INDIGO 893 



especially from Bengal, Oude, and Madras. The remainder is imported from Java, 

 Manilla, the Mauritius, and Senegal in the eastern hemisphere, and from Caraccas, 

 Brazil, and Guatemala in the western. The East Indian and Brazilian indigo comes 

 packed in chests ; the Guatemala in ox-hides, called serous. Its quality depends upon 

 the species of the plant, its ripeness, the soil and climate of its growth, and the mode 

 of manufacture. 



The plants which are cultivated in the East Indies, are the Indigofera tinctoria, 

 Anil, disperma, and pseudo-tinctoria. The districts of Kishenagar, Jessore, and Moor- 

 shedabad, in Bengal, ranging from 88 to 90 east lat. and 22f to 24 north long., 

 produce the finest indigo. That from the districts about Burdwan and Benares is of 

 a coarser or harsher grain. Tyroot, in lat. 26, yields a tolerably good article. The 

 portion of Bengal most propitious to the cultivation of indigo, lies between the river 

 Hoogly and the main stream of the Ganges. The ground having been ploughed in 

 October, November, or beginning of December, the seed of the indigo plant is sown 

 in the last half of March or beginning of April, while the soil being neither too hot 

 nor too dry, is most propitious to its germination. A light mould answers best ; and 

 sunshine, with occasional light showers, are most favourable to its growth. From 

 twenty -four to thirty pounds of seeds are required for sowing an acre of land. The 

 plants grow rapidly, and will bear to be cut for the first time at the beginning of July, 

 nay, in some districts, so early as the middle of June. The indications of maturity 

 are the bursting forth of the flower-buds, and the expansion of the blossoms ; at which 

 period the plant contains most colouring matter. Another indication is taken from 

 the leaves ; which, if they break across, when doubled flat, denote a state of maturity. 

 But this character is somewhat fallacious, and depends upon the poverty or richness 

 of the soil. When much rain falls, the plants grow too rapidly, and do not sufficiently 

 elaborate the blue pigment. Bright sunshine is most advantageous to its production. 

 The first cropping of the plant is best ; after two months a second is made ; but at 

 the present day, planters never undertake a third or fourth. 



Two methods are pursued to extract the indigo from the plant : the first effects it 

 by fermentation of the fresh leaves and stems ; the second, by maceration of the dried 

 leaves. , 



1. From the recent leaves. In the indigo-factories of Bengal, there are two large 

 stone-built cisterns, the bottom of the first being nearly upon a level with the top of 

 the second, in order to allow the liquid contents to be run out of the one into the other. 

 The uppermost is called the fermenting vat, or the steeper; its area is 20 feet square, 

 and its depth three feet ; the lowermost, called the beater or beating vat, is as broad as 

 the other, but one-third longer. The cuttings of the plant, as they come from the field, 

 are stratified in the steeper, until this is filled to within 5 or 6 inches from its brim. In 

 order that the plant, during its fermentation, may not swell and rise out of the vat, beams 

 of wood and twigs of bamboo are braced tightly over the surface of the plants, after 

 which water is pumped upon them until it stands about 3 or 4 inches from the 

 edge of the vessel. An active fermentation speedily commences, which is completed 

 within 14 or 15 hours, a little longer or shorter, according to the temperature of the 

 air, the prevailing winds, the quality of the water, and the ripeness of the plants. 

 Nine or ten hours after the immersion of the plant, the condition of the vat must be 

 examined ; frothy bubbles are then seen rising like little pyramids, at first of a white 

 colour, but soon becoming greyish-blue, and then deep purplish-red. The fermenta- 

 tion is at this time violent, the fluid being in constant commotion, and apparently 

 boiling, innumerable bubbles mount to the surface, and a dense copper-coloured scum 

 covers the whole. As long as the liquor is agitated, the fermentation must not be 

 disturbed; but when it becomes more tranquil, the liquor is to be drawn off into the 

 lower cistern. It is of the utmost consequence not to push the fermentation too far, 

 because the quality of the whole indigo is thereby deteriorated ; but rather to cut it 

 short, in which case there is, indeed, a loss of weight, but the article is better. The 

 liquor possesses now a glistening yellow colour, which, when the indigo precipitates 

 changes to green. The average temperature of the liquor is commonly 85 Fahr. ; 

 its specific gravity at the surface is T0015 ; and at the bottom 1-003. 



As soon as the liquor has been run into the lower cistern, ten men are set to work 

 to beat it with oars or shovels 4 feet long, called busquets. Paddle-wheels have also 

 been employed for the same purpose. Meanwhile two other labourers clear away 

 the compressing beams and bamboos from the surface of the upper vat, remove the 

 exhausted blue, set it to dry for fuel, clean out the Vessel, and stratify fresh plants in 

 it. The fermented plant appears still green, but it has lost three fourths of its bulk 

 in the process, or from 12 to 14 per cent, of its weight, chiefly water and extractive 

 matter. 



The liquor in the lower vat must be strongly beaten for an hour and a half, when 

 the indigo begins to agglomerate in flocks, and to precipitate, This is the moment 



