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The fission and spallation reactions produced in uranium by bombardment with high-energy protons (340 to 350 Mev) were investigated. The reaction products were separated from the target by chemical processes and identified by their radioactive properties. The relative yields of the observed fission products are calculated, and the results plotted as a function of mass number. Several of the spallation products are identified and their yields estimated.An attempt is made to determine the most probable atomic number for a nuclide of given mass formed directly from fission. Studies are made of the relative yields along several isobaric chains as a function of atomic number. From these data, estimates of the mass and charge of the fissioning nucleus are made.By using the reaction ${\mathrm{Al}}^{27}(p, 3pn){\mathrm{Na}}^{24}$ of known cross section to monitor the bombarding beam, the absolute formation cross sections for several fission product nuclides were measured. Values for these reference nuclides are used to transform all of the relative yields into formation cross sections. Summation integration over the range of mass numbers of the area under the plot of formation cross sections as a function of mass number leads to a value of 2.0 barns for the total fission cross section for uranium bombarded with high-energy protons, if one assumes binary fission.