270 ARCHELL. ORCHALL. 
when dried, are pulverized, and sold to dyers by the 
name of cudbear, which is a corruption of Cuthbert, 
the name of its inventor. In conjunction with alum, 
the powder of the tartareous lichen is used in dyeing 
scarlet, and also for striking a purple dye ; but the 
colour produced by it is not very permanent. 
285. ARCHELL, or PURPLE ROCK LICHEN 
(Lichen omphalodes), is a vegetable production, of somewhat 
crustaceous consistence, and leaf-like form ; the segments with 
many lobes, and of dark purplish brown colour, with dull purple 
saucers. 
This kind of lichen grows upon rocks on the high 
stony moors of several parts of England, Wales, and 
Scotland. When properly prepared, it imparts to 
woollen cloth a reddish brown colour, or a dull but 
durable crimson. If wool that has been dyed with it 
be dipped into a blue vat, it will acquire a beautiful 
purple tinge. It is sometimes used as a styptic ; and 
was formerly applied as a remedy in inflammatory 
fevers and other complaints ; but, in the latter respect, 
it is now entirely neglected. 
286. PRCHALL, or DYERS LICHEN (Lichen ro- 
cella), is a somewhat crustaccous and shrub-like vegetable pro- 
duction^ of nearly cylindrical form, solid, without leaves, but 
little branched, and with blackish brown alternate tubercles. 
In the Canary and Cape de Verd Islands, as well as 
in the Grecian Archipelago, orchall is found in great 
abundance. It likewise grows in Guernsey and in 
some parts of England, and is employed by dyers 
chiefly for giving a bloom to other colours. This is 
effected by passing the dyed cloth or silk through hot 
water slightly impregnated with it ; but the bloom thus 
communicated soon decays after it has been exposed to 
the air. When prepared in a peculiar manner, orchall 
yields a rich purple tincture, fugitive indeed, but 
very beautiful. Mixed with a solution of tin it is 
said to dye a permanent scarlet. Orchall is the 
