224 



POPULAR ECONOMIC BOTANY. 



Angola . 

 Madagascar 

 Mauritius 

 Canary 



Cape de Yerd 

 Azores 

 Madeira 



South American^ large and round 

 y, small and flat . 



Cape of Good Hope . 

 Barbary (Mogadore) 



Roccella fuciformis, 



R.fuciformis, 

 ? 



R, tinctoria, 

 R, tinctoria, 

 R, tinctoria, 

 R, tinctoria Sffuciformis, 

 R, tinctoria, 

 R,fuciformis, 

 R, hypomecha, 

 R, tinctoria, 

 R, tinctoria. 



Corsican and Sardinian 



The Angola and Lima sorts constitute the bulk of the 

 Orchella-weed imported ; it therefore consists principally of 

 R, tinctoria (Plate XIII. fig. 69). The colouring matter 

 of these lichens varies slightly; that of the Angola weed is 

 the best^ and consists of a peculiar vegetable acid called 

 erythric ; orsellic acid, of the variety aljjJia (there being 

 two sorts), constitutes that of the Lima weed. 



The article known in commerce under the names Archil 

 and Orchil is the colouring matter of Orchella-weed in 

 solution; it is used for dyeing purple and red. It does 

 not produce a fast colour, but so greatly improves other 



