Inorganic Constituents of Lichens. 45 



only a portion is dissolved, and the deposit from the alcoholic 

 solution, instead of presenting the lustre of the substance as 

 at first obtained, assumes the aspect of a brownish yellow 

 powder. 



Compositiofi of Parietin. 



The product of the second solution in alcohol, when dried 

 at 212^ and burned with oxide of copper, afforded the follow- 

 ing results : — 



3-16 grains gave 7-376 COg 

 1-410 HO. 

 This corresponds with 



Experiment. Calculated, 



Carbon... 20116 6365 40 atoms 63-82 40 atoms 62-51 



Hydrogen 01566 495 16 ... 4-25 16 ... 4-16 



Oxygen... 0-9918 31-40 15 ... 31-93 16 ... 33-33 



3-1600 100- 100- 



As it appeared from the preceding result that the parietin 

 was altered in its character by attempting to redissolve it in 

 alcohol, the parietin, after being extracted by alcohol from the 

 lichen, was, after the filtration of this solution, allowed to de- 

 posit by cooling. It was then thrown on a filter and dried on 

 a tile, and then digested in hot alcohol to remove any fatty or 

 resinous matter with which it might be contaminated ; or aether 

 may be employed for the same purpose. The colouring matter 

 thus prepared was dried at 212° and analysed. 



2*96 grains affl^rded, when burned with black oxide of 

 copper, 



7-15 grs. CO2 

 1-294. HO. 

 This is equivalent to 



Experiment. Calculation. 



Carbon . . 1-9500 65*87 9 atoms 65-85 



Hydrogen . 0-U37 4-85 4- ... 4-87 



Oxygen . . 0-8663 29-28 3 ... 29-28 



2-9600 100- 100^^ 



The formula, according to this view, would be CPH4O3; or 

 we may, as in the preceding case, consider it the oxide of 

 an oil of the turpentine type, and its composition, when calcu 

 lated, would be 



Carbon . . 40 atoms 65-21 

 Hydrogen . . 16 ... 4-34 

 Oxygen . . 14 ... 30-45 



100- 

 and the formula C4oHigOi4, in which we have exhibited a 

 stage in the oxidation of an oil similar to what we meet with 

 in the gradual production of resins from the oils which appear 



