  Titan, the main satellite of Saturn, has an active cycle of methane in its
troposphere. Among other evidence for a mechanism of evaporation at work on the
ground, dry lakebeds have been discovered. Recent Cassini infrared observations
of these empty lakes have revealed a surface composition poor in water ice
compared to that of the surrounding terrains --- suggesting the existence of
organic evaporites deposits. The chemical composition of these possible
evaporites is unknown. In this paper, we study evaporite composition using a
model that treats both organic solids dissolution and solvent evaporation. Our
results suggest the possibility of large abundances of butane and acetylene in
the lake evaporites. However, due to uncertainties of the employed theory,
these determinations have to be confirmed by laboratory experiments.
