It was not until the declaration of war that the world recognized the extent of the tribute it had been prepared to pay annually to the Teuton in this one field of trading. The sudden interruption of supplies of colouring agents derived from coal-tar, and made in the huge factories fringing the Rhine, Main and Spree, threatened a whole host of trades from China to Peru. The competitive nations were forced to turn their attention to the mastery of an industry which hitherto they had virtually neglected in order to keep their industries alive, only to discover that they had much to learn. In the United States thousands suffered want and distress from unemployment just because the stocks of dyes had run out and their domestic dye-manufacturing plants were unable to rise to the occasion with sufficient promptitude. Antiseptics were difficult to procure, especially those which had achieved such a wide measure of popular favour during recent years, because they were of German origin and were no longer forthcoming. Amateur photographers were compelled to pack away their cameras and to forgo the pursuance of their hobby until such time as the essential chemicals once more became procurable and cheaper, while doctors were forced to polish up long-forgotten or rusty knowledge concerning the herbaceous drugs which had been displaced by those derived from coal-tar. A few figures will serve to drive home the stranglehold which the Germans had secured upon the trade of the world from the scientific exploitation of a waste product. For 5,000 years India supplied the world with indigo which was of vegetable origin. Apparently it held an unassailable commercial position and was held in particularly high esteem by Japan and China. Bauer, the German chemist, resolved to solve the indigo riddle and at once set out to make it from coal-tar. It proved a difficult quest occupying many years and involving thousands of experiments. But perseverance brought its due reward although success was not recorded until a round £1,000,000 had been spent. Then, before it had become established upon the market, it suffered eclipse by an improved process which had also been perfected by a German. Within five years of its appearance upon the market synthetic indigo had driven its natural rival from India virtually into oblivion. The coal-tar competitor even established a firm foothold in the land where the vegetable article had held sway for so many thousand years. Throughout China and Japan a similar story was related. Indian indigo was no longer required. It was beaten hopelessly in price, the factor which counts in commercial circles, by the synthetic German article. Of the artificial colouring materials imported by China German indigo claimed two-thirds. A seventh of the artificial dyes imported by Japan was German indigo, while one-tenth of the dye-stuffs imported from Germany into the United States was artificial indigo.