Memo to File
Phone call to Caspersson at Férber's laboratory In Boston, April 19, 1961.

Caspersson is returning to Stockhotm on the 21st In any case, and our
change of plans In fact did not Inconvenience hin.

He will be In Stockholm throughout =!11 of August and does not plan
to go to the Moscow meetings, but will be bakk In the states about the early
or middie of September for a U.N. radiation meeting. He 1s also on the program
for the New York Academy of Sciences for October 5.'

We discussed the desirability of having readings below 250 nm, and
Indicated that this would be difficult, but perhaps still possible. He remarked
that the lenses are not altogether so good at lower wave lengths.

We also discussed spectrograms as Intermediary, but It turns “ut that he
has not operated in quite the fashion we have In mind. He has of course made
frequent use of pictures at a serfes of different wave lengths. He Indicated
the possibility of difficulties In view of the varying gamma of the photographic
motion at different wave lengths. However, this Is someth!ng that probably
can be rectified, but photographic stability may be a difficult thing to
achieve.

We also discussed the similarity of absorption spectra of cerlum and
lanthanum. He himself had recalled cerium but indicated that lanthanum [n
solution was quite transparent through the region of interest. The crystals,
as Jane Sanders has found some reports of, might of course, be quite different.

He's quite anxious to have samples from us for further study, and

{ promised that these would be forthcoming. He will also be pleased to see
Dr. Levinthal on his visit.

APR 20 1961