16 



COMMERCIAL TURPENTINES. 



Variations in amounts of turpentine distilled caused by different barometric pressures. 



[200 cc of turpentine distilled.] 



These results show that in the early stages of the distillation the 

 quantities distilled at the two pressures differed widely; more widely 

 on the turpentine distilling at the lower temperatures and within the 

 narrower limits. As distillation approached completion these differ- 

 ences decreased, becoming negligible when 90 per cent of No. 1 had 

 distilled, but remaining large when 80 per cent of No. 2 had passed 

 over. 



The distillation of normal fresh turpentine, of which more than 80 

 per cent passes over below 165 C. (329 F.), is greatly affected by 

 variations in pressure; and it is quite clear that in obtaining the 

 initial distilling temperature and other distillation data at tempera- 

 tures below 165 C., the pressure should always be the same. As 

 distillation proceeds and the temperature rises the effect of variations 

 in pressure on the total amount of turpentine distilled becomes less, 

 so that ordinarily (that is, on a turpentine 90 per cent or more of 

 which distills below 170 C.) when the distilling temperature rises to 

 170 C. the total quantity distilled at 740 mm or at 780 mm is almost 

 the same, and for all practical purposes the difference may be disre- 

 garded. When the percentage distilling above 170 C. is large, how- 

 ever, as in the case of No. 2, the difference due to the variation in 

 pressure is large and not to be ignored. If it is desired, therefore, 

 to determine the percentage distilled below 170 C. to determine 

 accurately the initial boiling point, or to trace the course of the dis- 

 tillation throughout its entire range, the barometric pressure should 

 always be corrected to 760 mm. 



DETECTION OF ADULTERANTS. 



The majority of the samples, analyzed were examined only for min- 

 eral oils, as these are the principal adulterants employed. Methods 

 for the detection of certain other adulterants were studied, however, 

 and the results obtained will be discussed. Wood turpentine was 

 not detected in any of the samples examined. 



