COSMETICS RESEARCH 51 scientific research may be true after the statement of the problem, the selection of variables, and the choice of standards for their measurement. But I prefer to think that quantita- tive measurement is a narrow though necessary and valuable pur- suit within the broad area of re- search. In fact, quantitative measure- ment is limited by the description of variables that can be measured and compared to preformulated or hypothecated standards. Develop- ment of instruments in other fields usually furnishes the yardsticks by which we in cosmetic research meas- ure our plodding steps. Examina- tion of our variables with borrowed instruments may illuminate new horizons whose glorious vistas but promise more and more of interest far out beyond. Except for instrumentation in our field of research, the criteria for judgment and measurement of vari- ables have been pathetically limited. Much of our advance has depended upon the use of ','comparison." We have relied heavily upon "be- tore" and "after" conditions and our interpretations of results have depended upon the imagination of the researcher and the imagined sub- jective reactions of the subject treated. From any such "com- parison" experiment, no two people draw exactly the same conclusions. This unavoidable difficulty has led to the adoption of another de- vice related to "before and after," which we call the "controlled ex- periment." This is really a "be- fore and after" where the variables that differentiate are deliberately and'specifically chosen and where a conscious attempt is made to limit their number to one or at least to one major altered result. Even with the simplifying device of the "controlled experiment" we are too often hopelessly limited in judgement by lack of any commen- surable standard or measurable change therein. For example: not long ago acidity or alkalinity in cosmetic products was measurable only in terms of hydrogen electrode potentials (seldom used) or by in- didator color changes. Unfortu- nately, color changes in indicators are often masked or altered by oxidizing, reducing, or other inter- fering ingredients in the composition to be examined. It was not until the introduction of the glass elec- trode and, later, of the improved electrode capable of giving direct readings at pH values greater than 10 that we have had available an exceedingly sharp tool for cosmetic research. Cosmetic art and science may deal with the skin and its appendages, the hair and nails. Sometimes the teeth are included in the field. I suppose the cosmeticJan's interest in teeth is limited' to the incisors, canines, and bicuspids, and only to their outer faces. Dentistry is ade- quate to deal with molars, cusps, and cavities. The skin, the hair, the nails present to cosmetic research an area large enough to keep most of us busy for a long, long time. It is interesting to note the chang-

52 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS ing direction of cosmetic research. Perhaps most people would char- acterize cosmetic research prior to fifty years ago as cosmetic art. It is true that few methods of instru- mental measurement of variables had been developed. But valuable pioneer work was accomplished despite handicaps. It is also in- teresting to note that early interest was directed more to the skin than to the appendages. True, nails were cleaned, polished, shaped, and sometimes mechanically protected, but they were not lacquered and colored to high-style elements as they are now. Also, hair had been cleaned, combed, curled, bleached, colored, powdered, and supple- mented with transformations since before the beginning of history. But by far the largest variety of early preparations was directed to application to the skin. Today, however, we witness a resurgence of commercial interest in both nails and hair. The modern develop- ment of nail products closely followed the adoption of pigments suspended in nail lacquers. The composition and structure of hair and of keratin as a plastic material have been studied extensively. The growth of hair is as yet a mystery. Its destruction by depilation ad- vanced only slowly from the use of offensive alkaline sulfides and poly- sulfides to the use of odorless mer- captans at controlled pH. Its re- formation from straight hair to curled or from curled hair to straight has developed more rapidly since Charles Nessler invented the per- manent wave prior to 1910. Per- manent waving progressed through the various steps of declining use of high temperature, from electrical to chemical heating, from machine to machineless methods, and from machineless to the cold wave. Waving solutions have changed from simple alkaline solutions to reducing sulfites for gentler hot waving methods, and, finally, rather quickly, to the cold waving of Willat and McDonough (2). It is in- teresting to note that the develop- ment of McDonough's method of altering the forces within the hair- shaft by using inoffensive ruercap- tans at controlled pH has resulted in the greatest single commercial addition to cosmetic usage. But while the demonstrable, spec- tacular developments relating to appendages have held the center of the stage, advances in our knowledge of the skin itself are being quietly made ready. What may prove an equally far-reaching, though less spectacular, achievement results from freeing cosmetic treatment of the skin from the limitations of soaps where surface~active agents must be used. Synthetic surface- active compounds have been studied extensively. They are valuable for cleansing, emulsifying, suspending, leveling, and softening purposes. Supplemented by the so-called se- questering agents such as poly- phosphates and amino acids, the surface-active group has ballooned so rapidly that, including true soaps, it offers agents active at almost all types of interfaces under