ABSTRACT
Coal-tar is an exceedingly complex material, being a mixture of a ‘great number of different substances. This chapter shows the chemical name of many of the substances obtainable from the coal-tar. It must not be supposed that these substances exist ready formed in the coal, and that they are merely expelled by the heat. The chief colour-producing substances contained in coal-tar are benzol, toluol, phenol, naphthalene, and anthracene. The introduction of aniline colours into dyeing and calico-printing has caused quite a revolution in these arts, the processes having become much more simple, and the facilities for obtaining every variety of tint largely increased. Anthracene was discovered in coal-tar by Laurent in 1832, and its properties were investigated by Anderson in 1862. Two colouring matters have been derived from anthracene, and are much used in dyeing; one is commercially named anthracene purple, the other is anthracene green, which supplies the calico printer with very fast shades of olive-green.
