his own home, where he prosecuted independent research. Here, in conjunction with Mr. (now Sir) A. H. Church, he soon discovered the fii-st representative of the group of azo-dyes, namely, 'azodinaphthyldiamine' or, in modern nomenclature, 'aminoazonaphthalene.' This substance was patented at a later date (Eng. Pat. 893 of 1863) and had a limited use as a dyestuff. During the Easter vacation of 1856, with the idea of synthesising quinine, Perkin tried, with a negative result, the experiment of oxidising a salt of allyltoluidine with potassium dichromate. On repeating the experiment with aniline, however, he obtained a dark-coloured precipitate which proved to be a colouring matter possessed of dyeing properties, and was the first aniline dye to be discovered. Encouraged by the favourable report made on his new product by practical dyers and especially by Messrs. Pullar of Perth, Perkin resigned his position at the Royal College of Chemistry and entered on the career of an industrial chemist. Assisted by his father and his elder brother, Thomas D. Perkin, he opened a chemical factory at Greenford Green. The new dye was patented (Eng. Pat. 1984 of 1856), and at the end of 1858 it was first manufactured at Perkin's works under the name of 'Aniline Purple' or 'Tyrian Purple.' The name 'Mauve,' by which it was afterwards generally known, was at once given to it in France. Perkin straightway devoted himself to developing processes of manufacturing his raw material (aniline) and to improvements in the methods of silk dyeing, as well as of suitable mordants for enabling the dye-stuff to be applied to the cotton fibre. To Perkin's discovery of the first of the aniline dyes was ultimately due the supersession of vegetable by chemical dye-stuffs. In recognition of his invention the 'Société Industrielle de Mulhouse' awarded him, in 1859, a. silver medal, and afterwards a gold one.
In 1868 the German chemists Graebe and Liebermann showed that 'alizarin,' the 'Turkey red' dyestuff or colouring matter of the madder-root, was a derivative of the coal-tar product anthracene and not of naphthalene, as had hitherto been believed. They then patented in Germany and in Great Britain a process for the manufacture of 'alizarin' which was too costly to hold out much hope of successful competition with the madder plant, requiring, as it did, the use of bromine. With the object of cheapening this process, Perkin in 1869 introduced two new methods for the manufacture of artificial alizarin, one starting from dichloroanthracene and the other, which is still in use, from the sulphonic acid of anthraquinone. This branch of the coal-tar industry developed rapidly, and, in spite of some competing effort of German manufacturers, the English market was almost entirely held by Perkin until the end of 1873. Perkin delivered before the Society of Arts in 1879 two lectures, which were published under the title 'The history of alizarin and allied colouring matters, and their production from coal-tar.' Meanwhile, in 1873, when the increasing demand for artificial alizarin rendered imperative an enlarged plant at Perkin's Greenford Green works, he transferred the concern to the finn of Brooke, Simpson & Spiller, and, retiring after eighteen years from the industry, thenceforth devoted himself to pure chemical research.
Concurrently with his industrial work Perkin had maintained a strong interest in pure chemistry, and had already published many important papers in the 'Transactions of the Chemical Society,' where his contributions finally numbered ninety. In 1858, in conjunction with Duppa, he discovered that aminoacetic acid could be obtained by heating bromoacetic acid with ammonia, and in 1867 he published a dascription of his method of synthesising unsaturated organic acids, known as the 'Perkin synthesis.' Next year the synthesis of coumarin, the odorous substance contained in Tonka bean, etc., was announced, and the continuation of this work, after his retirement from the industry, led to his celebrated discovery of the synthesis of cinnamic acid from benzaldehyde. Scientific papers on the chemistry of 'Aniline Purple' or 'mauve' were also pubhshed in the 'Proceedings of the Royal Society' in 1863 and 1864 and in the 'Transactions of the Chemical Society' in 1879. In 1881 he first drew attention to the magnetic rotatory power of some of the compounds which he had prepared in his researches, and mainly to the study of this property as applied to the investigation of the constitution or structure of chemical molecules he devoted the rest of his life.
Perkin's services were widely recognised. Having joined the Chemical Society in 1856, he held the office of president from 1883 to 1885, and received the society's Longstaff medal in 1888. He was elected F.R.S. in 1866 and received from the Royal Society a royal medal in 1879, and the Davy medal in 1889. He was president of the Society of Chemical Industry in 1884-5, receiving the gold medal of
