8 BULLETIN 989, U. S. DEPARTMENT OF AGRICULTURE. 



EXAMINATION OF KNOWN SAMPLES. 



In the spring of 1919 samples of pine oil were obtained from all 

 the manufacturers using the steam and steam-and-solvent processes 

 known to the Bureau of Chemistry, as well as from most of those 

 known to be doing destructive distillation. Some of those employing 

 the destructive distillation method were working at the time on crude 

 oils only. From these makers samples of the crude fraction from 

 which the pine oil would be obtained were secured. 



METHODS OF EXAMINATION. 



Specific gravity. — The specific gravity was taken with a Westphal 

 balance at 20° C. 



Distillation. — Distillation was conducted in an ordinary 250 cc. 

 distilling flask, using 50 cc. samples, and was at the rate of about one 

 drop a second. The temperatures are uncorrected. 



Resinous material. — In the case of the pine oil the content of resin- 

 ous material was very small, and it was determined by shaking out 

 the sample with two portions of 25 per cent sodium hydroxid solu- 

 tion, washing the solution twice with ether, acidifying the alkaline 

 extract with dilute sulphuric acid, extracting the resinous material 

 with ether, taking down on the water bath, and weighing. In the 

 case of the wood naphtha and the crude distillates it was determined 

 as directed under " Phenols." 



Phenols. — The total alkali-soluble material, extracted as described 

 under " Resinous material," was steam distilled after acidifying with 

 dilute sulphuric acid, and the distillate saturated with salt and ex- 

 tracted with ether. The ether solution was taken down on the water 

 bath and weighed as phenols. The residue in the distillation flask 

 was shaken out with ether, the ether evaporated off, and the residue 

 weighed as resinous material. With ferric-chlorid solution, all the 

 phenols gave a blue coloration, changing to brown on standing. 

 With solid potassium hydroxid and chloroform, they gave a reddish- 

 purple color, indicating the presence of guaiacol. 



Unpolymerized residue. — Twenty cubic centimeters of exactly 38 N 

 sulphuric acid, in a graduated narrow-neck Babcock bottle, were 

 cooled in ice water ; 5 cc. of the oil to be examined were slowly added 

 and mixed, care being taken that the temperature was kept below 60° 

 C. When the mixture no longer warmed on shaking, it was thoroughly 

 agitated, the bottle was placed in a water bath heated to from 60° 

 to 65° C. for 10 minutes, and the contents were thoroughly mixed 

 by vigorous shaking six times, for one-half minute each time, dur- 

 ing the period. The bottles were then cooled to room tempera- 

 ture and filled with concentrated sulphuric acid until the contents 

 came up to the graduations in the necks of the bottles. They were 



