ios 



is so valuable that, were the electric light to supersede gas as an 

 illuminating agent, it is probable that we should still have to 

 prepare tar almost, if not quite, in as large quantities as at 

 present. The lecturer then explained how the first aniline 

 colour was discovered. Aniline was first obtained by Unver- 

 dorben, a German chemist, by distilling indigo, and derives its 

 name from anil, the Portuguese for indigo. Later it was found 

 to be present in coal-tar. For ten years it was regarded simply 

 as a chemical curiosity, and was without practical application. 

 In the year 1856, however, Mr. Perkin, whilst endeavouring to 

 obtain quinine artificially, discovered that aniline, when treated 

 with oxidising agents, yields a splendid mauve dye. Thus the 

 first of the aniline colours was discovered by accident ; and the 

 lecturer pointed out how often it has occurred that investigations 

 of a purely scientific kind have led to important practical results. 

 This was the case with the discovery of chloroform, and also 

 paraffin. The mauve dye attracted universal attention, and, as 

 a consequence, the study of aniline and coal-tar products was 

 pushed on with great vigour, with the result that a large and 

 very profitable industry came into existence. The lecturer then 

 explained that the quantity of aniline present in coal-tar is so 

 minute that it would be very expensive if it could only be ob- 

 tained directly from the tar. But, fortunately, it can easily be 

 made from benzol, a hydrocarbon which is abundant in tar. 

 This, when treated with aquafortis, gives nitro-benzol, a sub- 

 stance smelling like oil of almonds, and used, under the name 

 of oil of mirbane, in perfumery. The nitro-benzol, when boiled 

 with vinegar and iron, gives aniline. Rosaniline was discovered 

 about the same time as the mauve dye, and is prepared from 

 commercial aniline by heating it with arsenic acid. It is a 

 splendid red-colouring matter of intense tinctorial power. Hof- 

 mann very carefully examined it, and found that it could not 

 be prepared from pure aniline, but only from a mixture of 

 aniline and a very similar substance found in commercial aniline 

 called toluidine. Rosaniline is the starting point for a great 

 number of very beautiful colouring matters. The first disco- 

 vered of these were the violets imperiales and bleu lumiere, which 



