THE AMERICAN CHEMICAL SOCIETY

DIVISION OF CHEMICAL EDUCATION

W. A. Noyes, chairman

B. S. Hopkins, secretary

Educating the public in the use of the metric system: HARVEY A. NEVILLE. All countries except Great Britain and the United States have adopted the metric system of measurement. When this step is taken here, it will be the duty of the educational system of the country to familiarize the public with the usage and advantages of metric units. For this purpose methods of visual instruction are suggested. The convenience of decimal relations and the interrelation of the fundamental units are emphasized. The metric equivalents of common quantities are graphically shown. Some practical conveniences of metric units are pointed out, and the economy of time and effort now dissipated in teaching several different systems of measurement is discussed.

Ethylene: F. B. ARENTZ. Ethylene gas, discovered in 1795 by four Dutch chemists, did not come into prominence until the World War. Its first use was in the manufacture of mustard gas, but now its use for cutting and welding, coloring of citrus fruits, as an anesthetic and in chemical synthesis is becoming more general. Ethylene is made by passing ethyl alcohol vapcr over a heated catalyst, condensing out the water formed, and compressing the pure gas into steel cylinders.

Some angles in the articulation of high school and college chemistry: CHARLES E. COATES. A discussion of the attitude of the college teacher and the nature of college requirements relative to this problem. The different purposes of various first-year courses in college chemistry and how these purposes can best be accomplished. The time in the high school course in which chemistry is given. Difference in qualifications of high school teachers of chemistry with regard to scholarship and teaching ability. The difference in qualifications of first-year teachers in college chemistry in regard to scholarship and teaching ability. The degree of maturity of high school students. The equipment of high school laboratories. Is high school chemistry a real help to the college student in chemistry, and if so, to what degree and why?

A tested method of teaching the history of chemistry: LYMAN C. NEWELL. Instruction in the history of chemistry is handicapped by the student's lack of historical background and his incomplete knowledge of chemistry. Attempts to give a consecutive or detailed course are doomed to failure. An experience of twenty-five years has convinced me that the only method suitable for a mixed class of beginners must possess certain features: (1) It must be built around the personality and specific contributions of prominent chemists, (2) it must be illustrated by portraits, books and memorabilia, (3) it should be supplemented by two kinds of papers prepared by students, viz.,

short papers at frequent intervals and one or more longer papers requiring special reading.

Systematic treatment of first-year chemistry: P. M. GLASOE. Approach the subject through familiar channels. Do not swamp the student with new definitions and new vocabulary from the start. Have student name a list of all the metals and non-metals he knows from everyday life. Carry the process forward by having him arrange the elements as found in a table of atomic weights in the order of their weights. Fifteen or twenty metals with half a dozen non-metals constitute a year's work. Arrange first two series, Li-Ne and Na-A, so as to show grouping. Study, by means of these series, the change of properties from metallic to non-metallic, positive to negative basis to acid. On the same basis take up chemical affinity, valence, structural formulas; acids, their derivation and structural formulas, bases, their derivation and structure; salts, their structural formulas and relative stability; the derivation and properties of the anhydrides of both bases and acids. Amphoterism is a natural deduction. Elements are studied in the order of their occurrence in the groups of the Periodic System.

The art of lecture table demonstrating: HERBERT F. DAVIDSON. Lecture table demonstrations are worth while because they make the subject concrete. Chemistry as usually taught is, to many students, a very abstract thing, but well-chosen, deftly performed experiments can make the subject very real to such students. Demonstrations should not be performed simply because they are spectacular, but because they teach a chemical lesson. The building of apparatus which above all should be simple and capable of expeditious exhibition, gives the teacher himself the kind of mental stimulation needed by those who teach the general chemistry. It is better to show no experiments on the lecture table than to have any appreciable percentage of failures. A number of experiments will be performed to illustrate the principles discussed.

Correlation of high school and college chemistry: LEROY L. SUTHERLAND. A discussion of the true function of a high school chemistry course as to purpose and scope. A plea that colleges and universities exercise greater caution in accrediting the science work of secondary schools. An exposition of the harm done to both chemistry and the individual student, when on entering freshman chemistry, he is given no recognition whatsoever for work done in his high school course, but told to "Forget all you have learned-we will now teach you correctly.' A claim that the study and teaching of chemistry should be a progressive growth, and not a planting of seed which as they begin to sprout are ruthlessly torn up and cast aside on the dump-pile to be replaced by more seed. This represents lost motion. We must see to it that the secondary schools plant the right kind of seed, and then build to but not destroy their work.

