CHAPTER XV 



PERMENTATIOISf OF INDIGO, TEA, COCOA, COFFEE, 

 AND TOBACCO 



Indigo. — The important series of researches carried on 

 during recent years on behalf of the Government of India on 

 the chemistry of natural indigo, and of the native processes 

 of manufacture, is of especial interest to the student of 

 enzyme chemistry. 



As with most native industries, a considerable amount of 

 empirical knowledge and skiU has been attained in the manu- 

 facture of indigo, through centuries of experience, and the 

 improvements to be effected do not usually lie on the surface, 

 although at first sight they may appear to do so. Scientific 

 research of a high order is requisite, together with special 

 knowledge of local conditions, if a real gain in efficiency is 

 to be achieved. 



It is partly for this reason that native methods of manu- 

 facturing indigo have been practically stationary for many 

 years. The author has recently seen indigo vats (Plate III (i) ) 

 near Mirzapur, U.P., whose construction and methods of use 

 do not greatly differ from the graphic description to be found 

 in a volume, ' Eural Life in Bengal,' pubhshed in 1860. 



The native method for extracting indigo from the indigo 

 plant is briefly as follows : — 



The plant is brought to the factory immediately after 

 cutting and placed in bundles in an upper series of stone 

 or concrete vats. The bundles are tightly pressed down 



