C.I.Acid Black 3

7-[[4-[(2-Hydroxy-3,6-disulfo-1-naphtyl)azo]-1-naphtyl]azo]-1,3-naphthalenedisulfonic acid tetrasodium salt

tetrasodium (4Z)-4-[[4-(6,8-disulfonatonaphthalen-2-yl)diazenylnaphthalen-1-yl]hydrazinylidene]-3-oxo-naphthalene-2,7-disulfonate