Teaching the growth of chemistry in industry by the

use. of maps: LOUIS W. MATTERN. From reports compiled by Professor Charles E. Munroe, expert agent in charge of "". "Chemicals and Allied Products" at the U. S. censuses 1900-1905-1910, several charts were prepared which he used during the course of an address, published in the January, 1925, issue of the Journal of Chemical Education, to show the growth of several chemical industries and the need of their extension into unoccupied fields. These charts are very instructive, so it has been suggested that the large body of important census statistics of chemical industries since 1900 could be used in producing a system of charts, by means of suitable characters on maps of the United States, which would clearly visualize the growth of chemistry in industry and the vast areas of latent resources which challenge chemistry to greater service. Such maps would prove most useful to teachers. Acting on the belief of the importance of this work, the author has conferred with Mr. William W. Stuart, director of the census, on the feasibility of this matter and who expressed his desire to furnish maps of intervening cen

suses.

The problem of high school chemistry: GUY CLINTON. The three principal factors recognized are matter, arrangement and method. The paper is restricted to the discussion of the latter two. One fundamental principle which determines arrangement is that matter should be presented in a progressive order, so that that which follows may not presume knowledge beyond what the preceding exercises give opportunity to learn. It is considered preferable to build a course around laboratory experiments rather than to take it from a text-book. Experiments should be grouped about principles rather than principles about experiments. The language of chemistry should receive the particular attention of teachers.

Museum experiments: R. A. BAKER. Any reaction which requires considerable time for completion, or which is of such a nature that its course is automatically recorded, may be utilized as a "museum experiment.'' The set-ups may be displayed long enough to attract general attention, and when properly placarded, stimulate interest and profitable discussion among students. A number of appropriate experiments are described.

The present status of the ionization theory: JAMES KENDALL. The original ionization theory, as formulated by Arrhenius, is unable to account for the most important type of all conducting solutions-strong electrolytes in water. These do not follow Ostwald's dilution law, but do conform approximately, nevertheless, to the solubility product principle. It may be deduced from this that the stumbling-block is connected in some way Iwith the undissociated molecule in solution. Recent research, indeed, demonstrates that the Arrhenius conception of kinetic equilibrium between undissociated and ionized solute is incorrect. The extension of the ideas of the Braggs on crystal structure and of Lewis and Langmuir on atomic structure to solution leads to the

conclusion that the undissociated molecule is practically non-existent, and that at high dilutions electrostatic forces between oppositely charged ions are the prime factors to be considered. At greater concentrations, interactions between solvent and solute must be taken into account, and rules regarding such interactions have been qualitatively established. The collapse of the theory of Ghosh discredited "complete ionization'' temporarily, but the more rigorous equations of Debye and Huckel are fully in accord with experimental data. Some points of difficulty still remain, but the rapid advances made in the last few years inspire the hope that the field will be entirely cleared up in the near future.

etc.,

Use of charts, motion pictures and other aids in the teaching of elementary organic chemistry: ALEXANDER LOWY. A number of charts, diagrams, such as "Products from a barrel of oil," "Products from a hundred tons of coal,' 99 "" "Organic type formulas,'' 'Organic chemical transformations," "Petroleum refining, will be shown. The use of motion pictures entitled "The story of petroleum' (4 reels, distributed by the Bureau of Mines) and "By-product coking" (2 reels, distributed by the Koppers Company, Pittsburgh) will be emphasized. Saving time at lectures by using colored crayons will be illustrated.

Minimum essentials:“Teach-test-reteach'': RACHEL E. ANDERSON. The determination of a definite course of study to fit the existing needs of a high school where college and non-college preparatory students are taught in the same class. The adoption of definite minimum essentials to be mastered by all students; the effective and rapid measurement of them to determine whether reteaching is necessary for the individual or the class collectively. The experiment has proved the effectiveness of teaching for mastery, rather than for distribution along a normal curve. In fact the application of the method of "Teach-test-reteach" has developed a mastery of fundamental principles that has made the curve of distribution top-heavy on the positive side. The plan breeds a closer correlation between laboratory and text-book assignment and the use of reference books. Furthermore, the plan is not complete until chemistry is built into everyday processes. Slosson's "Creative Chemistry" is read and the rather pleasant game of one hundred "false and true" questions measure the results. Chemistry has increased in popularity and there has been a marked decrease in the number of failures.

Teaching principles of electrodeposition: W. Blum. The importance of potential relations, and especially of single potentials during deposition, is emphasized. Potential changes involved in polarization can be most simply explained in terms of the changes in "effective metal ion concentration."' From polarization curves it is often possible to predict the direction of the effect. of different variables upon the distribution and crystalline structure of the deposited metals.

