102 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS antibiotics with high indices of sensitization, as well as of those which are commonly administered systemically even if they should prove effective in eliminating axillary odor. CHLOROPHYLL For the sake of completeness, brief reference should be made to the sub- ject of chlorophyll. Although chlorophyll as a deodorant commanded considerable attention in the recent past, its present position in this picture is probably one of decreasing importance. In contrast to other deodorants, a unique claim has been advanced originally for chlorophyll, or rather for one of its derivatives, viz., that its oral ingestion would reduce or eliminate body odor. This claim is based primarily upon the papers by Westcott (88), and by Montgomery and Nachtigall (89). In view of what is known about the genesis of axillary odor, such a claim would imply the absorption from the gastro-intestinal tract of the chlorophyll derivative, and its subsequent distribution through circulation in such a manner as to permit it, or an active conversion product, to reach the axillary area where it would inhibit bacterial activity or neu- tralize the odor due to it. Frankly, such a concept is difficult to visualize in the case of a compound such as chlorophyll or a chlorophyllin. However, beyond this difficulty, there is the highly controversial matter of its verification. Rapp (90) claims that the oral administration of chlorophyllin can control underarm odor. However, Killian (5) reports that the daily ingestion of chlorophyl- lins failed to prevent the development of malodor in samples of axillary perspiration. The findings of Shelley, Hurley and Nichols (1) were also entirely negative as were those of Brocklehurst (91) and Hopf (9). Where there is an opportunity for the direct contact with odorous material, a distinct deodorant action is in evidence as shown by Killian (5). Thus, the addition to stale perspiration specimens of water-soluble chlorophyllins brought about deodorization as well as reduction of the bacterial counts. It is of interest, although not with direct reference to the subject of this presentation, that chlorophyllins reduce the intensity of malodors originating in purulent infections and in certain other pathologi- cal processes, as reported by Collings (92), Bowers (93) and others. The soluble chlorophyllins show deodorant action on contact only in neutral or alkaline solutions, with the optimum lying in the pH range be- tween 8.0 and 10.5. A pH level of 5.7 or lower is antagonistic to their deodorizing action. This would indicate that the addition to acid-reacting deodorant creams of chlorophyllin is not likely to enhance their effective- ness.

ASPECTS OF ANTIPERSPIRANTS AND DEODORANTS 103 Now what about the mechanism of the deodorant action of chlorophyll or rather of its derivatives? Mitchell (94) atuibutes the effect to oxida- tion, having observed that one mol of chlorophyllin oxidizes three mols of benzyl mercaptan to dibenzyl sulfide, or of methyl mercaptan to dimethyl sulfide. These experiments are in agreement with Killian's who found that dried chlorophyllin reduced the odor intensity of diallyl sulfide and of an aqueous garlic extract, and that sodium copper chlorophyllin deodorized benzyl mercaptan, provided that the pH level was 8 or over. However, Mitchell rejects the possibility of deodorization by chlorophyllin for other chemical categories. Another inquiry into the mechanism of odor reduction by chlorophyllin is the subject of a paper by Hainer (95). In contrast to Mitchell, Hainer presents evidence that chlorophyllin, acting as a collodial polyelectrolyte, is capable of binding "odorants" by physical adsorption and also by chemi- sorption of polar molecules. Among such odorants, not of the mercaptan or other "thio" character, are di-isobutyl ketone, vanillin, trimethyl amine, lemonene, ethyl acetate, n-valeric acid and hexamethylene diamine. Reversible complexing was established for these odorants since they could be libe•'ated again by warming. By contrast, neither the mercaptans nor diallyl sulfide were released by this process. None of these data seem to have any direct bearing upon the primary function of cosmetic deodorants in suppressing the activity upon the skin of odor-forming bacteria. They are given here merely in view of certain claims and representations of questionable relevance made on behalf of certain deodorant preparations, viz., that they must be particularly effec- tive since they suppress the odors of garlic or onion on the skin. As to the practical application of chlorophyllin in cologne sticks, also soaps and shampoos, Barail (96) maintains that, in order to be effective, the concentration of the active ingredient would have to be so high as to stain the skin and clothes a distinct green color. Where this concentration is limited by considerations of the residual color, the deodorant effect is virtually nil. IO•r-ExcH^NOE RESINS A new principle appears to have been introduced into the field of deodo- rants with the work of Thurmon and Ottenstein (97), who showed that certain ion-exchange resins are capable of taking up lactic acid, ammonia and urea of sweat in vitro, thereby suggesting the possibility of removing its offensive odor by means of such materials. Subsequently, Thurmon was granted a patent (98) covering deodorant and antiperspirant composi- tions containing weakly acidic cation-exchange resins. The deodorant effect of these resins is attributed in part to their capacity of adsorbing