We propose to observe thermal emission from circumstellar dust
 grains around R CrB type stars (RCBs) at their minimums using the
 SWS in order to study the nucleation and grain formation around
 stars.  Our proposal consists of detecting the continuum emission
 due to carbon grains and searching for carbon cluster fullerenes
 (C60, C70, ...) around RCBs.

 RCBs are known to be hydrogen-deficient, carbon-rich stars and to
 undergo irregular decrease in light due to carbon grain formation.
 They provide a good opportunity to study the nucleation and the
 grain formation phenomena around stars because the condensible
 atoms are limited compared with that around normal carbon stars.
 Furthermore, there is high possibility of detecting fullerenes
 around RCBs since the condition for the formation of carbon
 particles is similar to that for fullerene formation.  Although
 ubiquity of fullerenes is widely recognized on earth, they have
 not yet been discovered in space.  This may be because fullerenes
 are not likely to be formed in the hydrogen-rich atmosphere which
 is the case in normal carbon stars.  RCBs are the best candidate
 at which fullerenes should be searched for.

 If one of our candidate stars shows decrease in light and will be
 observed with ISO at that time, we also propose to take spectrum
 of this star again after the star recovers its light, if time
 allows.  This spectrum together with the one taken at minimum can
 be used to determine the infrared properties of dust grains.

 Whether fullerenes will be discovered or not, the spectroscopic
 data can be used to identify dust grains and to understand the
 nucleation and the grain formation in carbon-rich environments.