INDIGO. 



government, have proved that, in a fuitable foil and expo- 

 fure, and with good feed, it may be cultivated in a foutherly 

 climate. Accordingly, he has obtained the indigo plant in 

 the gardens of the Chateau de la Venericj near Turin ; and 

 by fubmitting it to the procefs employed at St. Domingo, 

 he has extracted an indigo which might bear comparison 

 with the fineft indigo of the colonies. His plantations were 

 made towards the end of February. M. Icard de Batahgni, 

 another colonift, cultivated the plant in 1805, in the depart- 

 ment of Vauclufe, in France ; and his refults confirm the 

 hopes formed with refpeft to the culture of indigo in Eu- 

 rope. 



Labat has given a particular account of the culture of the 

 plant, and the preparation of the indigo. The ground be- 

 ing tlioroughly cleared from weeds (one of the principal 

 points in the culture), and, we may add, drained, a 

 number of flaves, ranged in a line, march acrofs, making 

 little trenches of the width of their hoes, and two or three 

 inches deep, about a foot diftance from one another every 

 way : then, retarning, they drop fome feeds in each trench, 

 and afterwards cover them with the earth taken o>it. The 

 foil, it is obferved by others, fhould be free and rich, and 

 the chmate warm : and the feafon of fowing fliould be rainy ; 

 as the earth muft either already have imbibed water, or rain 

 muft fpeedily follow the fowing ; otherwife the feed becomes 

 heated, corrupts, and is loft, after all the labour it has oc- 

 cafioned. During the procefs of vegetation the ground muft 

 be carefully weeded, in order to prevent any mixture of herbs, 

 which would injure the indigo in its manufafturc. In moift 

 weather, the plant comes up in three or four days ; and in 

 about two or three months after, it is fit for cutting : if fuf- 

 fered to fland till it runs into flower, the leaves become too 

 dry and hard, and the indigo obtained from them proves lefs 

 in quantity, and lefs beautiful : the due point of maturity is 

 known, by the leaves beginning to grow lefs fupple, or 

 more brittle. In rainy fealbns, the cutting may be repeated 

 every fix weeks : cutting in dry weather kills the plant, 

 which, if that is avoided, continues to afford frelh crops for 

 two years. 



A large quantity of the herb is put into a vat or ciftern of 

 ftrong mafon work, with fo much water as is fufficient to 

 cover it ; and fome wood laid above to prevent its rifing up. 

 The matter begins to ferment, fooner or later, according to 

 the warmth of the weather, and the maturity of the plant, 

 fometimes in fix or eight hours, and fometimes not in lefs than 

 twenty. The liquor grows hot, throws up a plentiful froth, 

 thickens by degrees, and acquires a blue colour, inclining 

 to violet. In proportion as the caloric increafes, azote is 

 difengaged, the herbaceous mucilage feparates, the vegeta- 

 ble is difcompofed, and the mixture abforbs oxygen. The 

 fermenting fluid pafles from a green to a violet tinge, and this 

 by degrees changes to a blue colour. The great art of the 

 manuwfturer is to check the fermentation at a proper degree. 

 If the fermentation is too feeble or too brief, the plant re- 

 mains impregnated with much effential fait, which diminifhes 

 the quantity of mdigo. If it be too long, the tender ex- 

 tremities of the plant undergo a putrefaftion which deftroys 

 the colour. Some years ago, the following criterion was 

 publifhed at St. Domingo, for afcertaining invariably the cor- 

 rect fermentation of the indigo. It is only requifite to write 

 on white paper with the matter to be examined. If this ink 

 be of very higli colour, it is a proof that the fermentation 

 is not yet at its true point. The experiment is repeated 

 every quarter of an hour, till it is perceived that tlie liquid 

 has loft its colour. This was pronounced an infalhble index 

 to Ihew the true point of fermentation. Others, however, 



judge of the proper ftage of fermentation by means of a 

 filver cup, into which they throw the liqrid, fliaking it till 

 grains are formed ; by their quality, and that of the fluid, 

 they judge of the fermentation. When the feculent parti. 

 cles begin to precipitate to the bottom of the cup, it is then 

 judged, that the herbs have attained the true degree of 

 maceration for obtaining indigo. It has been obferved, 

 however, that this procedure often led into error ; and, there- 

 fore, five or fix minutes after the liquid has been put into the 

 cup, it was perceived to form round its fides a cordon of 

 feculse, or fediment, at firft of a green colour, and then 

 blue. When the maceration is not at the requifite point, this 

 cordon, or girdle, detaches itfelf with difficulty from the 

 fides of the cup, but finally precipitates, and concentres at 

 the bottom, always towards the centre, and the water 

 above it becomes limpid, though of a yellowifli tinge. When 

 thefe figns are perceived, they indicate infallibly the fuccefs 

 of the firft operation. At this time, without touching the 

 herb, the liquor impregnated with its tinfture is let out, by 

 cocks in the bottom, into another vat placed for that pur- 

 pofe, fo as to be commanded by the firft. The firft vat is 

 called the " fleeper ;" the fecond and third are called the 

 " beaters." 



In the fecond vat, the liquor is ftrongly and inceffantly 

 beat and agitated, with a kind of buckets fixed to poles, 

 till the colouring matter is united into a body. A good dea\ 

 of nicety is requifite in hitting this point ; if the beating is 

 ceafed too foon, a part of the tinging matter remains dif- 

 folved in the liquor ; if continued a little too long, a part of 

 that which had feparated is diflblved afrefli. The exaCl 

 time for difcontinuing the procefs is determined by taking 

 up fome of the liquor occafionally in a httle cup, and ob- 

 ferving whether the blue fecula is difpofed to feparate and 

 fubfide. 



The facility with which the grain precipitates to the 

 bottom of the beater, is an unequivocal fign that the beating 

 has arrived at the correft point. 



The whole being now fuffered to reft till the blue matter 

 has fettled, the clear water is let off", by cocks in the fides at 

 different heights ; and the blue part difcharged by a cock in 

 the bottom, into another vat. Here it is iuffered to fettle 

 for fome time longer, then farther drained in cloth-bags, or 

 facks, and expofed in fliallow wooden boxes to the air, 

 without expofing it to the fun, and carefully keeping it from 

 the rain, till thoroughly dry. 



Before it is perfedlly dry, it is cut in fmall pieces of an 

 inch fquare, which detach themfelves readily from the box, 

 when the indigo is entirely dry. Yet, however well drained 

 and dried the indigo may be, it always experiences, in the firft 

 months of its fabrication, a diminution fufficiently evident to 

 warrant a haftening of the fale. It is cuftomary to pack the 

 indigo in barrels, and thus to circulate it in commerce. In- 

 digo is packed in facks of coarfe linen, and the fack is co- 

 vered with an ox's hide, fo hermetically fewed, that nothing 

 can penetrate it. Thefe packets are called " ceroons." 

 They are much preferable to barrels, as they are more fohd 

 and more convenient for tranfportation. Two " ceroons" 

 make the load of one animal. 



The author above-mentioned, from whom the greateft part 

 of the foregoing account is extracted, obferves farther, that 

 the goodntfs of the indigo depends greatly upon the age of 

 the plant ; that before it has grown fully ripe, the quantity 

 it yields is lefs, but the colour proportionably more beauti- 

 ful ; that probably the fecret of thofe whofe indigo has 

 been moft eftecmed, is no other than cutting the herb at the 

 time v\ hen it yields the finell colour ; that the fuperiority of 



fome 



