The PRERE UISITE and COLLATERAL VAL E of CHEMISTRY*
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ALEXANDER SILVERMAN University of Pittsburgh, Pittsburgh, Pennsylvania
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RECEDING speakers have discussed the r61e of chemistry in education, namely, the extent to which it is included in curricula; the cultural value of chemistry in general education, or its significance as a broadening influence; the training value of chemistry in general education, or its influence as an analytical reasoning factor and in the development of sound imaginative thinking. The present division of the topic has to do with the prerequisite and collateral value of chemistry. In other words, we want to
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* Contribution to the symposium on The R& of Chemistry in Education conducted jointly by Section C (Chemistry) and Section Q (Education) of the American Association for the Advancement of Science, Pittsburgh. Pa.. Dec. 27, 1934.
know to what extent it is required for an understanding of the professions and to what extent it serves as collateral material in the practice of these professions. ENGINEERING
This profession involves the practical application of' physical, chemical, and other scientific principles in iarge-scale construction or operation of one type or another. An understanding of the elementary principles of chemistry and physics in preparation for the engineering profession is essential. A few examples of the collateral value of chemical knowledge will make this evident.
Some engineers have to consider the matter of sanitation. This involves the treatment and care of air, sewage, water, and food supplies. Ventilation no longer means the mere supplying of fresh air from out of doors; the newer trend includes the filtering of that air. Hence a knowledge of materials, natural or artificially produced, which will serve as filtering media without too greatly retarding air flow is necessary. The older scheme of washing the air has largely given way to filtration systems which depend on fibers coated with deliquescent adhesives for attracting and holding dust particles. In humidifying problems, a knowledge of the vapor tension of the chemical compound water, a t various temperatures, is important. Especially is this knowledge of air conditioning, together with temperature control, essential in the manufacture of certain food products and in the storing of perishable foods. The engineer is responsible for the construction of systems for water purification. With the prevalent use of chlorine and hypochlorites he must so design storage units and conduits as to guard against corrosion. He is not merely concerned with the corrosion of the containers and conduits, but must further guard against the use of materials in their construction whose corrosion would harmfully contaminate the water or impart to it an undesirable taste. Water problems confront him to an even greater extent when he utilizes water for various industrial purposes. The corrosion factor in boilers and the tendency to cake in the conduits and in the boiler tubes are too well known to require elaboration. The treatment of the water according to its temporary or permanent hardness with any one of a number of the older chemical reagents to effect softening is an old story. The progressive engineer will consider the newer and better principles and appreciate the effects of zeolites and of sodium metaphosphate, the former a atering agent which produces softness, the latter a chemical agent which not only removes the hardness-producing substances but so sequesters them as to prevent their depositing in the various engineering units in which they are employed. +In marine construction he has to take the action of sea water into account. In connection with sanitation, the engineer is required to construct units for the disposal of sewage. He should have a sufficient knowledge of chemistry to interpret the chemist's report on the nature of the sewage which has to be treated, for again the life of the units in which the treatment is accomplished will depend on the nature of the sewage under consideration. Related to sewage in a way is the matter of garbage disposal. A glance a t these plants obviously indicates that the engineer has had a hand in the job. He must know the construction materials which will stand garbage incineration and extraction. Lacking this knowledge the plant that he constructs may prove faulty. Textiles are employed in certain engineering operations; we find them in belts, in pipe coverings, in insulating materials etc. The chemical nature of a textile
determines its suitability for a particular purpose. Durability and life of the fabric are essential to the satisfactory performance of the engineering units in which it is employed. Metals and their alloys are not only the products of engineering practice in the field of metallurgy but have utility in the construction of various engineering products. Is the engineer to employ aluminum, or copper, or iron, lead, nickel, zinc, or some other metal? Shall he use one alone, or one of these metals in combination with others? What he employs will depend on the purpose for which the metal or alloy is intended. In newer developments, such as aviation, he must have knowledge of light alloys of aluminum with other metals. Consideration is already being given to beryllium, which is lighter than aluminum and which alone, or in its alloys, has superior mechanical properties. The engineer may have to consider corrosion factors, conductivity, thermal insulation, protection against radiation, tensile strength, malleability, and what not. He must have a knowledge not only of the physical properties but of the life and behavior of the metal from a purely chemical standpoint; he should further be informed about the properties, or alteration of properties, resulting from heat treatment, or exposure to fairly high