The intensity-time behavior for protons, alpha particles, and carbon, oxygen, and iron ions has been measured during the June 9, 1974, July 4, 1974, and September 19, 1974, solar events for energies in the MeV per nucleon range. Whereas the C/O ratio at the same energy per nucleon is time independent during all three events shown, the Fe/O ratio at the same energy per nucleon during the June and September events decreases by about 1 order of magnitude. A similar decrease is measured for the alpha to proton ration. This strongly indicates that while carbon and oxygen are essentially fully stripped, iron nuclei are only partially ionized. The Fe/O ratio changes can then be explained by a mean free path increasing with increasing rigidity. During the July 1974 event we observe a small increase of the alpha to proton ratio as well as the Fe/O ratio with time. This is interpreted as being due to a mean free path decreasing with increasing rigidity. |