The next step in the oxidation of the para-phenylene-diamine is the formation of what is called Bandrowski’s base. Three parts of the quinone di-imine combine with themselves, forming a substance of a brown-black color, which was formerly regarded as the final oxidation product. The formula of Bandrowski’s base is represented by the following chemical hieroglyphics: (NH₂)₂.C₆H₃.N:C₆H₄:N.C₆H₃(NH₂)₂. Further investigation has shown that the oxidation proceeds beyond this stage with the formation of a compound of what is known as the azine type, which is depicted by the chemist as NH NH (NH₂).C₆H₃< >C₆H₂< >C₆H₃.NH₂. NH NH It is by no means certain that this substance is the true coloring matter obtained by the oxidation of para-phenylene-diamine, for the reactions may continue still farther, producing even more complicated oxidation products. Scientific research and study has not as yet gone beyond this stage. The reactions of the other dyes of the Oxidation type are quite similar to those of para-phenylene-diamine, some being simpler, and others being even more complex. The presence of certain chemical groups in the intermediate, or the relative position of such groups are factors responsible for the variations in shade. With the various mordants, the Oxidation Colors give different shades, and a great range of colors can be produced either by combining mordants, or combining dyes, or both. The following tables illustrate the shades formed with the customary mordants. ========================================================================= | CHROME | COPPER | IRON | DIRECT ---------+---------------+----------------+--------------+--------------- Ursol D | brown black | coal black | coal black | dark brown to | | | | brown black Ursol P | dull red brown| dull dark brown| grey brown | light brown Ursol 2G | yellow brown | dull yellow | yellow brown | dull yellow | | brown | | Ursol A | ... | ... | blue black | blue to blue- | | | | black Ursol 4G | light brown | medium brown | yellow | pure yellow Ursol 4R | orange brown | light yellow | red brown | orange red | | brown | | Ursol | | | | Grey B | greenish grey | greenish grey | mouse grey | ... Ursol | | | | Grey R | brownish grey | brownish grey | reddish grey | ... ---------+---------------+----------------+--------------+---------------