Roman vitriol

English

Noun

Roman vitriol (uncountable)

1. (possibly obsolete) Copper(II) sulfate; bluestone.
   • 1758, Valuable Secrets in Arts and Trades ...: Containing Upwards of One Thousand Approved Receipts Relative to Arts and Trades ..., page 219:

     Then add two ounces of gum-arabic, and one of Roman vitriol, which infuse four days before straining, and the ink is done.

   • 1785, The Sportsman's Dictionary; Or, The Gentleman's Companion: ...:

     The scalding mixture, generally used, is made in the following manner: Take of corosive sublimate, verdigrease in fine powder, and Roman vitriol, of each two drams; of green vitriol, or copperas, half an ounce; of oil of turpentine and train oil, ...

   • 1815, The Repertory of Arts and Manufactures, page 260:

     First in the liquor composed of mordant and fustic, then in green vitriol and Roman vitriol, washed off and repeated according to the colour wanted.