LOUK-KA. The green dye of China, louk-ka, lo-kao, or king-lok, was first made known to Europe in 1845. Its price in China has continued steady at 24 dollars the catty. In China, the green cloths dyed by this material are called liou-sai, but are known to the trade as so-lo-pou, green colour cloth, when dyed by the bark ; nghiou-lo-se (green nymphma colour) and nghiou lo-pou (green nymphma cloth), that is, cloth dyed with the lo-kao of the colour of the leaves of the nymphma. Each piece of liou-sai is one foot or one foot one inch broad, and in 1848 cost from 50 to 53 cents. In addition to the lo kao, the French consul, M. Montigny, sent one green dye-stuff called pih-ehou-elle, ten catties of which cost 4920 sapeques; and another called tong-loh, green paint, said to be prepared from no-me, fifty catties of which cost 20,800 sapeques. Lo-kao or lou-kao, in Chinese signifies green glue or green lac, and all who sent samples of the green dye itself, call it lo-koa or lo-kiao. In Canton it is louk-ko ; in Foh-kien, liok-koa and lek-ko. The first considerable consignment of the green dye was received in Paris in 1853, since which date it has become an article of trade. At the Universal Exhibition held at Paris in 1855, samples of green dye were exposed, and Dr. Royle subsequently stated that there were three kinds of the green dye of China, or green indigo from China, from Burma, and from Assam. That from the valley of the Brahmaputra, in .Assam, is called roum, and is extracted from a species of Ruellia. This plant, or a nearly allied species, is cultivated with the same object in Pegu and Burma. It is altogether different from the bila-roum, the product of the Wrightia tinctoria, R. Brown. Others point to the R. comosa, Rork, and the Buter-ma ulmifolia, De C. MM. Edan and Remi in 1854 reported that they had procured a very fine green from the fruit of the lo-za, but were unsuccessful in regard to the bark. Mr. Fortune informed M. Edan- that without doubt the bark of ' the lo-za was employed to furnish the stuff with which to dye cloth green, and that the fruit was used in the preparation of green paint for paper. These points were repeated by N. Remi in 1855. All the experiments hitherto made with the bark and the leaves of the Rhamnus chlorophorus and R. utilis have not been decisive. M. Persoz had succeeded in extracting a yellow dye from tho bark of R. eblorophorus and the berries of the R. utilis, but he could not discover a trace of the green dye in the extracts prepared from the berries of both kinds, which were sent to him by the Agri-Horticultural Society of India. Nevertheless the united testimony of Fathers Helot and Aymeri, MM. Arnaudtizon, Edkins, Fortune, and Remi, is to tho effect that it is the bark of the branches, and perhaps also of the roots of the R. chlorophorus and R. utilis, but especially of the former, that gives to the green dye that brilliant colour which it amines under the influence of artificial light. The fruit, at least that of the R. chlorophorus, probably yields a green colouring matter analogous to the bladder green, and differing from the true green dye both in colour and properties. The Chinese declare that other species of the same genus have dyeing properties. The po-piu-lo-chou is the R. chloro phorus, De Caisne, and the hong- pi - to - chou the R. utilis, but until some European chemist shall have discovered traces of the green dye in some of the parts of the plants, the flowers, the berries, the seeds, the leaves, the bark, or the root, it cannot be asserted that the plants are really those the Chinese use to dye their cottons with or from which they prepare the lo-kao. Some European plants dye a green colour ; the blue-flowered Scabiosa is used for that purpose in Sweden ; the Melissa officinalis yields, under the action of spirits of wine, a permanent green dye, and the Mercurialis perennis yields a per manent blue-green. The green dyes from the Ruellia, Justicia tinctoria, Lour. ; Adenoatemma tinctorium, Cass. ; Sanseviera lmte-virens, Ham. ; Asclepias tingens, Roxb. ; Melissa officinalis, Linn., have not yet been examined. Various plants stated to yield a green dye colouring matter have been examined, but in vain, for the green dye of China. These arc the Arundo phragmitis, Linn. ; the artichoke, deadly night shade, wild chervil, ash tree, lucerne, Lyeopersi cum esculentum, Mill. ; Mercurialis perennis, Linn.; Ronabea arborea, Blanco ; the groundsel, and the common field clover. M. Michel obtained tolerable greens from the berries of R. catharticus, Linn., and R. alaternus, Linn., but not improving by artificial light. He found that cloth taken out of the bath with a light nankeen dye, and placed at night on the grass, had assumed towards morning, and long before it was exposed to the rays of the sun, a deep green colour. A damp