temperatures in the fabricated units for which the metal or alloy has been employed. He may be called upon to construct fveproof quarters in buildings. Here, the behavior, especially a t very high temperatures, must be known, for, if the unit is complete and fails to meet the requirements of the Fire Underwriters' Laboratories, payment for the work done may actually be withheld. It is therefore of economic importance to provide the proper material for,the consumer, and to insure payment for the job tione. We live in an age of special alloys. In the cutting or welding of these, high-temperature blow torches may be required, even atomic hydrogen torches. Or we may have to employ special abrasives for finishing, or tungsten-carbide or oth&, hard, self-annealed tools for trimming and finishing parts. For the generation of power the engineer must plan for the use of various fuels, gaseous, liquid, or solid. The chemical nature of the fuel, together with the chemical nature of the unit which is exposed to that fuel, must be taken into account in planning the construction. The boiler may have a short life if unable to withstand the products of combustion of the fuel underneath. Its interior is a t the mercy of chemicals in the water, and because of improper treatment of that water may fare badly, suffering a weakening of structure. Investigation under way on the embrittling effect of various water-treating agents, or their reaction products, on boiler walls is significant. Again the engineer may be called upon to construct ovens for the destructive distillation of coal in the production of coke, or fire boxes or other heating units in plants for the manufacture of a variety of commercial products. He must know the nature of the fuel and, if solid, the nature of its ash and the reaction with the walls of the
Of course, you will say that observing too many precautions would require time and render medical service so expensive as to make it prohibitive for the average patient. Let us assume that you are correct regarding the economic aspect. Is it not too true that a physician considering the time factor alone is apt to follow cutand-dried methods instead of a t least becoming informed along chemical lines and thereby displaying better judgment in prescription? There are many comparatively simple things which our medical students could learn about the chemicals they employ. For example, which of the bromides, assuming equal effectiveness as sedatives, is best eliminated by the system? Any number of patients who have been given bromides have been annoyed by what is known as "bromide rash." There is really no necessity for this. Strontium bromide is more rapidly eliminated than other bromides which are commonly prescribed. In some instances the patient suffers a serious let-down through the use of bromides. Where this is the case ammonium bromide, which is also easily eliminated by the system, has the advantage of producing a combined sedative and stimulative effect. Numerous other examples might be cited in the field of inorganic chemistry. In the field of organic chemistry, the preparatory training must be supplemented by constant collateral reading and study, for hefe new chemicals are appearing on the market almost daily. The organic chemist has pretty well established that certain radicals in his compounds are responsible for the physiological effects obtained. There may be objectionable side effects in compounds already in common use, and a new one which has been announced may have the desirable effect of the radical without producing an objectionable reaction. If we take'into account anesthesia alone, we soon realize that while at one time there was practically no choice except chloroform, ether, and nitrous oxide, today there is an anesthetic to suit the need of almost every particular case. What has been said of MEqICINE anesthetics is true of modqomrnon remedies, namely, No student should enter the fi Id of medicine without the headache cures, laxatives, etc. One of the most a t least a knowledge of generafinorganic and organic commonly employed of the latter is phenolphthalein. chemistry, for without these he cannot even understand It is known that many individuals have an idiosynthe simple reactions that go on in the human body. crasy toward this compound and that it produces an Collateral with his practice of medicine, his knowledge undesirable 'dermatological effect. Antiseptics again open a huge field for thought. of chemical science should he much more extensive. He must know whether medicines prescribed for his What may prove beneficial in one instance may he an patients are compatible or not. All of us know of one irritant in another case. What.may seem mildest and or more cases where physicians have prescribed and least effective because it is common may pass the physiwhere it has been evident to us as chemists that the cian's notice entirely. The more powerful organic dmgs included in the prescription would react with antiseptics have now come into general use. That they each other before having an opportunity to serve their are not necessarily the most effective is shown in an exindividual purpose for the patient. The human body ample. The writer has in mind a group of botanists is our most precious possession and no physician has a who made a survey in the tropics. Plant poisons and license to expose it to the hazard of snap judgment. It the bites of harmful insects failed to respond to the would even seem desirable tliat he know the idiosyn- various powerful antiseptics that were employed. crasies of his patient, for it does not follow that because Finally, the one which we look upon as the mildest the normal dosage of iodides, for example, is satisfac- inorganic antiseptic, namely, boric acid, served the tory for the average patient, it is harmless to one who purpose perfectly. We must, therefore, not merely utilize the principles which have been included in our is hypersensitive to such substances.
