A HIGH-SCHOOL PROJECT in CHEMICAL RESEARCH. The PREPARATION of SKIN EMOLLIENTS, LOTIONS, and CLEANSERS NELSON J. ANDERSON Montana State College, Bozeman, Montana
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HE word "research" suggests a varied array of ideas, and indeed i t is defined in an English dictionary of recent publication as a "diligent investigation to ascertain something." In accordance with this definition, some of the best work of highschool pupils deserves to be classified as research. The research described in this report was directed by
the author and carried out by five pupils selected from the one hundred ten juniors and seniors enrolled in chemistry a t Waukegan Township High School, Waukegan, Illinois, during the school year 1935-1936. These pupils, four boys and one girl, had had a t least one semester of high-school chemistry and were all seniors but one, a junior. In order to select those best quali-
fied, their scholarship records were examined and con- times dangerous. The ingredients most commonly sidered together with their interests, aptitudes for physi- used in commercial face powders include talc, zinc cal science, and capacities for application to work. oxide, zinc stearate, precipitated chalk, kaolin, titanium The latter three factors were evaluated by a few dioxide, rice starch, perfume, and coloring matter. teachers who were well acquainted with the pupils Rice starch and other starches may be objectionable. under consideration. None was given advance notice At least two types of face powders, one for normal skin that they were under consideration, but each was ap- and one for oily skin, have been sold. The formula for proached individually after the faculty had made the normal skin contains more talc and slightly more zinc selections. stearate than the one for oily skin. The pupils read The five research pupils were quite willing to conduct of certain cleansers and stain removers, and they extheir investigations outside regular class time and in amined the "stain formularies" of the Central Scientific addition to their normal schedules. However, each one Company. They learned the important principle was allowed to substitute his investigation for about that the commercial success of a product often depends one-half of his regular chemical laboratory work for a more upon extensive advertising than upon the intrinsic semester. Each one devoted considerably more time value of the product. to his investigation than was saved by the reduction in The pupils found formulas for the preparation of his regular laboratory requirements. The laboratory lotions, and one pupil, testing a formula in a preliminary was open to these research pupils a t all times during the experiment, made a sample comparable to typical comschool day, and they frequently carried on research mercial products. The dehydrating property of glycwhen they otherwise would have been in "study hall." erine was cited as an objection to its use in lotions. In addition, they worked in the laboratory on a few Pursuant to a suggestion found in the literature, a pupil Saturdays when school was not in session. proposed that a neutral mixture might be more hygienic The pupils diiered in their abilities to maintain in- for the skin than an alkaline one. Another found the terest and to apply themselves to the particular re- statement that lotions slightly acid with citric acid were search task a t hand. All of them required careful desirable and hygienic. direction whereby (1) wasteful efforts and mistakes All five research pupils worked individually on exwere reduced to a minimum, and (2) encouragement perimental projects that were never alike. There was helped to keep up effective interest. From time to very little concerted effort among them, hut the director time the pupils made suggestions that were commend- so coordinated the work that ultimately each pupil had able and likewise expressed ideas that were quite im- effectively completed a project, and, taken together, practicable or absurd. Instruction was individual, the several projects constituted a unified program of since frequent personal conferences were indispensable. investigation. Individual projects were assigned to The pupils enjoyed their research work and regarded i t fit the individual pupil's interests, abilities, and traina privilege to participate in chemical investigation under ing, so that, with the completion of the program of inthe circumstances made available to them. vestigation, the pupils completed a training course best At the end of the school year, each research pupil's suited to their individual needs. Experimental work scholarship record was examined, and it was determined was limited to the preparation and testing of a few that each one had maintained his scholarship standards lotions, skin emollients, and cleansers. Each pupil of the previous year. This was not surprising because employed reports of the compositions of commercial the pupils selected were those who had given evidence lotions, face creams, emollients, and cleansers, and from that they desired to succeed in all of the