What was done in Germany in regard to Thuringia, was done in France in regard to Languedoc. In consequence of an urgent representation by the states of that province, the use of indigo was forbidden in 1598; and this prohibition was afterwards repeated several times. But in the well-known edict of 1669, in which Colbert separated the fine from the common dyers, it was stated that indigo should be used without woad; and in 1737 dyers were left at liberty to use indigo alone, or to employ a mixture of indigo and woad[657]. In England, where, I believe, woad was not at that time cultivated, the first mention of indigo in the laws occurs in the year 1581, under the reign of Elizabeth, not, however, on account of a blue but a black dye. No woollen articles were to be dyed black with the gall-nut, madder or other materials, till they had received the first ground, or been rendered blue by woad, or woad and indigo together[658]. In like manner it was long believed that no durable black could be produced unless the article were first dyed in a blue pan. Hats also were not considered to be properly dyed unless traces of a blue tint could be discovered on the place where they were cut[659]. At present our dyers can communicate a durable black without a blue ground, as well as dye a fixed blue without woad; and in every part of Europe foreign indigo will continue to be the most common material for dyeing, till its high price render it necessary to obtain a similar pigment from indigenous plants[660]. [The dye-stuff of indigo is obtained from the plant by allowing it to ferment with water; during this process it subsides in the form of a blue deposit, which is collected and dried. As it occurs in commerce, it contains several impurities, such as lime, silica, alumina, and oxide of iron, in addition to the colouring matters, which are three in number, a brown, red and blue; as also some glutinous matter.