  We obtained a deep 150ksec Chandra observation of the optically selected
cluster of galaxies, RCS 2318+0034, to investigate the gas mass fraction in
this system. Combining our deep {\it Chandra} observation with an archival
50ksec observation, we derive gas mass fractions of fgas=0.06 +- 0.02 and 0.10
+- 0.02 within r2500 and r500, respectively. The gas mass fraction in RCS
2318+0034 within r500 is typical of X-ray selected clusters. Further study
shows that the large scale properties of RCS 2318+0034, including the relations
between gas mass, X-ray luminosity and gas temperature are also consistent with
the observed correlations of X-ray selected clusters. However, the gas mass
fraction within r2500 is less than most X-ray selected clusters, as previously
reported. The deep Chandra image of RCS 2318+0034 shows that this system is
presently undergoing a major merger which may have an impact on the inferred
gas mass fraction within r2500.

Cosmology and Nongalactic Astrophysics