  Nova Cassiopeiae 1993 (V705 Cas) was an archetypical dust-forming nova. It
displayed a deep minimum in the visual light curve, and spectroscopic evidence
for carbon, hydrocarbon and silicate dust. We report the results of fitting the
infrared spectral energy distribution with the DUSTY code, which we use to
determine the properties and geometry of the emitting dust. The emission is
well described as originating in a thin shell whose dust has a carbon:silicate
ratio of ~2:1 by number (1.26:1 by mass) and a relatively flat size
distribution. The 9.7micron and 18micron silicate features are consistent with
freshly-condensed dust and, while the lower limit to the grain size
distribution is not well constrained, the largest grains have dimensions
\~0.06micron; unless the grains in V705 Cas were anomalously small, the sizes
of grains produced in nova eruptions may previously have been overestimated in
novae with optically thick dust shells. Laboratory work by Grishko & Duley may
provide clues to the apparently unique nature of nova UIR features.
