Most of the heathers make a yellow dye, but the one chiefly used is

the Ling, Calluna vulgaris. The tips are gathered just before

flowering. They are boiled in water for about half-an-hour. The wool,

previously mordanted with alum or chrome according to the shade of

yellow wanted, is put into the dye bath with the boiling liquor, which

has been strained. It is then covered up closely and left till the

morning. Or the wool can be boiled in the heather liquor till the

desired colour is obtained.