YELLOW DYES. 397 



duce a yellow dye, which is chiefly used for the coarser 

 woollen cloths, and as an ingredient with other dyeing 

 drugs. Applied in combination with indigo, a very 

 good and durable green colour is obtained. This is 

 an adjective colour, but with alum as a mordant it 

 becomes a permanent dye. The decoction is of a 

 brownish yellow hue : on being diluted with water it 

 is changed to a brighter tinge ; by adding a solution 

 of pure potash it acquires a darker shade. The 

 addition of a small quantity of muriate of ammonia 

 converts the colour into a reddish brown ; which may 

 again be rendered of a golden tint by the addition of 

 pure water. Poerner observes, that alum and gyp- 

 sum, the latter forming the deeper shade, appear to 

 be best calculated for extracting a fine colour from, 

 this plant. 



In the neighbourhood of Rochdale in Lancashire, 

 and in some parts of Yorkshire, the clothiers make 

 use of common heath for their yellow and orange 

 dyes. This well-known plant abounds in many un- 

 cultivated spots. It is taken from the moors and 

 unenclosed land, and mowed down when in full bloom. 

 It is then spread out, and treated in the same manner 

 as grass for hay ; when dry it is laid up in barns or 

 ricks. In combination with a tin mordant, it is said 

 that this plant produces a more beautiful colour on 

 woollen cloths than either weld or quercitron. But, 

 though more bright and intense, it is not so per- 

 manent *. 



The branches or twigs of the Dyer's Broom' (Ge- 

 nista tinctoria) afford an adjective lemon-colour. 

 This plant was used by the Romans for dyeing, and 

 is described by more than one ancient writer. It is 

 still applied to the same purpose in some of the Gre- 

 * Parkes' Chemical Essays, 



2M 