container. He must know how the material used in the container will react with gaseous, liquid, or other products arising from the fuel, or in the manufacturing process involved. In units like ceramic kilns or glass-melting furnaces, he has not only to take into account the products of fuel combustion, hut chemical vapors which result in the heat treatment of the ware in firing, or which escape through reaction or vaporization during melting processes in the glass tanks. Environmental influences which involve chemical reactions may also be factors. We have learned only too often about electrolytic effects on pipe lines and other metallic units which have been employed in engineering construction. The study of conditions obtaining in the area in which a plan is to be carried out can be determined in advance, though one may not necessarily foresee all possibilities. The proper grounding or insulating of the constructed units may, however, anticipate possible electrolytic difficulties and guard against them. The engineer has occasion to employ adhesives. If these are to resist the action of moisture, he has one problem; if they are to adhere without penetration, he has another. If there is a tendency to penetrate the structure where they are employed, still another factor is involved. The adhesives must not only serve the purpose of holding parts together h l y , hut must be of such a nature chemically as to prevent the corrosion of the parts held, to prevent the consequent lowering of mechanical strength. Adhesives are not employed entirely to form cementing bonds. The protection of surfaces of various kinds is equally dependent on the adhesive properties of the paints, varnishes, or other protective coatings employed. Obviously the engineer must have some training in chemistry, a certain minimum to prepare him for the profession, and as much more to serve him collaterally as his ambition toward success prompts.
preparation for the field of medicine, but must look back to some of the simpler remedies which have only too often been forgotten. Nor shall the medical practitioner get the idea that the newer thought is to be ignored. Frequently is his mind closed to these newer principles. The current developments in the use of dyes, not only as antiseptics but as specifics for the treatment of certain ailments, is a case in point. A closer relationship and a better appreciation must come between physician and chemist. Developments in the field of narcotics and hypnotics, etc., may find exceedingly important applications. Two cases occur to your speaker. The &st involves the use of certain opiates in the treatment of colds. Some of these may actually become specifics for pneumonia. If they do, it will be because of the confidence which one medical man had in a chemist. Experiments have already progressed satisfactorily in the treatment of animals which respond to pneumonia much as human beings do. The coming winter will probably see the direct application to patients in one of our hospitals. The other case has to do with the use of organic substances in connection with the treatment of mental disorders. An eminent physical chemist in one of our universities has found that certain compounds restore some so-called insane persons to normality, while others may induce insanity in a normal person. While all decry the prescription of habit-forming drugs, there is no doubt that their proper application in abnormd individuals toward the production of normality is merciful. The medical profession has been slow to appreciate this chemist's findmgs. Mention might also be made of the value of his findings to the criminologist. The recent literature on certain barbituric acid derivatives, e. g., sodium amytal, and their destruction of defense reactions under cross-examination, does not require repetition. Suffice i t to say that defense reactions are practically entirely broken down through the use of such agents and that an individual suspected of crime cannot resist answering truthfully. Scopolamine acts similarly. C . Every physician should be informed concernlug antidotes for poisons. How many know that sodium formaldehyde sulfoxalate is a positive antidote for the very common mercnry bichloride poison, if given by mouth and rectum and through intravenous injection, and that remarkably little kidney damage results? The collateral value of developments in the field of biochemistry is rapidly receiving deserved recognition. Many physicians are already well informed regarding the function of vitamins, hormones, and enzymes and are utilizing these for the well-being of their patients. Not only has this knowledge contributed to an understanding of plant and animal physiology, histology, and embryology, but i t furnishes a chemical background which is essential to modern advances in the fields of pathology and psychology. As the microscope has, in the past, provided a tool with which the and others could look beyond the body to individdal cells, so chemistry, through the
