4 JOURN,A,L OF THE SOCIETY OF COSMETIC CHEMISTS removal of odors. In only one in- stance was i:here odor present after one hour as follows: One case of original OTN of 12.10 showed as much as 8.30 one hour after using the plain dentifrice. On the other hand, there was no trace of odor left one hour after using the chloro- phyll dentifrice. There were 25 cases of presence of odor after two hours with the plain tooth paste and only one after the same length of time with the chlorophyll, tooth paste. After four hours, 33 cases showed an OTN with dentifrice P and 13 with dentifrice C. Qualitatively, dentifrice P com- pletely removed mouth odors in 25 subjects for two hours and in 17 subjects for as long as four hours or respectively 50 and 34 per cent com- plete removal. Dentifrice C com- pletely removed mouth odors in 49 subjects for two hours and in 37 subjects for as long as four hours, or respectively 98 and 74 per cent complete removal. VII. CONCLUSIONS These results are based on close to lOO0 odor measurements made with the osmometer on both types of tooth paste. They demonstrate the superiority of the chlorophyll dentifrice over the plain dentifrice of the same formula, containing in- soluble sodium metaphosphate as a polishing agent, in ability to remove and retard the development of mouth odors. REFERENCES Burgi, E., Co•r.-BL f . Schweiz. •lertze, 46, 446 (1916). Dent. Med. IVochenschr., 48, 1159 (1922). Klin. ItZochenschr., 17, 789 (1930). Schweiz. Med. IVochenschr., 67, 1173 (1937). Ibid., 68, 483 (1938). "Das CMorophyll Mx Pharmakon,"Georg Thimme, Le{pz{g (1932). Grusk{n, B., •lm. f. Snrgery, 49, 53 (1940). Bowers, W. F., Ibid., 73, 37 (1947). Members who have not received Volume II, No. 3, please advise the Editor at once. The issue was printed in England and mailed from there.

HYGROSCOPIC AGENTS AND THEIR USE IN COSMETICS* Bv W. C. GRIFFIN, R. W. BE•RENS, and S. T. CRoss /ltlas Powder Company, 1/Filmington 99, Del. HYGROSCOPIC agents, or humectants, are materials that ex- hibit the property of absorbing water from moist air. They ex- tract water from the air until a given dilution is attained, depend- ing upon the nature of the humec- rant and the amount of moisture in the air. Two conditions may exist when a humectant is being used. First, while the humidity is changing, or has just been changed, the humec- rant or product in which the humec- rant is used, will gain or lose water, at which time the rate of change is of importance. Second, if condi- tions are constant for a suitable time, equilibrium is finally attained, at which time the amount of water held is important. Unfortunately, much of the published data repre- sent a combination of these condi- tions, at times further complicated by loss of the humectant itself. This promotes confusion in the in- terpretation of hygroscopicity data and the choice of humectants. * Presented at the December 8, 1949, Meeting, New York City. DEFINITIONS The three properties of major importance are defined as follows: Equilibrium hygroscopicity is the state or condition that exists when an aqueous solution will neither gain nor lose water at a given rela- tive humidity. In our work this is usually expressed as the weight percentage of water in the solution in equilibrium with the given rela- tive humidity. A single value does not characterize the behavior of a compound rather the values must be expressed as a curve of solids content rs. relative humidity. Dynamic hygroscopicity is the speed with which a compound or its aqueous solution will gain or lose moisture while approaching equilib- rium. Since the rate depends on both the initial and final conditions as well as the exposed area-to- volume ratio, absolute units are usually not assigned and the dy- namic hygroscopicity is expressed in comparison with another ma- terial. Folatility is the tendency of the product to evaporate and may be expressed as weight loss per unit