METHODS OF TESTING A GERMICIDE 251 manufacturer but to the consumer. (1) Schwartz., Louis, and Peck, Samuel M., "Cosmetics and Dermatitis," Paul B. Hoebet, Inc., New York (1946). (2) Sulzberger, Marion B., "Dermatologic Allergy," Charles C. Thomas (1940). (3) Rostenberg, A. J., "Studies on Eczema- tous Sensitization," •7. I•vest. Derm.• 8,345 (1947).

METHODS OF TESTING A GERMICIDE INCORPORATED IN SOAP* By EuG N. F. TauB, M.D. New York, N.Y. OUR STUDIES on this problem extended over a number of years and totaled in the neighborhood of 200 washing experiments. The com- pound studied was 2,2'-dihydroxy- 3, 5, 6-3',5',6'-hexachloro-diphenyl - methane, hereafter called for brevity "G-11." Before the preparation had been submitted to us, various in vitro studies had been done using the F.D.A. standard tests for germi- cides as outlined in Circular 198, U.S. Department of Agriculture. Also the wet filter paper technique described in the same pamphlet had been done and the rate of killing of the organisms had been studied. The phenol coefficient had been de- termined and the effect of the com- pound in the presence of serum had been studied. In view of the favor- able reports, the next question that it was .necessary to settle was whether or not the preparation was a skin sensitizer. We performed a series of over 200 patch tests using * Presented at the May 19, 1948. Meeting of The Society of Cosmetic Chemists, in New York City. 0.5 per cent G-11 in petrolatum and 1 pe, r cent G-11 in petrolatum, al- lowing the closed patch .tests to re- main on the skin for forty-eight hours. As the results were negative, the preparation did not seem to be a primary irritant. The same sub- jects were then re-tested ten days to two weeks later at approximately the same sites. Similar tests were allowed to remain in place for forty- eight hours, and were read. The readings were all negative, indicat- ing that G-11 was non-irritating to. the skin and was not a skin sensi- tizer. Subsequently, several hundred more patch tests were done with similar results. A hand-washing experiment was then done. The procedure was described in detail as follows: ß Hands were rinsed with 70 pe•.r cent alcohol (by weight) and allowed to dry in air. One cubic 5.½ntimeter of 24-hour culture of F.D, A. si•and- ard strain of Staphylococcz•'s, 'a•reus was added to the palm of one hand,. and cultm e was spr•ead'•)• er.the surface by means of a sterile tooth