58 Weeding, Cutting, Carting, Manufacturing. 



boiler (see sketch) and heated to boiling point /* it is 

 then run out of the boiler on to the " table " to settle 

 (see sketch), and all that runs out with the water 

 through the table sheet is at once pumped back into 

 the sheet again (see same sketch) until it runs off 

 perfectly clear, leaving the indigo on the sheet with 

 a small quantity of water in it, which must be re- 

 moved by pressure. The sheet is now doubled 

 carefully over the indigo, and weights put on to press 

 it ; much of the water is thus got rid of, and when 

 no more will run, it is uncovered and lifted in buck- 

 ets or square wooden vessels into the screw presses 

 (see illustration). Here it is put into square boxes 

 or presses, well and neatly lined with pressing cloth, 

 the boxes themselves having holes bored in them 



* Copper boilers were mostly used in the old Bengal indigo factories, 

 as they are much superior 1 for indigo boiling purposes to iron boilers ; 

 they are thinner than the iron-plate ones, and transmit the slightest 

 heat readily, which is a great point, as indigo is less likely to burn and 

 get blackened, and can be gradually raised to boiling point without 

 overdoing it. Copper, also, does not corrode with damp nor flake oft 

 under the action of fire. They are more expensive than iron boilers, 

 much more so, but the money is well laid out on them : they last for 

 many years, a less quantity of fuel is required than with a thick iron 

 boiler, and the heat can be regulated with a thin copper boiler which 

 cannot be done with a thick iron plate boiler, inasmuch as the latter 

 sometimes gets nearly red-hot and almost fires the indigo when the 

 firing has been careless and excessive. Every instant indigo is over 

 boiled, it loses quality in colour to a proportionate extent. 



