Chrome alum Meaning, Definition & Usage

  1. noun a violet-colored salt used in hide tanning and as a mordant in dyeing

WordNet

Definitions
  1. (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.

Webster 1913