Large areas of photographic emulsion have been flown on balloons, at small atmospheric depths, in order to record tracks of relativistic highly charged nuclei of the cosmic radiation. Sixty tracks due to relativistic nuclei with Z > 40 have been found and the resulting charge spectrum is presented. One nucleus with Z > 90 penetrated the detector, indicating a lower flux of extremely heavy nuclei than was suggested by the previous experiment (Fowler, Adams, Cowen & Kidd 1967). The observed structure in the charge spectrum again suggests that nuclei of the cosmic radiation have been synthesized by the process of rapid neutron capture. Detailed consideration is given to the fundamental assumptions made in the interpretation of the measurements and assignment of the charges.