required and these he estimated proportions of components to be used elective subjects in their chosen courses. in trial mixtures. The results of an experiment often The general topics chosen for preliminary study were suggested necessary alterations. cosmetics and cleansers. To begin the study of these An ingredient of all materials prepared by the pupils subjects, the research pupils were directed to use the was the synthetic oil, 8-hydroxydiethyl ether 8'-laurate, high-school library, the city library, and any other HOCZH~OCZH~OOCHZ~CI~, having the abbreviated available sources of literature. From the materials name, diglycol laurate. This substance is self-emulsilithat they read, the pupils learned some generalizations able in water; completely soluble in alcohols, mineral and likewise acquired certain specific and detailed in- oils, vegetable oils, and hydrocarbon solvents; and i t formation. For example, they learned that hand lo- rapidly penetrates surfaces of many materials. These tions may be classified into two general groups: (1) are the required properties of any substance suitable variations in mixtures of glycerine, rose water, and for use in the preparation of the various emulsions tragacanth, (2) milky mixtures of glycerine, soap, which were important for the research done by the five alcohol, water, and a mucilage such as tragacanth. pupils. On account of its unusual emulsifiability, The pupils learned that a typical commercial lotion diglycol laurate is useful for lecture demonstrations of is mainly an emulsion of alcohol, partly saponified the preparation of emulsions. From the beginning of the experimental work, everyglycerine, beeswax, borax, and oil of bitter almonds. Lotions containing phenol might be dangerous, but one concerned observed that the consistency of a mixsuch lotions are on the market. Furthermore, depila- ture containing diglycol laurate depended upon the tories and bleaching creams are objectionable and some- amount of this substance present. When two ml.
of diglycol laurate and 0.5 ml. of water are shaken together in a test-tube, a cloudy fluid results. If an additional 1.5 ml. of water is added to the mixture and the contents are stirred or vigorously shaken, the resulting material has the appearance of lard a t about 20°C. and will not flow from the inverted test-tube. If three more milliliters of water is added and thoroughly shaken with the emulsion in the test-tube, there is no noticeable change in the appearance or consistency except a change from a pearly whiteness to a snowwhite. After the sixth milliliter of water has been mixed with the emulsion, fluidity reappears and gradually increases until a soupy liquid results by the time 8 ml. has been added. The emulsion containing 2 ml. of diglycol laurate and 10 ml. of water resembles milk, and in fact there appears a thin layer of "cream" consisting of particles of diglycol laurate large enough to rise to the surface. All of these emulsions are permanent (they do not separate into layers) within the temperature range 10" to 40°C. A permanent emulsion, which we called lotace IV, that may be used as a lotion is readily prepared by shaking together 2 g. of diglycol laurate, 8 or 9 ml. of water, and 2 drops of oil of bergamot. The components of this emulsion are not poisonous. Diglycol laurate can be used as a medium in which to fry foods, and oil of bergamot is used as a flavor in candies. It serves as a mild petfume in lotace IV. But lotace IV is not always a satisfactory lotion because diglycol laurate is a detergent and it sometimes "brings out the lines" in a s k i that would have a better appearance if the "lines" were hidden. However, lotace IV is satisfactory to reduce oiliness of the skm, and it does not have the dehydrating effectthat glycerine sometimes has. One of the pupils who, a t the beginning of his experience in research; had had very little experience with library work, was assigned the task of learning from the literature what ingredients were hygienic or desirable for emollients. This pupil acquired the needed library training and his efforts to solve the problem a t hand were successful. As one accomplishment, he learned that lanolin is often an ingredient of the best commercial emollients, lotions, and face creams, and also that lanolin is useful for chapped skin or skin that needs to be softened by addition of oil. He, and another working independently, prepared a number of permanent emulsions from mixtures of lanolin, digylcol laurate, and water. For example, to prepare a lotion, named lotace 11, 5 g. of hydrous lanolin, W.S.P., and 5 g. of diglycol laurate are mixed in a beaker and gently warmed with a Bunsen flame until a nearly homogeneous clear liquid results. Then 22 g. of water is slowly added with vigorous stirring and, finally, five drops of oil of bergamot together with 5 drops of red cake coloring are put in and the mixture is thoroughly stirred until i t appears homogeneous. Anhydrous lanolin may be used in lieu of hydrouslanolin. Lotace I1 is a good fluid lotion, but an excess of it tends to make the skin temporarily "greasy." However, a little powdered talc will remove the greasy appearance. Diglycol lanrate carries
