SCIENTIFIC METHOD in GENERAL CHEMISTRY LABORATORY WORK* IRA D. GARARD New Jersey College for Women, Rutgers University, New Brunswick. New J e r s q
There i s constant complaint that the teaching of chemistry i s ineffective from the stendpmnts of both-employers of lechnical men and those who are interested in cultural education. General cheraistry must bear the brunt of the latter complaint and much of the former. The laboratory work is p i m r i l y at fault in that i t i s not scientific. A n examinatinn of twenty-eight laboratory manuals shows
only three that use the scientific method and thcse three are of recent publicalion. Quotalions from manuals are given to illustrate the empirical nature of the work, and work of a scient$c character i s suggeded as a n dteynative and illuslrated. Each experzment presented to a student should have a n introduction giving a background for this Nrticular experiment.
OMPLAINTS about the effectivenessof the teaching of chemistry in the colleges have been numerous and varied. The industrialist often claims that the college graduate is'of little use in industry until industry trains him. Philosophers and educators agree that courses in chemistry, like those in other sciences, leave little impression on the minds of the graduates. A comprehensive list of published complaints of this kind would be too long to include here and too familiar to be useful in this paper. A quotation from President Butler of Columbia will serve to summarize the complaints of the latter type.'
ject t o the results of verification, modification or overthrow by later inquiry or by the discovery of new methods and processes of research. One would suppose t h a t after a half-century of this experience and this discipline the popular mind would bear same traces of t h e influence of scientific method, and that i t would be guided by that method, a t least in part, in reaching results and in formulating policies in social and political life. If there be any evidence of such an effect, i t is certainly not easy t o find. Paqsian, prejudice, partisanship, unreason still sway men, whether as individuals or in the mass, precisely as if scientific method had never been heard of. How i s i t Dossible that with all the enormous advances of science and with all its literally stupendous -achievements i t has produced such negligible results on the mass temperament and the mars mind? This is a question which may well give us pause, for something must be lacking if intelligent men and women, long brought into contact with scientific method and scientific processes, pay no attention whatever to these, and show no effect of their influence, when making their ~ r i v a t eor public judgments.
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For two generations a vety considerable part, perhaps a major part, of the effort of educational systems and institutions has been expended upon the development of teaching and research in the natural and experimental sciences and in making adequate provision for this work in men, in laboratories and in apparatus. The essential fact in all scientific study is the use and the comprehension of the scientific method. Nothing is t o be taken for granted and no test, whether quantitative or qualitative, is t o be overlooked. Every conclusion as i t is reached is held sub-
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*Presented before the Division of Chemical Education a t Chicago. Ill., September 12. 1933. 1 Annual Report of the President of Columbia University for 1925.
The burden of these complaints, in so far as chemistry is concerned, must fall upon the course in general chemistry, for this is the only course usually taken by the liberal arts student and it is here also that the mold of the industrial chemist is cast. Several years spent as a student, teacher, and administrator of science work lead me to the simple con-
clusion that the courses in general chemistry, along with the general courses in the other sciences, do not expose the student to the scientific method a t all, unless i t be on rare occasions by inference. In the classroom the student is told things that he is expected to remember; in the laboratory, he follows recipes like the cook in the kitchen. The courses in analytical chemistry are practically the only exponents of the scientific method in the undergraduate curriculum. This training alone is not sufficient to make a chemist, and, of course, the arts student does not take analytical courses a t all. It is the laboratory work of the general chemistry course that is primarily a t fault. The difficulties encountered in large lecture sections do not apply to the laboratory, for here the student is taught as an individual and, in large measure, by a book. The results in laboratory work, in spite of all the expense, have been so meager that many teachers have seriously recommended the complete elimination of laboratory work from the general courses for the arts student. The chief cause of the failure of the laboratory work in general chemistry, and thereby the whole course, for both types of students mentioned above, is apparent when the laboratory guides in use are analyzed. The author finds on his shelves twenty-eight laboratory manuals written by twenty-eight authors and published by eleven of the best known publishers of college textbooks. Nineteen of these manuals by twenty