326 VEGETABLE SUBSTANCES. 



length to other pursuits where industry might find a 

 surer recompense*." 



To this melancholy statement may be added the 

 fact, that of all the productions that have been made 

 objects of great commercial speculation, not one has 

 of late years so tended to swell the sad list of bank- 

 ruptcy and ruin as " indigo." 



The prepared indigo of commerce is usually im- 

 ported in square, or oblong cakes, of an intense blue 

 colour, approaching to black. The specific gravity 

 of the best quality is small. It has a peculiar and 

 disagreeable smell. 



There is no article of commerce which fluctuates 

 more in its price and is of greater variety of quality 

 than indigo. It is distinguished according to its dif- 

 ferent shades of colour, arising from the manner of its 

 preparation and the proportion of foreign substances 

 with which it is mixed. The principal shades are blue, 

 violet, and copper colour ; the blue being the best 

 quality. These are again subdivided into fine, good, 

 and middling. The indigo which is imported from 

 different countries is known in commerce by its rela- 

 tive value, and accordingly there are no less than 

 twenty-four kinds in the English market, each bear- 

 ing a different price, varying through all the inter- 

 mediate proportions from Ss. Gd. to 2s. per Ib. ; 

 Bengal is the best, and Manilla" indigo the worst 

 in quality. In 1831, 7,307,313 Ibs. of indigo were 

 imported into England. The duty on that coming 

 from British possessions is 3d., on other sorts 4c?. 

 per Ib. 



However carefully indigo may be prepared, there 

 are always more or less of impurities mixed up with 

 it. The relative quantity of these is ascertained by 

 the specific gravity of the indigo, which is lighter in 

 proportion to its purity. Bergmann found that the 

 * Quarto edition, vol. ii. p, 282. 



