312 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS proposed method allows a quick and easy estimation of cysteine in solutions containing amounts as little as 0.3 •gm./ml. The presence of cystine even in concentrations reaching 50 times those of cysteine does not interfere with the procedure. REFERENCES (1) Artigas, J., Buscar6ns, F., and Rodriguez-Roda, C., Alnles real soc. espah. f4s. y qufm. (Madrid), 56-B, 377-8 (1960). (2) Vassel, B., )e. Biol. Chem., 140, 323 (1940). (3) Nakamura, K. and Binkley, F., [bid., 173, 407 (1948). (4) Mentzer, C., •. pharm. chim., 27, 145 (1938). (5) Hazeloop, E., Chimie & inustrie, 33, 325 (1935). (6) Sch6berl, A., Ber., 70B, 1422 (1937). (7) Hellerman, L., •. Arm. Chem. Soc., 63, 2551 (1941). (8) Barnstein, H. D., •. Biol. Chem., 89, 125 (1930). (9) Kolthoff, I. M., and Stricks, W., Atril. C,•em., 26, 366 (1954). (10) Kolthoff, I. M., and Stricks, W., [bicl., 23, 763 (1951). (11) Kolthoff, I. M., and Stricks, W., •. Aim. Chem. Soc., 72, 1952 (1950). (12) Buscar6ns, F. and Artigas, J., Atril. Chim. Atcta, 19, 4343 (1958). (13) Buscar6ns, F. and Artigas, J., [bid., 16, 452 (1957). (14) Artigas, J., Buscardns, F., and Rodriguez-Roda, C.,/lnles real soc. espa•. fis. y qufm. (Madrid), 56-B, 369 (1960). (15) Artigas, J., Buscar6ns, F., and Rodriguez-Roda, C., [3id., 56-B, 373 (1960). EFFECT OF VARIOUS METALLIC IONS ON THE GROWTH O F Penicillium glaucum, Aspergillus niger and Achorion quinckeanum By R. BP. trN and A. MAGGIORA* Presenled at the Conference InternationaL' de la Soci4td Suisse des Chimistes Cosmeticiens, Genbve, /lugust 26-28, Iv •T •s true that the growing of micro6rganisms is dependent on the presence of metal ion traces, it is no less certain th_•t some cations in a specific concentration have the opposite effect. Of the latter, silver is the best known and its antiseptic effect has been used prof- itably for quite a long time. Nowadays in spite of the synthetic disin- fectants and antibiotics, the antiseptic properties of the silver salts are still used. The process of inhibition by metals has been studied mainly on the growth of bacteria, and on Staph. aureus in particular in particular. Here related researches result from several observations. First: when observing the growth of .4chorion quinckeanum on pieces of guinea pig * Depart. of Dermatology (Chairman: Prof. W. Jadassohn), University of Geneva, HSpital Cantonal• Geneva, Switzerland.

EFFECT OF VARIOUS METALLIC IONS 313 skin in vitro, we noticed that when the skin of the animal had been fixed in the culture medium with a nickel clamp the growth of the fungus was checked. Secondly: in the course of our research aimed at finding self-sterilizing tissue, we became aware that tissues impregnated with silver nitrate, blackened by the sun, retained their antistaphylococcic property even after having been through the automatic laundry seven times (Fig. 1). Finally during the past year we have seen three patients suffering from contact eczema due to propyl or methyl p-hydroxybenzoate which are also used as preservative agents in numerous preparations of Figure. 1 .--Tissue pieces after seven washings, on Staphyloeoccus aureus culture. Left, control, right, previously impregnated with AgNOa solution and exposed to the sun. cosmetic and food products. Therefore we have thought it of value, from the thecretical point of view as well as practically, to examine the effect of certain metals on a pathogenic fungus of the guinea pig, •4chorion quinckeanum and on two molds that may be of concern to manufacturers of cosmetic products, Penici//ium glaucum and •4spergi//us niger. TECHNIQUE The culture medium used is BBL Sabouraud Maltose Agar.* The metal salts in the form of chlorides (except AgNOa) are added in aqueous solution while the medium is still warm and liquid. The concentrations are calculated to make the number of metallic ions equivalent and are given in milliatomgrams of the metal in one liter of the culture medium. The controls are •un on the culture medium alone and on the medium with C1 ions (in the form ofHC1)that correspond to the several concen- tratiors. A week after culturing one records the first results and three weeks later one reads the final outcome. This affords the possibility to es- tablish a probable retarding effect on the growth as well as its inhibition. Three culture tubes are used for the test yet, for some slight diverge•- cies the response has been the same in all three experiments. * Baltimore Biological Laboratory Co.