LEGUMINOSiE. 247 



obtained is small in quantity, and inferior in quality. Besides, 

 as Indigo contains an immense proportion of carbon, and, as it 

 is a well established fact in Vegetable Physiology, that it is not 

 secreted by plants in the shade, but only when they are exposed 

 to the direct influence of the sun's rays ; it is evident, that In- 

 digo requires much and continued sunshine to render its juices 

 ricli in this principle. 



The proper period for cutting the plant is previous to 

 flowering. The leaves at this time change from a light to a 

 dark green, and, according to the French indigo planters, they 

 crack when they are squeezed. It is of importance to determine 

 the exact time when the plant comes to this state, since the 

 branches, if they are prematurely cut, would be deficient in the 

 quantity of the produce, and the quality would be inferior. 



The Indigo plant is retained in cultivation for a year, during 

 which period it yields three or four cuttings. The Indigo 

 obtained from the first cutting is the greatest in quantity, 

 and is of the finest quality. The succeeding cuttings become 

 gradually less productive, so that one part of the first, yields 

 as much as two parts of the second cutting. 



There are several methods employed in the manufacturing 

 of Indigo. The 1st. is styled \\\e fermenting process, and is that 

 which Avas formerly practised in this country, when Indigo was 

 generally cultivated. The branches, having been cut by means 

 of a sickle, are placed, with the stalk upwards, 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 

 with 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 

 steamboat, put in motion by means of a horse or mule. The 

 efi^ect 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 