THE SPECIFIC IMMUNITY OF THE TISSUES AND ITS BEARING

ON TREATMENT1

Ar the present time, in this day of rapidly increasing knowledge in all lines of human endeavor, we accept at first as wonders and then more or less as commonplaces the marvels that have been accomplished even during the past fifty years. We tacitly predict the future by the accomplishments of the past, and this has given us an almost unlimited optimism, even to a greater extent than previous generations have ever had. The various lines of study have been brought into closer contact with each other than ever before and have become interdependent.

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The above applies equally as well to medical work as to other fields. Advances have been tremendous, and yet it seems that we have only begun to get into very close contact with what we do not know. vances in surgery have not exceeded those in internal medicine, and the wonderful work done in the field of infection and immunity can be appreciated only by the trained student.

Advances in medicine have been made by improvement in existing theories and methods, and also by the introduction of new theories and methods. The latter has always been due to the utilization of previously existing knowledge, and could not have been possible without it. Modern scientific work abounds with instances of this, of which research in diabetes over the past forty years is a very good one. New ideas are readily tested by research work and the good separated from the worthless. This is putting the scientific imagination to its best use. Improvement in clinical results, even though slight, would be relatively considerable, as it would be in diseases that had previously offered special resistance to our efforts.

There is no more interesting or important subject in the whole field of medicine than that of infection and immunity. Cases of infection comprise most of those with which the practicing physician comes in contact. I mean by that the primary and secondary results of infection, whether they be specific diseases, infection of tissues by organisms that do not cause specific diseases or the general results of the absorption of bacterial toxines. By far the greatest part

1 Address of the president of the Southwestern Division of the American Association for the Advancement of Science, Boulder, Colorado, June 8, 1925.

of human mortality is due to diseases that are caused by living organisms, and even in many cases that are not of such origin, the factor of infection must sooner or later be taken into account. This subject of infectious diseases constitutes our most important medical problem, and includes, of course, that of our natural and acquired immunity to them.

I will deal especially with the resistance of the tissues to the invasion of living organisms, which in clinical medical work are usually bacteria, but do not wish to be understood as minimizing the importance of the immune bodies that are present in the blood serum, either before infection takes place, or which develop as the result of our resistance to infection.

Every species of animal and plant has special preferences of habitat and food. These factors vary within extremely wide limits, in fact, to very nearly the same extent as living organisms do in structure and physiology. The same applies to bacteria, whether living outside of the body or in it.

The differences in the species of infecting organisms, the food required by each, the toxines formed and all the other factors concerned explain the wide variation in the human diseases caused by them. This constitutes the basis of human infectious diseases.

I will refer to bacteria as the infecting organisms, as they are the ones that most frequently cause human infectious diseases.

The problem presented by the growth of bacteria in the human body may be compared with the growth of a vegetable seed. The seed represents the infecting agent. It is well known that the seeds of different species grow with varying rapidity, that some are much hardier than others and also that different individual seeds of the same species do not have the same ability to grow, some producing small and others large and healthy plants. This corresponds with the virulence of the various infecting organisms, and the differences in individuals and strains. The seed can grow and reproduce only within definite limits of temperature, but can live above and below these lim

its. The gases with which it comes in contact are important, as are also the amount and character of the light. The water, and the chemicals dissolved in it, represent the body fluids, and the soil represents the tissues.

In agriculture one of the most important factors that is considered is the character of the soil. Does it contain the proper nutriment for the seed, are there present in it injurious chemicals and what is its biological content? The agriculturist wishes to know definitely about these points. The composition of the soil should be altered, when advisable and possible, to meet the varied requirements of the different seeds. Also, if the seed does not grow well, he wants to know

why and always takes into consideration as a possible explanation the composition of the soil used.

In cases of human infection there must be good reasons why the bacteria do or do not grow on the tissues, that is, infect them. The changes in the tissues resulting from infection have been very carefully studied, but we have not given sufficient attention to the character of the tissues as far as it relates to their ability to resist infection. It is possible, and indeed probable, that this immunity of the tissues is the most important single factor in the institution of an infectious process.

The factors governing the growth of the seed in the ground and the bacteria in the human tissues are very complex. The total result in either case may depend upon only slight changes in any one factor. Bacteria in human infections must meet favorable conditions if they are to survive or grow actively on the tissues. Unfavorable conditions are quickly reflected in the results. This applies to variations in all the factors concerned.

Only a comparatively few of the organisms that get on or into the human body meet with sufficiently favorable conditions to grow on the tissues enough to injure them or produce a definite disease. Many bacteria and microscopic animal organisms enter the body, in one way or another, and are either killed quickly, die for lack of favorable conditions or are eliminated without growing on the tissues, but some may find a lodging and either do not injure them at all or so slightly as to be negligent. These are known as non-pathogenic organisms. However, others grow on account of meeting with conditions that are especially favorable to them; there is the kind of nourishment desired in the tissues affected and an absence of unfavorable chemicals in them and the fluids supplying them, or both. On the other hand, the tissues that are not affected either do not contain the food necessary for the infecting organisms or contain substances injurious to them which prevent or inhibit their growth, or both.

