198 



Cultivation and Manufacture of Indigo. 



[July 



" There are several methods employed in the manufacturing of 

 Indigo. The 1st is styled the fermenting process, and is that which was 

 formerly practised in this country, when Indigo was generally cultivat- 

 ed. The branches having been cut by means of a sickle, are placed, 

 with the stalk upwnrds, in the steeping vat, till it is nearly three parts 

 full. This vat is a large cistern of mason work or wood, about 16 feet 

 square. It is then filled wilh water, and to prevent the branches from 

 floating, they are kept down by means of rails loaded with planks. 

 Soon after, the fermentation commences, and goes on till, in 24 hours, 

 the contents of the vat are so hot, that the hand cannot be retained in 

 it. The water gradually becomes opaque, and assumes a green colour, 

 bubbles of carbonic acid gas are emitted, and a smell, resembling that 

 of volatile alkali, is exhaled. When the fermentation has gone on 

 sufficiently far, the liquor must be immediately let into the second 

 cistern : for were it to be allowed to remain after a certain time in the 

 fermenting vat, the pigment would be spoiled ; and if, on the other 

 hand, it were drawn off too soon, much of the Indigo would be lost. 

 This second vat, which is lower than the first, is called the battery, and 

 is commonly in size about 12 feet square, and 4i feet deep. Here the 

 liquor is agitated and beaten up, to perform which a variety of machines 

 have been invented. The best adapted for the purpose is one with 

 paddles, resembling those of a steam-boat, put in motion by means of 

 a horse or mule. The effect of this agitation is, that the liquor will 

 become as if curdled, and the indigo will be observed to separate into 

 flakes. The manufacturer ascertains when the agitation is carried 

 sufficiently far, by examining from time to time a small portion on a 

 white soup plate. A quantity of lime water is now^ added, and the blue 

 floccules are allowed to subside. The clear water is then drawn off by 

 plugs placed at different heights in the cistern, and the sediment is 

 drained in sieves made of horse-hair. It is after this put into coarse 

 linen bags, and having remained for some time suspended in the shade, 

 is subjected to pressure in order to get rid of as much of the moisture 

 as possible. Lastly, the Indigo, having been converted into a stiff con- 

 sistent mass, is cut into small squares, and allowed to dry in the shade. 



The 2nd method of manufacturing Indigo is known by the name of 

 the scalding process. It appears to be a revival of the ancient Indian 

 mode, as practised at Ambore, and described by Col. Martine in the 

 third volume of the Asiatic Researches. He there mentions, that the 

 natives boil the plant in earthen pots of 18 inches diameter, till the 

 colouring matter has been extracted: it is then removed into larger 

 jars, and agitated by means of a bamboo, until a granulation of the 



