1838.] 



Clillivation and Manufacture of Indigo. 



fecula takes place. A precipitant of red earth and water is then added 

 and the fecula is allowed to subside. The clear liquid is lastly drawn 

 off, and the Indigo is dried in small bags suspended in the shade. 



" The modern process is conducted on similar principles. Large 

 coppers are about two-thirds filled with the branches of the Indigo, 

 which are not to be pressed down. Cold water is then added to within 

 a few inches of the brim, and the fire is lighted and kept up rather 

 briskly, till the liquor acquires a deep green colour. During this part 

 of the process, the mass must be constantly stirred, otherwise the 

 bottom will be overscalded before the surface is ready. The fire is now 

 to be withdrawn, and the liquor passed through a haircloth into th© 

 beating vat, where it must, while still hot, be agitated in the common 

 way for half an hour. Lime water is now to be added, and after stand- 

 ing for about two hours and a half, the supernatant liquor, which is of 

 a Madeira wine colour, is to be drawn off. The rest of the process is 

 similar to that followed in preparing common fermented Indigo. 



" The advantages of the scalding over the fermenting process, are, 

 according to Dr. Roxburgh, that :— 1. The produce is larger. 2. The 

 health of the labourers is not endangered by the noxious effluvia, as is 

 the case in the fermenting process. 3. Much less agitation, and very 

 little precipitant is necessary. 4. The operation may be performed 

 several times in the course of the day. 5. The Indigo dries quickly, 

 without acquiring a bad smell, 6. Indigo so prepared has not the 

 flinty appearance common to fermented Indigo, but in softness and 

 levity is equal to Spanish flora. 



" The 3d manner of manufacturing Indigo is called the dry process, 

 and is that at present followed in the large factories in the southern 

 provinces of India. It is described at great length by Charles H. 

 Weston, Esq., in the Quarteily Journal. According to this writer, the 

 branches are cut early in the morning, and spread out in the sun. In 

 the afternoon, the leaves are so dry, that they are easily separated from 

 the branches by simply beating them with a stick. After this they are 

 collected and closely packed in warehouses, and trodden down. As 

 they are not immediately used, but are kept for some time, it is of im» 

 portance that there be no dampness, as otherwise fermentation would 

 ensue, and their value be destroyed. When the leaves have been kept 

 about a month, their colour is found to have changed to a pale lead 

 colour, which afterwards passes into black. It has been ascertained, 

 that the maximum quantity of indigo is obtained when the leaves have 

 acquired the lead colour, and that the colouring matter is only sparingly 

 given by the fresh green leaves, or when they have paSfSed to the op* 

 posite extreme, and acquired the black colour. 