In the case of some diseases, like typhoid fever, the infecting organism gets into the general circulation and goes to all the tissues of the body, but only a few of these are infected, that is, permit the bacteria to multiply actively in them. Why are not all the tissues infected equally? The only possible explanation of this is that the tissues themselves in some, at present, unknown way resist invasion. This is a very important biological fact and is universal, as can be readily understood by a study of other infectious diseases. There are very important reasons for it which are not well understood, and the subject has received very little attention from bacteriologists and pathologists.

With regard to the influence of the blood serum, it may be said that the immune substances in it are too frequently not enough to prevent infection, but they develop sufficiently in time after infection has taken place to be a very important factor in killing the infecting agent. The composition of the serum is evidently not responsible for the resistance of certain tissues, and the inability of others to resist. The determining factor must be the chemical composition of the tissue itself.

After an injury to the tissues, whether it be mechanical, chemical or bacterial, the white blood cells exert a powerful protecting influence by collecting there in large numbers, but are not concerned in the incidence of infection of healthy tissues by bacteria.

As we may refer to the ability of certain organisms to grow on certain tissues as specific infection, so we may refer to the special ability of certain tissues to resist certain organisms as the specific immunity of the tissues.

Kolmer, in referring to the causes of this tissue immunity, states that "in general, we must conclude that either (1) microorganisms tend to be destroyed in every tissue or organ except those that are poor in defensive forces and are susceptible or (2) microorganisms or their products circulate passively through a tissue and do not lodge because they possess no affinity for these cells."2

The relative influence of the food supply needed by bacteria and the presence of chemicals poisonous to them could be determined by the addition of tissues to various bacterial cultures, using different media. A number of tissues have been used in the preparation of culture media, but they have been added for the purpose of encouraging the growth of bacteria and not to discover what power they have to prevent it.

If the cause of this immunity of the tissues were due equally to the lack of food supply and the presence of a poisonous substance, it would warrant the formulation of a natural law, as follows: The human body contains preformed within itself a natural defense against, and a possible cure of, all infections to which it is liable.

This infers that if the chemicals in the tissues that are poisonous to the infecting organisms could be isolated and made in sufficient quantities, they could be used not only in the treatment of these infections, but possibly also in prevention in special instances. This would be making use of one of the most important causes of our inherent resistance, which is certainly effectual and also probably the best that can be found. The presence of these substances is only hypotheti

2 Kolmer, "Infection, immunity and specific therapy," 1915.

cal, but the same may be said of numerous others commonly referred to in medical work and whose presence we do not doubt. I refer especially to the various immune chemicals present in the blood developing as the result of infection. The latter vary with the nature of the infection and the composition of the toxine produced by the infecting agent, and are entirely hypothetical. This subject, which we may term hypothetical chemistry, is a large and important one.

The vitamines will, no doubt, be isolated and identified before long. This will lead to their manufacture for therapeutic purposes. They are at present hypothetical, but we do not question either their presence or what they do.

The isolation of these protective chemicals present in the tissues will, of course, be a question of time and careful work, but should be as possible as the other successes of physiological chemists.

I will now review briefly the essential features of some infectious diseases that illustrate the points mentioned above. Hookworm infection is a good example. The life cycle of this parasite is as follows: Let us start with the worms adhering to the mucous membrane of the upper part of the human small intestine. The eggs are thrown off in large numbers and are discharged with the feces. They then develop only under favorable conditions of soil, moisture and heat, when they form motile larvæ. When these come into contact with human skin, generally on the hands or feet, they adhere to it, gradually work their way through it and enter the circulation. They are carried to the lungs, pass through the tissues, enter the air cells, pass up through the bronchioles, bronchi and trachea, and are then coughed up through the larynx. Most of them are probably then expectorated by the patient, but some are swallowed. On entering the stomach they are not killed by the gastric contents, but leave the stomach and attach themselves to the mucous membrane of the small intestine. They seem to know just what tissues in the human body to make use of in passage, and do not take up a permanent residence anywhere except in the small intestine. They do not attempt to go to any other tissues in the body, which they could no doubt do if they tried to, as other similar parasites do.

In trichiniasis the trichina spiralis is ingested in infected meat, and in the gastro-intestinal tract the larvae are set free from their enveloping sheaths, grow to maturity and produce numerous eggs, from which larvae develop. These pass through the intestinal mucosa and find their way to the muscles. Other tissues are not infected. The parasite seems to know instinctively where to go and how to get there.

The amoeba histolytica is also highly selective and finds its most suitable location for growth in the hu