314 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS •i-.__ Achorion G Peniciltium gl. Aspergittus n. 0,3 1 3 10 30 0,3 ' 1 3 •10 •30 0,3 1 3 t0 30 Li * d- -I- -i- -I- -I- -t- -I- -+ 4- -I- -I- -t- Sr ++ H- H- + -F -F -+ + -+ + d- -F -+ _ ___ AI +*+ -b -F + -- + + -I- -- -k '+ + +--_ Cr *+* -+ -F + -- -k -t- -t- -- + 4 + _+ - Fe *+* + + - _ + + + - + . + + • -- Co +* -+ + -- -- -i- + -I- - + '• -- - ¾ + • - Ni ** -F _ -- -- + _ -- -- -I- - • -- Cu** -+ -• -- -- + + - - + -• - - Zn +* + -t- - - + 4 - - + 4 + - _ Ca ** + .... -• 4 + _ _ 4 + + •F - Au *"•' + + - + 4- -- -l- .+ _ Ag" H- + -- -F + - + '+ -- p.** + -?- _ + - ,. - ß i• t 3 t0 30 90 1 3 10 30 90 1 3 10 30 90 HC• + + + + - 4- + 4- + 4,. + + + + + Plate 1.--+, normal growth, 4-, delayed growth, -- inhibition. RESULTS (SEE PLATE 1) Of the metals that have been examined for inhibiting the growth of /Ichorion, cadmium has been found the most active followed by nickel, cobalt and silver. Some activity has been noticed with zinc, copper, gold, palladium and iron. The Cr +++ and A1 +++ may be rated as inactive, for the control with HCl (90 millimoles) which is equivalent in C1 ions to the concentration 30 of these two salts provides an inhibited culture. (In this case, to make sure, one considers all the molecules hydrolyzed and so an AI+++ ion corresponds to 3 HCl.) The metallic ions most active on Penici//ium g/aucum and Atspcrgi//us niger are first Cd, Ni and Ag, then Co, Zn, Cu, Pd and Au. The other cations tested have but a slight effect. DISCUSSION These experiments show that of the metals that have been examined, cadmium is the most effective. Unfortunately the ions of this metal are known as being markedly toxic to man this limits their possible use as an antifungal agent to some particular cases. Nickel and silver have an equivalent effect, yet the first has an eczematogenic power not to be disregarded which also puts a limitation upon its utilization. Silver, which does not have the unfavorable features of cadmium and nickel, can be used for preserving finished products. The concentration in which it has

EFFECT OF VARIOUS METALLIC IONS 315 ... • :.•: .. • .? "!•,: '.•7. ß ß: :'•- •: • ?-5 Figure 2.--Culture tubes one month after seeding. Left to right: Achorion quinckeanum (3 tubes) Ag + 10/3/1 milliatomgr./liter, Penicillium glaucum (3 tubes) Ag -• 10/3/1 milliatomgr./ liter, ,lspergillus niger (3 tubes) Ag -• 10/3/1 milliatomgr./liter. an inhibiting effect on the fungi is about 100 times greater than the one observed in parallel experiments with Staph. aureus (limit 0.03 milliatom- gram Ag in one liter of broth). The other metals which have been studied, vis., copper and zinc, though less active, can also be used, as they are practically inoffensive and well tolerated by the skin. It is well to call to mind that it may not be possible to transpose into practice the results found in these experiments. On one hand, re- actions could take place between the metallic ions and the substances to be preserved, reactions which might effect a diminution of the antimicrobial power on the other hand the culture medium used for these experiments being very favorable to the growing of fungi, lower inhibitory concentrations might be found adequate in practice. SUMMA RY Experiments in vitro indicate that some metal ions inhibit the growth of zlchorion quinckeanum, Penicillium glaucum and zlspergillus niger. The most active ions are, in decreasing order: Cd, Ni and Ag, Cu and Zn.