III. Colouring-matters derived from aromatic azodiamines

Whilst we were engaged with the study of the blue colouring-matter produced by the action of aromatic monamines on azodiphenyldiamine our attention became directed to a beautiful red tar-pigment, which has been known for some time by the commercial name of Safranine, being extensively used as a substitute for safflower in dyeing silk and cotton. Safranine has not as yet been minutely examined; but, as far as can be judged from the scanty information we possess regarding its production, it is scarcely doubtful that this important dye must be looked upon as being the derivative of an azodiamine. The analysis of safranine thus promised to throw considerable light upon the nature of the compounds under examination. The starting-point of our studies was the dye such as it occurs in commerce. The greater portion of it was supplied to us by Messrs. Tillmanns, of Crefeld. Another specimen was received from Dr. J. Wolf, and for a third one we are indebted to our friend M. Charles Girard, of Paris. Both the first-mentioned specimens were assigned to us as produced on the large scale ; the last was prepared by M. Girard himself.