euchroic

from The Century Dictionary.

• In chem., used in the phrase euchroic acid, a dibasic acid forming a white crystalline powder, obtained by heating paramide with alkalis.
• Noting an acid, a colorless compound, prepared, together with paramide, by heating ammonium mellitate. It crystallizes in quadratic prisms which melt and decompose above 250° C.

from the GNU version of the Collaborative International Dictionary of English.

• adjective (Chem.) Having a fine color.
• adjective (Chem.) an organic, imide acid, obtained as a colorless crystalline substance, C12H4N2O8 by heating an ammonium salt of mellitic acid. By reduction it is changed to a dark blue substance (euchrone), -- hence its name.