I 



On the Manvfacturmg of Indigo in this Country. 241 



I have been recently informed, that many first rate makers of in- " 

 digo in Bengal condemn the process of obtaining it from the dried 

 leaves, on the plea that the article obtained is no better, and Is much 

 less In quantity. If any of our planters sliould be disposed to try the 

 dry process, it will be necessary to inform them, that should the 

 leaves, between gathering and drying, be subject to fermentation, only 

 a small pordon of coloring matter will be obtained, and tliat the 

 loss sustained will be as the degree of fermentation. 



During tlie precipitation of the coloring feculae the coarsest par- 

 ticles, possessing the greatest specific gravity, subside first, constituting 

 the lower strata of the pulp, and the lighter and finer particles sub- 

 siding die last, form the upper part. It is necessary that indigo ma- 

 kers should take advantage of this circumstance, by first taking off 

 the upper layer, and moulding it by itself, and the lower part by itself. 

 By this means they may obtain several qualities of indigo from one 

 mass of pulp. 



It appears from analysis made by Bergman, Quatremere, and 

 other chemists, that indigo of good quality does not contain more 

 than from 46 to 47 per cent of coloring matter, and tliat the very 



best samples do not contain more than 48 per cent. 



good 



quality, and of the menstruua in which tire impurities are soluble. 



Mucilaginous parts separable by water, - - » 12 

 Resinous parts soluble in alcohol, - - • - 6 



Earthy parts soluble in acetic acid, - • - •- 22 

 Oxide of iron soluble in muriatic acid, - - - - 13 



almost 



47 



100 



There cannot be a doubt, that manufacturers of indigo might pro- 

 duce, by attending to tlie analysis made by chemists, an article far 

 superior to any hitherto offered to the pubUc. It will also appear cer- 

 tain, when experience shall have confirmed the value of a superior 

 indigo, that a more tlian remunerating price could be obtained for a 

 purer article. For certain purposes a pure indigo would command 

 double, and even treble prices, provided die supply were not too great 

 for the consumption. This being die case, it would be well for our 

 manufacturers to pay some attention to the subject, and endeavor^ by- 



some 



XVIIL— No. 2. 31 



