54 WOOD TUKPENTINES. 



were therefore probably due to the presence of some materials other 

 than terpenes, with boiling point, gravity, and index of refraction not 

 much different from the terpenes; the only strong indication of the 

 presence of materials other than terpenes was in the high index of 

 refraction of the first 30 per cent. From the method of production 

 of this turpentine, these other materials can only be high-temperature 

 decomposition products of wood fiber or of rosin. Decomposition 

 products of wood fiber could not be present in very appreciable 

 proportion, because the oils from this source, which would be in- 

 soluble in caustic soda, with boiling points 155 to 180, and gravity 

 in the vicinity of 0.85 to 0.87, are extremely small in amount. The 

 destructive distillation of rosin, however, will yield yellow oils 

 answering these requirements; the odor of these rosin oils (rosin 

 spirits, rosin naphtha) is very similar to the fractions of this de- 

 structively distilled wood turpentine, and it is likely that the peculiar 

 odor and color of destructive wood turpentines are due largely to the 

 presence of " rosin spirits." 



These comparisons of composition show that most wood turpen- 

 tines will be sufficiently different in composition from gum tur- 

 pentines, so 'that the method of analysis used in these investigations 

 will readily distinguish between them; a wood turpentine produced 

 from green timber at such low temperatures that no dipentene is 

 formed and so refined that no heavy oils are present is, however, very 

 similar to a gum turpentine; that is, the terpenes present in the 

 wood from freshly cut long-leaf pine are very similar to the terpenes 

 in the oleoresin obtained by chipping the live tree. The boiling 

 point, the specific gravity, and the index of refraction curves from 

 the two turpentines do not differ greatly, but these properties seem 

 to be slightly lower in the fractions from the wood turpentines (com- 

 pare figs. 2 and 37) . This difference is, however, not great enough to 

 provide a sure means of distinguishing between the two kinds of 

 turpentines, since a gum turpentine with low values might be almost 

 the same as a wood turpentine with high values. It is probable, 

 therefore, that the same constituents are present in each, but that 

 more of the higher boiling and higher gravity terpenes are generally 

 present in the gum turpentines. 



ODOR. 



There is a considerable difference in odor between the gum turpen- 

 tines and the wood turpentines, even between those which are nearest 

 alike in composition. In most cases, however, this difference in odor 

 is not due to differences in the main constituents. For instance, in 

 the refined turpentine from No. 4 the main constituents are probably 

 the same as in the gum turpentine shown in figure 2, and yet there is 

 a decided difference in the odor of these two turpentines, Even the 



