504. 



HISTORY OK THE VEGETABLE KINGDOM. 



superintended liy persons who are deeply inter- 

 ested in their success, would be conducted in the 

 best possible manner; while improvements would 

 be continually suggesting themselves, by which 

 favourable results might be attained with greater 

 certainty. Surprise must therefore be excited 

 when we find that very little scientific know- 

 ledge is engaged in the pursuit, and that the 

 whole is arranged and conducted by means at 

 variance with philosophical principles, a due 

 attention to which might often produce totally 

 different results. 



Until within the last few years, since the 

 appointment of Lord'William Bentinck as gover- 

 nor-general of India, Europeans were not allowed 

 to take the land in their own hands for agricul- 

 J;ural purposes, and they were therefore of neces- 

 sity dependent on native industry for the pro- 

 duce of the soil. The cultivation of indigo was 

 thus left to the care of the indolent and preju- 

 diced Hindoo, who from age to age is found 

 obstinately pursuing the same track, without 

 deviation or improvement, making no attempt 

 to discover the cause, or atrest the progress of 

 those ravages so often fatal to his whole crop, 

 but which the superior intelligence of skilful 

 European agriculturists might perhaps success- 

 fully combat. 



The uncertainty of this production, though 

 in the present day more known and felt in tlie 

 East, was equally great in the West Indies dur- 

 ing the time when its cultivation formed there 

 an object of importance. In a statement of the 

 comparative advantages of different crops, Mr 

 Edwards, after dwelling on the extreme produc- 

 tiveness of indigo, thus continues : " Unhappily, 

 however, the golden hopes which speculations 

 like these have raised in the minds of thousands 

 have vanished on actual experiment like visions 

 of the morning. I think I have myself, in the 

 course of eighteen years in the West Indies, 

 known at least twenty persons commence indigo 

 planters, not one of whom has left a trace by 

 which I can now point out where his plantation 

 was situated, except perhaps the remains of a 

 ruined cistern covered by weeds and defiled by 

 reptiles. Many of them too were men of know- 

 ledge, foresight, and property. That they failed 

 is certain, but of the causes of their foilure I 

 confess I can give no satisfactory account. I 

 was told that disappointment trod close at their 

 heels at every step. At one time the fermenta- 

 tion was too long continued, at another the liquor 

 was drawn off too soon. Now the pulp was not 

 duly gianulated, and now it was worked too 

 much. To these inconveniences, for which prac- 

 tice would doubtless have found a remedy, were 

 added others of much gre.iter magnitude, — the 

 mortality of the negroes from the vapour of the 

 fermented liquor, the failure of the seasons, and 

 the ravages of the worm. These or some of 



these evils drove them at 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 specula- 

 tion, not one has of late years so tended to swell 

 the sad list of bankruptcy and ruin as indigo. 



The prepared indigo of commerce is usually 

 imported in square, or oblong cakes, of an intense 

 blue colour, approaching to black. The specific 

 gi-avity of the best quality is small. It has a 

 peculiar and disagreeable smell. 



There is no article of commerce which fluctu- 

 ates more in its price, and is of greater variety 

 of quality than indigo. It is distinguished 

 according to its different 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 knovra in 

 commerce by its relative value, and accordingly 

 there are no less than twenty-four kinds in the 

 English market, each bearing a different price, 

 varying through all the intermediate proportions 

 from 8s. Gd. to 2^. per lb,; Bengal is the best, 

 and Manilla indigo the worst in quality. In 

 18.31, 7,307,313 lbs. of indigo were importtd 

 into England. The duty on that coming from 

 Britisli possessions is Sd., on other sorts 4rf. 

 per lb. 



However carefully indigo may be prepare<l, 

 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 best indigo which he 

 could procure contained more than half of 

 extraneous matter, being in these proportions : — 



100 



Proust, on subjecting indigo to analysis, found 

 it to contain a large proportion of magnesia. 

 This substance has very singular chemical pro- 

 perties. It is now well ascertained to be com- 

 posed of the fecula of the plants combined with 

 oxygen, to which it has so great an affinity that 

 its transition from green to blue on exposure to 

 the atmosphere is instantaneous. Pure indigo 

 is insoluble in water, alcohol, ether, or oils; 

 neither alkalis nor earths have any action on it, 

 nor have any of the acids hitherto tried, except 

 the nitric and sulphuric. Nitric acid converts its 

 colour into a dirty white, and finally decomposes 



