20 



WOOD TUKPENTINES. 



dilation curves there are all the evidences of better fractionation, 

 i. e., lower values for the physical constants of the fractions over the 

 first part of the distillation, more nearly vertical curves, and sharper 

 breaks in the direction of the curves. On account of the better frac- 

 tionation it is possible to judge the composition of the turpentine with 

 a considerable degree of accuracy and it apparently contains very 

 nearly 80 per cent of pinene, the remainder being heavy oils with all 

 the physical properties much higher. From the steam-distillation 

 curves, on the other hand, it would be impossible to make an accurate 



judgment of the propor- 

 tion of pinene present in 

 the turpentine, because 

 the separations are so in- 

 complete and the curves 

 change direction so grad- 

 ually. This distillate is 

 practically pure pinene 

 up to about 70 per cent, 

 but for some distance be- 

 yond that point it is an 

 indefinite mixture of pi- 

 nene with heavier and 

 higher boiling materials. 

 Similar distillations 

 were made on another 

 kind of turpentine (re- 

 fined turpentine No. 5) 

 giving even more striking 

 differences in the separa- 

 tions obtained. Figure 7 

 shows the results obtained 

 by fractionation of three 

 samples of the same tur- 

 pentine (1) by steam dis- 

 tillation with a Geer 

 dephlegmator, (2) by direct distillation without a dephlegmator, 

 and (3) by direct distillation with a Le Bel-Henninger dephleg- 

 mator, the three sets of curves being plotted together on one sheet 

 for easier comparison. The curves obtained by steam distillation 

 with a dephlegmator, and by direct distillation without a dephleg- 

 mator show very simlar characteristics; there are no rapid 

 changes in direction until about 90 per cent is reached and then 

 there is a rapid increase in all the physical constants; that is, 

 these curves indicate about 90 per cent pinene and about 10 per 

 cent of material with all physical constants higher. The curves ob- 

 tained by direct distillation with a dephlegmator are, however, quite 



96 97 98 99 BOILIM6 FOIMT-5TEAM DISTILLATION 



JBG. ^- 9 .89 .90 5PEC1RC SCAVITY AT I5"C. 

 TON. 1410 1412 UT4M16U18W80 U8Z L4. 



FIG. Q. Comparison of fractionation obtained by 

 steam distillation with a Geer dephlegmator and 

 direct distillation with a Le Bel-Henninger 

 dephlegmator. 



