266 Notices respecting Netxi Books* 



Weston, Esq., in the Quarterly 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 importance that there be no dampness, as other- 

 wise 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 in- 

 digo 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 passed to the opposite extreme, and ac- 

 quired the black colour. 



*' After the leaves have been kept a sufficient time, they are trans- 

 ferred to the steeping vat, which is an uncovered reservoir, built of 

 brick work, and lined with Roman cement, or stucco prepared from 

 burnt shells, and filled with water. They remain there for two hours, 

 and are every now and then turned ; after which, the water having 

 acquired a fine green colour, is run off, and passed through strainers 

 into the beating vat. Two hours may appear to be a very short 

 time for infusing the leaves. It has been found, however, that when 

 the process is prolonged beyond this, a partial precipitation of the 

 Indigo takes place, 



" The liquor, when in the beating vat, is agitated by paddles for 

 about two hours, during which the fine green colour gradually dark- 

 ens, and acquires a blackish blue. As soon as this last hue appears, 

 and the froth thrown up in beating becomes more or less white, and 

 the incipient separation of the particles of Indigo can be detected, 

 a certain proportion of lime water is well mixed with the liquor, and 

 the whole is allowed to settle. In the course of three hours the in- 

 digo will have fallen to the bottom, and the supernatant liquid, which 

 ought to be of a fine Madeira colour, is allowed to run off by means 

 of cocks, placed at different heights. The indigo is, after this, con^ 

 veyed into the covered part of the laboratory, where it is spread on 

 strained cloth, and allowed to drain. 



" On the following morning, the Indigo is put into a copper, with 

 a quantity of hot water, and fire is applied. As the mass heatens, 

 a quantity of scum rises, which is immediately removed, and, as 

 soon as the whole is brought to the boiling point, the fire is with- 

 drawn. The Indigo is then again taken to the strainers, and having 

 been again drained, it is well worked with the hands, and afterwards 

 subjected to pressure in square boxes, in order to get rid of as much 

 moisture as possible. In this manner large square cakes, about 2^ 

 inches in thickness, are formed, which are subsequently divided into 

 smaller cakes, and allowed to dry gradually in the shade. 



" The boiling process, although not generally adopted, is said to 

 improve very considerably the quality, and enhance the value of the 

 produce. 



