SOCIETY OF COSMETIC CHEMISTS OF GREAT BRITAIN 233 in a specification. Since precision bore glass tubing is now readily obtain- able the apparatus can be accurately reproduced. In control work it is sufficient to time the arrival of the sample at two or three points along the tube, but the non-Newtonian character of the flow is best seen from a complete curve of distance against time. Designed by Dr. B. D. Sully. Exhibited by Mr. G. 3/1. Howard. . SENSITIVE INIEPHELOMETER. This instrument works in the range of low light scattering and although it was originally designed for biological work it is also very suitable for testing the clarity of high-quality tiltrates. Designed by Mr. N. V. Needham of the Cooper Technical Bureau. Exhibited by Mr. E. J. Miles. GLUE JELLY TESTING APPARATUS. This instrument was designed as a simplification of the Standard Bloom Gelometer against which it can be readily calibrated to give values in standard units. Designed by Mr. R. Barry Drew of British Glues and Chemicals Limited. Exhibited by Mr. E. J. Miles. OPTICAL ANISOTROPY VIEWER. This is a simple and convenient means of examining liquids for streaming birefringence in colloid systems. Designed by Dr. P. A. Winsor of the Shell Chemical Company. Exhibited by Mr. E. J. Miles. PHOTOMETER. Many cosmetic products are dispersions of one phase in another as, for example, liquids in liquids giving emulsions or solids in liquids giving suspensions. When light is passed through a thin film of a dispersion, it is scattered by an amount depending on the phase volume relationship, the degree of dispersion and the difference between the refractive indices of the dispersed and the continuous phase. For a system of constant composition, the amount of light scattered will therefore be determined by the degree of dispersion of the discon- tinuous phase. Thus, provided the droplets are not of colloidal dimen- sions, an emulsion in which the droplets are finely dispersed will scatter

234 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS more light than one in which the droplets are coarsely dispersed. Therefore, when light is passed through a thin layer of an emulsion, the amount of light transmitted will be determined by the size and size distribution of the droplets in the emulsion. The simple Photometer which is demonstrated consists of a hght source, a cell of standard thickness and a photo-electric cell. The meter is set at 100 per cent transmission without any sample in place and the reading then taken with the sample in position. In general, the lower the amount of light transmitted, the finer will be the emul'sion. This reading is an average which cannot distinguish between the various possible particle size distributions. It should therefore be used in conjunction with a microscope in order to assess the effect of the varying particle size distributions in the experimental systems. The instrument thus forms, for a system of constant com- position, a rapid quality control check on the average degree of homo- genisation or dispersion of many two-phased dispersions. Exhibited by Dr. A. M. Posner. o ROTATING CUP VISCOMETER. The apparatus shown is a modification of an oscillating disc vis- cometer in which the cup is rotated on a constant speed. The sample is carefully placed into the cup and the disc gently lowered into it and covered with the cream. The disc is then attached to the weighted bob at the lower end of the torsion wire and the motor switched on. The maximum deflection on the scale is noted and this gives the approximate measure of the yield point. The way in which the viscosity changes with time may then be determined by reading off the values of varying times. If necessary, the instrument may be calibrated using liquids or systems of known viscosity. Exhibited by Dr. A. M. Posner. . HAIR STRETCHING MACHINE. It is often necessary to assess the changes in the mechardcal strength of hair brought about by various treatments. This can be most simply done by the apparatus described below: The apparatus consists of a balance beam, to one end of which is attached the hair to be stretched, the other end being loaded at a constant rate by a varying length of chain. The change in the length of the hair and the load applied are recorded by means of a pen or• the drum at right angles to one a_aother. The curve produced is a load/extension curve. The ler•gth of the initial straight line portion of the curve, the