newer micro methods, provides facilities for interpreting living processes in t m s of molecules and atoms within the cells. It is now possible to determine quantitatively how many organs function, and thus learn, for example, just where the acid and pepsin in the stomach are generated. Microtome sections a t various depths from the inner stomach wall have already been analyzed. While radiotherapy may seem to belong more properly to the field of physics than to chemistry, the utilization of radium and other radioactive substances does involve chemistry, or a t least chemical substances. Here is a field in which good may be accomplished beyond appraisal if the reagents are applied properly, but where untold haxm may result if they are utilized by one who is ignorant of the technic and precautions that are necessary. The use of radium and other radioactive substances, among the latter the less expensive radon which may be administered in implants or spicules, has been valuable in the arresting of cancer, especially in its incipient stages. Properly informed individuals may therefore employ such substances with good results. The young man in general practice should omit their use until he has become fully informed regarding the proper procedure. In the field of physical radiations such as X-rays, ultraviolet rays, etc., the same may be said. These radiations may prove beneficial or, with excessive or improper application, decidedly harmful. What has been said rather briefly regarding chemistry as a prerequisite and collateral subject for medicine could be elaborated almost endlessly. May I suggest in closing this phase of my topic that the individual, who wishes to appreciate the value.,of chemistry in medical practice, include not only the inorganic and organic chemistry, but analytical chemistry which is a prerequisite to physical chemistry, and the latter which has so many applications in properly interpreting what goes on in the human body. Biological chemistry will prove a further asset. The significance'?f chemistry to medicine is aptly implied by the title of a recent volume, "Medicine in an Age of Chemism." DENTISTRY
Here again the student should prepare himself a t least to the extent of covering the eIementary inorganic and organic chemistry. The teeth and jaw bone and certain secretions of the mouth contain inorganic compounds, while the tissues in which bones and teeth are embedded are of an organic nature. The chemistry of the mouth must then take into consideration what might happen to either of these types of compounds. Some of the older dentists still adhere to the notion that i t is unnecessary to use cleansing preparations for the teeth or antiseptic solutions for oral treatment. They feel that nature provides the defensive materials that are necessary. The majority of the more modern m u a do.. however. favor the use of the cleansine agents and antiseptics, and all of us who read the advertise-
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ments in the daily papers and the popular magazines know how the manufacturers of hoth types of preparations vie with each other regarding the efficiency of their products. A paste may cleanse but be too abrasive. In certain other cases, greater abrasive power may prove desirable. A knowledge of the substances contained in these preparations is essential and there is just as much reason for prescribing a cleansing preparation for a patient as there.is for looking after his teeth periodically. In other words, preventive measures are even more important than treating the effects of carelessness. When it comes to mouth washes, the mere gem-killing or tartar-removing power of a preparation is not a sufficient criterion unless you take into account the effect of this preparation on the tissues and the teeth in the individual case. One mouth may stand a wash that contains a hypochlorite or a phenolic body; another may he irritated by these. The wash employed for oral prophylaxis should therefore serve the specific need of the individual rather than be utilized on the basis of generally known properties. A great variety of chemical suhstances is utilized in the preparation of dental cements of various kinds, whether for temporary or for permanent filling. What may prove suitable in one case may he decidedly unsuited for another. Through the application of a few simple chemical tests, the dental practitioner should he able to ascertain what best serves his patient. And then there are the metallic fillings aad inlays and crowns. A certain individual may be so sensitive that an amalgam filling adjoining a gold inlay will set up a d c i e n t galvanic current to cause real misery. Where two kinds of metal or alloy fonn a contact the needs of the patient should he taken into account and i t might even he better for the dentist to consider the electrical potential differences that exist between metals and avoid such possibilities entirely. Compositions employed in the manufacture of artificial teeth and in the production of the various plastic materials in which these are embedded are also factors in dentistry. While most devists no longer engage in this type of work because of the long experience that is necessary for its proper execution, the.chemical nature of substances employed for either the teeth or their supporting material is important. And then there are the chemicals which are employed in the treatment of the patient. Phenolic bodies and oils are still largely used under temporary fillings to re: lieve pain or treat infections. High-melting waxes of various kmds cover these so as to insure contact with the area to be treated and a t the same time prevent seepage into the mouth. How many dentists realize that some of these reagents are soluble in the very wax that covers them, and therefore gradually work their way through to the annoyance of the patient for days or even weeks during such treatment? It is possible to employ suhstances which are odorless and practically tasteless and which are just as effective without annoying the patient. Dietetics has come to play an important part in con-
