QUERCITRON BARK. 383 



few hours absorb the moisture, leaving the colour 

 dry and fit for use. The liquor poured off from the 

 colour is, with the addition of water, used again ; the 

 old plants are likewise boiled a second time previously 

 to the addition of fresh ones, so that no colouring 

 matter is lost. Iron vessels must not on any account 

 be used in this process, for the gallic acid, which is 

 extremely abundant in weld, would instantly dissolve 

 the iron, and " the smallest particle of that metal is 

 fatal to the delicacy of the weld yellow*." 



Although cultivated in the parts of England we 

 have mentioned, a sufficient quantity of weld is not 

 produced for our home consumption, and we con- 

 sequently draw it from foreign markets. Some 

 writers have recommended the extension of its culti- 

 vation, and argued that it would thrive and render a 

 handsome profit on some of our poorest lands, which 

 for any other purpose are not worth ten shillings per 

 acre. Marshal, in his ' Rural Economy of Norfolk,' 

 says, it prefers a good soil, but others assert that it 

 becomes stalky in a rich soil ; and the author of * the 

 Journal of a Naturalist ' supports the opinion that 

 very poor land is the best for the purpose. " With 

 us," he says, " it grows luxuriantly (i. e. in its wild 

 state), three or four feet high, on a thin, stony, un- 

 dressed soil, apparently the very statioji it prefers." 



QUERCITRON BARK. 



Quercitron bark, though long in common use in 

 those countries where it is indigenous, was not intro- 

 duced into England until the year 1785, when Dr. 

 Bancroft first applied it to the purpose of dyeing, 

 and obtained a patent for its exclusive use. The 

 Quercus tinctoria, which produces this dyeing sub- 

 stance, has already been described in the accoum} 

 * Phil, Mag, vol. xiii, 



