other constituents which may be present, regarding the identity 

 of which but little is known, have specific gravities of from 0.865 

 to 0.950 and refractive indices as high as 1.5200 at 20 C., and boil at 

 from 160 C. to 215 C. (320 to 419 F.). Turpentines which have 

 been kept long, particularly those held in partly filled vessels, fre- 

 quently have higher specific gravities, refractive indices, and boiling 

 points than freshly distilled turpentine. In changing they become 

 more oily and usually somewhat darker in color. 



The quantity of each constituent present in commercial American 

 turpentine is influenced not only by the physiological processes of 

 the individual trees, but also, and probably more largely, by the 



' Gildemeister, Die Aetherische Oele, 2d ed., 1910, p. 328; Allen, Commercial Organic Analysis, 3d ed., 

 vol. 2, pt. 3, p. 263. 



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