230 BROOKS. 



converting it into pinene nitrolbenzylamine. The fraction boiling from 159° to 

 161°, 35 per cent of the oil, was tested for /3 pinene by the method of Wallach 3 

 and a small quantity of nopinic acid, melting point 121°, was obtained. The yield 

 of nopinic acid was less than 1 per cent. 



The colophony remaining after the distillation of the turpentine consisted 

 almost entirely of abietic acid. No other acid has been isolated from it. A 

 sample of the colophony was crystallized once from dilute alcohol and a yield of 

 90 per cent of crude crystalline abietic acid was obtained. I have found that 

 the yield of crystalline abietic acid which it is possible to obtain depends very 

 much upon whether the turpentine has been removed by steam or dry distillation. 

 A sample of dark brown American colophony when treated in the same manner 

 separated as an oil, which crystallized only after several days, standing in an 

 ice box. 



When the original samples were collected, some of the clear, honey-yellow 

 exudate Mas poured into glass vials and sealed from the air. In two hours 

 crystallization had set in, the mass changing to a white crystalline mixture. 

 On returning to the laboratory the crystals were isolated by spreading 30 grams 

 of the mixture on a porous plate which was then placed in a desiccator filled 

 with hydrogen. After standing one week the crystalline residue remaining on 

 the plate weighed 17 grams. The substance was recrystallized twice from dilute 

 alcohol and it then melted at 128° to 131°. By repeated crystallization from 

 dilute alcohol alone, a melting point higher than 129° to 131° could not be 

 obtained, but by crystallizing fi;om alcohol diluted with strong aqueous hydro- 

 chloric acid, crystals were deposited which melted at 154° to 156° without 

 further recrystallization. The angles of the latter crystals were measured under 

 the microscope and proved to be identical with those given by Mach 4 for abietic 

 acid. Several concordant combustions agreed fairly well with the numbers for 

 abietic acid. 0.1980 gram substance gave 0.5690 gram C0 2 and 0.1760 gram ELO. 



Calculated for C 19 H 28 Oo. Found 

 Per cent. per cent. 



C 79.16 78.40 



H 9.72 9.87 



Klason and Kohler s suggested that abietic acid itself did not occur in turpen- 

 tine oleoresins, but was probably formed from another acid which was very sen- 

 sitive to heat. Wiesner ° states that the substance crystallizing from ordinary 

 turpentine oleoresin is abietic acid. 



In the present state of our knowledge it is impossible to state exactly what 

 abietic acid is. 7 The nomenclature used by different authors is by no means 

 uniform, yet there is no doubt but that the high melting acids, obtained by 

 crystallization from solutions containing hydrochloric acid, are isomers of the 

 original low melting acids. 8 In view of the fact that the properties of the acid 

 obtained by me by crystallizing from dilute alcohol and hydrochloric acid agree 

 well with those of the abietic acid described by Mach, this name is given the 

 preference. 



3 Ann. d. Chem. (Liebig) (1908), 356, 228. 



i Monatsh. f. Chem. (1894), 15, 629. 



5 Journ. f. prakt. Chem. (1906), N. F. 181, 337. 



°Die Rohstoffe des Pflanzenreiches. 2d ed. Leipzig, (1900), 1, 216. 



'Bucher, Journ. Am. Chem. Soc. (1910), 32, 382. 



s Leskiewicz, Journ. f. praJct. Chem, (1910)^ N. F. 81, 411. 



