The Collaborative International Dictionary of English v.0.48:

Perchromic \Per*chro"mic\, a. [Pref. per- + chromic.] (Chem.)
   Pertaining to, or designating, a certain one of the highly
   oxidized compounds of chromium, which has a deep blue color,
   and is produced by the action of hydrogen peroxide.
   [1913 Webster]