A new colorimetric method of analysis for acrolein has the advantages over previous methods of a spectrally purer color with e maximum in the absorption curve, a colorless blank, and greater specificity. The method is based on the color produced by the condensation of acrolein with tryptophane Induced by concentrated hydrochloric acid, and is capable of detecting quantitatively as little as 15 micrograms of acrolein. The method is suitable for quantitative work only in the absence of other aldehydes, unless their concentration is relatively much less than that of the acrolein.

The time of the year at which the oleoresin was collected seems to have exerted little or no effect upon any of the physical constants of the turpentine obtained, provided that fairly large samples only are considered.Work is now in progress having for its object the determination of the physical and chemical characteristics of the samples of rosin obtained during the investigation. AcknowledgmentThis investigation is being carried out in cooperation with the Industrial-Farm Products Division, Bureau of Chemistry and Soils, United States Department of Agriculture, Washington, and is under the immediate supervision of F. P. Veitch. Acknowledgment is made to him for many helpful suggestions. The authors are indebted also to C. F. Speh, secretarymanager of the Pine Institute of America, for assistance and suggestions. They desired to express especial appreciation to Lenthall Wyman, in charge of the Southern Forest Experiment Station at Starke, and to Harper, Busch, Pease, and Olsen, of the station staff, who have made the individual tree studies, photographed the trees, and performed all field work in connection with the project. Literature Cited(1) Betts, XJ. S. Forest Service, Bull. 116 (1922).(2) Herty, C. H., Ibid., 90 (1911).(3) Herty, C. H., unpublished work. (4) Herty and Dickinson,

source of nicotinic acid activity. In patent flour the relation of thiamin and nicotinic acid is similar, since both contain approximately 10 per cent of the whole wheat total. However, because thiamin is more concentrated in the tissues represented by the second clear flour, red dog, and shorts, longer extraction flours will not show the large increases in nicotinic acid activity that they show in thiamin.

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