  We study finitely additive extensions of the asymptotic density to all the
subsets of natural numbers. Such measures are called density measures. We
consider a class of density measures constructed from free ultrafilters on
$\mathbb{N}$ and investigate absolute continuity and singularity for those
density measures. In particular, for any pair of such density measures we prove
necessary and sufficient conditions that one is absolutely continuous with
respect to the other and that they are singular. Also we prove the same results
for weak absolute continuity and strong singularity.
