PRESERVATION OF TOILET PREPARATIONS CONTAINING NONIONICS 217 TABLE II FORMALDEHYDE (all media adjusted to pH 7) Formaldehyde Formaldehyde q- 6% Nonionic 0.05 0.01 0.005 0.001 0.05 0.01 0.005 0.001 % % % % % % % % staph. a -- -- +++ +++ -- ++ +++ +++ albus b -- -- ++ +++ -- + ++++++ Strep. a -- -- ++ +++ -- + +++ +++ bovis b -- -- -- +++ -- -- ++ +++ Ps. a -- -- ++++++ -- +. ++++++ fll•or- -- escens b -- -- q-q-q- q-q-q- -- -- q-q-+ q-q-q- -- Proteus a -- -- + + + + -- -- + + + + vulgaris b -- -- -- +++ -- -- -- +++ %%% Gram Gram TABLE III BENZO!C ACID Owing to the fact that this preservative is only fully active at pH 5.5 and below, the pH of the test media was adjusted to 5.5. All four test organisms were found capable of virulent growth in 24 hours in nutrient broth adjusted to pH 5.5 in the absence of any preservative. Benzoic Acid Benzoic Acid q- 6% Nonionic 0'2 0.15 0-1 0.05 0.2 0.15 0.1 0'45 % % % % % % % % S tap h. a -- q- q-q- q-q-q-, -- q-q-q- q-q-q- q-q-q- albus b -- -- q-q- q-q-q- -- q-q- Strep. a + ++ ++ +++: ++ ++ ++++++ bovis b -- + ++ +++ + ++ ++++++ 9-- Ps. a -- -- +++ +++ -- +++ +++ +++ fluor- escens b -- -- +++ +++ -- ++ +++ +++ Proteus a -- -- -- ++ -- + + ++ vulgaris b -- -- -- ++ -- -- + ++ Gram /// GramS ///

218 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS •D • * oo