nection with tooth preservation. Many dentists realize the necessity for the cooperation of specialists in this field. The writer has his own parents in mind a t the moment. We all sat together and partook of the same food, practically in the same proportions. Mother's teeth crumbled as a result of some metabolic disturhance, while father attained his three score years and ten in full possession of a mouth of sound teeth with the exception of one which had been extracted. Undoubtedly a recognition of the cause on the part of the dentist or physician in mother's earlier years would have resulted in a diet or treatment which would have insured sound teeth through a period as long as that enjoyed by father. There must he many cases that want just such consideration. Even a presumably harmless thing like water may cause trouble. In a mid-western region, all the inhabitants had brown spots in the tooth enamel. It developed that small amounts of fluorides in the water caused the trouble. With the substitution of a water free from fluorides, the spots disappeared. Dental students should a t least study general inorganic chemistry with special reference to its metallurgical aspects, and general organic chemistry with special reference to antiseptic and other organic agents employed in oral practice. If the student can afford the time, i t would be well for h i to include a general course in physics and a course in biochemistry. MISCELLANEOUS PROFESSIONS
While the value of chemistry has been discussed more extensively in connection with engineering, medicine, and dentistry, it is hoth of prerequisite and collateral value in other fields. Some of these will now he discussed briefly. " Biological science in its various branches a t least demands an elementary knowledge of inorganic and organic principles and reactions. In zoology the processes are closely allied to those discussed in medicine, hut through a wealth of expfxhpental material one is in a position to study chemical influences, and there is almost no limit to the application of chemical knowledge. The very fact that animals of various types are used as assay standards for certain drugs indicates the importance of chemical science in one type of zoological studies. Here it is possih!e to select a variety of animals which according to their choice react similarly to man, and so important advances have been made on the effects of anesthetics, insulm, the vitamins, the hormones, enzymes, and a host of other chemical materials. In the field of botany, we again encounter a large variety of possibilities. Many of us have experimented in our own gardens with the introduction of metals of various kinds into the soil to see their influence on the color of the bloom produced in the plant. The types of fertilizers employed in a limited botanical way or on a larger agricultural scale offerfurther evidence of chemical values. Whether we have utilized the rapid effect of a highly soluble nitrogen hearer, like urea, or the slower ammonium compounds or alkali nitrates;
whether we have employed the natural phosphate rock which has been treated by one chemical process or another to render it more suitable for a specific pnrpose; whether we have strewn certain salts on the greens of a golf course to destroy worms without affecting the grass; or whether we have scattered chemicals between the ties along the roadbed of a railway toprevent the growth of weeds, chemistry was involved. The chemical treatment of the. ties themselves prevents attack upon them by parasites of various types. Or again .we may have used chemical gases in the drying of fruits to prevent fungus formation. The older applications of fungicides and insecticides by Pasteur and his successors are well known. The newer treatment for coloring the rind of fruit through exposure to ethylene and other organic vapors has enabled us to pluck fruit while i t looks green and improve its appearance. A knowledge of the effects of temperature on the rate of chemical reactions has resulted in lowtemperature storage, or in the freezing of products a t temperatures still lower than those formerly available, through the newer introduction of dry ice. These frozen fruits have the natural flavor which is lost in canning or preserving processes. In bacteriology, the chemical nature of the media is now highly significant. We not only prepare a culture of a certain type but it must have a definite pH. In other words, the hydrogen-ion concentration of the medium is a significant factor. The