Elemental abundances of the VH group of cosmic radiation have been measured in the energy interval 250-550 MeV nucl-1 in a balloon exposure at Sioux Falls (South Dakota) of a plastic detector LeXAN stack. The so obtained abundances have been extrapolated to the sources in the frame of the homogeneous model correcting for energy loss. After taking into account solar modulation, the best fit to model values has led to a escape mean free path λe = 5 E-0.4 g cm-2, where E is the energy in GeV nucl-1, for E>1 GeV nucl-1, and a constant λe = 5 g cm-2 for E≤1 GeV nucl-1. When turning to the diffusion model, also including an energy loss term, a diffusion coefficient D=3×1028 cm2 s-1 has been estimated. © 1983 D. Reidel Publishing Company.