60 WOOD TURPENTINES. 



of course, small amounts of these substances may be present in the 

 refined wood turpentine. (See p. 52.) 



Since none of these five substances is known to be produced by the 

 rapid oxidation of pinene or of the other terpenes in turpentine it is 

 probable that the composition of the heavy oils in a wood turpentine 

 (due to incomplete separation in refining) is not the same as those in 

 a gum turpentine (produced by atmospheric oxidation). (See p. 52.) 



The heavy oils in destructively distilled wood turpentines probably 

 consist of these same materials, together with some decomposition 

 products of the rosin (rosin oils). 



SPECIFICATIONS FOR WOOD TURPENTINES. 



The comparisons show that specifications for gum turpentine, based 

 on physical properties, would not be applicable to all classes of wood 

 turpentine. Especially would the presence of dipentene make such 

 specifications inapplicable, because dipentene has a lower specific 

 gravity and at the same time a higher boiling point than the terpenes 

 in a gum turpentine. Also it might be desirable to include wood tur- 

 pentines which contain small amounts of low boiling material (No. 3, 

 fig. 33) ; such turpentines would certainly be excluded by any speci- 

 fications based on the properties of gum turpentine. 



It is apparent that, in drawing up turpentine specifications, these 

 variations in composition must be taken into account ; and the method 

 of examination should differentiate (1) between high boiling points 

 due to dipentene, and high boiling points due to heavy oils; (2) be- 

 tween low gravity due to dipentene and low gravity due to adultera- 

 tions; and (3) between low boiling points due to incomplete separa- 

 tion of light oilsj and low boiling points due to the addition of sub- 

 stances not normally present in crude wood turpentines. Such speci- 

 fications can not be definitely recommended at the present time, be- 

 ciuise there is not sufficient information available on the technical 

 value of wood turpentines of various compositions. Meanwhile, 

 however, the method of analysis which is here presented will be of 

 value in determining the composition of wood turpentines, and the 

 various distillation curves will furnish, for comparisons, an idea of 

 the variations possible in authentic wood turpentines. 



