288 CURIOUS OR USEFUL PLANTS. 



digo, has run into the second vat, they agitate it till it heats, froths, 

 ferments, and rises above the rim of the vessel in which it is con- 

 tained : to allay this violent fermentation, oil is thrown in as the 

 froth rises, which causes it instantly to subside. After this beat- 

 ing has been continued from twenty to thirty minutes, a small 

 muddy grain begins to be formed ; and when this is completed 

 lime water is added from an adjacent vessel ; when the indigo gra- 

 nulates more fully, the liquor assumes a purple colour, and after 

 being well stirred together with the lime water is allowed to settle. 

 The clear water is then permitted to run off into a succession of 

 vessels, so that every portion of the indigo carried away may have 

 an opportunity of settling and being preserved; when the thick 

 purple sand, which forms the. residuum, is put into bags of coarse 

 linen. These are suspended till the moisture is drained off, after 

 which the clotted material is turned out of the bags and worked 

 upon boards of a porous timber with a wooden spatula. It is, at 

 the same time, frequently exposed to the morning and evening sun, 

 but only for a short period at a time, and is then put into boxes 

 or frames, where it is again exposed to the sun in the same cautious 

 manner; till with great labour and attention the operation is 

 finished, and that valuable drug called indigo fitted for the market. 

 The greatest skill and care is required in every part of the process, 

 without which there is great danger of spoiling the whole. 



In the American states much attention has been paid to encou- 

 rage the cultivation of indigo; for which purpose, the uniform of 

 the national troops is blue, as also that of the militia in general : 

 the clergy are also allowed, by the established custom of the coun- 

 try, to wear that colour ; and it is generally adopted, both by the 

 most frugal and most expensive people : all which circumstances 

 operate favourably for the indigo planters, without any expence to 

 the country. 



In Hindustan the indigo-shrub grows to the height of a goose- 

 berry bush, and has a thick round head, but no thorns. The people 

 strip off the leaves, and having laid them in a heap, they lie several 

 days, till they have sweated, and are then put into deep vessels, 

 with a sufficient quantity of water, to which they give their blue 

 tincture. The water is afterward drained into broad shallow ves- 

 sels, made of a kind of plaster of Paris, where the sun having ex- 

 haled all the moisture, there remains at bottom a hard dry cake, 



