FORESTRY OF WEST AFRICA. 457 



making a refreshing drink, which is diluted with water 

 before use. Most of the Capillaire sold in London is 

 composed of syrup flavoured with orange flowers. — 

 'Dictionary of Economic Plants,' Smith, p. 91. 

 Distribution : Cape Verd Islands. 



Lichens. 



Ramalina scopulorum, Ach. — This lichen has been 

 used to yield a red dye. So high an opinion did 

 Lightfoot form of its tinctorial qualities, that he spoke 

 of it as a formidable rival to Roccellce. — 'Popular 

 History of British Lichens,' Lindsay, p. 142. 



Distribution : Cape Verd Islands. 



Orchella Weed, Dyer's Weed, Rock Moss {Roccella 

 tinctoria, D C). — Perennial thallophyte, two to six inches 

 high. Litmus, a colouring matter obtained from this 

 and other species of Roccella, is prepared chiefly if not 

 exclusively in Holland, and usually enters commerce 

 in the form of rectangular cakes, from a quarter of an 

 inch to an inch in length, which are light, friable, finely 

 granular, and of an indigo-blue or deep violet colour. 

 Litmus is used as a test for acids and alkalis, for which 

 purpose it is made officinal in the British Pharmaco- 

 pcEia and the Pharmacopoeia of India. Orchil, Archil 

 and Cudbear are colouring matters which are also 

 prepared from the same lichens as those from which 

 litmus is manufactured, and are used for staining and 



