WOOD 



TABLE 2. Relation between temperature of production and composition of 



crude wood turpentines. 



1 For a more plausible reason than difference in temperature for the smaller amount 

 of dipentene in turpentine No. 4, see page 53. 



COMPARISON WITH GUM TURPENTINES. 



A study of the variations in composition of gum turpentines just 

 completed at the Forest Products Laboratory indicates that the vola- 

 tile oil freshly distilled from oleoresin obtained by chipping live 

 trees of longleaf pine contains" only very small amounts of heavy oils 

 (with gravity above 0.875). Therefore the 5 per cent of heavy oil 

 shown in figure 2 is probably due to a partial oxidation of the ter- 

 penes in the original freshly distilled oil. Except for the presence 

 of these heavy oils, figure 2 represents the composition of a typical 

 gum turpentine, though in some the range of the values for the 

 physical properties of the fractions might be slightly lower; in 

 others, slightly higher. 



HEAVY OILS. 



On the other hand, the volatile oil obtained by the distillation of 

 pitchy longleaf pine contains considerable quantities of heavy oils, 

 and their presence in refined wood turpentines may result from in- 

 complete separations of heavy oil from turpentine, even with an effi- 

 cient column still. Still less perfect separations can be made with the 

 pot stills commonly used, and there is a natural tendency on the 

 part of the refiner to increase the quantity of refined turpentine by 

 increasing the proportion of heavy oils in the refined product. 



The usual presence of heavy oils in wood turpentines and their 

 usual absence in gum turpentines is, then, the first difference between 

 the two. Even in an old gum turpentine which contains heavy oils 

 (like fig. 2), it is probable that the composition of these heavy oils 

 is different from those in wood turpentines (see Composition of heavy 

 oils, p. 58). 



DIPENTENE. 



The presence of dipentene in wood turpentines and its absence in 

 gum turpentines is another difference. The refined turpentines ob- 



