ANDERSON, FERMI  AND SZILARD                286
 
 
 
large that even at the optimum, concentration of hydrogen it is at present quite uncertain whether
neutron production will exceed the total neutron absorption. More information concerning the
resonance absorption of uranium as well as more accurate measurement of some of the values
which enter into our calculation are required before we can conclude whether a chain reaction is
possible in mixtures of uranium and water.
     We wish to thank Dr. D. W. Stewart, of the Department of Chemistry, and Mr. S. E.
Krewer, for adyice and assistance in carrying out some of these experiments. We are much
indebted to the Eldorado Radium Corporation for enabling us to work with large quantities of
uranium oxide in our experiments, and to the Association for Scientific Collaboration for the use
of the photoneutron source and other facilities.