ASSIMILATION OF INGREDIENTS BY MICROORGANISMS 86.5 whether it was at the near end of the chain or at the far end. For any given carbon number, the degradation was slower with increased branch- ing. As mentioned previously, this study was not carried out using' com- pounds having the same carbon number, but by using branched-chain compounds and increasing the length of the branched chain so that the microbial assimilation could be retarded. Our conclusion is in agree- ment with the general findings on branched-chain derivatives utilization by microorganism. ACKNOWLEDGMENT The authors wish to express their sincere thanks to Professor M. Nakano, Faculty of Agriculture, Meiji University, for his useful sug- gestions during this study. They also wish to acknowledge the technical assistance of Mr. T. Sakamoto, Mrs. Y. Hirano, and Miss Y. Dobashi. (Received May 26, 1971) REFERENCES (1) Thijsse, G. J. E., and Zwilling de Vries, J. T., The oxidation of straight and branched alkanes by Pseudornonas strains, Antonie van Leeuwenhoek, 25, 332 (1959). (2) Takahashi, J., The utilization of hydrocarbons by microorganisms, J. Agr. Chern. Soc. Jap., 41, R27 (1967). (3) Barua, P. K., et al., Comparative utilization of paraffins by a Trichosporon species, Appl. Microbiol., 20, 657-61 (1970). (4) Walters, A. H., and Elphick, J. J., Biodeterioration of Materials, Elsevier Publishing Co., Ltd., New York, 1968, pp. 48-52. (5) Swisher, R. D., The chemistry of surfactant biodegradation, J. Amer. Oil Chem. Soc., 40, 648-56 (1963).

]. Soc. Cosmet. Chem., 22, 867-877 (December 9, 1971) Distribution Cosmetics. Determination of Particle Size of Selected Aerosol II. Cascade Impactor Use in Fluorometric and Weight- by-Difference Methods* JOHN J. SCIARRA, Ph.D., and DAVID ADELMAN, M.S.* Presented May 24-25, 1971, Seminar, Washington, D.C. Synopsis--This report describes the evaluation of two methods of analysis which can be used in conjunction with the CASCADE IMPACTOR when dctermining the PARTICLE SIZE DISTRIBUTION of AEROSOLS. The Cascade Impactor was employed to separate and classify areosol particles into the 0.5-, 1-, 4-, 8-, 16-, and 32-/z range. A series of determina- tions was carried out to ascertain the acceptability of a WEIGHT-BY-DIFFERENCE method and a FLUOROMETRIC method for determining the amount of product deposited at each stage. Two different hair spray formulations and two suspension-type aerosols were used. Findings showed that the fluorometric method produced results similar to the weight-by-dif- ference method, with the added advantage of being less time consuming. Solids of known particle size distribution were used for those aerosols containing insoluble material. In this manner, a comparison could be made between the known particle size distribution of a material and the particle size distribution determined by both of these methods. The re- sults indicated that this procedure was applicable for the determination of the particle size distribution of aerosols having particles in the range of 0.5 to 32 tz. • Abstracted in part from a dissertation submitted by David Adelman to the Graduate Division, St. John's University, College of Pharmacy, in partial fulfillment of the require- ments for the Master of Science degree, June 1970. t st. John's University, College of Pharmacy, Jamaica, N.Y. 11432. 867