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The November 1, 1952 thermonuclear explosion ("Mike") produced all of the uranium isotopes U 239 , U 240 , • • • U 255 through multiple neutron capture by U 238 . The long-lived products of successive 0~ decays from these isotopes were measured mass spectrometrically and radiometrically. The logarithms of the abundances decline smoothly with increasing mass number; the even-mass abundances slightly exceed the geometric mean of adjacent odd-mass abundances. Some nuclear properties of neutron-rich heavy nuclides, not subject to ordinary investigation are inferred.

Xenon and fluorine combine readily. Xenon tetrafluoride is a colorless crystalline material, stable at room remperature. The existence of at least one other fluoride and two oxyfluorides has been demonstrated. The heaviest "inert gas," radon, also reacts with fluorine, yielding a compound less volatile than xenon tetrafluoride.

The quantum yield of chlorophyll fluorescence in Nitzschia closterium was found to be constant, within rather large limits of experimental error, for exciting light of wave length 6000, 5780, 4700, or 4358 A. Light absorbed by yellow pigments in Nitzschia can therefore reappear as chlorophyll fluorescence. This leads to the conclusion that the previously observed carotenoid-sensitized photosynthesis in N. closterium takes place principally through the transfer of absorbed energy from carotenoid to chlorophyll molecules with subsequent reactions the same as though chlorophyll molecules were the primary absorbers. In acetone extracts of N. closterium light absorbed by the yellow pigments did not contribute appreciably to chlorophyll fluorescence, indicating that little or no energy was transferred between the pigments in acetone solution.