MONO-ESTER CONTENT OF PROPYLENE GLYCOL MONOSTEARATE •1 slurry is transferred to a simple tube column as described in the paper. With a reservoir arranged at the top, to keep the level in the column substantially constant, the eluate is collected at a rate of approximately 700 ml/h. The distearate content is the first to be determined followed by the combined figure for monostearate and for fatty acids. The propy- lene glycol and water content is estimated separately. The results obtained by this method agree quite well with those obtained by the hydroxyl value method. MI•. S. J. Busa: Is the lecturer satisfied that the moisture content of the silica gel is sufficiently dosely controlled ? We have done only a very few runs and have obtained anomalous results using a washed and dried sample of propylene glycol monostearate. The distearate and monostearate, plus stearic acid fractions have been not more than 90% of the total sample and in some cases, the supposed distearate fraction has had a hydroxyl value as high as 24. We find that when passing liquid through the column at a rate of one drop per second, it takes about six hours to pass a litre through the column which makes the estimation slow. Tag LECTOI•EI•: Of course, the moisture content of the silica gel is critical. We find that B.D.H. Silica Gel Chromatographic Quality treated in the manner described, gives satisfactory results. The rate of flow which we find to be satisfactory is about 700 cc per hour. We are pleased to have some particulars of your experience as the pooling of information from different laboratories should lead to a better understanding of the variables which have to be controlled and the limits which must be set. MI•. D. Bass: Can the lecturer say whether this method is applicable to self-emulsifying propylene glycol monostearate ? TaE LECTUI•R: Provided that the emulsifying agent is soap, then, with the hydroxyl value method, the soap would be destroyed in the washing process. The only difference would be a higher acid value in the washed sample which would not materially affect the hydroxyl value. With the chromatographic method, the soap is insoluble in the solvent and is mech- anically retained by the column. MI•. M. G. D•NAvAImE: You may be interested to know that com- mercially available propylene glycol is not all 1.3 propane diol. Some samples contain as much as 5% 1.3 propane diol. Esters of 1.3 propane diol could cause some discrepancies. TaE L•CTUI•: Thank you for this information. Although we have

JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS been aware of this problem, we do not think that it is a serious one as the percentage of 1.3 propane diol is so low. We must admit, however, that this point has not been investigated. CARE OF THE SKIN, WITH PARTICULAR REFERENCE TO CLIMATE AND SEASON W. SCHNEIDER, Dr. Med.* Delivered at the Summer Conference of the Society on 25th Aug•tst 1960. Care o• the skin shoultl be relatetl, more than ever, to climate aml season. This al•lffies not only to l•rotection against ratliation during changes o• climate aml season, but also to &y ichthyotic skin during the winter. Cleansing o• the skin tlel•emls on the intlivitluah TttE MOST important concern of skin care and cosmetics is the retention or the regulation of the fat and water content of the skin. The so-called lipid covering, as many investigations have shown, contains not only water- repellent trig!ycerides, but also waxes and components which stimulate moistening. Alterations in this composition can, in analogy to a chemical buffer system, regulate water content. In the final analysis, both water and fat content depend on the same biological sub-stratum. The acid covering, or buffer protective covering, can be added as the third component. The selfprotective functions of the skin can be considerably affected both by loss of fat, or alternatively defatting, and by the destruction of the water retaining components whereby the acid covering is simultaneously affected, or to put it another way, the so-called lipid covering of the skin can be rolled up both from the fat or the water side. In both cases, drying out and defatting are the final consequences. That seasonal changes in the weather, with varia- tions in temperature and humidity, have considerable influence can be ascertained by deduction alone, and is known empirically as well as from the experiments of Gaul and Underwood'. Much simpler and more revealing is the dependence of the light protection on the season of the year. Man will always be confronted with more or less extreme variations in air pressure, humidity, air movement, temperature and in the radiant energy of the sun. The most important factors in our opinion are (1) the sun's radiant energy in the framework of its energy distribution on earth, (2) the temperature and (3) the humidity. Gaul and Underwood' include atmos- pheric pressure as a decisive factor. Apart from these weather and climatic *St•tdtische Hautklinik, Augsburg, Germany.