1907.] 0)1 Problems of A2:)2)Jied Chemistry. 575 



discourse upon many other prol)lems which present themselves in 

 inorganic applied chemistry, and only a few minutes are left to speak 

 of those belonging- to the domain of organic chemistry. 



I will point to only two problems of this kind. One of these is 

 the substitution of artificial for natural colouring matters. This, 

 indeed, has now been carried out almost to the bitter end. Long 

 ago, one of the oldest and most widely-used colouring matters, that 

 contained in madder, succumbed to the attacks of the chemists, 

 among whom the names of Edward Schunck and William Henry 

 Perkin testify to the glorious share taken by Englishmen in that 

 victory. The colouring substance of madder — alizarine — is now made 

 from English coal-tar, and has altogether taken the place of the 

 impure form in which it occurs in the madder plant. The growers 

 of this plant in the south of France and elsewhere have had to 

 abandon its culture altogether, to their great sorrow. 



A similar fate has already partly overtaken, and may, in the end, 

 destroy entirely, the culture of indigo, most of which, as you know, 

 comes from British India, and formerly represented a value of some 

 four million pounds sterling per annum. At first, after the great 

 Munich chemist, Adolf Baeyer, had prepared the colouring matter of 

 indigo by synthesis in his laboratory, the planters merely shrugged 

 their shoulders, and that with good reason, since Baeyer's processes 

 could not compete with their produce in respect of cost price. 

 Another circumstance which at that time militated against artificial 

 indigo was this, that it started from toluene, the total available 

 quantity of which substance would not have sufficed for producing 

 anything like all the indigo required, even if no toluene w^ere used 

 for other purposes, which is out of the question. But this state of 

 matters has changed. Twelve years ago the late Carl Heumann, 

 assistant professor in my laboratory at Ziirich, discovered the synthe- 

 sis of indigotine from naphthalene. This, like toluene, we get from 

 coal-tar, but in about ten times the quantity, so that there is no fear 

 of any scarcity of naphthalene even in the future. The late 

 Dr. Piudolph Knietsch at the Badische Anilin und Sodafabrik at 

 Ludwigshafen gradually transformed Heumann's laboratory process 

 into a factory process, which is working with entire success on a large 

 scale. Synthetic indigotine is now manufactured at such a low price 

 that its competition has proved a severe blow to the indigo-planting 

 interests. Thus the triumph of scientific investigation and practical 

 skill in chemical manufacturing, gratifying though it be as a splendid 

 achievement of applied chemistry, is a sad trial to many thousands of 

 Indian ryots and their British masters ; and this is merely the fore- 

 taste of what will inevitably happen in many other cases. What is 

 food for one is poison for another. But yesterday this was the 

 bitter experience of the French madder-grower ; to-day it is the turn 

 of the Indian indigo-planter ; and to-morrow it may be some one 

 else's lot. 