application of stains for the identification of various organisms has made advances. Thinking of color, an interesting point comes to your speaker's mind. While in France, he visited a famous pottery and was surprised to see the windows, in the room in which the slip for the body of the pottery was being prepared, coated with a deep magenta dye. Upon asking the purpose, he was informed that light of the particular wave-length absorbed encouraged the growth of an organism which grew in the slip, and whose charring during the firing discolored the ware. The absorption of these light rays by the dye on the windows entire prevented the growth of the organism. AErobic antanaerobic hacteria depend on the presence or absence of the first element we study, oxygen. As geology is somewhat tied up with organic life, especially in the carboniferous period, we might give thought to this field for a moment. There is still considerable controversy as to the origin of coal, petroleum, and natural gas. The effects produced may have been thermal or bacteriological. In either case, they involved chemical changes. The existence of an entire volume on geochemistry, and extensive journal literature, afford a sufficient appraisal of the r81e of chemistry in geology. There are the igneous rocks, the sedimentary depositsin the one the high temperature reactions, in the other the effects of substances in solution or the cementing intluence of chemical compounds. The weathering and decomposition of rock masses, such as the feldspars, limestones, and phosphate rocks, result in'soil enrichment. Chemistry is not only
involved here but affords an interesting field for further research. For example, books on mineralogy and inorganic chemistry have for ages implied that the feldspars are decomposed through the influence of carbonic acid with the production of potassium carbonate for the soil, and the various clay deposits. Comment is in order concerning a note which has never been published. During the World War, with a dearth of potash in America, i t was the speaker's hope that by increasing temperature and pressure he might be able to accelerate the weathering of feldspar with the production of potassium carbonate. Although steam and carbon dioxide were used a t high temperatures and under considerable pressure, the desired reaction did not materialize. Is the classical and generally accepted theory true? Hardly. Possibly soil acids, the products of organic decay, may he the reagents. Colloid chemistry has applications in study of the phenomena leading to the formation of deltas and the precipitation of silts. Mineral composition is expressed chemically, and in recent years we have applied X-ray studies in crystal structure. Perhaps we are crossing the border into the realm of physics, but the structure determines the nature of the chemical compound. We now know that ions already exist in many natural crystalline solids. Mining and metallurgy involve the development and utilization of natural biological and mineralogical products. Here again chemistry is indispensable. Let us now devote a few minutes to chemistry in everyday business lqe. If you have scanned advertisements in the daily papers or popular magazines, you have observed that chemistry is a talking point to further the sale of a given product. The chemist can hardly back all of the claims'that are made in some of these glaring displays, but many of them have sound foundations. In a department store, you may be shown a true color tone under suitable light, or may he told that ultra-violet light rapidly produces fading of the colors, which fading would progtqss more slowly on exposure to sunlight. The fastness of dyes and colors employed in everyday commodities is determined by such acceleration tests. Another department may demonstrate that a material is cotton or wool, silk or rayon, by some simple chemical method. The toy department sells chemical se$ though the safety of some of the contents is questionable. Some florists have silica gardens. Perfumers utilize synthetic aromatics. Food labels indicate permissible perservatives and artificial colors. Wine labels show alcoholic content. Recently the blenders of a whiskey have claimed that the furfural content of the bonded article is higher than that of the freshly manufactured product, as an inducement for the sale of the lower-priced and, in their estimation, equally wholesome spirits. One manufacturer of rubber goods claims advantages for a product electro-deposited from latex. Another tells us that the colloidal nature of materials introduced into his product insures greater value. There are controversies. They are along chemical lines and they will
