632 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS Table V Increase in Bubble Size Range with Age of Foams from Aqueous Triethanolamine Myristate/Mineral Oil/Freon Propellant Systems Aqueous Concentrate Method of preparation TEA/MA ratio Diameter range of emulsified droplets (t•) Aerosol Emulsion Diameter range of emulsified droplets Aerosol Foams Dianaeter range of bubbles with age (t•) 1 rain 2 rain 5 rain 10 rain I 14 I 14 Excess Excess Excess Excess MA MA TEA TEA 2--5 • 2--35 • 2--70 15--190 ( 2-40) ( 2-40) (Rough (Rough estimate) estimate) 2-8O • 2-120 10-80 10-115 15-140 20-175 20-140 25-170 25-215 20--245 30-205 35-220 65-360 50-410 55-265 50-275 110-600 95-• 700 Figure 3. Increase in bubble size xvith age of foams from the best aqueous triethanolamine myristate/mineral oil/Freon propellant aerosol enmlsion xvith excess myristic acid Top left. I min right, 2 min Bottom left. 5 rain right, 10 rain Effect of Discharge of the Aerosol Emulsion The rango of droplet sizes of the dispersed propellant in an aerosol emul- sion has been shown to decrease as the product is discharged (1). This also occurs when the propellant/mincral oil emulsions are discharged as shown by the data in Table VI and the photomicrographs in Fig. 4. The change is

AEROSOL EMULSIONS AND FOAMS Table VI Ellect of Discharge upon Droplet and Bubble Size Ranges from Aqueous Triethanolamine Myristate / Mineral Oil / Freon Propellant Systems Aqueous Concentrate Method of preparation 1 14 1 14 TEA/MA ratio Excess MA Excess MA Excess TEA Excess TEA Aerosol Emulsions l)iameter range of emulsion droplets 5% discharge 2-40 2-40 2-80 2-120 75% discharge 2-30 2-30 2-60 2-110 Aerosol Foams Diameter range of bubbles 5% discharge 10-80 10-115 15-140 20-175 75% discharge 10-140 10-125 10-180 20-225 Figure 4. Effect of discharge upon the best and poorest aqueous triethanolamine myristate/ mineral oil/Freon propellant emulsions with excess triethanolamine Top left. Best aerosol enmlsion after 5% discharge right, best aerosol enmlsion after 75% discharge Bottom left. Poorest aerosol emulsion after 5% discharge right, poorest aerosol emulsion after 75% discharge not as marked as with emulsions containing only propellant as the dispersed phase. This is probably because the concentration of mineral oil in the emul- sions does not change with discharge as does the propellant. The increase in the range of bubble sizes in the foam with discharge is con- sistent with the results previously reported for emulsions without mineral oil (1). However, the increase is smaller when mineral oil is present. Although the range of bubble sizes in the foams increases with discharge, it is assumed that the average bubble diameter decreases with discharge. This was shown