In aqueous solution it gives a red colour with ferric chloride.
The aqueous solution is turned bluish black by ferrous sulphate containing a ferric salt.
It is obtained by the oxidation of orthophenylene diamine with ferric chloride; when a mixture of para-aminodimethylaniline and meta-toluylenediamine is oxidized in the cold, toluylene blue, an indamine, being formed as an intermediate product and passing into the red when boiled; and also by the oxidation of dimethylparaphenylene diamine with metatoluylene diamine.
With ferric chloride it gives a violet coloration, and with bromine water a white precipitate of tribromphenol.
Ferric thiocyanate has been suggested, and sulphur is said to have been detected in the mineral.