The Romance of Modern Chemistry

HOW MAN COMPETES WITH NATURE product, and a similar fate seems to be in store for another well-known dye-stuff, namely, indigo. It is some time now since chemists managed to produce indigo synthetically in the laboratory, but, as is frequently- found, it is quite a different thing to turn out products profitably on the manufacturing scale. Dividends become a prime consideration, and the question arises whether the artificial product can be manufactured cheaply enough to compete successfully with the natural article. In the case of indigo the interval of time between the laboratory synthesis and the successful manufacture on a large scale was considerable. Years elapsed before all difficulties were overcome, but Science prevailed in the end and the artificial production of indigo on commercial lines is an accomplished fact. The raw materials on which the manufacture of indigo depends are (1) the hydrocarbon naphthalene; (2) am- monia, both obtained from coal; (3) acetic acid, obtained from wood; (4) oxygen, from the air. Starting with these, chemists have elaborated a process whereby artificial indigo is turned out sufficiently cheaply to compete with the natural dye-stuff. Already the latter has been hard hit, and the cultivation of the plant from which it is obtained is apparently doomed. The value of the indigo exported from India was .£3,570,000 in 1895, and only in 1904, while of the total quantity of indigo consumed in the various countries of the world at the present time, between 80 and 90 per cent, is the artificial product. This latter, it must be clearly understood, is not a mere substitute; it is exactly the same chemical compound as is derived from the plant The synthesis of indigo on a manufacturing scale is indeed one of the most remarkable achievements of modem 255