RESEARCH AND THE COAL-TAR DYE INDUSTRY 241 



At first nitrobenzene was prepared by heating benzene 

 and strong nitric acid in glass boltheads, according to a patent 

 originally taken out by Mansfield ; later the method of nitrating 

 by means of a mixture of nitric and sulphuric acid in iron 

 vessels was worked out and has continued with few modifi- 

 cations up to the present day. 



The reduction of the nitrobenzene so obtained was carried 

 out by means of iron filings and acetic acid in large iron stills 

 with removable tops, and seems to have been a somewhat 

 exciting process if we are to credit the fact that at first it was 

 customary for a workman to stand by with a water-hose ready 

 to play on the retort if the reaction showed signs of becoming 

 too turbulent ! 



Later the cheaper hydrochloric acid was used in place of 

 acetic acid. The aniline so produced was then dissolved in 

 dilute sulphuric acid, oxidised with potassium bichromate, 

 the insoluble product filtered off and purified, and was then 

 ready to be sold as " Tyrian purple," or later " Mauvein " or 

 " Mauve," the latter name being given to it by French 

 dyers. 



There can be no doubt that in the working out of the 

 technical methods for the preparation of aniline Perkin accom- 

 plished a work of even greater importance than the discovery 

 of mauve itself, a fact frequently overlooked, for mauve was 

 destined to have a brilliant but short career, being soon 

 eclipsed by various other new dyes ; but aniline was, and still 

 is, the ultimate foundation of by far the greater number of 

 dyes now in use. 



The difficulties of the young discoverer, however, in no way 

 ended with the production of the dye-stuff. 



It was still necessary to convince the dyers of the value of 

 the new colours, and we are told that the English dyers did 

 not take kindly to it, and it was, in fact, due to the initiative 

 of the French printers, who quickly saw the possibilities of 

 the new dye, that a demand began to arise for it ; indeed, until 

 French-dyed prints done with mauve began to come into 

 England, the English printers refused to interest themselves 

 in it at all. 



The yield of mauve was of necessity small, as is shown by 

 the following table (given by Sir W. H. Perkin in a lecture 

 before the Royal Society of Arts on December 7, 1868) : 



