LEOUMINOSit. 
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 
rich in this principle. 
1 he 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 th e fermenting process, and is that 
which was 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 oft’ 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 4^ 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 
effect 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 flu-, by examining from time to time a small portion 
