  We have performed muon spin relaxation and susceptibility measurements of
CaV_4O_9 and CaV_2O_5, systems in which spin gap-like behavior has been found.
We observe spin freezing in the two compounds below 12K and 50K, respectively.
Our results indicate the possibility that a substantial fraction of the of the
vanadium magnetic moment is not in a spin singlet sate at low temperatures in
either material.
