PIGMENTS Generally speaking, the pigment dyestuffs commercially available pos- sess high tinting strength and very good fastness to light coupled with good to very good fastness to acid and alkali, but with some tendency to bleed in oil and waxes. It is not proposed in this paper to discuss black pigments, since it is believed that the present company will have adequate information about these from their manu- facturers. In closing, I would like to express my sense of the honour you have conferred upon me by inviting me to address you and hope that the talk has been of some use to you all, and, finally, to express my gratitude to the directors of Lewis Berger (Great Britain) Ltd., for permission to give this talk. ADVERTISERS IN THIS ISSUE page STAFFORD ALLEN & SONS, LTD. Wharf l•oad, London, N. 1 ................... Cover iv A BOAKE, I-•OBERTS 8½ GO., LTD. Carpenters l•oad, London, E. 15 ... 140 BRITISH INDUSTRIAL SOLVENTS (A Division of the Distillers Co., Ltd.) 4 Carendish Square, London, \V.1. 134 W. J. BUSH & Co., LTD. Ash Grove, London, E.8. ... Cover iii ANTOINE CHIRIS, LTD. Bridge House, Tadworth, Surrey ... 136 CRODA, LTD. Croda House, Snaith, Goole, Yorks .... ... 242 FIELD & CO. (AROMATICS), L•D. Stonefield Close, l•uislip, Middlesex .................. 243 FIRMENICH 8½ Co., LTD. 414 London [Road, Isleworth, Middlesex ............ Cover ii GIVAIID-kN 8½ Co., LTD. Whyteleafe, Surrey ... 135 HOWARDS OF ILFORD, LTD. Ilford, Essex ...... ... 133 •/[ARCHON PRODUCTS, LTD. Whitehaven, Cumberland ... 137 IN'IPA LABORATORIES, LTD. See under P. Samuelson •_• Co. POLAK • SCHWARZ (ENGLAND), LTD. 50 Great Cambridge l•oad, Enfield, Middlesex ............ RONSHEIM & MOORE (Proprietors: The Gardinol Chemical Co., Ltd.) Grosvenor Gardens House, London, S.W.1 ............... P. SAMUELSON & Co. l•oman Wall House, 1 Crutched Friars, London, E.C.3 ... SSFLOR, LTD. •radsworth l•oad, Perivale, Greenford, Middlesex 138 239 244 241 149

THE EVALUATION OF A SHAMPOO By WM. W. MYDDLETON, D.Sc., F.R.I.C.* THE SHAMPOO user is supremely conscious of one characteristic, foam- iness, which, therefore, above all others, influences his judgment of shampoo quality. The fact of the independence of foaminess and the cleansing action, for which pre- sumably the shampoo is purchased, brings about no relaxation in the general demand for a shampoo which lathers freely. In 'this paper it is proposed to deal with the assess- ment of shampoo value on the basis only of foaming power, which is the veritable sine qua non of the popular shampoo. The evaluation of a shampoo may be required either for the major project of assessing the appeal of the product to the shampoo-using public or for quality control in manufacture and for the selection, grading and blending of raw mater- ials to be used in manufacture. In the present discussion we shall con- sider only the assessment for quality control and examination of raw materials. The ultimate test of shampoo quality must be its per- formance on the head, but, as we shall see, great care must be taken * Chief Chemist, County 12erfumery Co. Ltd., London. in the planning of the test and in the interpretation of the results. In a practical shampoo test we have to decide first of all who is to operate, who is to make the observations, and on what type of head the test is to be applied. Secondly, we must know what observations are to be made, and what conditions of opera- tion will provide the most reliable information. It will be useful for us to examine first of all the nature of the evidence we require to collect. It must cover all those features which the critical user will expect to find in a shampoo, namely: (a) The product must have an attractive appearance. (We are not considering the attrac- tiveness of the pack or its presentation, but of the sham- poo material itself.) (b) It must be simple in applica- tion, for example, if it is a cream shampoo it must be easily extruded from a tube and easily spread on the hair. If a powder, it must dissolve readily without scattering irri- tant dust. (c) There must be no failure to foam on the first application, 150