DYES. 

 ORCHELLA WEEDS. 



Rocella tinctoria, De C. Cape de Verde, Canary, Corsican, Sardinian, 

 Azores, Mogadore, a portion of Madeira, and perhaps a portion of 

 American Orchella. 



Rocella fuciformis, De C. Angola, Madagascar, a portion of Madeira, 

 and a portion of American Orchella. 



There is also Mauritius Orchil. 



ROCK MOSSES. 



Lecanora tart area, Ach. Tartareous Cudbear. 

 Gyrophora pustulata, Ach. 

 Parmelia perlata, Ach. 



And besides these we have Corsican, Sardinian, and Norwegian Rock 

 Mosses. 



Orchil is a liquid pulp prepared by the mutual action of tinctorial 

 lichens, air, and an ammoniacal liquor. Cudbear is similarly prepared, and 

 is in the form of paste as well as liquid. Litmus occurs in small, rectan- 

 gular, blue cakes, imported from Holland. It is often called Turnsole, 

 because it was once suspected to have been prepared from French rags 

 (tournesol en drapeau) dyed in the blue juice of Croton tinctorium, Linn. 

 (Crozophora tinctoria, Juss.) of South Europe, a plant allied to Crozophora 

 plicata, Juss. (Croton tinctorium, Lam.) of Western India. Turnsole is 

 the common name of plants of the genus HeUotropium, plants described 

 by Theophrastus, Dioscorides, and Pliny, under that name. But Sprengel 

 identifies, Croton tinctorium with Dioscorides' rfkiorpoinov TO p.iKpbv, and 

 Litmus is called Succus Heliotropii in old books. Rocella tinctoria is 

 probably the (j)v<os daXdo-oriov, (f)v6fj.evov ev Kpf)Tr), of Dioscorides ; and used 

 there in olden times for dyeing purple cloths. 



Many astringent barks used for dyeing, have been omitted from the 

 above list, as they must be detailed under Tans. 



306 



