Coulson (1910-1974) was a theoretical chemist and physicist who developed a molecular orbital theory and the concept of partial
valency. Franklin had worked with him during her time at BCURA, and asked him to review her first submission to Nature, the
eminent British scientific journal. The "letter," titled "On the Influence of the Bonding Electrons on the Scattering
of X-Rays by Carbon," was published in January 1950. It was Coulson who suggested that Franklin look for a position at
King's College if she wanted to work in the new field of biophysics.
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1949-06-11 (June 11, 1949)
Coulson, C. A.
King's College London
Original Repository: Churchill Archives Centre. The Papers of Rosalind Franklin
Courtesy of the Churchill Archives Centre.
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The Holes in Coal: Research at BCURA and in Paris, 1942-1951
Thank you very much for sending me a copy of the letter which you are offering to Nature. I have read it with very great interest.
I am obviously quite unable to judge the experimental side of it but your conclusion seems to me entirely reasonable and I
cannot help thinking that some more detailed calculations might reasonably be made. We do know sufficient about the nature
of the electron distribution in graphite to justify the calculation of atomic scattering factors.
Are you thinking of doing anything of this sort yourself or would you like us to take it up here? I am afraid that until
next October term we shall not have anybody available to do new problems but I think it might be possible then. I do not
think that it ought to be a very long job but one never knows until one has got started.
I was interested in what you said in your letter about the difference in layer spacing between the random orientations and
the proper graphite crystal. I imagine you are aware of the work that has been done on the heats and combustion of different
graphites at the National Bureau of Standards. They found that with random layers there was a regular variation in the heat
of combustion with the decreasing amount of hydrogen present but that this value did not tend asymptotically to the value
for the infinite crystal although they do not attempt to explain the situation. It is quite clear that in fact what they
showed was that there was a substantial difference in cohesive energy between a genuine three dimensional crystal and the
random two dimensional one. All that fits very nicely with your own observations.
Alas that I shall be out of London during the period 18th June to 26th. I am very sorry about this because it would have been
nice to meet again and discuss these things. We are actually taking our summer holiday at that time. I do not expect to
be back until about 4th July. If you are still in London at about that time I do hope that you will let me know.
With kind regards,
C. A. Coulson
P.S. I am returning the copy of your letter which you sent me. If you can spare it, however, I should be quite glad to keep
it until your letter has actually been published.