'Chrome alum' definitions:

Definition of 'chrome alum'

From: WordNet
noun
A violet-colored salt used in hide tanning and as a mordant in dyeing

Definition of 'Chrome alum'

From: GCIDE
  • Chrome \Chrome\, n. Same as Chromium. [1913 Webster]
  • Chrome alum (Chem.), a dark violet substance, (SO4)3Cr2.K2SO4.24H2O, analogous to, and crystallizing like, common alum. It is regarded as a double sulphate of chromium and potassium.
  • Chrome green (a) The green oxide of chromium, Cr2O3, used in enamel painting, and glass staining. (b) A pigment made by mixing chrome yellow with Prussian blue.
  • Chrome red, a beautiful red pigment originally prepared from the basic chromate of lead, but now made from red oxide of lead.
  • Chrome yellow, a brilliant yellow pigment, PbCrO4, used by painters. [1913 Webster]