28 SCIENTIFIC AND APPLIED PHARMACOGNOSY 



stearic acid; several organic acids, as oxalic, tartaric and fumaric 

 (lichenic); about 15 per cent of cellulose; about 3.6 per cent of an 

 uncrystallizable sugar; 3.7 per cent of gum; a principle resembling 

 chlorophyll, thallochlor, which is unaffected by hydrochloric acid; 

 and yields less than 2 per cent of ash. 



The bitter principle in Cetraria may be removed by treating the 

 drug with a 1 per cent solution of potassium carbonate at about 60 

 C. for several hours. 



Iceland moss jelly (Gelatina lichenis islandica) is official in the 

 German Pharmacopoeia, and is prepared by making a decoction 

 of 3 parts of washed cetraria and 100 parts of water, adding 3 parts 

 of sugar and evaporating the whole to 10 parts. Dried, saccharated 

 Iceland moss, which is official in the French Codex, is prepared some- 

 what similarly to the Iceland moss jelly, but the product is evaporated 

 to dryness and then powdered. 



Allied Plants. Usnea barbata and Cornicularia aculeata contain 

 a principle resembling lichenin, which on hydrolysis yields glucose. 

 Evernia prunastri contains a carbohydrate evernin, which resembles 

 lichenin but is dextrogyrate. The following lichens do not contain 

 lichenin, but yield carbohydrates which on hydrolysis give little 

 or no glucose: Cladonia rangiferina contains 30 per cent of mannose; 

 Stereocaulon pascale and Peltigeria aphthosa yield on hydrolysis 

 dextromannose and dextrogalactose. 



Literature. For illustrations consult Kraemer's Applied and 

 Economic Botany; the Microchemistry, Tunmann, Apoth. Zeit., 

 1913, p. 892. 



ORCHIL. Archil. A coloring substance obtained by the fermen- 

 tation of Roccella tinctoria, R. fuciformis and other lichens. R. 

 tinctoria is abundant in the Levant, the Canary Islands and the Cape 

 Verde Islands while R. fuciformis is quite common on the islands of 

 the Indian Ocean adjoining the African coast. The lichens grow on 

 the rocks near the sea and after being cleaned they are ground into a 

 pulp with water. They are then treated with some ammoniacal liquid, 

 at the present time dilute solutions of ammonia being used, and 

 allowed to ferment for nearly a week. As a result of fermentation the 

 mother principle, which is colorless, changes to orcinol, which is also 

 colorless, and is finally converted into orcein, which produces scarlet 

 solutions with either water or alcohol. Orcein is readily soluble in 

 alcohol, somewhat soluble in water, and insoluble in ether. It forms 

 beautiful lavender-colored solutions with the alkalies. 



CUDBEAR. Persio or Red Indigo. A dried paste obtained in 

 much the same manner as orchil and is made from Lecanora tartarea 



