Source : Webster's Revised Unabridged Dictionary (1913)

Pittacal \Pit"ta*cal\ (p[i^]t"t[.a]*k[a^]l), n. [Gr. pi`tta,
   pi`ssa, pitch + kalo`s beautiful: cf. F. pittacale.] (Chem.)
   A dark blue substance obtained from wood tar. It consists of
   hydrocarbons which when oxidized form the orange-yellow
   eupittonic compounds, the salts of which are dark blue.