24 GUIDE TO THE STUDY OF LICHENS. 



and readily accessible substitute for quinine. Sanders, 

 who secured the prize in part, proposed Physcia 

 parietina as such a substitute. It proved, however, 

 very unsatisfactory and its use was soon entirely dis- 

 continued by physicians. 



From their alleged aptitude for imbibing and 

 retaining odors and scents the powder of several fruti- 

 cose lichens formed the basis of certain perfumes 

 which were celebrated in the seventeenth century. 

 The astringency of some species rendered them ser- 

 viceable in tanning and even in brewing ; the beer of 

 a certain Siberian monastery, celebrated for its peculiar 

 bitterness, owed this to Sticta pulmonaria. French 

 and Scandinavian chemists employed Cetraria island- 

 tea and Cladonia rangiferina in the manufacture of 

 alcohol. The method of procedure is essentially as 

 follows: The lichens are treated with sulphuric or 

 hydrochloric acid, which transforms the lichenin into 

 glucose ; this, being allowed to ferment, produces 

 alcohol. Two pounds of the lichen furnishes about 

 one pint of alcohol. 



Attempts were also made to use lichens in the 

 manufacture of paper but the results were very unsat- 

 isfactory, as these plants contain no tenacious fibres. 

 They are still very extensively used in the decorative 

 work of the taxidermist. Some species furnish a gum 

 used in the manufacture of pasteboard. 



In conclusion, it may be stated that the medicinal 

 virtues of lichens are largely imaginary. The only offi- 

 cinal lichen to-day is Cetraria islandica, a decoction of 

 which is recommended as a tonic for convalescents. 





