432 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1957 



We know now, of course, that his reasoning was wrong, based as 

 it was upon an incomplete knowledge of chemical structure. 



Nevertheless, it was this "happy experiment" which Perkin in his 

 eighteenth year attempted to perform in his home laboratory during 

 the Easter vacation of 1856. He began with toluidine, a coal-tar de- 

 rivative, which he treated with allyl-iodide, getting allyl-toluidine 

 which was converted into a salt and precipitated with potassium 

 dichromate. A dirty reddish-brown substance was the result, but it 

 was not quinine. This did not discourage Perkin. He found the 

 reaction interesting and he thought that a clue to the synthesis of 

 quinine might be found by using the same procedure on a simpler 

 base. He therefore chose aniline. He treated aniline sulfate with 

 potassium bichromate and now he got a black precipitate. But again, 

 it was not quinine. 



At this point many investigators would have become discouraged 

 and quit. In fact, it is often stated, without much foundation in fact, 

 that Perkin did get discouraged and dumped his residue into the sink 

 whereupon a purple color appeared. This makes a good legend but is 

 not borne out by the facts. For Perkin did not throw his residue into 

 the sink. He decided to take a second look. He began to investigate 

 the nature of the precipitate, and what he found was most interesting. 

 When this black precipitate was purified and dried and then digested 

 with spirits of wine, it gave a brilliant purple solution. Then came 

 an act of genius. Perkin immersed a piece of silk in this colored solu- 

 tion and found that his aniline purple was a dye. 



Perkin put the quinine problem aside and concentrated on a study 

 of the coloring matter. When he returned to the Royal College of 

 Chemistry he showed the new substance to one of his colleagues who 

 strongly urged him to patent it. But Perkin was hesitant. He 

 doubted the practical value of the dye because it appeared difficult 

 to make on a large scale. Nevertheless, he did send a sample of dyed 

 silk to a textile firm and received a most enthusiastic response, with 

 a reservation, of course, about price. The new coloring matter was 

 found to be not only attractive but also faster than any similar color 

 available. This latter quality was highly important to textile manu- 

 facturers. So fugitive were the contemporary purples that if a lady 

 put a violet ribbon on her hat in the morning she could never be sure 

 that it would retain its color till evening. 



Encouraged by the reception of his first samples, Perkin continued 

 his pilot experiments, and by August 1856 he was sufficiently sure of 

 his results to obtain a patent. He now decided to leave the College 

 to become an industrial chemist. As he later wrote about this episode : 



Although the results were not so encouraging as could be wished, I was per- 

 suaded of the importance of the colouring matter, and the result was that, in 



