THE USES OF LICHENS. 21 



Theophrastus and Dioscorides described Rocella tincU 

 oria as a " marine fungus growing upon rock, possess- 

 ing coloring properties," from which it is concluded 

 that dye made from the lichen was known before that 

 time. It was in use before the time of Pliny. The 

 "blue and purple" of the Old Testament (Ezekiel, 

 xxvii, 7) no doubt refers to the coloring substance 

 obtained from this lichen. 



After the fall of the Roman empire the knowledge 

 of the use of the dye obtained from Rocella seems to 

 have been lost. About the year 1300, Federigo, a 

 Florentine of German parentage, accidentally redis- 

 covered the method of preparing and using this dye. 

 He is said to have achieved such great success in his 

 commercial transactions therewith that in time he be- 

 came the head of a distinguished family, the Oricellarii, 

 who were later known as the Rucellarii and Rucellai. 

 From these names are derived orseille, the name 

 given to the coloring substance, and Rocella, the group 

 of lichens from which orseille was prepared. For 

 more than a century Italy supplied the market with 

 orseille derived mainly from lichens collected on the 

 islands of the Mediterranean. After the discovery of 

 the Canary Islands, in 1402, much of the dye was ob- 

 tained from those islands; still later from the Cape 

 Verde Islands, as well as from other islands and coun- 

 tries. Later it was found that species of Lecanora, 

 Pertusan'a, Umbilicaria, Gyrophora, etc., yielded ex- 

 cellent dyes. 



The method of preparing the dye is quite compli- 

 cated and many complex chemical reactions are in- 



