462 DYES AND COLORING STUFFS. 



about twelve to sixteen hours, according to the weather, begins to 

 ferment, swell, rise, and grow sensibly warm. At this time spara 

 of wood are run across, to mark the highest point of its ascent ; 

 when it falls below this mark, they judge that the fermentation 

 has attained its due pitch, and begins to abate ; this directs the 

 manager to open a cock, and let off the water into another vat, 

 which is called the beater ; the gross matter that remains in the 

 first vat is carried off to manure the ground, for which purpose it 

 is excellent, and new cuttings are put in, as long as the harvest 

 of the weed continues. When the water, strongly impreg- 

 nated with the particles of indigo, has run into the second 

 vat or beater, they attend with a sort of bottomless buckets, 

 with long handles, to work and agitate it, when it froths, 

 ferments, and rises above the rim of the vessel that contains 

 it. To allay this violent fermentation, oil is thrown in as 

 the froth rises, which instantly sinks it. When this beating 

 has continued for twenty, thirty, or thirty-five minutes, according 

 to the state of the weather (for in cool weather it requires the 

 longest continued beating), a small muddy grain begins to be 

 formed; the salts and other particles of the plant united, dissolved, 

 and before mixed with the water, are now re-united together, and 

 begin to granulate. To discover these particles the better, and to 

 find when the liquor is sufficiently beaten, they take up some of it 

 from time to time on a plate, or in a glass ; when it appears in a 

 hopeful condition, they let loose some lime water from an adjacent 

 vessel, gently stirring the whole, which wonderfully facilitates the 

 operation ; the indigo granulates more fully, the liquor assumes a 

 purplish color, and the whole is troubled and muddy ; it is now 

 suffered to settle ; then the clearer part is permitted to run off 

 into another succession of vessels, from whence the water is con- 

 veyed away as last as it clears dn the top, until nothing remains 

 but avthick mud, which is put into bags of coarse linen. These 

 are hung up and left for some time until the moisture is entirely 

 drained off. 



" To finish the drying, this mud is turned out of the bags, and 

 worked upon boards of some porous timber, with a wooden 

 spatula ; it is frequently exposed to the morning and evening sun, 

 but for a short time only ; and then it is put into boxes or frames, 

 which is called the curing, exposed again to the sun in the same 

 cautious manner, until, with great labor and attention the operation 

 is finished, and the valuable drug fitted for the market. The greatest 

 skill and care is required in every part of the process, or there may 

 be great danger of ruining the whole ; the water must not be 

 suffered to remain too short or too long a time, either in the 

 steeper or beater ; the beating itself must be nicely managed, so 

 as not to exceed or fall short ; and in the curing the exact medium 

 between too much or too little drying is not easily attained. 

 Nothing but experience can make the overseers skilful in these 

 mnttors. There arc two methods of trying the goodness of 

 indigo ; by fire ai.d by water. If it swims it is good, if it sinks 



