INDI30FERA TINCTORIA. 



47 



tinned for from 1^ to 3 hours, and may be stopped so soon as a little of the liquid placed 

 in a saucer readily throws down a dark blue precipitate remaining itself of a clear sherry 

 tint. It is now allowed to stand until the fecula has settled, \vhich takes place in about 

 a couple of hours, and is sometimes assisted by pouring some cold water into the vat. The 

 surface liquid is then carefully drained out of the vat by holes which have been made in 

 its walls for the purpose, and the dark blue sediment which remains is conducted along 

 a masonry channel into the boiling vat, where it is kept over a moderate fire for about 

 5 hours, and is then repeatedly passed through a cloth strainer, which effects the sep- 

 aration of the dye particles from the water. The dye matter is then allowed to lie on 

 the strainer until partially dry, when it is carried to the press and placed in boxes with 

 moveable sides, in which it is subjected to gradually increasing pressure for about 12 

 hours, at the end of which time it will have taken the form of firm slabs 3| inches 

 square, which are then cut into cakes of the same length, and are ready for being stamped 

 and finally dried. The whole process from plant to cake occupies therefore about 4S 

 hours, and at a large factory one follows the other in constant repetition for some 45 days 

 in August and September. Good indigo cake should contain about 50 to CO per cent, 

 of indigotine ; it should be bright, of a dark blue colour, with a coppery gloss, breaking 

 with an evenly coloured fracture ; it should not part with its colour by light friction. 



The outturn of indigo from plant varies with the season from 2| to 4 per thousand, 

 being highest in years of moderate or light, and lowest in years of heavy rainfall. 



The prices which N.-W. Provinces indigo commands in the Calcutta market vary 

 from year to year between very wide limits. In very few cases does the price come 

 within 20 per cent, of that obtained by Tirhoot cake, and of N.-W. Provinces produce 

 that of the Benares Division is considered the best, facts which indicate the greater suit- 

 ability of the climate of the Eastern Districts for indigo manufacture. The average 

 price of the N.-W. Provinces indigo is further kept down by the very large proportion 

 formed by native made cake, which sells at a much lower price than that made under 

 European supervision. Almost the whole of the cake exported from Tirhoot is returned 

 as of European manufacture, which is the case with only 13" 5 per cent, of the N.-W. 

 Provinces indigo. The average prices per factory maund of 74 lbs. 10 oz. obtained by 

 N.-W. Provinces and Tirhoot indigo during the last three years are given below : — 





1879. 



1880. 



1881. 



N.-W. Provinces — 



lis. 



ES. 



ES. 



Doab, 



... 227 



175 



200 



Benares Division, 



... 261 



210 



240 



Tirhoot, 



... 287 



245 



2G0 



The cost of manufacture (including price of plant) is much higher for European 

 than for Native factories, being about Es. 125 per maund in the former, and Es. 85 in 

 the latter case. 



Thus far of indigo manufactured for export, A large proportion, however, of the 

 indigo intended for local consumption is manufactured much more roughly, all boiling 

 being dispensed with, the cake being known in this case as ffddh, — the ffaud of the 

 Calcutta market. The factory in this case merely consists of a few masonry vats 

 sunk in the ground. The process is substantially the same as that described above, ex- 

 cept that in the steeping vat fermentation is artificially excited by the addition of gum 