lanolin with it as i t soaks into the skin. In this way the skin is supplied with its needs more readily, and the surface of the skin is left less greasy than it would be if lanolin alone were used. The materials required to prepare lotace I1 are not expensive enough to be prohibitive. Hydrous lanolin and diglycol laurate each cost about fifty cents a pound, and enough oil of bergamot to perfume four quarts of emulsion can be purchased for about ten cents. Another pupil, having studied the work of those who had prepared lotace 11, became interested logically in the possibility of preparing an emulsion that was less fluid than lotace 11. Accordingly, this problem was assigned to the interested pupil and, by considerable experimental work, he prepared an emulsion called lotace I, which has the consistency of vaseline a t room temperature and is useful as an emollient. Variation of the proportion of water will vary the consistency of the resulting emulsion. Lotace I was prepared from 5 g. of hydrous lanolin, 5.5 ml. of water, 2.5 g. of diglycol laurate together with perfume and coloring mixed in the manner described for the preparation of lotace 11. Like lotace 11, lotace I does not become rancid; thus no preservative is necessary. At temperatures above 40°C. a little separation occurs and a thin layer of transparent oil forms upon the surface. However, the mixture acquires its normal uniform opacity when it is cooled and shaken or stirred. Lotace I is good for the skin of the hands hardened or chapped by exposure or by labor. Twenty-five persons who have tried lotace I report it desirable to use as a lotion or to add oil to the skin from which natural oil has been removed by the solvent action of alkalies such as are present in soapy water. The research pupils made use of the detergent property of diglycol laurate in the preparation of non-alkaline cleansers for the skin. They found that lotace IV is the best one of the mixtures already described to remove paints, oils, grease, stains, varnishes, and gums from the skin. This detergent property of lotace IV was attributed to its essential ingredient, diglycol laurate. In this investigation of cleansers, the pupils often demonstrated originality. For example, they found an interesting application for lotace IV. To clean woodwork in chemical laboratories, janitors use such cleansers as "Challenger Liquid Scrubbing Compound'' sold by Huntington Laboratories of Colorado. A cleanser of this type removes materials from the varnished surfaces and covers the hands of the worker with gummy matter and stains. Ordinary soaps and other alkaline cleansers fail to remove these materials from the skin, but lotace IV, and even lotace I, have proved satisfactory for this purpose. As another example, students preparing isovaleric acid in the laboratory experience a very objectionable and highly persistent odor on their hands that have been in contact with some of the reacting materials or even with the vapors of the materials. Lotace IV readily removes the objectionable odor whereas ordinary alkaline soaps do not. The experience of the pupils, cooperating with twenty-five per-
sons who were using the various emollients and cleausers, indicated that lotace I or lotace I1 are more desirable cleansers, as a rule, than lotace IV, except in cases where it was necessary to remove exceptionally persistent materials from the skin. In other cases the objection to lotace IV is that it removes natural oil as well as dirt from the skin. To clean the skin with lotace I, 11, or IV, a little of the emulsion is applied, thoroughly rubbed in, and then the excess is wiped off with a cloth or washed off with water. The pupils performed several experiments to test the cleansing properties of diglycol laurate and of emulsions containing diglycol lanrate. A mixture, called cleanace, containing equal parts by volume of diglycol laurate and ethyl acetate was found to be a good cleanser for the removal of grease, paints, gums, varnishes, stains, and inks from the skin and from certain fabrics. The mixture was found to be a more effective cleanser than pure diglycol lanrate. However, ethyl acetate has the objectionable properties of being inflammable, highly volatile, and of possessing an odor not agreeable to everyone. On the other hand, diglycol laurate has none of these objectionable properties. The advantages of such oil cleansers as cleanace or diglycol laurate are : (1) Water is not necessary for the cleaning process. (2) The emulsifying tendency of the oils is much more pronounced than that of typical alkaline soaps. (3) In many cases the removal of residual cleanser is not a problem as i t is in the case of the alkalies. For example, i t is convenient for a motorist to have some oil cleanser and a cloth in his car so that, without water, in case of necessity he can remove a spot of grease from his hand. The pupils demonstrated that cleanace, lotace I, 11, and IV were all much better than alkaline soaps to remove dyes, inks, paints, stains, gums, varnishes, and grease. Of