EVALUATION OF ANTIPERSPIRANTS UNDER NORMAL CONDITIONS 21 treatments. (This effect was not quantitatively assessed owing to lack of post-treatment data.) TEST PREPARATIONS Although there are many potential antiperspirant agents available, aluminium chlorhydrate is the only one in widespread commercial use. It was decided, therefore, that at this stage only aluminium chlorhydrate would be evaluated, and its performance from different bases compared. The following were the products tested. Test An aqueous solution containing by weight 25• aluminium chlorhydrate and 30• Industrial Methylated Spirit, which was thickened to an appro- priate viscosity with hydroxyethyl cellulose. The product was dispensed from a bottle with a roll-ball applicator. Test 2 An experimental aerosol preparation, where the concentrate was a W/O emulsion. The aqueous phase of the emulsion consisted of 50• aluminium chlorhydrate solution, and this was emulsified into light mineral oil. The phase ratio of the emulsion was 80: 20 water/oil. The emulsion was dis- persed in propellant 12/114 in an aerosol giving an overall concentration of 11.0• aluminium chlorhydrate and 5.5• mineral oil on can contents. Unlike other aerosols the aluminium chlorhydrate in this product is deposited on the skin in aqueous solution. Test 3 A leading brand of aerosol antiperspirant believed to contain 3.5• aluminium chlorhydrate powder, suspended in an emollient, and dispersed in aerosol propellant in conjunction with a silica suspending agent.