COMPATIBILITY STUDIES OF ALUMINUM TABLE II (CosT•SVEI) 319 Chemicals Corn- Expo- posi- sure tion Time, % days Observations Expo- Weight sure Loss, Phase gin. Fluorocarbon 11 22.5 160 Fluorocarbon 12 22.5 Ethyl alcohol (95%) 45 Water 5 Fluorocarbon 11 25 41 Ethyl alcohol (95%) 22.5 Water 52.5 Fluorocarbon 11 25 218 Ethyl alcohol (95%) 22.5 Water 52.5 Pitting--sediment Liquid 0.0064 Extensive pitting Vapor 0.0789 No evidence of corrosion Liquid ... No evidence of corrosion Vapor ... Extensive pitting Liquid 0.1764 Few shallow pits Vapor 0.0004 the corrosion for periods of one or two months, after which extensive corrosion began to appear in the form of widespread pitting of the surface. RETARDATION STUDIES WITH VARIOUS INORGANIC AND ORGANIC SALTS IN MIXTURES OF FLUOROCARBONS, ETHYL ALCOHOL AND WATER Many interesting observations are recorded in Table III which demon- strate that certain combinations of inorganic salts show remarkable retardation effects when dissolved up to the limit of their solubility in fluorocarbon, alcohol and water solutions. In many cases it was necessary to have extra water present beyond that contained in the 95% ethyl alcohol in order to dissolve sufficient quantities of the salts. The salts can be divided into three classes based on their retardation effectiveness. These classes are: (a) additives which effect complete or almost complete retardation, (b) additives which offer no significant retardation, and (c) additives which actually seem to increase the degree of corrosion. The results from Table III indicate the following chemicals offer the most promise as retarding additives: EFFECTIVe RETARDERS Chemical Longest Period of Test 1. Sodium citrate (Na3C6H•O,. 2H20) 946 days Sodium nitrate 2. Sodium citrate (see above) 146 days Sodium benzoate 3. Sodium citrate (see above) 311 days Sodium phosphate (NaH2PO4.H•O) 4. Sodium phosphate (see above), 387 days Sodium citrate (see above) Sodium nitrate 5. Sodium tetraborate (Na•B40•. 10H•O) 387 days .Sodium metasilicate (Na•SiOa. 9H•O) Sodium nitrate

320 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS o o c• o o I + + + + • • I + + I + + I • • q_ q- + + + +