DEFINITION OF TERMS
The original prontosil, the hydrochloride or 4-sulfamido-2′, 4′-diaminazobenzene, is an azo dye. This red crystalline powder has a melting point of 247 to 251 C. and is soluble in water up to about 0.25 per cent.Prontosil soluble1 is a 2.5 per cent watery solution of disodium-4-sulfamido-phenyl-2′-azo-7′-acetylamino-1′-hydroxynaphthalene-3′, 6′-disulfonate, which is a reddish crystalline material and soluble up to about 4 per cent in water.Sulfanilamide was selected by the Council on Pharmacy and Chemistry of the American Medical Association as the name for paraaminobenzenesulfonamide. This white crystalline powder has a melting point of 165 C. and is soluble in water up to about 1 per cent.In citations of the literature, the foregoing terminology has been adhered to wherever it has been possible to determine which preparation was used. When the term "prontosil" was used in a report and no information