Heat-capacity measurements between 1.6 and 4.2\ifmmode^\circ\else\textdegree\fi{}K were made on a series of copper-zinc alloys covering the entire range of the face-centered cubic phase. The density of states at the Fermi surface is found to decrease initially with alloying rather than to increase. Alternative explanations of the data are considered, and a possible model involving overlapping of electrons into the second Brillouin zone is suggested.