RUELLIA INDIGOTICA. Fortune. The Room of Assam and Tien-ching of China. In one part of the Che-kiaxig province of China, and also amongst the Fung IIwa mountains to the west ward of Ningpo, large quantities of a blue dye are produced, which is, in fact, the indigo of that part of the country. Fortune (Wanderings, 1846) gives an account of a valuable kind of indigo, made frotn a species of woad (Isatis indigotica), which is cultivated extensively in the level country a few miles to the westward of Shanghai. The kind in Che-kiang is equally valuable, if not more so. It is made from a species of Ruellia, which until it gets a better name may be called Ruellia indigotica. The same plant apparently bas been discovered in the Assam country in India, where it is also cultivated for the blue dye, it affords ; alongside of the Chinese kind, they bear a most striking resemblance. This Ruellia seems to be easily cultivated, it grows most luxuriantly, and is no doubt very productive. In the province of Che kiang it is planted, in the highland valleys, in the end of April or beginning of May, after the spring frosts are over, and is cleared from the ground in October before those of autumn make their appearance. During this period it attains a. height of a foot or a foot and a half, becomes very bushy, and is densely covered with large green leaves. When the stems are cut down for the manufacture of indigo, a sufficient quantity have their leaves stripped off, and are afterwards taken into a house or shed to be pro perly prepared. The leaves thus stripped from the cuttings are thrown into the tanks with the stems and leaves, so that nothing is saved except what is actually required for the purposes of propagation. The stems are DOW tied up firmly in large bundles, each containing upwards of 100, and the ends of each bundle are cut across, so as to leave them perfectly neat and even both at top and bottom. These bundles are each about a foot long, and, of course, nearly round. They are carried to a dry shed or outhouse, where they are packed closely and firmly together, and banked round with very dry loam. A portion 'Of,the dry soil is also shaken in between the 13uddles, and this being done the operation is complete. Should the winter prove unusually severeln Jitge,.,dry straw or litter is thrown over the surface of the cuttings, but nothing else is required. Dining the winter rnonths, the cuttings remain green and plump ; and although no leaves are produced, a few roots are generally found formed, or in the act of forming, when the winter has passed and the season for planting has come round. In this state they are taken to the fields and planted. The weather during the planting season is gener ally showery, as this happens about the change of the monsoon, when the air is charged with moist ure. A few days of this warm showery weather is sufficient to establish the new crop, which now goes on growing with luxuriance, and requires little attention during the summer ; indeed none, except keeping the land free from weeds. In the district where this dye plant is grown, there are numerous pits or tanks on the edges of the fields. These are usually circular in form ; one measured eleven feet in diameter and two feet in depth. About 400 catties of stems and leaves are thrown into a tank of this size, which is then filled to the brim with clear water. In five days the plants are partially decomposed, and the water has become lightish green in colour. At this period
the whole of the sterns and leaves are removed from the tank with a fiat-headed broom made of bamboo twigs, and an admirable instrument for the purpose. When every particle has been re moved, the workmen employed give the water a circular and rapid motion with the brooms just noticed, which is continued for some time. During this part of the operation another man has em ployed himself in mixing about thirty eatties of lime with water, which has been taken out of the tank for the purpose. This is now thrown into the tank, and the rapid circular motion of the water iB kept up for a few minutes longer. When the lime and water have been well mixed in this way, the circular motion is allowed to cease. Four men now station themselves round the tank, and commence beating the water with bamboo rakes made for this purpose. The beating process is a very gentle one ; as it goes on the water gradually changes from a greenish hue to a dingy yellow, while the froth becomes of a beauti ful bright blue. During the process the head workman takes a pailful of the liquid out of the tank, and beats rapidly with his hand. Under this operation it changes colour at once, and its value is judged of by the bue it presents. The beating process generally lasts for about half an hour. At the end of this time the whole of the surface of the tank is covered with a thick coating of froth of the most brilliant colours, in which blue pre dominates, particularly near the edges. At this stage, it being desirable to incorporate the froth with the liquid below it, there is made a most beauti ful chemical operation. A very small portion of cabbage oil, only a few drops, is thrown on the surface of the froth, the workmen then stir and beat it gently with their flat brooms for a second or two, and the whole disappears as if by some enchanter's wand. So small a quantity of oil is necessary for this purpose, that even when the cup has been emptied, and has only the oil that is necessarily adhering to its edges, it is thrown into another tank, and produces the desired effect. The liquid, which is now darker in colour,' is allowed to stand quiet for some hours, until the colouring matter has sunk to the lower stratum, when about two-thirds of the surface is drawn off and thrown away. The remaining third part is then drawn into a small square •tank on a lower level, which is thatched over with straw, and here it remains for three or four days. By this time the colouring matter has separated itself from the water, which is now entirely drained off, the dye occupying three or four inches of the bottom, in the form of a thick paste, and of a beautiful blue colour. In this state it is packed in baskets, and ex posed for sale in all the country towns in that part of China, at rates varying from 50 to 100 cash a catty, say from 2d. to 4d. per lb. Sotne is sold as low tts 30 cash, but this is very inferior ; the greater part produced is sold at from 60 to 80 cash a catty, and it must be of a very superior quality if 100 cash is paid. Liko the Shanghai indigo made from Isatis indigotica, it is called Tien-ching by Chinese. During the season of its preparation every mountain stream is coloured and polluted with the refuse liquid drawn off from the tanks, and the stench which fills the air is almost unen durable.—Fortune's Residence, p. 189; Fortune's lranderings.