The Collaborative International Dictionary of English v.0.48:

Ligroin \Lig"ro*in\ (l[i^]g"r[-o]*[i^]n), n.
   A trade name applied somewhat indefinitely to some of the
   volatile products obtained in refining crude petroleum. It is
   a complex and variable mixture of several hydrocarbons,
   generally boils below 170[deg] Fahr., and is more inflammable
   than safe kerosene. It is used as a solvent, as a carburetant
   for air gas, and for illumination in special lamps.
   [1913 Webster]