47 



according to the temperature and the nature of the plants. 

 It is always difficult to fix the exact moment at which 

 the fermentation-process is completely finished ; a long 

 experience alone teaches this. 



After the fermentation, the water, which must 

 smell like beer and be coloured yellowish green, is allowed 

 to run avaj^ from the fermentation-basin into another 

 basin placed below, where it is at once set in motion by 

 a wheel provided with zinc pails. The turning movement 

 of the wheel causes the water every time to be taken up 

 b}' the pails and to be ejected again from a certain 

 height. In this way 240 litres of water come into contact 

 with the ox^'gen of the atmosphere and gradually the 

 colour changes from yellowish-green into green or dark-green 

 and the indigoprecipitates. 



The turning of the wheel is stopped as soon 

 as the grains of indigo are distinctly noticeable and sep- 

 arate themselves from the water. Then all must be allowed 

 to clarify, which takes 2 or 3 hours; after that the water 

 is poured off and the paste resulting therefrom is collected 

 in filtering-basins from which the water oozes, this pro- 

 cess lasting 5 to G hours. The paste is now taken off the 

 filtering-cloth and put in casks, which are conveyed to the 

 kitchen where the paste is mixed with a certain quantity 

 of water and then boiled, at the same time being stirred 

 continually so as to avoid its burning. 



When well boiled, the matter is poured on a filter- 



