among others, the following points' !i?•11!:?i• • 1. The defatting of the skin pro- duced by synthetics is not the same as true defatting caused by the use of organic solvents. 2. The short chain alkyl naphtha 4 lene sulphonates, which are not good detergents or fat emulsi- fiers, produce the same type of effect on the skin as do the high molecular weight alkyl aryl sulphonates, whereas oleic acid soaps, generally considered to be good fat emulsifiers, do not "dry" the skin. Zussman likens the effect of syn- thetics on the skin to the "scroop" finish to textiles, characterised by a high coefficient of friction and rustle on rubbing. He puts forward the suggestion that the artionic agents should rinse better at slightly alkaline pH's, the cationics at slightly acid pH, and that harshening of the hair, un- manageability, and difficulty in combing after shampooing may very well be the result of increases in friction as a result of absorption of surface active ions on the skin, and that adjustment of pH may over- come these difficulties. The effect of conditioners in sham- poo formulations does not in my experience have much effect on the suppression of harshness produced by some shampoos, notably by anionics having an aromatic ring in their constitution. The aromatic character of these surface •active agents (alkyl aryl) is known adversely to affect lubrication (incidentally, this is also brought out in packaging SYNTHETIC DETERGENTS problems connected with household detergents based on alkyl aryl sul- phonates) and is particularly notice- able at the high concentration used in shampoo techniques, and although considerable work has been done on the additions of conditioners such as nonionic esters, lanolin fractions, etc., the problem of the harshness of the alkyl aryl sulphonates under sham- poo conditions has not yet been overcome (otherwise these are excel- lent and cheap products). Before leaving the question of shampoos, a further point, not directly concerning surface-active agents, is noteworthy--this is the use of small amounts of lime and magnesium sequestering agents of the ethylenediamine tetra-acetic acid type (available as Sequestrene, Irga- Ion, etc.) these are finding applica- tion in the preparation of shampoos based on both soap and some syn- thetic agents, to improve their hard water stability. With regard to the use of the water-soluble and oil-soluble surface- active agents in the preparation of cosmetic emulsions, the number and variety of these products on the market is considerable, the main ones being the fatty acid esters of glycerol, the glycols and condensed glycols, sorbitol and mannitol and pentaerythritols--the products are often available either non-self-emul- sifying, or rendered self-emulsifying by the addition of soap, or anionic products such as sodium lauryl sulphate, or a cationic such as Sapa- mine. The fatty alcohols--cetyl and ceto-

JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS stearyl--are available under various proprietary names, made self-emulsi- fying by the use of anionic or non- ionic products. Many proprietary waxes are sup- plied to the industry for the manu- facture of cold creams, vanishing creams, hair creams, etc., and these often appear to be various mixtures of mineral oils, spermaceti, cetyl alcohol and the like. A fundamental study on emulsion formation which is of both academic and practical interest was carried out by Schulman and Cockbain, and reported in Transactions of Faraday Soc., June 1940. They suggest that interfacial complex formation has a marked stabilising influence on emulsions. They observe that: (1) the emulsifying power of water-soluble paraffin chain salts is increased if amphi- pathic molecules such as cetyl alcohol, oleyl alcohol or chole- strol, are incorporated in the oil phase and (2) the order of effectiveness of combinations of surface-active compounds is in general the same as the order of their tendency to form stable com- plexes at air/water interfaces. This theory satisfactorily explains the practical applications of the Cera Emulsificans B..P. type of pro- duct and its predecessors of the 1930's, as well as the familiar Speakman patent for the addition of oleyl alcohol to wool lubricat- ing oils, to render the oils readily removable from the wool on subse- quent scouring. One interesting practical applica- tion to the cosmetic chemist is the fact, previously pointed out by J. Pickthall in this Journal, that, in the preparation of Empiwax and similar Emulsifying Wax types of emulsion, for example, a stabler and more easily prepared emulsion is obtained by dissolving the fatty alcohol component in the oil phase and the sodium lauryl sulphate in the aqueous phase. TRADE-MARKED PRODUCTS. An endeavour has been made to distinguish trade-marked products by means of initial capital letters. So many of these are mentioned in this paper that it has not been considered practicable to attri- bute them to their proprietors but, should any reader be interested in obtaining further information on this subject, the Honorary Editor will be glad to furnish relevant names and addresses. 216