2 CHEMISTRY 



the suggestion proved a fruitful one and by a chain 

 of events, which constitute a marvellous achieve- 

 ment of theoretical reasoning and of practical 

 skill, indigo was produced from coal tar products. 

 The technological possibilities of the synthetic indigo 

 problem were, however, studied simultaneously 

 with its purely scientific aspects and consequently 

 artificial indigo is now manufactured at so low a cost 

 that the production of the colouring matter from the 

 plant has almost ceased. It is true that the manu- 

 facture of natural indigo, up to the present day, 

 is carried out by methods which the Pharaohs might 

 have criticised as conservative; it is also fairly 

 certain that a comparatively small sum of money 

 devoted to improving the culture of the indigo 

 plant would so reduce the cost of natural indigo 

 as to ruin the artificial manufacture. These 

 obvious facts have not been acted upon, and con- 

 sequently we find that in 1913 the German works 

 manufactured artificial indigo to the value of 

 about 2,000,000 and the producing companies 

 paid annual dividends up to 30 per cent. 



Whilst scientific and technical progress in 

 Chemistry are intimately connected, and react so 

 rapidly one upon the other that the two cannot 

 be kept apart in any comprehensive discussion, 

 it must also be remarked that all the different 

 branches of chemical science and technology are 

 interdependent to an extraordinary degree. The 

 unhappy events of the last two years have given 