atmosphere and dew were found to increase the intensity of the tint. The lower side near the grass was scarcely at all coloured, and a cloth left all night in a dark room was found in the morning to be unchanged. M. Persoz found the fruit of a buckthorn to yield a pretty lilac on silk. The green fruit of the R. infectorius, Linn. (Avignon berries ; R. saxatilis, Linn.), Persian berries of R. alaternus, Linn., and R. amygda linus, Defy:, afford a yellow colour. The fruit of the R. frangula, Linn., gathered in July and August before they are ripe, yield, according to Dainbourney and Leuchs, a fast and brilliant yellow ; according to Buchoz, a green ; and when they are ripe, in September and October, they dye a purplish-blue without any mordant, and green, violet and blue violet or blue, according to the nature of the mordant employed. Dam bourney obtained on wool, from the juice of the ripe berries fermented, very fine and fast greens, varying from an apple to a dark green. Tho colouring matter of the berries of the R. infec torius is yellow before they are ripe, and dark purple-red so soon as they have attained maturity. Buchoz notices similar peculiarity in the fruit of the R. catharticus ; before ripening it yields a saffron red; after maturity, a green, known as a bladder green, and still later a scarlet. According to Waldstein and Kitaible, the green berries of R. tinctorius have dyeing properties similar to those of the fruit of R. catharticus, but more esteemed by the dyers. The inner bark of R. infectorius dyes yellow, when fresh ; brown-red, when dry. The dry bark of the R. frangula yields a brown or dark red, and the fresh a yellow dye ; and the root as well as the bark and seeds of R. catharticus, a yellow and volatile colour, named Rhamno-xanthine, which is dis solved by the alkalies, and converted into a magnificent purple. The bark of R. catharticus and R. alaternus dye yellow ; the wood of the latter species dyes dark-blue, and the root of R. infectorius a brown. The leaves of R. alaternus yield a yellow colour, and those of R. frangula a greenish-yellow. A mixture of the cuttings of R. alaternus, which yield a dark-blue, with the fresh bark of the same buckthorn and of R. catharticus, R. frangula, and R. infectorius, which contain a yellow colouring matter, ought to produce a green. The European Rhamni contain a volatile principle, and nearly the same changes take place in the colouring matter of the several species, from red to violet, to blue, to green, and to yellow. The lo-kao possesses similar qualities ; and it is possible that the green dye, so remarkable when exposed to light, is a compound of blue and yellow having separately the same property, and united in the bark of R. ehlorophorus. But M. Rondot suspects that the supplementary yellow requisite to produce the green of lo-kao is not obtained from one of the Rhamni, but from the hoang-chi, the fruit of Gardenia, or the hoai-hoa, the flower-bud of the Styphnolobium Japonicum. In 1855, when Mr. Robert Fortune was sent to China by the E. I. Company to procure tea plants for the nurseries in the Himalaya, he was par ticularly directed to give his attention to plants of that country stated to produce a green dye. Accordingly be sent seeds and samples to the Agri-Horticultural Society of Bengal, from which numerous plants were forwarded to all parts of India. It seems established that the trees from which the green dye is prepared are two species of Rhamni, one wild, called by the Chinese white skin, and which grows in abundance in the vicinity of Kiahing and Ningpo. The other is called yellow skin by the Chinese, is cultivated at Tsoh-kaou-pang, where some thirty men are em ployed in the preparation of the dye-stuff. The flowers, leaves, roots, bark, and fruit have all been indicated as the part of the plant from which the lo-kao was prepared. Mr. Fortune sent to India and to England plants of both the cultivated and wild species. The wild species is a shrub, and is called hom-bi-lo-za from the circumstance that when its bark is boiled in water a white scum is formed, which subsequently passes to rose-hom-bi, meaning red scum bark. The pe-pi-lo-chou, or R. chlorophorus, is culti vated between lat. 25° and 36° N., but more especially about lat. 30° and 31° N. The hong pi-lo-chou, or R. chlorophorus, is mentioned as high as lat. 39° N., and down to lat. 30° N. This seems the hardier buckthorn, and capable of withstanding the severe frosts of Che-li, but it is evident that both species exist in abundance in the northern parts of the province of Chekiang, over a space of 45 square miles. Report on the Green Dye of China.