22 GUIDE TO THE STUDY OF LICHENS. 



volved. In general, it may be stated that the lichen is 

 pulverized and macerated for some time in some alka- 

 line solution, as lye, or ammonia, whereby a beautiful 

 purple color is obtained. Orchill, cudbear and lit- 

 mus are different names for the same coloring sub- 

 stance. The first is the English preparation which 

 occurs as a rich purple paste ; the second is the Scotch 

 preparation which is found in the market as a carmine 

 or crimson powder ; the third is the Dutch prepara- 

 tion and occurs in small oblong cakes of an indigo- 

 blue color. Litmus, as well as the other dyes, 

 has the peculiarity of turning red in the presence of 

 an acid and blue in the presence of an alkali. The 

 litmus-paper so extensively used in chemical labora- 

 tories is ordinary filter paper dipped into a neutral 

 solution of litmus. 



Later orseille was used principally in dyeing silken 

 goods. France more than any other country improved 

 upon the methods of extracting the dye, as well as in 

 applying it. As to the value of the dye it may be 

 stated that about the middle of this century the 

 " orchella-weed " sold at prices ranging from $100 to 

 more than $1,000 per ton. The chief objection to the 

 use of orseille is its instability, being subject to fading ; 

 furthermore, the process of dyeing is very apt to injure 

 the cloth. Orseille is also used by artists as a pigment. 



In Sweden Evernia vulpina is known as " Ulf- 

 mossa" (Wolf's moss), because it was said to have 

 been used in poisoning wolves. According to Virey, 

 the lichen is powdered and mixed with powdered 

 glass, which is sprinkled upon meat exposed for wolves 