the cleansers tested, cleanace was found to be the best for the removal of dried paint from the skin. By proper choice of an oil cleanser adapted to a particular need, one may make it unnecessary to remove the residual cleanser which need not be objectionable. Two of the research pupils performed some experiments on the removal of spots of grease, paints, stains, gums, and varnishes from fabrics, although they did not make a complete investigation. However, their work indicated that cleauace, for example, did not weaken fabrics, although i t readily removes grease, inks, gums, paints, and varnishes from cotton, woolen, rayon, and silk fabrics. The residual cleanser was removed by lukewarm water because diglycol laurate so readily emulsifies in water and tends to cany with it the materials which are to be removed from the fabric. The high emulsifyingpower of diglycol lanrate proved useful to remove oily mixtures from glassware. As an illustration, a beaker that had contained a mixture of olive oil, diglycol laurate, and other oils was flushed free of oil by a stream of cold water flowing from a faucet into the beaker for one or two minutes. After this
treatment, the beaker was dried by means of a clean white cloth and no oil could be seen on the cloth. In a library study, one of the pupils found that occasionally human skin is "sensitive" to animal oils such as lanolin. Accordingly, this pupil prepared some lotions and emollients containing olive oil in lieu of lanolin. In the same manner as that described for the preparation of lotace 11, a permanent fluid emulsion, called lotace 111, was prepared from 5 g. of diglycol laurate, 5 g. of olive oil, 15 ml. of water, 2 drops of oil of bergamot, and a few drops of red cake coloring. As a perfume, oil of wintergreen, for example, may be substituted in place of oil of bergamot. Lotace is a viscous fluid, but there are a number of emulsions containing olive oil and diglycol laurate which have the consistency of lotace I a t room temperature. One such emulsion, lotace V, is made up in the proportions, 5 g. of diglycol laurate, 2.5 g. of olive oil, and 9 ml. of water. Lotace I, 11, 111, IV, and V are opaque and white unless they are tinted by additiou of coloring. A research pupil, who had read of the pH of an emollient or lotion as a significant factor determining the quality of the product, indicated his interest in some pH experiments. Similarly, this pupil was interested in the significance of pH. Quite appropriately, he was encouraged and directed to perform suitable experiments. He determined that the permanency and the emulsifiability of the diglycol laurate are functions of the pH of the mixture in which diglycol laurate is contained. For example, a mixture of 5 g. of olive oil, 2.5 g. of diglycol laurate, and 9 ml. of water was prepared in the usual way and then made slightly acid to litmus by additiou of citric acid. At first the mixture was a white, frothy, viscous fluid a t room temperature. But within three days the sample left in the test-tube had largely separated into three layers. A little sodium carbonate was stirred into the mixture until a drop of i t was neutral to litmus. This mixture was heated until sputtering began and then was continually stirred while it was allowed to cool in a beaker. The resulting emulsion was a frothy viscous fluid which did not separate into layers when it stood in a test-tube for several days. To prepare a permanent emulsion that was acid to litmus, more diglycol laurate was required than for any neutral mixture of the same ingredients. The same requirement applies, qualitatively, a t least, as the pH is further increased. A similar effect was observed when different amounts of water were used with various samples containing the same proportions of oil. A permanent alkaline emulsion can contain more water, the proportions of the other ingredients remaining the same with respect to each other, than a permanent neutral emulsion can. CONCLUSIONS
1. Carefully selected high-school pupils can conduct worthwhile chemical research. The training not only provides an outlet for the particular bent of a pupil but also gives him a better appreciation of the possibilities in chemistry. Chemical research activities do not neces-
164 sarily interfere with other aspects of high-school pupils' training. 2. Five high-school pupils, working individually, were directed in research so that they completed a unified program of investigation, l-.hey examined rnercial lotions, emollients, and cleansers, and made both librarv and ex~erimentalstudies of them. Bv , original procedures, the pupils prepared and tested several samples of good emollients, lotions, and cleans-
JOURNAL OF
CHEMICAL EDUCATION
ers that are very different in composition and in properties from typical ~. commercial products.
3. Each research pupil learned something of importance concerning the methods of using available literature and chemical laboratory facilities to study a problem from the research viemoint. In addition. each pupil acquired individual training that he needed, although no two pupils' needs were wholly alike.
