Scientific American 6, 6.2.1864
A. H. Hoffman, of London, has taken out a patent for an improvement in manufacturing aniline colors. He takes the substance known as rosaniline, which is the base of the various salts called roseine, magenta and fuchsine, and he mixes it with the iodides or the bromides of the alcohol radicals, such as iodide of ethyl, methyl, amyl, propyl, or capryl, or bromides of these. He takes one equivalent of rosaniline and three of the salt of the alcohol radical, and heats the micture to a temperature of 212° Fah., or somewhat higher, in a close vessel. An iron vessel with a safety valve is the best to use for this purpose. During the heating the mixture passes through several phases of coloration, and is eventually converted into a blue violet; but the longer it is subjected to heat, under pressure, it becomes more nearly a pure blue. This color is employed, dissolved in alcohol, for dyeing and printing.