if a more wholesome sentiment toward the subject among high school students can be created.

I have been wondering for some time past if we might not be obliged, as we are in some other subjects, to offer an elementary phase,-to better prepare our young people for an understanding of the regular text. If this should not seem advisable, then, by all means, let us have physics a required subject for the senior year, when the minds of high school students are more able to grasp it. It might keep some from graduation, for there will still be failures, but there is the greater hope that this larger insight into the mechanical universe will create a desire for further investigation, and will tend to the upbuilding of our higher institutions of learning.

THE RELATION OF HIGH SCHOOL PHYSICS TO OTHER SCHOOL STUDIES.

MISS LOA GREEN, BIG RAPIDS.

A few years ago I thought I was very courageous to even attend the Conference of Physics as almost the only woman present. I could never have promised to appear upon this program but for the fact that as one of a numerous family I early learned that this is a give as well as take world and felt I had no right to refuse to give just a little to an organization from which I have received so much inspiration, as well as hints, suggestions, and facts connected with the teaching of both chemistry and physics.

I feel it is unnecessary to dwell upon the relationship existing between these two subjects, as they really overlap since no division line can be drawn. So will call them twins, physics being the stronger twin.

When I started to prepare this paper, I asked the members of my physics class to write out for me the relation of Physics to other High School studies as it appealed to them. We, by the way, have physics in the senior year.

One-third of the class mentioned spelling as a closely related subject, giving as an illustration the greatly increased vocabulary, especially from derivation.

I feel that the spelling of all words which strictly belong to any subject can and should be taught as part of the subject. Aside from the advantage of being able to spell such words correctly, accuracy and observation are being cultivated.

A still greater number mentioned reading as a very near relative of physics and pointed out that a careful, intelligent reading is necessary in this subject in order to understand what is wanted and what is given. If definitions and laws are understood, these three questions: 1st. What is wanted?

2d. What is given' and 3d What relation exists between these factors? will usually make the solution of seemingly difficult problems possible for very ordinary pupils with very ordinary preparation in mathematics, at the same time impress upon the pupil the necessity of careful, thoughtful reading. The poorest English student of my class made it clear that English Grammar is at least a second cousin of Physics since the meaning of difficult definitions and laws can be understood if analyzed. This particular young man seemed unable to understand the meaning of the dyne, until he had analyzed the definition.

We will next take a look at physiology. This subject if well understood will furnish illustrations for about 115 definitions, laws, and principles,— some for every subdivision of physics. On the other hand, physics makes a better understanding of the various bodily functions possible.

Arithmetic is an older half-brother of Physics who has failed to do his duty, most of us recognize, but I will not humiliate him by going into details. However, I will say that in my estimation much blame that is laid upon his own brother Algebra rightfully belongs to Arithmetic. If accuracy, neatness and order in arrangement with a proper understanding of principles and formulæ are required in these subjects, a foundation of rock is laid for Physics.

Nine of our juniors are taking Algebra over as a fifth subject without credit, because they wanted better preparation for Physics. Many more would be doing so if it were possible with their other work.

Geometry as a sort of step-brother who having done his duty by Physics, will make graphic solutions and the study of light a healthful recreation for the average High School pupil of Physics.

To emphasize the relationship existing between the last three mentioned subjects and Physics I will quote the exact words of one of my young lady pupils, who, by the way, is one of the best in the class: "In the ninth, tenth and eleventh grades the student has had arithmetic, algebra, and geometry, and physics coming as it does, after these have been completed, serves as a reviewer and field of application of all the mathematical principles learned before."

"Physics not only serves as a reviewer and place of application but accuracy becomes a necessity, and the ability to work correctly and speedily is developed as would be impossible in the lower phases of mathematics. The true purpose of mathematics in the High School course is to develop the reasoning powers, and physics bringing all the different principles in relation to each other, helps high school mathematics to its best and highest purpose."

Another young lady, who has surprised me by the ability she has shown in physics, said: "Physics is very detrimental to the progress of other High School subjects. It is so interesting and applicable as it teaches us things we have often wondered about and which most of us have always wanted to

know. It gives us such enjoyment that the other subjects seem dry and uninteresting, we are spoiled for them. We don't take much interest in mathematics, perhaps, we can't see where it's going to be of any use, but alas! how it looms up a hob-goblin of a monster, when we are told to 'stand right there before the class' till we derive a formula so simple."

Still another young lady wrote: "In order to become familiar with this interesting science one must be well acquainted with the English grammar, so that he may properly understand the numerous laws and definitions. He must also have a good knowledge of arithmetic, algebra and geometry, for they are all used continually in solving the various problems. Therefore these are very necessary to the study of physics, for without them there could be no practical utilization of the wonderful and advantageous truths which are all the time being absorbed by our eager minds."

Physics makes many pupils feel the need of a course in trigonometry, and furnishes a field of direct application which I do not need to describe to a body of physics instructors.

One of my young men pupils wrote in this connection, "For instance in trigonometry physics is indispensable."

Bookkeeping can certainly claim a relationship as in this subject the pupil should get a training which would enable him to tabulate results in a neat, accurate, systematic manner as well as increase his respect for practical application in school work.

