Preparation of Lu-Kao, or " Green Dye^ 377 



Lu-Kao is grown chiefly in tlie northern provinces, exten- 

 sive plantations of this valuable plant existing in the country 

 around Foo-Chow and the environs of the city of Haening. 

 The valuable green dye matter is obtained, however, from 

 the rind, not of one but of two species of Rhaninus^ of which the 

 " yellow" grows on the flats, the ''white" on the high-groimds 

 in a wild state. The preparation of the substance, which does 

 not differ much in appearance from common indigo, is exceed- 

 ingly primitive. Both plants are boiled for a considerable 

 time in iron kettles, the yellow deposit or residuum being 

 suffered to remain undisturbed for several days. Transferred 

 thence into earthen vessels, a piece of cotton cloth is steeped 

 into it five or six times, after which the adherent dye is wrung 

 out, and exposed a second time to the process of boiling in 

 iron pans. The next step in the manipulation consists in per- 

 mitting the dye stuff, which now has much more consistence, 

 to be soaked up by some pieces of cotton, when it is once 

 more washed, sprinkled upon thin paper, and, lastly, exposed 

 for some time to the sun. 



The Chinese have as yet only used the dye for colouring 

 cloths of coarse texture ; all attempts hitherto to apply it to 

 silks, &c., have proved fruitless. But the great development of 

 chemical science in Europe justifies us in expecting that a 

 method will ere long be de\4sed for fixing this beautiful, dur- 

 able light green tint, which does not alter even in candle- 

 light, upon fabrics of fine smooth textm-e, and thus greatly 

 enhance its value in the industrial arts. The Lu-Kao has 



