DISCUSSION OF RESULTS. 25 



investigation, even in those produced at atmospheric pressure, and 

 it is very probable that dipentene was present, as such, in the wood. 

 In order to make sure that this material with low specific gravity 

 and high boiling point was dipentene and not some other terpene 

 with similar physical properties, a chemical examination was made 

 of the fractions from 165 to 185 from some of the turpentines pro- 

 duced at atmospheric pressure and dipentene was identified by means 

 of the tetrabromide, m. p., 125-126. 



In order to determine the possibility of the transformation of 

 pinene into dipentene! under the condition of steam distillation, the 

 sawdust from run 29 was air dried and moistened with 1,175 c. c. of 

 gum turpentine (an amount equal to the total volatile oil originally 

 present) and then distilled at atmospheric pressure. The resultant 

 oil, on analysis, showed no indications of dipentene. The experiment 

 was repeated, making the distillation at 50 pounds pressure, but with 

 the same result. These results preclude the possibility of a formation 

 of dipentene from pinene at 50 pounds pressure or less, and indicate 

 strongly that dipentene occurs, as such, in lightwood. 



LIGHT OILS. 



Figures 3 and 4 also illustrate another effect of pressure on the 

 composition of the crude turpentines. In these analyses, as in many 

 others, the crude turpentines produced at pressures as high as 70 

 pounds show a considerably higher value for the specific gravity of 

 the first fraction than do the turpentines produced at lower pressures. 

 This indicates that some substance with low boiling point and high 

 gravity (above 0.870 at 15 C.) is produced at the higher pressures; 

 this substance might come from the incipient stage of a decomposition 

 of some portion of the resin at the temperature to which it is sub- 

 jected. The first fractions from the analyses which contained this 

 substance were slightly yellow and had a peculiar odor. A treatment 

 with caustic soda reduced the gravity of these fractions but deepened 

 the yellow color.- It was found, however, that by the caustic-soda 

 treatment of a turpentine such as that shown in figure 3, followed by 

 a distillation, it was possible to prepare a refined turpentine which 

 showed no abnormality of the first fraction in color, odor, or gravity. 

 The presence of this substance should not, therefore, introduce any 

 difficulty in the refining process. 



Another test for the presence of decomposition products was made 

 on several of J,he samples produced at different pressures by treating 

 the oil with concentrated hydrochloric acid. A red color produced 

 in this way is supposed to indicate the presence of rosin oil. There 

 was only a very slight coloration of the oils produced at atmospheric 

 pressure, but this coloration increased with the pressure, becoming 

 very marked in the oils produced at 50 and at 70 pounds pressure. 



