(8-5 FARMER'S ASSISTANT. 



We shall therefore merely insert the directions of Dr. 

 Roxburgh^ for extracting the coloring matter from the 

 plants. 



< By the scalding process (says he) I have always, on a 

 small scale, made from the common indigo plant better 

 indigo, than I could by fermentation (the old method) und 

 in one-fourth of the time ; and, what is also of great im- 

 portance, without the smallest degree of that pernicious 

 effluvia, which attends the manufacture of indigo by fer- 

 mentation.' 



He further observes, in substance, that the Hindoos, of 

 the northern Provinces of Indostan, make all their indigo 

 by boiling the plants, and precipitating the pulp or coloring 

 matter with a cold infusion of the bark of the jambalong 

 tree: Yet, says he, 



< Notwithstanding the inferiority of this bark, as an 

 astringent, when its effects are compared with those of 

 limewater, I have always found their indigo of an excelent 

 quality, and very light; a cubic inch weighing only about 

 one hundred and ten grains, and being of a blue violet- 

 color. The superior quality of this indigo must alone be 

 imputed to the nature of the process by which the color, or 

 rather the base of the color, is extracted from the plant* 



4 Besides the superior quality of the Indigo obtained by 

 the scalding-process, the quantity is generally increased by 

 it : Moreover, the health of the Laborer in this way is not 

 endangered, as in the fermenting process, by constant and 

 copious exhalations of putrid miasma. The heat employed 

 expels most of the fixed air during the scalding, which ren- 

 ders a very small degree of agitation, and very little of the 

 precipitant, necessary. The operation can also be perform- 

 ed two or three times a day, upon a large scale ; and the 

 indigo dries quickly, without acquiring any bad smell, or 

 putrid unwholesome tendency.' 



After the boiling or scalding has been properly executed, 

 the liquor is to be drawn off, and is then to be agitated or 

 churned, 



See CHURN, 



Until the coloring matter begins to granulate, or float in 

 little flakes on the water; and when this curdling or coagu- 

 lation has been completely effected, which is usually done 

 in about fifteen or twenty minutes, a strong impregnation 

 of limewater, prepared in a vat for the purpose, is gradually 

 to be added, not only to promote the separation, but like- 

 wise to fix the color, and preserve the matter containing it 

 from putrefaction. 



In the operation of churning, particular care must how- 

 ever be uken, not to exceed, or to fall short of, the proper 

 degree of agitation ; as too little of this will leave the indigo 



