INDIGO -891 



Ebulus, Sodbiosa suocisa, and Vaecinium Myrtillus. According to the investigations of 

 Giobert and others, however, none of these plants afford any indigo-blue, though several 

 of them, such as the Mercurialis pcrennis, contain a blue colouring matter of a peculiar 

 nature. The indigo-bearing plants growing in tropical countries furnish far more 

 indigo-blue than the Isatis tinctoria. Such are the various species of Indigofera, natives 

 of the East and West Indies, the Nerium tinctorium and Calanthe veratrifolia of Hindo- 

 Btan, the Asdepias tinotoria and Marsdenia tinctoria of Sumatra, the Polygonum tincto- 

 rium, the Isatis indiffotica, the Justicia tinctoria, and the Bletia Tanker villece, of China, 

 and the Amorphafrutioosa of Carolina. Most of these plants belong to the natural order 

 Leguminosa. The others belong respectively to the orders Crucifera, Apocynece, 

 Asdcpiadece, Polygonea, Acanthacea, and Orchidece. Indigo-blue has sometimes 

 been observed to form in the milk of cows, especially such as have been fed ex- 

 clusively on saintfoin. It has also been found by Prout, Hassall, and others in 

 the urine of individuals suffering from various diseases ; and Schunck has shown 

 that the urine of men and animals, even when in a perfectly healthy state, may be 

 made to yield indigo-blue in small quantities by treatment with strong acids. Hence 

 it appears that this colouring matter may be obtained from a variety of sources, though 

 it is nowhere found in great abundance. 



The use of woad for the purpose of dyeing blue seems to have been known in 

 Europe from the earliest times. We are told by Caesar that the Britons stained their 

 bodies blue with woad, in order to give themselves a more formidable appearance in 

 battle ; and Pliny informs us that their women, before entering on certain sacred rites, 

 which were performed in a state of nudity, employed the same means of colouring their 

 bodies, whereby they acquired the appearance of negroes. During the middle ages 

 the cultivation of woad was carried on very extensively in several countries of Europe, 

 especially in Thuringia in Germany, in the province of Languedoc in France, and in 

 the neighbourhood of Bieti in Italy. The leaves of the plant were ground into a 

 pulp, and then submitted to a long process of fermentation, by which means they 

 were converted into a mass of a dark colour which was moulded into balls for the 

 use of the dyer. (See WOAD.) No attempt to extract the blue colouring matter 

 from the plant seems, however, to have been made before the commencement of the 

 present century. 



Whether indigo in its present form was known to the ancients has been doubted. 

 Pliny and Dioscorides refer to a pigment called Indicum, which seems to have been of 

 a blue colour, though there is little doubt that the article to which the name Indicum 

 nigrum was applied was identical with our Indian ink. Of indicum Pliny says that 

 it comes from India and is obtained from the slime adhering to reeds ; that it is black 

 when rubbed, but of a fine mixture of purple and blue when dissolved ; and that 

 there is another kind which is found swimming on the dye-vessels where purple is 

 dyed, this being the scum of the purple-fish. He adds that those who adulterate 

 indicum dye pigeons' dung or chalk with woad, but that the genuine substance may 

 be known by heating it, when it gives a beautiful purple vapour and emits a smell 

 like that of the sea, and for this reason it has been supposed to be obtained from the 

 rocks. It can hardly be doubted that in this passage indigo is referred to, and that 

 the second kind of indicum mentioned by Pliny consisted probably of the scum of 

 indigo-blue found floating on the surface of the liquor in which the dyeing was per- 

 formed. It seems, however, that at that time the colouring matter was not so com- 

 pletely separated from the other vegetable matters of the plant as at the present 

 day, since pigeons' dung coloured with woad would bear very little resemblance to 

 our present indigo, but would be a fair imitation of the preparation usually made 

 from woad. It is probable, therefore, that at that period the process of manufacturing 

 indigo was a very rude one, and consisted merely in the separation of a portion of 

 the vegetable from the remainder. Even at the present day the natives of some 

 countries, where the arts have not attained any high degree of development, produce 

 an article from indigo-bearing plants which serves the purpose of dyeing blue, though 

 not much resembling indigo in appearance. In Sumatra, for instance, as Marsden 

 informs us, the natives do not manufacture indigo into a solid substance, but leave the 

 stalks and branches for some days in water to soak and macerate, then boil it, and 

 work with their hands some chunam (quicklime) among it, with leaves of the pacoo 

 saba (a species of fern) for fixing the colour, after which they drain it off and use it 

 in the liquid state. On the west coast of Africa the leaves of the indigo-plant are 

 moulded into balls, which are then dried in the sun and stored up until they are 

 wanted. These balls, which have a slight blue tint, may be preserved a long time, 

 and be transported to great distances. When they are to be used for dyeing they are 

 broken and reduced to a fine powder. This powder is then mixed with water to which 

 the ashes of a certain plant are added, and the liquid is boiled in large earthenware 



