The grain densities of stopping C-12, O-16, and Ne-20 ions were measured as a function of velocity (beta greater than 0.145) in insensitive Ilford emulsion types K minus 1 and K.O. The measurements were carried out using photomicrographic techniques. An exponential gap-length distribution is observed for gap lengths greater than 0.25 microns for rates of energy loss up to 2.35 MeV/micron. The composition of the grain density is analyzed in terms of primary and secondary grain densities. It is concluded that the secondary grain density, which is due principally to delta-rays, accounts for about 35 percent of the total grain density observed in these insensitive emulsions. A generalized formula derived from these data expresses the observed grain density as a function of the particle's velocity and charge, and the sensitivity of the emulsion. (Author).