ANTIPERSPIRANTS :/ tion when ironed) both showed somewhat less damage in the oven test, their positions were reversed. The one which had shown 24% destruction when ironed dropped to lfi%, and the other dropped from aa% to only 12%. These results The net result so far seems to be this: While a well formulated cream will give reasonably compar- able results with the two procedures, we cannot yet conclude that all formulas will show the same degree of progressive destruction by both TABLE 1--COMPARATIVE LOSSES IN TENSILE STRENGTH BETWEEN IRONING FOR 10 SEC. AT 275-295øF. ANt) EXPOSURE IN A HUMIDIFIED HOT AIR OVEN FOR 2 HR. AT 67-70øC. Sample Average Loss Average Loss High Loss High Loss No. Ironer, % Oven, % Ironer, % Oven, % 1 5.99 4.83, 13.46 11,85 2* 8.31 6,68 30.35 14,99 3 1.05 7.51 7.63 9.80 4 7,11 9.12 17.70 17.06 51 24.59 16.11 47.73 27.43 6 32.61 12.44 49.79 27.24 7 100.00 32.58 100.00 37.79 8 100.00 24.73 100.00 58.53 * Slight irregular bleed. t Extensive bleeding. are confusing, and might easily lead to false conclusions on unknown products. We ran a second series of oven tests (Table 2) with no attempt to humidify. Only two formulas, both giving satisfactory results in the ironing procedure, were used, and the destruction at four time inter- vals--30 minutes, 1 hour, 1i/2 hours and 2 hours was determined. While the results with these two products by the ironing procedure--not once but many times--have been so close as to be considered excellent checks, they did not seem to react to the oven exposure quite so uniformly. Formula No. 1 gave very little in- crease in destruction after the first hour--the level rose only four per cent in the second hour. Formula No. 2 showed little increase between 1 hour and 11/2 hours, but jumped 10% between 1i/2 hours and 2 hours. methods. Therefore, we cannot yet adopt the oven procedure as a standard, even if a known satis- factory formula is used as a control. There is too much danger of a false evaluation of an unknown product. Hoping to throw some light on these differences in behavior, a careful study of pH changes under varyifig conditions was made on the eight formulas used in the first oven 'series (Table 1). After the pH of the creams themselves had been TABLE 2--LossEs RESULTING FROM EX- POSURE IN A DRY HOT AIR OVEN AT 100øC. AT VARYING TIME INTERVALS Sample Sample Time No. 1', % No. 2, t % 30min. 9.06 17.62 1 hr. 30.66 40.18 1•/• hr. 34,70 42.74 2 hr. 34.35 52.82 * Loss by ironing procedure 5.99%. l Loss by ironing procedure--8.31%.

4 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS •d o 0 c,') ß