PRODUCTION OF DYES 323 



as to whether good quality indigo can ever be produced under 

 cultivation at so cheap a rate as that at which the synthetic 

 substance is now manufactured. It has been stated that the 

 two products are more effective when mixed in equal proportions, 

 and if this be always true it is possible that it may contribute 

 more than anything else to the support, and perhaps to the 

 expansion of the cultural industry." 



On the other hand it is asserted that synthetic indigo is 

 capable of producing all the varieties of shade previously obtained 

 by the use of the natural dye and equally permanent, with the 

 advantage of uniformity of composition and freedom from im- 

 purities which saves much trouble to the competent dyer. It 

 has also been urged that indigo as a crop has always been more 

 or less uncertain, and provided that the change does not come 

 about too suddenly, the substitution of crops which supply food- 

 stuffs would be on the whole an advantage to the country. 



What has happened in British India represents what has also 

 occurred in other countries in which indigo has been cultivated. 

 It is probable that the position of the planter may be somewhat 

 ameliorated and the growth of indigo continued on the scale to 

 which it has now been reduced. It appears to have been decided 

 that the best chance of improving the yield of the dye is a 

 botanical study of the crop and selection of the best type of 

 plant with improved cultivation. Experiments in this direction 

 are going on at Pusa. In the meantime it is probable that the 

 custom or prejudice existing in the dye-houses will lead to the 

 continued employment of natural indigo in association with the 

 chemical product for securing certain effects for a long time to 

 come. 



The artificial production of indigo from constituents of coal- 

 tar has a long scientific history, but in this case, as in so many 

 other cases, success in the laboratory does not necessarily imply 

 success in the factory. For while in the former case the purposes 

 of science and additions to knowledge are the chief objects in 

 view, in the latter the process ultimately to be adopted is deter- 

 mined not alone by practicability, but ultimately by the cost. 

 The various synthetic methods which have been proposed since 

 1875 are to be found in the chief textbooks of organic chemistry. 

 Here we can only review those which have had a practical success 

 and form the present source of the synthetic dye. 



One other point for consideration has also had a large influence 