serve as sales factors. Certainly one who is going into consider not only esthetic values but also the material modern business and wants an understanding of these universe about us which is the "Handiwork of God." talking points should a t least have a n elementary howl- He feels that a clergyman to interpret this handiwork edge of chemistry. His busines might even carry him properly and give his congregation the appreciation of into the newer motor fuels or industrial chemicals. In the grandeur of nature, must have an appreciation of the latter field he can hardly meet competition unless he science; of the ordered Law under which nature opercan speak intelligently regarding the relative merits of ates. If the minister is a philosopher, he must apprecihis product compared with the products of competitors. ate the iduence of the modern theory and the material A leading Pittsburgh banker, later Secretary of the developments of science on human thought, and their National Treasury, has said that every man preparing influence on history and civilization. If he fails to for business should take a course in chemistry because realize this, he should think of the time when his voice such training disciplines the mind and develops clear was conhed to the four walls of his temple of worship, analytical thinking power. in contrast to our day when his message may be broadMany who prepare for the legal @ofessb still enter cast to the world a t large by radio. this field without any knowledge of forensic chemistry. Finally we shall devote the few minutes that are left It is inconceivable that chemistry should be omitted to the general collateral value of chemistry. We have as a prerequisite for the practice of the law. So many been taught to sleep in well-ventilated rooms because controversies today involve our science-in criminal- of the wholesome effect of fresh air. We are provided ogy, in litigation over manufacturing or technical proc- with water which is safe for domestic use and clear for esses, in determining the authenticity of documents, the refreshing bath. We cleanse ourselves with what and in other w a y s t h a t elementary chemistry would may a t one time have been prepared on a small scale a t least seem essential to a lawyer, for understanding in the home but what is now a large-scale commodity. what special witnesses may have to prove. Rodents and vermin no longer abound, for sanitation And now what about journalism? That some train- and chemical poisons have been their Nemesis. Our ing in chemistry is important is obvious to those read- food is preserved a t a temperature which prevents ing the articles of feature writers, science editors, and spoilage and, for the emergency, food may be taken also the routine news of the day in our daily and Sun- from a sealed container in which its preservation is day papers. Some of the largest salaries in the field are safe over long periods through prior treatment which paid to men with a knowledge of science. The various prevents chemical decomposition. The morning news international news agencies employ men who devote comes to us on a sheet which was once a tree of the their entire time to science news. Interviews with forest, or some old rags which have undergone change scientists and popular articles on new applications ap- as striking as that of our own civilization. The clothpear in weekly and monthly magazines. We have quite ing which keeps us cool in the summer and warm in the a few popular science periodicals. One day you read winter is better for the, chemical attention the fibers in the morning paper about twenty or more different have had, and more attractive through the rainbow alcohols; on another about heavy water; on a third which has arisen from a lump of coal. We go back and about some criminologist who has detected a poison in forth in conveyances whose construction is chemically a murder case, etc., etc. The wise man preparing for dependent in every detail and whose motive power journalism will not neglect chemical training, for he comes from a chemical product. The affairs of the will want to publish tme'and accurate statements, day are endlessly involved with chemistry, and our though he may have to make &em popular or even entertainment, whether by radio or motion picture, spectacular. would be impossible were i t not for the chemical deThe thoughts expressed concerning chemistry as a velopments which brought about these modem marvels. prerequisite and collateral factor in education are not It was said a t one time "a little knowledge is a dangerthose of your speaker alone, but include suggestions ous thing"; without a t least a little chemical knowledge which have come to him from his colleagues in the today it would seem thatone is woefully ignorant. We Chemistry Department of the University of Pittsburgh. need it for an appreciation of the blessings of our time One of these has gone so far as to include the student of . and for the rounding-out and enrichment of our very theology, for he claims that in the ministry we have to lives.
I n treating any particular subject I wouldf;rst of all make some experiments, because my design is$rst to refer to experimenfs and then fo demonsfrafe why bodies are constrained fo act i n such a manner. This is the mefhod we ought tofollow i n investigating the phenomena of Nature. Theory is the general, experiments are the soldiers. Experiment is the interpreter of the artcfies of Nature. I t is never wrong; but our judgment is sometimes deceived because we are expecting results which experiment refuses to give. We must consult experiment and vary the cirDAA VINCI RDO cumstance>, fill we have deducedgeneral hws,for it alone can furnish us with ~ ~ ~ ~ . - L E O N
