BESULTS OF EXAMINATIONS. 15 



by recrystallization from the same solvent. They softened at 145, 

 melted at 155, and were perfectly liquid at 159. 



The fact that the resin acids begin to soften several degrees below 

 their melting point and are not completely liquid until several degrees 

 above it, even when slowly heated, may account, in part, for the 

 diverse melting points recorded. In this work the first appearance 

 of liquefaction has been taken as the melting point. 



A portion of the original rosin was subjected to distillation at 

 reduced pressure. The distillate passing over between 245 and 265 

 C. at 22 mm. solidified to a hard, pale amber mass. After a second 

 crystallization from acetone, snow-white crystals were obtained; 

 these softened at 145, melted at 150 to 151, and became com- 

 pletely liquid at 156. Dissolved in alcohol, they gave the specific 

 rotation, [a] D = 54.29, computed from the values: 



a=-0.72 p=l.Q3 



1= 1 d = 0.8137 



It is important to note that the crystals obtained in the presence of 

 hydrochloric acid melted at 159 to 160, those obtained from acetone 

 alone melted at 155, and those obtained from the rosin distilled under 

 reduced pressure melted at 150 to 151. Schkateloff 1 claims that 

 the various acids described in the literature are but different modifica- 

 tions of abietic (sylvic) acid, and that, according to the treatment 

 given, the acid varies in melting point and crystalline form. His 

 opinion is in part confirmed by the results given in this bulletin. 



CONCLUSIONS. 



From the distillation data it has been estimated that the vola- 

 tile oil of Pinus ponder osa from California contains about 5 per cent 

 Z-tf-pinene, 60 to 70 per cent Z-/?-pinene, and 20 to 25 per cent 

 Z-limonene. The rosin contains about 90 per cent abietic acid. 



Pinus Ponderosa scopulorum Engelm. (Arizona). 

 EXAMINATION OF THE OLEORESIN. 



Two analyses of the oleoresin of the Rocky Mountain form of the 

 western yellow pine (Pinus ponderosa scopulorum) from the Coco- 

 nino National Forest, Ariz., gave the following average: 



Per cent. 



Volatile oil 19.6 



Rosin (grade M, or fourth grade) 75. 



Chips, needles, etc 3. 8 



Water (by difference 2 ) 1.6 



Total 100. 



Monit. Scientif., pp. 217-227, vol. 22, 1908. 2 Determined directly, 1.85 per cent. 



