8 OLEOKESINS OF SOME WESTERN PINES. 



of abietic acid, such as melting point, optical rotation, and crystal- 

 line form, depend upon the methods by which the crystalline acid 

 has been isolated ; 1 a statement as to the method of isolation is espe- 

 cially necessary when melting points are given. The empirical for- 

 mula of abietic acid has long been disputed. Numerous investigators 

 have advanced the formula C 19 H 28 O 2 , 2 but the weight of evidence is 

 in favor of the formula C 20 H 30 O 2 . 3 



PURPOSE OF THE STUDY. 



Because of the rapid decrease in the supply of longleaf pine and 

 Cuban pine available for the production of naval stores, the Forest 

 Service conducted tapping experiments on several species of western 

 pines to determine their value as a source of turpentine and rosin. 4 

 The oleoresins of these species were examined to determine to what 

 extent they agree with the similar product obtained from the south- 

 ern pines. The investigation was purely a chemical one, and no 

 practical experiments were made to ascertain what value the vola- 

 tile oils would have in the paint and varnish industries. While no 

 one of the oils from the western species agrees entirely with standard 

 gum turpentines, there is no reason to conclude that the oils from sev- 

 eral of the species examined will not serve for various industrial 

 purposes. 



KINDS OF OLEORESINS EXAMINED. 



The oleoresins examined were from western yellow pine (Pinus 

 ponderosa Laws.) grown on the Coconino National Forest in Arizona, 

 and from western yellow pine, digger pine (Pinus sabiniana Dougl.), 

 lodgepole pine (Pinus contorta Loud.), and sugar pine (Pinus lamberti- 

 ana Dougl.) grown on the Sierra National Forest in California. These 

 samples were secured in the fall of 1910. During 1911 the same 

 species were tapped systematically from May to October. The oleo- 

 resins representing the collections of the entire period were analyzed 

 also, and the results were entirely in accord with those previously 

 obtained. Therefore, except in a few instances, the results of the 

 later analyses are not given. However, during the year 1911, pinon 

 pine (Pinus edulis Engelm.) was tapped on the Montezuma National 



* Compare Schkateloff, Moniteur Seientifique, pp. 217-227, vol. 22, 1908, and Leskiewicz, Jour. f. prak. 

 Chem., p. 412, vol. 189, 1910. 



2 Compare Tschirch, Die Harze und die Harzbehalter, 2d ed., pp. 670-671, 1906; Mach, Monatsh. fur 

 Chemie, p. 186, vol. 14, 1893; ibid., p. 627, vol. 15, 1894; Easterfleld and Bagley, Jour. Chem. Soc., p. 1238, 

 vol. 85, 1904; Tschirch and Studer, Archiv. d. Pharm., p. 495, vol. 241, 1903; ibid., p. 5 23; ibid., p. 3, vol. 

 245, 1907. 



3 Compare Valente, Atti della R. Accad. dei Lincei, p. 13, vol. 1 (4), 1884; Fahrion, Chem. Rev. iiber 

 Fett- und Harz-Ind., p. 237, 1898; Levy, Zeit. f. angew. Chem., p. 1740, vol. 18, 1905, and Ber. Deutsch. 

 Chem. Ges., p. 3043, vol. 39, 1906; Vesterberg, Ber. Deutsch. Chem. Ges., p. 121, vol. 40, 1907; Koritschoner, 

 Zeit. f. angew. Chem., p. 642, vol. 20, 1907; and Leskiewicz, Jour. f. prak. Chem., p. 412, vol. 189, 1910. 



* The results of the tapping experiments are given inForest Service Bulletin 116, " Possibilities of Western 

 Pines as a Source of Naval Stores," by H. S. Betts. 



