14 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS though the amino-acids themselves are only of limited importance in this respect. IMPROVED WASHING SIMULATOR Smeenk was prompted to resume the washing experiments with an improved washing simulator, in which the mechanical forces during the washing procedure could be more uniformly regulated (Figs. la and lb). Since the method was now more sensitive, it could be proven that solutions of all five detergents washed out more amino nitrogen than water alone, and that there were differences between the five detergents tested. The same holds for the estimation of the materials that react positively with the Folin-Ciocalteu reagent. This reacts both with the free amino acids tryptophane and tyrosine, and with the same radicals when included in protein molecules. About the nature of the F.C. positive substances in the washing fluid I can give you the following information: In 1966, Vermeer et al (16) claimed that all substances present in the washing fluid that react positively with the Folin-Ciocalteu reagent are free amino acids, because he failed to find proteins in the washing fluid. Smeenk, however, proved in the following manner that proteins are also washed out. When washing fluid (containing the amino acids) is filtered through a pressure filter arresting proteins with a molecular weight of more than 10,000 and the residue is hydrolysed, amino-nitrogen can again be proved to be present with the [•-naphtho-quinone 4-sulphonic acid reagent. Table VII Elution results with modified washing simulator pH Amino N. (T/mil) F.C. positive material (¾/mil) mean (n---- 12) mean (n-• 12) -- water 2.7 water 20.1 T 3 34.2 5.7 7.8 5.8 T 3 4.9 T• 5.8 T 1 6.1 T 5 47.6 T 1 47.8 9.5 T O 6.8 T O 55.2 10.2 T 6 7.1 T 6 61.5 The new washing simulator--unlike the one we had used originally-- made it possible to distinguish between various detergents both in respect to their capacity to wash out amino acids and to elute "soluble proteins". The results are shown in Table VII.

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