June 22, 1943

Dr. Henry B. Bull

Northwestern University

The Medical School

305 East Chicago Avenue

Chicago, Illinois

Dear Dr. Bull:

I am sorry to say that my wife and I have not, because of our duties here, been able to get away on a vacation. I am still hoping that we can take a few days off.

I do not agree with your idea that the manufacture of artificial antibodies should be delayed until information about the configuration of the surface of the globulin molecule is at hand. If we need to know about the structure of proteins before working with proteins no protein experiments at all could be carried out. I agree, of course, that experiments aren't worth very much until they are reproducible.

Thanks for your suggestions about experiments to be carried out.

I shall be glad to see the report on your work, when you get time to prepare it and send it to me. I understand that it is not satisfactory for publication, but I need to have a detailed account of the work in order to plan what should be done next and to avoid duplication of effort.

Sincerely yours,

Linus Pauling

LP:jr

June 22, 1943

Dr. L. Michaelis

The Rockefeller Institute

for Medical Research

66th Street and New York Avenue

New York, New York

Dear Dr. Michaelis:

I feel some concern about your statement in your letter of June 15 that in the quinone-hydroquinone system where there is the possibility of complete resonance, the proton is in the average equidistant from the two oxygen atoms. In a certain sense this is presumably correct; however, this statement might be interpreted as meaning that the stable position of the proton is midway between the two oxygen atoms, which is, I think, not so. It is very probable instead that the proton is practically always much nearer to one oxygen atom than to the other. This point is discussed in Section 38 of THE NATURE OF THE CHEMICAL BOND. In view of the fact that the frequency of motion of the proton from one equilibrium position to another would be very small, and hence that the resonance energy resulting from this motion would also be very smell, the symmetry of systems involving hydrogen bonds is not so significant with respect to resonance energy as the symmetry of systems involving electronic resonance.

I am completely satisfied with the situation regarding acknowledgment of my suggestion. I am not discussing scientific matters with you because I want to get acknowledgement, but in the hope that I can be of some use to you in connection with your work. I shall continue to send my opinions to you, in the hope that you may find some of them useful.

Sincerely yours,

Linus Pauling

LP:jr