Using projections operators in the code for column density, one is performing the integral operation,

\sum n_i dx = \bar{n} L_x

which has the rather strange units of computational number density times computational length. We can not just assume that the resultant product will have units of 1/computational length cubed. Thus, we can not simply multiply our projected quantity by lscale.

Instead, we should multiply our projected number density by nscale*lscale, if both scales are in cgs. That will give the quantity we are looking for, n in 1/cm³.