648 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS (9) Hamilton, J. B., J. Clin. Endocrin., 1, 570 (1941). (10) Poehi, P. E., Strauss, J. S., Rao, G. S., Sarda, I. R., Forchielli, E., and Dorfman, R. I., Ibid., 25, 1660 (1905). (11) S½oggins, R. B., Briefer, C, Jr., and Kliman, B., Clin. Research, 13,282 (1905). (12) Strauss, J. S., and Poehi, P. E., Arch. Derre., 87, 86• (18) Strauss, J. S., and Poehi, P. E., JAMA, 190, 815 (14) Strauss, J. S., and Pochi, P. E., in Greenblatt, R. B., Ovulation, J. B. Lippin½ott, Phila- delphia, 1900.

J. Soc. Cosmetic Chemists, 19, 649-667 (Sept. 16, 1968) Color and Its Measurements* MICHAEL BORNSTEIN, Ph.D. t Synopsis--An account is given for the fundamental principles of diffuse and tristimulus re- flectance measurements. The experimental basis for these measurements, including the CIE and Munsell systems for defining color space, is also discussed. These principles are sup- ported with qualitative and quantitative examples for color matching, as well as interaction studies with reflectance values and the Kubelka-Munk equation. A review of several availa- ble commercial color measuring devices, reference standards, and sample preparation tech- niques are also presented. INTRODUCTION The stability and appearance of colored cosmetic and pharma- ceutical dosage forms are dependent on the dye or lake employed, as well as many other parameters. These may include adjuvant absorp- tion coefficients of microscopic and macroscopic structures as well as other physical and chemical properties (1). Although most formulators still rely on empirical knowledge in the subject of color measurement, many articles have appeared with respect to color instrumentation. Swartz and Cooper (2) have reviewed a number of pharmaceutical colorants and their properties. Lachman and associates have applied various parameters to color stability of tablet formulations (3-5). Goodhart, Lieberman, and associates (6, 7) have also studied the stabil- ity of certified dyes in tablets. Raft (8, 9) has presented reports of color measurements obtained from FD&C colorants. The purpose of this communication is to discuss principles and instru- ments used in diffuse and tristimulus reflectance measurements and their application to the development of colored pharmaceutical dosage forms. * Presented October 2, 1967, Sixth Annual A. Ph. A. Industrial Pharmaceutical Techno- logy Meeting, Chicago p Pitman-Moore Division, Dow Chemical Co., Research Center, Zionsville, Ind. 46077. Present address, Eli Lilly & Co., Indianapolis, Ind. 46206. 649