Recently, it was observed that oscillations arise in the turbidity and appa
rent specific heat of mixtures of water, oil and surfactant, when the phase
separation of a phase of water droplets into a phase of smaller droplets c
oexisting with a water-rich phase is induced by constant heating. Here, we
develop a model for this oscillatory phase separation, and compare it to da
ta from detailed experimental studies. A scaling relation describing the co
mposition and heating rate dependence of the period of the oscillations is
established. Moreover, it is pointed out that similar behaviour should also
be observable in other phase-separating systems, since the model is based
on arguments of a general nature.