242 On tfie Mamifactwing of Indigo in this Country. 



possible. To promote this object, I offer the following extracts and 

 observations. 



Bergman dissolved, by means of ebullition in vi^ater, a ninth part 

 of the weight of indigo. 



Quariremere also separated, by means of water, the parts which 

 are soluble. He states their quantity to be more considerable, the 

 worse the quality of the indigo; and that, after this operation, the 

 residuum has acquired the qualities of the finest indigo. He there- 

 fore proposes to purify what is of inferior quality, by boiling it in a 

 bag, and renewing the water till it ceases to acquire color. 



If sulphuric acid be diluted with water, it attacks only the earthy 

 matter that is blended with the indigo, and some mucilaginous in- 

 gredients. 



Muriatic acid digested or even boiled with indigo, takes up the earthy 

 part, the iron, and a little extractive matter, which colors it yellowish 

 brown, but without attacking in any manner the blue color. 



It is evident from the analysis, that to make indigo far superior to 

 any now brought to market, requires only an application of known 

 facts to the art of making it. It is a well ascertained fact, that if indi- 

 go be boiled in water containing muriatic acid, twenty five per cent 

 of the impurities contained in the best samples would be extracted, 

 and that the coloring matter remaining would form an indigo far su- 

 perior to the best now offered for sale. 



The best Bengal indigo, and I never remember it in a more de- 

 pressed state, is worth, wholesale, one dollar eighty cents per pound. 

 The average value of all the indigo imported from foreign countries 

 is about one dollar and fifteen cents per pound, whilst the average 

 value of that made in the United Stales is not more than fifty cents, 

 and this great difference in the value is owing almost entirely to the 

 great impurity of the article. The first object with our manufactu- 

 rers, therefore, should be to make their indigo equal in quality to the 

 best Bengal, and the second to go as far beyond them as is practi- 

 cable. 



In the best samples of the indigo of this country there is evidently 

 too much extractive matter, and there is no doubt that this defect arises, 

 in a great measure, from their taking the pulp from the beater, instead 

 of their running it into a vat of clear water, and after well agitating 

 it there, letting it settle in the third vat. This third receiver should 

 undoubtedly be added where it has not been already done. Those 

 manufacturers who would wish to avoid the expense of a third re- 



