Institute for Theoretical Physics
Munich, December 17, 1926
Dear Dr. Noyes:
I had hoped that the enclosed paper on the Theoretic cal Prediction of the Physical
Properties of Many Electron J and Mole-refraction would reach you in time to act as
a Christmas greeting. The delay arose from my having to type it myself, for the typing
agencies require double hourly price and also double time for typing in English. [Some
of the keys on German typewriters differ from ours, which explains why I occasionally
put “ä” in place of “g”, etc.]
This paper will (unless some unforeseen circumstance arises) be sent to the Proceedings
of the Royal Society in a few days. I have not forgotten your advice regarding publication
in our own journals. Professor Sommerfeld became a Foreign Member of the Royal Society
last spring, and I believe that he feels that he should submit some paper to the Society.
I have felt that his kindness to me required me to act in accordance with his desires.
Moreover, I had been anticipating with considerable lack of pleasure the arguments
that the Physical Review would advance against the publication of such a long paper,
and the multitude of small but annoying changes that they would doubtless require
to be made when (after several months) they had decided to publish it. My first paper,
which was to appear in the January issue, will not do so, for I was sent the proof
of a Japanese investigator’s paper, instead of mine. They haven’t reached a decision
regarding the electron-affinity paper. (I hear now that it is accepted)
I believe that this work is of considerable value, in showing the theoretical
treatment of the properties of complicated atoms and ions. The possible extensions
and applications of the method are numerous; for example, I am now working on the
sizes of ions in crystals, and the question of the occurrence of the various types
of crystals. This work, if it turns out well, will be suitable for the Journal of
the American Chemical Society, I think. I think that it is a very interesting that
one can see the ψ- functions of Schrödinger’s wave mechanics by means of the X-ray
study of crystals. This work should be continued experimentally; I believe that much
information regarding the nature of the chemical bond will result from it, and I am
hoping that it might be possible to do the experimental work in Gates.
I feel that the theoretical (and experimental) study of the properties of complicated
atoms and ions (i.e. with many electrons) and of molecules could really be classed
with chemistry; for usually a study of the different phenomena exhibited by different
chemical substances is called chemical, and the study of phenomene without especial
reference to the chemical substances exhibiting them is called physical. However,
we can hardly class this with Physical Chemistry, as ordinarily understood; possibly
Molecular Chemistry would be a suitable description.
I wrote to Moe regarding my application a couple of months ago, making it very clear
that I would have to have a decision made about a renewal of my Fellowship in time
to return to America if it were not granted. In reply he said nothing definite, but
said that I cam to send in a budget of my expenses before February 1. I am now preparing
my application for renewal, a copy of which I shall send you in a few days. My plans
are the following: to leave here about February 15 for Gottingen, spending about four
weeks there, and then two weeks in Berlin. After that four or six weeks in Copenhagen,
to learn the developments made under Bohr and Keisenberg, who is a fine young man.
Then we shall go to Zurich for the summer semester with Schrödinger, who will have
returned in May. Debye will be in Zurich only for the month of June, during which
he will lecture. In August we shall go to England, especially to visit W.L. Bragg
in Manchester; and then home in September.
I am sorry to do so much traveling, for I like the repose of one locality, and
I’m afraid that my work will not progress very fast. However, I think it highly profitable
for me to visit these important places, staying long enough in each to get a pretty
good idea of the work being done. I have enjoyed very much the two semesters with
Professor Sommerfeld, who is a fine teacher (in particular have I learned much mathematics
in his seminar); and I’d rather like to stay longer. Traveling is expensive, and perhaps
the Guggenheim Board will not grant the entire amount of my budget (which I haven’t
yet estimated), in which case I’d have to omit part of my schedule.
I shall soon have Selmayr begin work on making our crystal models. I am sure
that you will be pleased with them.
I am continuously surprised at the number of books continually appearing here
– especially handbooks. We seem by contrast to write very little in the United States.
Every university has at least one chemist and one physicist who are more or less authorities
in some field, and who write about it in one of the many handbooks, such as the 23
(or more) volumed Handbuch der Physik.
I am learning a good deal of the foundations of quantum theory from Sommerfeld,
and I hope to get an idea of the opinions of Bohr, Heisenberg, Schrödinger, and of
others. Accordingly I am looking forward to being back at the Institute, and especially
to the Chem. Seminar. Sommerfeld told me that he would put out a new English edition
as soon as he found time – I assume in about a year. He will write two volumes, the
first elementary, the second specialized. I am sure that the new quantum mechanics
will be in it, but I think that he himself has not yet decided upon how to include
it, and upon how many changes to make over the 4th edition. He said that it will be
some time before he publishes another German edition, as the publishers still have
several thousand copies of the 4th edition on hand. Have I not mentioned before that
he accepts completely the wave mechanics, as a good mathematician would, for all quantum
theory problems are thus reduced to the boundary conditions problems of the old mathematical
I hope to see the Travel Prize boys somewhere. Perhaps they will not reach Zurich
before we arrive there.
The news regarding the people at Gates was most welcome. I read Prescott’s interesting
paper; I would surely feel lost without the Journal. A trip to Europe has served to
show me, as well as Dr. Dickinson, that crystal structure still has a future before
J. I assume that Yost did not continue to work in crystal structures; I noticed that
Robertson said that he and Yost were going to measure absorption edges. It would be
fine if they would, but I’m afraid that I must interpret your lack of mention of it
as meaning that Robertson merely put the reference in for effect.
I am glad the new edition of Chemical Principles is getting along well. I think
it is a wonderful book. You know, of course, that all my knowledge (which is not encylopedaic,
but is good) of physical chemistry was obtained from that book, and except for the
last three chapters came from solitary study of the proof sheets you so kindly sent
me. Have you prepared the crystal section? I suppose that Dr. Dickinson will be of
great assistance with it. I should glad to contribute something (other than my mimeographed
notes), if you desire me to.
P.S. December 28, 1926
We had a pleasant but not exciting Christmas, and remembered the most enjoyable
time we had with you a year ago.
I kept this letter so as to be able to send a copy of my Fellowship application
to you; I mentioned, you see, that I am asking you and Dr. Millikan to write to them
I have just realized that the time will soon be here when the Institute, we all
as other universities, makes its decisions regarding the staff for the next year;
so that definite arrangements regarding my position and salary will also soon be made.
I have had no offers from any one, for I have thought, and accordingly expressed myself
as believing, that I would return to the Institute.
Most people seem to think that work such as mine, dealing with the properties
of atoms and molecules, should be classed with physics; but I (as I have said before)
feel that the study of chemical substances remains chemistry even though it reach
the state in which it requires the use of considerable mathematics. The question is
more than an academic one, for the answer really determines my classification as a
physicist or chemist.
I hope you are pleased with the paper I am sending you, and are not displeased
that it has been sent to the Royal Society.