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Gaussian analysis of new, high-angular-resolution interstellar 21-cm neutralhydrogen emission profile structure more clearly reveals the presence of thepreviously reported signature of the critical ionization velocity ({\it CIV})of Helium (34 km s$^{-1}$). The present analysis includes 1496 component linewidths for 178 neutral hydrogen profiles in two areas of sky at galacticlatitudes around $-$50$^\circ$, well away from the galactic plane. The new dataconsidered here allow the interstellar abundance of Helium to be calculated,and the derived value of 0.095 $\pm$ 0.020 compares extremely well with thevalue of 0.085 for the cosmic abundance based on solar data. Although theprecise mechanisms that give rise to the {\it CIV} effect in interstellar spaceare not yet understood, our results may provide additional motivation forfurther theoretical study of how the mechanism operates.

The Role of the Critical Ionization Velocity Effect in Interstellar Space and the Derived Abundance of Helium