214 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS In many toilet preparations various nonionics are combined, and in order to investigate the effect of combinations on preservatives, mixtures of various surface-active nonionics have also been tested. Preservatives Investigated Toilet preparations rarely contain preservatives at concentrations above 0.5 per cent, this limitation being imposed by considerations of toxicity, solubility, cost, etc. For this reason not more than 0-5 per cent of preserva- tive was used in any test. The following compounds were assessed: 1. Nipa 82121. Mixed esters (methyl, ethyl, propyl and butyl) of p-hydroxy benzoic acid. 2. Nipagin M. Methyl ester of p-hydroxybenzoic acid. 3. Phenoxetol. /•-phenoxyethylalcohol. 4. Propylene phenoxetol. /•-phenoxypropylalcohol. 5. Parachlorphenoxetol. /•-p-chlorphenoxyethylalcohol. 6. Parachlormetacresol. 7. Hibitane. Bis-p-chlorphenyldiguanidohexane diacetate. 8. Benzalkonium chloride. Alkyl-dimethyl benzyl ammonium chloride. 9. Octaphen. /•-p-tert-octylphenoxyethyl diethyl benzyl ammonium chloride. 10. Cetavlon. Cetyl trimethyl ammonium bromide. 11. Arquad S. Tri-methyl soya acid quaternary ammonium chloride. 12. Armeen Z. N-Coco/•-amino butyric acid. 13. Anti-mould C. Cinnamic aidehyde. 14. Formaldehyde. 15. Hexamine. 16. Monomethylol dimethyl hydantoin (this compound liberates 18.9 per cent of its weight as free formaldehyde). 17. Sorbic acid. 2,4-hexadienoic acid. 18. Benzoic acid. Benzenecarboxylic acid. 19. Sodium benzoate. Sodium salt of benzoic acid. 20. Dehydroacetic acid. 3-acetyl-6-methyl-l,2-pyran-2,4(3H)-dione. 21. Sodium dehydroacetate. Sodium salt of dehydroacetic acid. 22. Ethylenediaminetetra-acetic acid (di-sodium salt). 23. Potassium hydroxyquinolin sulphate. 24. Phenyl mercury nitrate. 25. Phenyl mercury acetate. 26. Phenyl mercury borate. Effects of Nonionics on Preservatives Table I shows the effect of some typical nonionics on the bacteriostatic efficiency of several preservatives. The nonionics were all tested at 2 per

PRESERVATION OF TOILET PREPARATIONS CONTAINING NONIONICS 215 TABLE I Preservative Nontonics at 2 per cent per cent Nipa 82121 0.15 -- -- ++ ++ ++ q_q_ q_q_ q_q_ Nipagin M 0.1 -- -- ++ q_q_ ++ ++ ++ q_q_ q_q_ Parachlor- phenoxetol 0.15 -- -- + ++ ++ ++ ++ ++ ++ P.C.M.C. 0.1 -- -- + ++ ++ ++ ++ ++ ++ Hibitane 0.01 -- -- + + + + + + + Benzalkonium chloride 0.1 -- -- + + + + + + + Octaphen 0.1 -- _ q- q- + + , q-+ +q- Cetavlon 0.1 -- -- + + + + ++ q-+ Cinnamic aldehyde ] 0'01 -- -- ++ ++ ++ ++ ++ ++ ++ Formaldehyde 0.1 Sorbic acid 0.3 Benzoic acid i).2 Sod. benzoate 0.5 -- -- ++ ++ ++ ++ ++ ++ __ Dehydroacetic acid 0.3 -- -- q-q- +q- ++ q-+ q-q- q-q- _ E.D.T.A. 1.0 -- -- ++ ++ ++ ++ ++ ++ ++ Pot. hydroxy- quinolin sulph. 0.1 -- -- ++ ++ ++ ++ ++ ++ ++ Phenyl mercury nitrate 0.01 ......... Phenyl mercury acetate 0.01 .......... Armeen Z 0-5 -- -- +q- q-+ +q- q-q- ++ q-q- _ -- No inactivation. q- ---- Some inactivation. q- q- = Complete inactivation.