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In all of the above separation procedures, each step was tested for completeness by placing a small portion of the material in question on the phosphoric acid-impregnated paper and treating the spot with ferric chloride. When the mixture being tested was so strongly colored as to mask the color of iron complexes, a small portion of iso-octane was allowed to migrate through the spot, carrying with it any tropolone present and leaving behind the interfering substances.Chromatography. The phosphoric acid procedure of Zavarin and Anderson1 was used throughout most of the work. Sonic streaking tendency of the tropolones wvas still encountered, particularly in the case of nootkatin. Removal of the highly colored, phlobaphenic impurities from the tropolonic fractions seemed to be of utmost importance for control of streaking. Development of the chromatograms at a constant temperature near 21' was also helpful. The streaking was reduced when Whatman No. 3 wm substituted for LVhatman KO. 1 paper.As in the phosphoric acid procedure, the Rf values of nootkatin and hydroxytropolones T-11 and T-10 are rather close. The resolution mas achieved by the dimethylsulfoxide procedure of Wachmeister and Wickberg, le using kooctane as the developing solvent. This method completely separated the three compounds; in addition, nootkatin showed much less tendency to streak.The 5y0 ferric chloride sohtion was mostly used as chromogenic agent. The tendency of the spots obtained to fade with time was overcome by neutralizing the phosphoric acid of the paper with gaseous ammonia. This treatment also regenerated the partially faded spots. The color of the spots Tvas changed characteristically by this treatment.ilnother chromagenic agent used was a solution of diazotized o-aminobiphenyl, prepared by dissolving 0.1 g. of oaminobiphenyl In 0.3 ml. of lOYc hydrochloric acid, t r e a t ing the resulting mixture with 1 ml. of 10% sodium nitrite for 5 min. with stirring, decomposing the excew of nitrous acid with 0.5 g. of urea, and diluting the whole to 10 ml. The solution gave a characteristic purple color with ythujaplicin, and buff to pink colors with the other tropolonee, after the sprayed paper was treated with gaseous ammonia. The diazo compounds of the other amines teated, such aa aniline, benzidine, p-nitroaniline, p-aminobenzoic acid, and sulfanilic acid, were much less stable to the treatment with ammonia, and produced background color which interfered with that of the formed azodyes.For semiquantitative evaluation of the concentration of tropolones in wood, the intensities of the spots containing known amounts of substance were compared visually nith the intensity of the spots from the extracts. Greater accuracy was considered unnecessary because of the natural variation of the tropolone content within the species.Acknowledgment. The authors wish to thank Dr. Nicolas Mirov of the California Forest and Range Experiment Station, Mr.

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