“Yet Nature is made better by no mean,
But Nature makes that mean: so, o’er that art,
Which, you say, adds to Nature, is an art
That Nature makes.”

The story told in this chapter is chronologically summarized below—

1820.Naphthalene discovered in coal-tar by Garden.
1832.Anthracene discovered in coal-tar by Dumas and Laurent.
1834.Phenol discovered in coal-tar by Runge.
1842.Picric acid prepared from phenol by Laurent; manufactured in Manchester in 1862.
1845.Benzidine discovered by Zinin.
1859.Corallin and aurin discovered by Kolbe and Schmitt and by Persoz; leading to manufacture from oxalic acid and phenol.
1860.Synthesis of salicylic acid by Kolbe.
1864.Manchester yellow discovered by Martius, leading to manufacture of alpha-naphthylamine and then to alpha-naphthol.
1867.Magdala red discovered by Schiendl.
1868.Synthesis of alizarin by Graebe and Liebermann, leading to the utilization of anthracene, caustic soda, potassium chlorate and bichromate, and calling into existence the manufacture of fuming sulphuric acid.
1870.Galleïn, the first of the phthaleïns, discovered by A. v. Baeyer, followed in 1871 by cœruleïn, and in 1874 by the eosin dyes (Caro). These discoveries necessitated the manufacture of phthalic acid and resorcinol.
1873.Orthochromatic photography discovered by Vogel.
1876.Azo-dyes from the naphthols introduced by Roussin and Poirrier and Witt, leading to the manufacture of the naphthols, sulphanilic acid, &c.
1877.Preparation of quinone from aniline by Nietzki, utilized in photography in 1880 for manufacture of hydroquinone.
1878.Disulpho-acids of beta-naphthol introduced by Meister, Lucius, and Brüning, leading to azo-dyes from aniline, toluidine, xylidine, and cumidine.
1879.Acid naphthol yellow introduced by Caro.
"Biebrich scarlet, the first secondary azo-colour, introduced by Nietzki.
"Nitroso-sulpho acid of beta-naphthol discovered by the writer; followed in 1883 by naphthol green (O. Hoffmann), and in 1889 by eikonogen (Andresen).
"Beta-naphthol violet, the first of the oxazines, discovered by the writer; followed in 1881 by gallocyanin.
"Coal-tar saccharin discovered by Fahlberg; manufacture made practicable in 1884.
1880.Synthesis of indigo by A. v. Baeyer.
"Quinoline synthesised by Skraup’s process.
1881.Kairine introduced by O. Fischer, the first artificial febrifuge.
"Indophenol discovered by Köchlin and Witt.
"Azo-dyes from new sulpho-acid of beta-naphthol introduced by Bayer & Co.
1883.Antipyrine introduced by L. Knorr, leading to manufacture of phenylhydrazine.
1884.Congo red, the first secondary azo-colour from benzidine, introduced by Böttiger. Beginning of manufacture of cotton azo-dyes, and leading to the production of benzidine and tolidine on a large scale.
1885.Secondary azo-dyes from benzidine and tolidine containing two dissimilar amines, phenols, &c., introduced by Pfaff.
"Tartrazine discovered by Ziegler; manufacture of sulpho-acid of phenylhydrazine and of dioxytartaric acid.
1885.Thiorubin introduced by Dahl & Co., leading to manufacture of thiotoluidine; followed by primuline, discovered by A. G. Green in 1887.
1886.Secondary azo-dyes of stilbene series introduced by Leonhardt & Co.

ADDENDUM.

By passing steam over red-hot carbon, a mixture of carbon monoxide and hydrogen is formed. This mixture of inflammable gases is known as “water-gas,” and in the preparation of the gas on a large scale, coke is used as a source of carbon. If, therefore, water-gas became generally used, another use for coke would be added to those already referred to (p. [47]).

With reference to the consumption of coal in London (p. [46]), it appears from the Report of a Committee of the Corporation of London, issued at the end of 1890, that the present rate of consumption in the Metropolis is 9,709,000 tons per annum. This corresponds to 26,600 tons per diem. It has been proved by experiment, that when coal is burnt in an open grate, from one to three per cent. of the coal escapes in the form of unburnt solid particles, or “soot,” and about 10 per cent. is lost in the form of volatile compounds of carbon. It has been estimated that the total amount of coal annually wasted by imperfect combustion in this country is 45,000,000 tons, corresponding to about £12,000,000, taking the value of coal at the pit’s mouth. Taking the unconsumed solid particles at the very lowest estimate of 1 per cent., it will be seen that, in London alone, we are sending forth carbonaceous and tarry matter into the atmosphere at the rate of about 266 tons daily; and volatile carbon compounds at the daily rate of 2660 tons (see p. [32]). At the price of coal in London this means that, in solid combustibles alone, we are absolutely squandering about £10,000 annually, to say nothing of the damage caused by the presence of this sooty pall. Such facts as these require no comment; they speak for themselves in sombre gloom, and in the sickliness of our town vegetation—they give a new meaning to the term “in darkest London,” and they plead eloquently for science and legislation to show us “the way out.”