  The distinction between type I and type II superconductivity is re-examined
in the context of the SO(5) model recently put forth by Zhang. Whereas in
conventional superconductivity only one parameter (the Ginzburg-Landau
parameter $\kappa$) characterizes the model, in the SO(5) model there are two
essential parameters. These can be chosen to be $\kappa$ and another parameter,
$\beta$, related to the doping. There is a more complicated relation between
$\kappa$ and the behaviour of a superconductor in a magnetic field. In
particular, one can find type I superconductivity even when $\kappa$ is large,
for appropriate values of $\beta$.
