306 DYEING AND CALICO PRINTING. 



lowing simple and ingenious method has been devised. Benzine, one of 

 the most volatile products of coal-tar, and now well known, is treated 

 with strong nitric acid, when a violent action ensues, which gives rise 

 to a substance called nitro-benzine ; this is then mixed with acetic acid 

 and iron filings, and the result of the chemical action is to convert the 

 nitro-benzine into aniline, which is easily separated from the iron filings 

 and other impurities by careful distillation. It is this substance which 

 Mr. W. A. Perkin took in 1856, mixed with sulphuric acid and bichro- 

 mate of potash, and successfully converted into the well-known dye 

 called aniline purple, the applications of which in the late Exhibition 

 were so beautiful and endless. To obtain this colour in the state recpired 

 by the dyer it is necessary to extract it from the mass resulting from 

 the action of sulphuric acid and bichromate of potash, by washing it 

 with coal naphtha, which removes various useless tarry products, and 

 then with alcohol, which dissolves the colour and renders it fit for use- 

 Shortly after Mr. Perkin's mauve was introduced to the trade, Messrs^ 

 Renard Freres, of Lyons, obtained from aniline another colour, since 

 well known under the name of magenta. This colour, which was first 

 ' observed by Mr. Natanson, in 1856, and produced by Dr. W. A. Hof- 

 mann, in J 857, was commercially made in 1859 by M. Verguin, and 

 successfully introduced into commerce by Messrs. Renard Freres. To 

 prepare their magenta, or, as they called it, fuchsine, they heated for 

 about twenty minutes at a temperature of 392° , a mixture of aniline 

 and bichloride of tin. The dark mass so obtained was left to cool, and 

 then boiled with hot water, and the solution of luchsine filtered off. It 

 was then only necessary to throw down the fuchsine from the solution 

 by common salt, and to re-dissolve it in slightly acidulated water to 

 render it fit for the dyer. This colour is now prepared in England most 

 successfully, and in a high state of purity by Messrs. Simpson, Maule, 

 and Nicholson. Their process consists in heating aniline with arsenic 

 acid, and treating the mass when cold with boiling water. The colour 

 is then purified and combined with acetic acid, which compound, being 

 soluble in water, is ready for the dyer. 



Whilst dwelling on aniline, a blue colour also obtained from it 

 should be noticed. It was first produced by Messrs. Persoz, De Luynes, 

 and Salvetat, and subsequently manufactured commercially by Messrs. 

 Renard Freres. This firm employs Girard's method, which consists in 

 mixing magenta with aniline, and heating the whole for several hours 

 at a temperature of 359°, when the " Bleu de Lyon " is produced, and 

 it is brought to a state of purity by acting on the mass at a boiling 

 temperature, with a weak solution of hydrochloric acid. 



It would not be conveying a correct idea of the present state of 

 knowledge respecting the aniline colours if 1 omitted to mention the 

 interesting discovery recently made and published by Dr. A. W. Hof- 

 mann, F.R.S., showing that the substance which gives the magenta 



