  We start with the classic result that the Cauchy problem for ideal
compressible gas dynamics is locally well posed in time in the sense of
Hadamard; there is a unique solution that depends continuously on initial data
in Sobolev space $H^s$ for $s>d/2+1$ where $d$ is the space dimension. We prove
that the data to solution map for periodic data in two dimensions although
continuous is not uniformly continuous on any bounded subset of Sobolev class
functions.