authors and from ten publishers are quite useless so far as the scientific method is concerned. None of them places before the student the kind of work the trained chemist does when he enters his laboratory. Many of these manuals are as much alike as the copyright laws permit, particularly when the same author feels obliged to write two or more manuals. A few typical quotations taken from any of these manuals illustrate the futility of such laboratory work as scientific training. "Add to 2 cc. of sulfuric acid a few drons of barium chloride. Write the equation. Is the precipitate soluble in hydrochloric acid? How can sulfites be distinguished from sulfates?" "Into one of the bottles of chlorine sprinkle a bit of powdered antimony. Results? What is obtained? Add a little water and shake the contents. Color and composition of the product?" ‘I. Allow the solution to cool and examine the product (boric acid). For what is i t used? What is the anhydride of boric acid? Of what acid is borax a salt? What is its anhydride? Is boric acid more or less hydrated than the acid corresponding to borax?" These quotations are from three different manuals and are typical. In each case the student performs a simple experiment requiring a few minutes and then spends an hour or more passing an examination on the textbook or the lecture. While such work no doubt has some merit, it does not possess a single attribute of scientific procedure. Practically all the directions in these nineteen manuals instruct the student to do something and then to answer questions which can be
answered only from the textbook or the lecture notes. Six of the twenty-eight manuals a t hand constitute a second group which is a slight improvement over the first. These six represent six authors, only two of whom are absent from the first list, and two publishers, both of whom are included in the first list. All six of these manuals begin each exercise with a statement of its object. Here the student is a t least given some intimation of what he is trying to do. Beyond this beginning, however, these books are not much better than the first group. The exercises are of the same type and are mainly descriptive. The thud group of three manuals represents the work of five authors, none of whom appears in either of the other two lists. They are published by three companies, two of which appear in the other lists. All three of these manuals constantly illustrate the scientific method and perhaps it is significant that the copyright dates are 1923, 1931, and 1932. One of them is adapted to beginners, but, unfortunately, the other two assume a little too much knowledge of the subject for many college classes. So far as these twenty-eight manuals cover the field, i t may be said that about ten per cent. of the students learn general chemistry by the scientific method, and only in the last two years has the percentage been above four per cent. Of course, many students have used instruction sheets devised by their teachers, but not published. Some of these dfier from the printed manuals chiefly in the selection of experiments, but it is hoped that in the others the scientificwork constitutes a higher percentage than i t does in the printed manuals. The experiments that have appeared in the JOURNAL OF CHEMICAL EDUCATION in the last five years, however, have been no improveme'nt over those in the available manuals so far as the scientific method is concerned. Perhaps it would be well to indicate what I mean by the scientific method in the laboratory. Briefly, it is this. All the laboratory work of chemistry may be classified under five heads: manipulation, determination of properties of substances, preparation and purification of substances, study of chemical reactions, and analysis. Every laboratory course in general chemistry should contain exercises in all these types of work and the object of each exercise- should be presented to the student clearly and frankly. For example, an exercise on the use of heat in the laboratory might be included in which the necessity for applying heat in chemical experiments would be explained and mention made of all the different methods used together with their relative advantages. The common methods and their relative advantages could be illustrated by proper exercises. Not many manipulatory exercises need be included. Neutralization, titration, the determination of solubility, filtration, and many other processes can be included in experiments for the determination of properties or the study of reactions, but the manual should make it clear to the student that such technic is not
