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 twenty 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, till this be filled within five or six inches of 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 tight over the surface of the plants, after which water is pumped upon them till it stands within three or four inches of the edge of the vessel.  An active fermentation speedily commences, which is completed within fourteen or fifteen 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 appear, which rise like little pyramids, are at first of a white colour, but soon become grey, blue, and then deep purple red.  The fermentation is at this time violent, the fluid is in constant commotion, apparently boiling, innumerable bubbles mount to the surface, and a copper colored dense 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 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 color, which, when the indigo precipitates, changes to green.  The average temperature of the liquor is commonly 85 deg.  Fahr.; its specific gravity at the surface is 1.0015; 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 four feet long, called busquets.  Paddle wheels have also been employed for the same purpose.  Meanwhile two other laborers clear away the compressing beams and bamboos from the surface of the upper vat, remove the exhausted plant, 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 twelve to fourteen 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