NORTHWESTERN UNIVERSITY

CHICAGO, ILLINOIS

June 17, 1943

Dr. Linus Pauling

Gates and Crellin Chemistry Laboratories

California Institute of Technology

Pasadena, California

Dear Doctor Pauling:

We are safely Back in the windy and warm city of Chicago and remember with some regret the cool nights in Altadena.

I hope you and Mrs. Pauling had an enjoyable vacation. It was good of you to have had us to your home and we are quite envious of your wonderful view and all that goes with it.

You have my good wishes in your endeavor to prepare artificial antibodies, but I must confess a feeling of pessimism in regard to this problem. I cannot help but believe the attempt to be premature. We do not know what configurations on the surface of the globulin molecule are necessary for antibody properties, nor do we know how to produce a given surface configuration even if we knew the one we wanted. In short, any success one might have must be regarded as just plain luck. Frankly, I am not impressed by experimental procedures which work sometimes but which do not at other times, and no cause can be assigned for the failure. No doubt you are as well aware of this as I, but I thought it best to put it down for what it is worth.

If the experiments on heating at 57°C. are to be continued, I suggest that concentrated solutions of antigen and of serum globulin be used. In fact, I should think the favorable condition would be to dry a mixture of antigen and of globulin down in somewhat the same manner as Dr. Wright and I did and then hold this material at 57°C. for the desired length of time in a moist atmosphere.

Another experiment which might be worth trying would be to mix with the antigen and globulin some urea and have the concentration of urea such that when the mixture is dried down, it will be about

-2-

8 molar. You can count on about 35 to 40 per cent water remaining if the relative humidity be held near unity. Upon resolution, sufficient water is to be used so that there will be no further action by the urea. I hope these two suggestions may prove of some use to you.

There is a matter which I wanted to ask you about before my departure from Pasadena, but I didn't get around to it. We would like to have Swingle and Wright make an electrophoresis cell for us. They both agreed to construct such a cell providing they had your permission. They felt that $75.00 would be sufficient to reimburse them for the trouble. I should like to hear from you in regard to this.

Both Mrs. Bull and myself thoroughly enjoyed our visit to California; please accept our sincere thanks for making the visit possible.

Sincerely yours,

Henry B. Bull

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