  We report optical extinction properties of dust for a sample of 26 early-type
galaxies based on the analysis of their multicolour CCD observations. The
wavelength dependence of dust extinction for these galaxies is determined and
the extinction curves are found to run parallel to the Galactic extinction
curve, which implies that the properties of dust in the extragalactic
environment are quite similar to those of the Milky Way. For the sample
galaxies, value of the parameter $R_V$, the ratio of total extinction in $V$
band to selective extinction in $B$ & $V$ bands, lies in the range 2.03 - 3.46
with an average of 3.02, compared to its canonical value of 3.1 for the Milky
Way. A dependence of $R_V$ on dust morphology of the host galaxy is also
noticed in the sense that galaxies with a well defined dust lane show tendency
to have smaller $R_V$ values compared to the galaxies with disturbed dust
morphology. The dust content of these galaxies estimated using total optical
extinction is found to lie in the range $10^4$ to $10^6 \rm M_{\sun}$, an order
of magnitude smaller than those derived from IRAS flux densities, indicating
that a significant fraction of dust intermixed with stars remains undetected by
the optical method. We examine the relationship between dust mass derived from
IRAS flux and the X-ray luminosity of the host galaxies.The issue of the origin
of dust in early-type galaxies is also discussed.