The languages, especially Latin has the everlasting gratitude of physics because it teaches pupils what work means. Another relationship was pointed out by one of our excellent language students who wrote as follows: "The relation of languages to physics is that so many terms used in physics are formed directly from Latin and German words, also the mental training which one gets in studying languages is not unlike that gotten in studying physics.'

Two other second cousins of Physics are History and Literature as Physics creates a desire for general information which can only be supplied by these two subjects. On the other hand History and Literature are much more interesting for a knowledge of the laws which govern the universe. Physics teaches that certain conditions give certain results while history and literature do the same thing as "cause and effect."

Physical geography as a little brother of Physics has a great opportunity to get the pupil started in the right direction by teaching him how to take notes, how to use and care for simple apparatus, properly, that the laboratory period is a period of work, that fooling is not to be tolerated, and create in him the desire to know physics.

All this may also be said of the sister subjects, Botany and Zoology or Biology.

Manual Training and Domestic Science are near kind to Physics for the same and similar reasons.

In all these subjects observation, reason, memory, judgment, respect for apparatus, the habit of minding his own business and the necessity of truthful reports can be developed to such an extent in the pupils as to make physics come as naturally as the heavy voice comes to the boy and the womanly modesty comes to the girl.

In showing the relation of physics to "Senior Reviews," one of my young lady pupils wrote: "Talk about senior reviews, why it can't begin with physics. We review everything we ever knew or thought, or dreamed and quite often just things we would like to think," while one of the young men wrote: "So in order to get physics one must get everything before it and get it in a thorough manner, then there is no doubt about physics being one of the most interesting subjects ever taught."

In his article, "The Aims and Needs of High School Physics," Prof. R. A. Milliken says: "The development of the power of self-control as it manifests itself especially in industry and application to the mastery of difficult situations" is the second factor in order of importance that is "to give to the rising generation the best possible preparation for perpetuating and improving upon the civilization which it inherits." I feel that one of my pupils meant the same when she said of physics, "It teaches us to be quite worldly and thoughtful and gives us a respect for nature's wonders."

In "The Present Status of High Schoool Physics" Dr. Henderson says that one of the great lessons that our schools should teach is the lesson of self-mastery, and it is one of the qualities that high school physics is preeminently fitted to give, provided we do not reform it beyond recognition or possible use." One of my young men pupils expressed the same feeling as follows: "Physics teaches us to be very careful and independent. To notice things in the best way, so that when we get out into the world we will have the principles by which to 'paddle our own canoe'."

CHEMICAL ENERGY, AFFINITY AND VALENCE.

PROFESSOR S. LAWRENCE BIGELOW, UNIVERSITY OF MICHIGAN.

INTRODUCTION.

It has seemed to the writer that there is a lack of uniformity, and sometimes of clearness, in the definitions given for the terms chemical energy, affinity and valence, and that this results in unnecessary confusion of ideas in the minds of students. Precise definitions, correct so far as they go, are especially desirable for first courses, for opinions formed at an impressionable age quickly turn to convictions and it is a hard and timeconsuming process to pry them loose, as in some cases we must, before the

student's mind becomes pliable and judicious enough to evaluate fairly, new facts and new ideas, and to follow the advance of the science critically yet appreciatively.

The following method of presenting these ideas has been found to give satisfactory results, both in beginning and in advanced courses, and it has the advantage that it may be built upon indefinitely. It requires no modification, but remains fundamental and useful, even though the student elects to pursue the study of chemistry to the frontiers of the science.

CHEMICAL ENERGY.

There is a force which causes substances to combine and which holds them together, more or less firmly, in what we call chemical compounds. We name this chemical energy, and all chemical reactions are manifestations of it. Its measurement, and the formulation of its modes of action as a mathematical expression, something as Newton formulated the attraction of gravitation, are the main ends of the science of chemistry. No matter what particular process we happen to be studying, we are, in fact, all the time trying, directly or indirectly, to measure and to formulate manifestations of chemical energy. The term "chemical energy" covers then, the central, ever present, most important problem in all branches of the science. If we could succeed in these efforts at formulation, there is no telling what marvellous and practical results would follow. We seem however, to be rather far from this desideratum in spite of earnest efforts extending over hundreds of years, and in spite of the fact that the problem has been attacked from almost every conceivable standpoint. The isolated facts and processes we have studied and recorded are almost countless, the generalizations we have secured are few, and the science is still waiting for its Newton.

It would be interesting and profitable to trace the history of these efforts to formulate the manifestations of chemical energy, but if we began, it would be hard to stop, for in truth, an historical review of the ideas for which our three terms stand is but little less than the history of chemistry. We must avoid this temptation and adhere to our purpose, merely to define what we mean by these terms; and while we shall in one sense fail, for in truth we do not understand this force, we shall find we have defined the problem in such manner that we are in a better position than before to appreciate what has been done and what remains to do.

ENERGY AND ITS FACTORS.

It is a well known fact that we can classify all processes we are competent to study according to the form of energy manifested, transferred, or transformed, and that these forms of energy are few in number. We know and can study mechanical energies (which are conveniently subdivided into kinetic, potential, and so on), heat, electrical energy, light or radiant energy, and chemical energy.