220 Miscellaneous Inicllujence. 



On commencing,' tlic operation, 50 or 55 lb. of pulverised madder 

 arc to be put into the first vcvsscl, water is to be added, and stirred 

 into the mass until it stands 1 J inch above the madder. The whole 

 is then to be letl until fermentation ymes on and has formed a 

 doat of madder at the surface ; this usually takes place in 36 hours, 

 and at latest in 48 hours, according- to the temperature. The mass 

 should now be transferred into the second vessel, which is then to 

 be filled with water, and being left for two hours, the madder will 

 fall to the bottom. The upper cock is then to be opened, after that 

 the second, and then the third ; and the water which runs from the 

 two latter is to be put into the third vessel, that the rest of the madder 

 may separate from it. The madder in the second vessel is then to 

 be washed a second, third, or fourth time until the washing water is 

 colourless. Thus purified, the madder may be used in the processes 

 of dyeing, according to the known methods ; but it is important in 

 summer that it should be used immediately, that a new (the vinous) 

 fermentation may be avoided. The madder deposited in the third 

 vessel, when washed and deposited, may be used like the rest. The 

 liquid first separated after the fermentation may be used in the 

 preparation of hot indigo baths, &c. instead of madder. — Bull. 

 Univ. P. vii. 352. 



38. On Indigo and T?idigogene, by M. Lieheg. — \^ part of pure 

 indigo, 2 parts of proto-sulphate of iron, 2\ parts of hydrate of 

 lime, and from 50 to 60 parts of water, were digested together for 

 24 hours in a close vessel, which had previously been filled with 

 hydrogen. The clear liquor over the sulphate of lime and oxide of 

 iron, had a yellowish red colour, and was separated by a syphon 

 filled with hydrogen, and mixed with diluted muriatic acid, contain- 

 ing some sulphite of ammonia dissolved ; a dense white precipi- 

 tate was formed, becoming blue in the air. This was gathered in a 

 filter without contact of air, and washed with boiled water contain- 

 ing sulphite of ammonia in solution, and dried at 212°, in close 

 vessels, through which a current of hydrogen was continually passed. 

 The upper surface of the mass became of a blue colour, but the 

 lower remained of a dull white. 



This white substance was called Indigogene. It did not change 

 colour in dry air, but under water became of a deep blue, which 

 by drying, assumed a coppery appearance. The blue substance vola- 

 tilized by heat without leaving any residue, forming purple vapours, 

 which condensed, when cold, into crystals differing in nothing from 

 sublimed indigo. Indigogene dissolves in alkalis without neutral- 

 izing them : it is also soluble in alcohol, but insoluble in water 

 or acids. 



A given quantity of this indigogene was acted upon by ammonia, 

 and the weight of the undissolved blue portion ascertained, it 

 appeared that the weight of the pure portion dissolved was 0.404 

 grammes (6.224 grains.) The solution was put into an inverted 



