18 



INDIGO. 



Remarks afterwards carefully examined, there appeared to 



on East-India ^ / \ 



Indigo. be the following different qualities : 



s. d. 



3I oz. Flora worth 10 o per lb. 



i| „ Strong Copper „ 89,, 



7 „ Middling ditto „ 83,, 



3| „ Inferior ditto „ 76,, 



J „ White streaked or drossy „ 60,, 



As it may be an object with you to know how 

 the East-India indigos may be prepared to the 

 best advantage, I will give you the outlines of the 

 usual methods of making indigo, and some hints 

 for improving the process, which I will notice 

 under the terms of fermentation, precipitation, 

 and manner of drying. 



1st. The fermentation is begun by steeping the 

 leaves and stalks of the indigo-plant in a large 

 vessel, adding water thereunto, and suffering the 

 whole to ferment, until the colour is separated 

 from the leaves of the plant, and diffused in a full 

 dark green colour through the whole mass of 

 liquid in the vessel. 



2d. When properly fermented, the coloured 

 liquid is drawn off into another reservoir under- 

 neath, and agitated by buckets or levers for a 

 long time, until the coloured liquor granulates, 

 and precipitates (by subsiding for some time) the 

 indigo to the bottom of the reservoir. 



3dly. The useless yellowish brown coloured 

 liquor which covers the precipitate is suffered to 



run 



