osmic

a. (Chem.) Pertaining to, derived from, or containing, osmium; specifically, designating those compounds in which it has a valence higher than in other lower compounds; as, osmic oxide. [ 1913 Webster ]

Osmic acid. (Chem.) (a) Osmic tetroxide. [ Obs. ] (b) Osmic acid proper, an acid analogous to sulphuric acid, not known in the free state, but forming a well-known and stable series of salts (osmates), which were formerly improperly called osmites. --
Osmic tetroxide (Chem.), a white volatile crystalline substance, OsO4, the most stable and characteristic of the compounds of osmium. It has a burning taste, and gives off a vapor, which is a powerful irritant poison, violently attacking the eyes, and emitting a strong chlorinelike odor. Formerly improperly called osmic acid. [ 1913 Webster ]