Before revision: The first method of electrochemical coloring of metals are certainly Nobili's colored rings, discovered by Leopoldo Nobili, an Italian physicist in 1826.Thomas O'Conor Sloane, The Standard Electrical Dictionary: A Popular Dictionary of Words and Terms, London 1898, p. 392 Buchner ,G. Metallfaerbung,Berlin 1920.,p.54 In addition to the multicolored coatings mentioned, he has also been able to obtain monochrome coatings, and he called that technique metallocromia.
After revision: The first method of electrochemical coloring of metals are certainly Nobili's colored rings, discovered by Leopoldo Nobili, an Italian physicist in 1826.Thomas O'Conor Sloane, The Standard Electrical Dictionary: A Popular Dictionary of Words and Terms, London 1898, p. 392Buchner ,G. Metallfaerbung,Berlin 1920.,p.54 In addition to the multicolored coatings mentioned, he has also been able to obtain monochrome coatings, and he called that technique metallocromia.