•:,:-: ß PENETRATION AND COMPLEX-FORMATION IN MONOLAYERS 393 •g!3:: !': I. H., and Stewart, H. C., ]roe. Roy. Ross, S., and McBain, J. W, Ibid., 68, '?f•f• 7•oc., 184A, 102 (1945). 296 (1946). ß '(10) Schulman, J. H., and Cockbain, E.G., (17) Harkins, W. D., Mattoon, R. W., and ' :i•i:': ' I Trans. FaradaySoc.,36,651,661 (1940). Corrin, M. L., Ibid., 68, 220 (1946). ii$}ii:(l ) Alexander, A. E., and Schulman, J.H., Matloon, R. W., Stearns, R. S., and Ibid., 36, 960 (1940). Harkins, W. D., y. Chem. _Phys., 15, •)' '•i/!}.11:"i i2 ) Schulman, J. H., and Friend, J.A., 209 (1947). Harkins, W. D., and Mir- unpublished work. telman, R., y. Colloid Sci., 4, 367 (1949). :i•?!:(13) Schulman, J. H., and McRoberts, T.S., (18) Schulman, J. H., and Hoar, T. P., Na- • •: :. Tran. Faraday Sot., 42B, 165 (1946). Schulman, J. H., and Friend, J. A., un- (19) !?•ublished work. mess, K., and Gundermann, J., Ber., 70, (20) 1800 (1937). Hess, K., Kiessig, H., and Philippoff, W., Naturwiss., 26, 186 (21) (1938). Hess, K., and Kiessig, H., Chem. Bet., 81, 327 (1948). (22) McBain, J. W., and O'Connor, J.J., (23) .7..fro. Chem. Soc., 62, 2855 (1940). lure, 152, 102 (1943). Schulman, J. H., and Riley, D. P., y. Colloid Sci., 3, 383 (1948). Schulman, J. H., and Friend, J. A., Ibid., 4, 497 (1949). Matalon, R., and Schulman, J. H., y. Coil. Science, 4, 689 (1949). Matalon, R., unpublished. Wolstenholme, G. A., and Schulman, J. H., Trans. Faraday Soc. (in press). ::: ,

A sIMPLIFIED METHOD FOR DETERMINING THE APPROXIMATE BACTERIOSTATIC POTENCY OF CHEMICALS* By ARTHUR •R. C^DE, Ph.D. Research oea3oratories, Givaudan-Delawanna, Inc., Delawanna, THE l'OX30SE or this pres- entation is threefold: (a) to pre- sent a general outline of the phe- nomena of bacteriostasis as it is understood and' employed at the present time (b) to show where and how bacteriostasis is applied in a practical way and (c) to show how its relative effectiveness, as exhibited by different chemicals, is determined. DEFINITIONS In order that it may be more clear as to what we are talking about, and especially because the terminology as used in the literature is somewhat confusing, we are pre- senting here definitions of some of the terms as we shall employ them. First, we will endeavor to make a clear distinction between the terms germicidal action, antisepsis, and bacteriostasis. These words have become used to designate situations which overlap considerably. For example, many so-called bacterio- static conditions are not truly * Presented at the May 20, 1949, Meeting, New York CitY. 39'1- "static" ones, but rather situations in which the functions assumed to be static are merely retarded in their speed of activity such that the end result is the same as though they were truly static. Likewise, the word antiseptic has become so badly misused as to mean almost anything, covering the whole range from truly bacteriostatic action down to truly germicidal efforts should be made to discontinue its use for defining purposes other than for its original meaning. Literally it means "against sepsis" and, therefore, describes a situation wherein putrefaction (or other forms of decomposition) of the substrate has been prevented. It will be noted that antisepsis refers to a con- dition in the substrate (i.e., outside of the bacterial cell) brought about by certain activities of the cell whereas, germicidal and bacterio- static conditions are situations within the cell itself. It is thus pos- sible to have bacteria present and growing in a substrate (e.g., a cos- metic cream), yet at the same time to have an antiseptic situation exist,