The Collaborative International Dictionary
cerulic sulphuric
Sulphindigotic \Sulph*in`di*got"ic\, a. (Chem.) Of, pertaining to, or designating, a sulphonic acid obtained, as a blue solution, by dissolving indigo in sulphuric acid; -- formerly called also cerulic sulphuric acid, but properly called indigo-disulphonic acid.