86 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS tests with lower concentrations of formaldehyde showed, as would be expected, heavier growth, but in no case was it more than moderate. At the end of one series of tests using Jaag medium, Atspergillus and methyl p-hydroxybenzoate in concentrations of 0.1, 0.15, and 0.2 per cent, we added 0.1 per cent of a commercial perfume compound dissolved by 2 per cent G-3720 to the group. In two months tubes preserved with 0.1 per cent methyl p-hydroxybenzoate showed a very heavy growth. At a concentration of 0.15 per cent methyl p-hydroxybenzoate, a heavy growth took place in one year. At a concentration of 0.2 per cent methyl p- hydroxybenzoate no growth was discernible at the end of one year. It was of interest to note the profound effect of the nonionic G-3720 on the growth of At. niger in Jaag medium containing Duponol C. At 0.1 per cent concentration of Duponol C alone, tubes were free of growth at the end of one year. When 0.1 per cent G-3720 was added, moderate growth was observed in five months. At a concentration of 0.3 per cent G-3720, and 0.1 per cent Duponol C, heavy growth occurred in four days. When the sodium alkyl sulfate was ethoxylated with 11/2 to 2 moles ethylene oxide, moderate growth was readily noticeable in three weeks. Based on a suggestion made in Geneva in 1957, we used five materials because their main action was fungicidal. Jaag medium was made with 2 per cent G-3720 and variable amounts of the fungicides with the fol- lowing results. Vancide 89 (5) showed a very heavy growth in a 0.01 per cent concentra- tion in thirty days. Isothan Q-15 (6) in 0.1 per cent concentration showed a heavy growth in twenty days. Salicylanilide 0.1 per cent took one hundred fifty days to give a very heavy growth. Rotax (7) 0.1 per cent gave a moderate growth in one hundred twenty days, while TMTD (8) 0.1 per cent has shown no growth for nine months. We find that not only nonionics but other macromolecules inactivate preservatives when tested in Jaag medium. Thus, 0.5 per cent Carbopol 934 (9) containing 0.2 per cent methyl p-hydroxybenzoate shows moderate growth of At. niger in from two to four months depending on the alkali used in neutralizing the material. Cellosize (10) can be preserved with as little as 0.15 per cent methyl p-hydroxybenzoate against At. niger. How- ever, 2 per cent tragacanth in Jaag medium shows slight growth of At. niger in five months in the presence of 0.2 per cent methyl p-hydroxybenzo- ate. Methocel 1500 (11) gives moderate to heavy growth of At. niger in concentrations of 0.1 to 0.2 methyl p-hydroxybenzoate. PVP, two types, shows moderate growth of At. niger in 0.2 per cent methyl p-hydroxy- benzoate after five months. We now have indications that the presence of around 8 per cent ethyl alcohol in the preserved nonionic medium, may retard inactivation of the preservative toward At. niger.

INTERFERENCE OF EMULSIFIERS WITH PRESERVATIVES VIII 87 Another observation indicates that the incorporation of 20 per cent of a quaternary germicide, such as Hyamine 10 X, Roccal or Ethyl CETAB based on the weight of the nonionic, will prevent growth in the presence of 0.2 per cent methyl p-hydroxybenzoate but not in its absence. These tests have now been running continuously for eighteen months. S UM/VfA RY The prevention of inactivation of preservatives by alkoxylated nonionics appears a step closer to solution. The addition of 10 per cent and in some cases less, of ethyl alcohol propylene glycol 1,3-propanediol 1,4- butanediol or 2, methyl 2,4-pentanediol is effective for this purpose against four bacteria and •. ni•er, using 0.2 per cent methyl p-hydroxybenzoate and 2 per cent Tween 80 or G-3720. These results are to be expanded to include other preservatives, nonionics and micro6rganisms. REFERENCES (1) Barr, M., and Tice, L. F., •. •im. P/•arm. •issoc., $ci. Ed., 46, 445 (1957). (2) aleNavarre, M. G., y. $oc. Cosmetic C/•emists, 8, 68 (1957). (3) Pisano, F. E., and Kostenbauder, H. B., Am. Pharm. Assoc., Sci. Sect., Los Angeles Meeting, April (1958). (4) Lach, J. L., Ravel, K., and Blaug, S. M., •. •im. Pharm. •issoc., $ci. Ed., 46, 615 (1957). (5) A brand ooe N-trichloromethylmercapto-4-cyclohexene-l,2-dicarboximide. R.T. Van- derhilt Co., Inc., New York 17, N.Y. (6) A brand of lauryl isoquinolinium bromide, Onyx Oil and Chemical Co., Jersey City, N.J. (7) A brand ooemercaptobenzothiazole, R. T. Vanderbilt Co., Inc., New York 17, N.Y. (8) Tetramethyl thiuram disulfide. (9) A brand of polymethylene carboxvlate, B. F. Goodrich Chemical Co., Cleveland 15, Ohio. (10) A brand of ethoxylated cellulose, Carbide and Carbon Chemicals Div., Union Carbide and Carbon Corp., New York 17, N.Y. (11) A brand of methyl cellulose, The Dow Chemical Co., Midland, Mich.