JOURNAL OF THE SOCIETY of pigment is retarded and the skin grows lighter. Our method of recording and measuring the skin lightening pro- duced by the use of Bleaching Creams depends upon photography. By it we obtain permanent records in the form of films and prints. We recorded the relative colour density of the skin by photographing it against a background composed of standards of known reflectance value, under carefully controlled, uniform conditions. We use a special apparatus in making our films. A circle is com- posed of neutral grey s,hades of known reflectance value, extending from actual black to actual white. The subject stands behind the circle and places her cheek against the opening in the centre, exposing ap- proximately 15 per cent of the area of that side of her face. The appar- atus and the camera are firmly fixed and the studio is light-proof. The illumination is at equal distances and at equal angles with a controlled voltage of 108 volts. We use super- sensitive panchromatic film, stop 11 and exposure of l/lOth second and the Wratten X-2 filter. .This combination of film, filter and illum- ination is recommended by Eastman for producing monochromatically the colours of the subject in the same relative value as the eye. would see them in daylight. A typical print made from one o.f our films shows a round central area which is actually the subject's• cheek. The segments around it are of measured reflectance, expressed 180 OF COSMETIC CHEMISTS in terms of Munsell Neutral Value Scale. This scale is a series of regularly graduated greys of known reflectance extending from actual black to actual white. Films like this are made of the right and left cheeks of each subject at the start of the test and after two, four and six weeks, which is the end of the test. Our films are then measured on a photovolt Densiometer Model 505 using the special illuminator designed particularly for measuring the den- sity of films. The skin area of the film is first measured and then the segments of known reflectance which are immediately lighter and immedi- ately darker. By linear interpolation we obtain the percentage of light re- flected from the skin, or percent re- flectance •4. Comparison of the percentages at the start and finish of the tests indicate if the skin is becoming lighter or darker. Thus we have a method of recording and measuring the relative colour density of the skin that is entirely independ- ent of comparisons made by the eye. For further simplification, we have also expressed our results in terms of shades. The validity of the term shades, or the just noticeable differ- ence in shades of neutral grey, is es- tablished by extensive experimental data published in 1933 by Munsell, Sloan and Godlove •. Our test procedure was compara- tively simple. The subjects• re- ported to our studio. daily where they carried out the routine under our observation and direction. The test groups washed their faces with a

BLEACHING CREAMS lnilled toilet soap, rinsed thoroughly and dried. They then applied about 1 gram of the ointment and allowed it to remain on the skin • hotlr. Then they' removed the remaining oint- ment with a tissue, washed again with soap and water and were dis- missed. Control subject• did not apply the ointment. They washed their faces twice daily in our studio with the salne brand of soap. Here is a summary of the various group tests wc have made to date. Group 1785, 9 white subjects, and group 1749, 6 coloured subjects, were performed at the sarnc time. The white subjects lightened an aver- age of 5{ shades and the coloured subjects lightened 8• shades, indicating, as would naturally bc supposed, that the greater degree of lightening would be observed in the darker skins. }towever, wc do not have sufficient data to •nake this a positive statement. Group 1891, 9 white subjects, treated with 1 per cent ointment in the smnmer months, showed 2.54 per cent increase over the original reflectance. The non- t•t C-1 group, perforlned at the same time, showed a darkening of 3.30 per cent. It is reasonable to presume that if the test group had not used the ointment, they would have darkened to the extent o[ the uon-test group. Thus the net result to. the test group would be the sum of the changes, or 5.84 per cent in- crease in reflectance, a lightening of 3-3/4 shades. Applying the same reasoning to group 2071 control, and group 2081 test, we find a net lightening of 4:} shades in the test group. The natural seasonal varia- tion of skin colour is made apparent by comparison of the summer and winter control groups, C-I and 2071. The summer group, C-i, darkened two shades and the winter group, 2071, showed practically no change. While conducting these experi- ments in skin measurement, we made a series of full face photographs to record the over-all effects. Our start and finish photographs are of course made 6 weeks apart, but the films are developed the same day they are exposed. For greater uniformity, the prints of both films are made at the sanhe time, at the end of the test. We make about 15 prints of each film. We then measure tile control disc on all of these prints, and usu- ally obtain two or three sets of matched start and tinish photo- graphs, which read the same. By this procedure, we obtain start and finish prints of uniform density in which the only remaining variable is the change in reflectance of light from the subject's. skin. (The autho.r hcrc show'cd Slide 7, consisting of the 3'tart and l•nish photographs o! subject 2089, who is said to have shown a lightening of 8 shades). Mr. Nealon continued as follows: We find a peculiar psychological effect on viewing this slide. As we now observe it, we •nay or may not notice that the skin in the December 17th picture is lighter. Our minds direct our major attention to the familiar details of the features, such as the eye, nose, lip, etc. However, 181