1,5-NAPHTHALENEDISULFONIC ACID 3-[[4-[[4-[(6-AMINO-1-HYDROXY-3-SULFO-2-NAPHTHALENYL)AZO]-6(OR 7)-SULFO-1-NAPHTHALENYL]AZO]-1-NAPHTHALENYL]AZO]-,TETRASODIUM SALT