roche alum

1 definition found

roche alum - Collaborative International Dictionary of English v.0.48 :

  Roche alum \Roche" al`um\ (Chem.)
     A kind of alum occuring in small fragments; -- so called from
     Rocca, in Syria, whence alum is said to have been obtained;
     -- also called rock alum.
     [1913 Webster]