The present problem arises from a consideration of some of the experimental and theoretical results which were obtained previously, some of which will now be briefly mentioned. Fission fragment mass distributions which were derived from data obtained from double ionization chambers using argon plus carbon dioxide gases disagree with those obtained by means of radiochemical analysis of the fission products. Fission fragment velocity distributions which were also derived from double ionization chamber data disagree with those obtained from a direct measurement of velocities. Further, these double ionization chamber measurements of the total kinetic energy of fission give lower values than those estimated from calorimetric measurements. These disagreements are explained by assuming the W (average energy per ion pair) values of fission fragments stopped in an ionization chamber gas are of the order of 5 percent larger than those for alpha particles which were used as the basis to calculate fission energies. On the basis that fission fragments lost greater percentages of initial energy through elastic collisions and that recoil argon gas atoms had reduced ionization efficiencies, a theoretical calculation in terms of an ionization defect appeared to justify this viewpoint. The ionization defect. is thought to arise from energy transfer through elastic collisions and hence should be a function of the atomic mass of the gas.