86 



POPULAR HISTORY OF LICHENS* 



that which covered thee/' and the celebrated "purple of 

 Amorgos/' were orchill. These dyes, which we may hence- 

 forth, for convenience' sake, denominate Orchill, — the name 

 by which their chief form has been longest familiar in com- 

 merce, — are now largely employed, chiefly in combination 

 with other colouring matters, in dyeing or staining with 

 various shades of red, purple, or blue, woollen, silk, and 

 cotton fabrics, leather, wood, marble, feathers, and paper ; 

 in the making of size-paint for walls, and of the pigments 

 termed lakes. The rationale of their manufacture is the 

 making of the cleansed and powdered Lichen into a pulp 

 with w r ater ; the addition of an ammoniacal liquid, chiefly 

 in the form of gas-liquor ; and the maceration of the mass 

 in a moderately w 7 arm locality, for periods varying from 

 several clays to several weeks. A process of fermentation 

 takes place, and by the end of this period the mass has 

 assumed a beautiful purple colour, and retains a peculiar 

 ammoniacal aroma. This process the student may imitate 

 for himself on the small scale, and may thus be enabled to 

 test the colorific valae of common native species. He has 

 merely to macerate, in a small vial or other convenient 

 vessel containing a mixture of hartshorn (liquid ammonia) 

 and water, sufficiently strong to be disagreeably pungent, 