simply part of that speafic exercise, but a general method for the acquisition of certain information. Iu later experiments where the same technic is needed, instructions should not be repeated unless variations are necessary and, if they are, the reasons for such variations should be given. The instruction in laboratory technic should teach the student how to learn things and not how to do things. Controlled conditions, which are the essence of scientificprocedure, should be continually emphasized. Every beginner in chemistq, whatever his aim in taking the course, needs to determine the chemical and physical properties of numerous substances for these are the basic facts without which there would be no science of chemistry. No amount of reading or listening to lectures can replace actual observation of properties. It should be emphasized that each chemical substance is known by its properties rather than by a formula. Oxygen, for example, is not Oe, but an odorless gas, of density 1.42, slightly soluble in water, and so on. That is, it is that substance with the properties which its discoverer and others found i t to possess. These ate the items that come to the mind of a chemist when he thinks of oxygen. Each laboratory exercise should contain a single problem. In the determination of properties, the introduction to the experiment should list properties that the student will not determine and say why he will not. It should also discuss the property or properties which are sufficiently distinctive to constitute a test for the substance. Here is the best opportunity in this type of work to emphasize by actual experiment the importance of controlled conditions in science. Even the student who has studied chemistry in the secondary school should determine properties of a sufficient number of substances to gain the more advanced point of view here outlined. The exercises for the preparation of substances as they now appear in the manuals are primarily rule-ofthumb methods for the preparation of gases. Since it is diicult to purify gases this is wobably the reason why the purification of chemical substances is almost completely neglected. Over eighty per cent. of the inorgauic substances listed in the International Critical Tables, and over seventy per cent. of those given in the market reports of Industrial and Engzneering Chemistry are salts, but most of the manuals now available devote little or no space to the preparation of salts or their purification. This omission has considerable bearing on the tendency of young chemists to assume purity in the chemicals on the market. Aside from the predominance of salts among inorganic chemical substances, they constitute almost the only opportunity for familiarizing the student with crystals and crystallization. The shelf reagents will not impress the idea of crystals upon the student because very few of them consist of crystals large enough to be noticeable. The preparation of solids and their purification, including tests for purity and even a rough determination of the formula, furnish abundant opportunity to
provide valuable observation, impart practical information, and illustrate the scientific method. The study of chemical reactions provides even better opportunity for presenting the scientific method than any of the three preceding types of work. Students continually ask: "How does one tell what will be formed in a given reaction?" The question discloses the weakness in the usual type of laboratory work, since the majority of manuals force the student to rely upon his textbook or his instructor for the answer. Experiments, however, can be devised so that the student learns the answer just as a chemist does when he is in doubt. For example, he can show that iron and sulfur comb'me to form ferrous sulfide by first learning the properties of this salt and then applying his knowledge to the product of the reaction. Again, the introduction to an experiment might say that heating potassium chlorate under certain conditions gives potassium chloride and under other conditions gives the perchlorate. Then, by first becoming familiar with the outstanding properties of these three substances, as well as those of free oxygen, the student is in a position to study this reaction intelligently. Probably every student of chemistry has been told that zinc reacts with dilute sulfuric acid to give hydrogen and zinc sulfate, but 1 venture the assertion that not one in ten thousand has ever verified the formation of the zinc sulfate. Most manuals do not even show that a solid substance is obtained, and practically none of them attempts to have the student go further and prove that such solid resulted from the reaction. Finally, although analytical chemistry furnishes an excellent medium for the presentation of the scientific method, courses in general ,chemistry seldom allow sufficient time to do much work of this sort. In analysis conditions must be controlled in order to get results. Enough analysis should be included to make use of the tests learned by the student when properties were studied. Interest can be added to the course and the ends of training served a t the same time by the investigation of some common things. Ashes can be tested for several substances, tin foil may be tested for lead, drink'mg water for chlorine and chloride. Many such examples come to mind and may be introduced if time and the object of the course permit. In conclusion i t may be said that few of the laboratory manuals of general chemistry available touch the scientific method a t all. A suitable manual should state the object of each experiment clearly and frankly. Each experiment should have an introduction that gives the essential part of the background that a trained chemist would bring to bear in solving the same problem that is given to the student. The experimental directions should be such that the work done by the student leads to the accomplishment of the object of the experiment. Perhaps laboratory work as here outlined covers fewer substances than the more usual type, but, in the author's experience, it leaves the student with a far better grasp and appreciation of the science of chemistry.
