Aniline
Aiton's Encyclopedia (1910)
an i-lin, an oily, colorless liquid, discovered as a product of the distillation of indigo in 1826. Chemically it is composed of carbon, nitrogen, and hydrogen in the atomic proportions of 6, 1, and 7. The new substance at once attracted attention from chemists, although at first it was of no value commercially. Eight years after the first discovery of aniline, it was found to exist in small quantities in coal tar . The scientist who proved this fact noticed also that aniline gives brilliant colors when brought into contact with chloride of lime. The next step was the discovery that aniline could be manufactured from benzol, another product of coal tar. Since no practical use was made of aniline, the importance of this discovery was not realized, until, in 1856, a beautiful mauve or purple dye was made from it. Aniline acquired commercial importance immediately. Soon experiments resulted in the discovery of a series of brilliant dyes of almost every conceivable color, tint, and shade. These colors received in several instances fanciful names. Magenta and solferino are named from battles of the French-Austrian War, which were fought about the time of their discovery. Others, as azuline, violine, and emeraldine were derivations of the names of existing colors. Several series or classes of colors have been produced since that time from coal tar products other than aniline. Each of these series has its chemical name, but they are all classed under the term, coal tar colors or coal tar dyes. The popular name of aniline dyes is inaccurate, as it includes properly only one series of these dyes. Aniline dyes, the first of these colors to be discovered, may be said to have revolutionized the dyer's art. At the present time coal tar dyes are used to color wool, cotton, silk, soaps, inks, leather goods, confectionery, paper, and other substances. Aniline when pure is somewhat heavier than water. It has a vinous smell and a burning taste. Aniline is a poison, so acting upon the blood as to destroy the red corpuscles. The pure food laws of many states forbid the sale of candy and articles of diet colored with aniline. The Germans prepare aniline so inexpensively that they have a monopoly of the world's market. See Dyes; Dyeing
What Has Changed in the Last Century
Aiton's stated in 1910 that "the Germans prepare aniline so inexpensively that they have a monopoly of the world's market" — a monopoly broken within a decade, when the First World War cut off German supply and the United States and Britain built dye industries of their own, partly on seized German patents. The bigger reversal is in what aniline is for: dyes are now a minor outlet, and the great majority of the world's aniline, made in millions of tonnes a year from benzene by way of nitrobenzene, goes into MDI for polyurethane foam and insulation. The warning that aniline "acts upon the blood as to destroy the red corpuscles" was sound — it causes methaemoglobinaemia, and it is handled today as a toxic, probably carcinogenic industrial chemical. Coal-tar food colours were not banned outright but brought under certification schemes, and many of the early ones have since been delisted as unsafe.
Written for this edition, 2026.