258 Dr. E. Schunck on the Substances discovered in 



Evernate of potash : — 



Stenhouse. 

 a 



4889-5 100-00 lOO'OO 100*00 



Evernate of baryta :- 



Stenhouse. 



A 



36 eqs. Carbon . 

 16 ... Hydrogen 

 14 ... Oxygen . 

 1 ... Baryta 



2700 



199-6 

 1400 



956-8 



51-36 



3-79 



26-65 



18-20 



I. 



50-30 



4-10 



27-08 



18-52 



II. 



50-31 



3-96 



27*38 



18-35 



5256-4 100-00 100*00 100-00 



If from 1 eq. evernic acid . . 

 we subtract 1 eq. lecanoric acid 



and add 1 eq. water . . . 

 we obtain 1 eq. evernesic acid 



— Cs6H 17 15 

 = C 18 H 8 Q 8 



Ci8 ^9 O7 

 = H O 



— Ciq H 1n Oo 



Evernic acid may therefore be considered as a coupled 

 acid, consisting of lecanoric and evernesic acids. It con- 

 sequently appears probable that the Evernia Prunastri may 

 sometimes contain lecanoric acid only, as found by Rochleder 

 and I Jeldt, and sometimes lecanoric and evernesic acids com- 

 bined to evernic acid, -as found by Mr. Stenhouse. The 

 orcine which is produced on treating evernic acid with alka- 

 lies, must be derived from the lecanoric acid. Evernesic 

 acid being a more stable body than lecanoric, resists the action 

 of alkalies ; and on supersaturating with a mineral acid, it is 

 precipitated. It seems probable that if evernic acid were dis- 

 solved in caustic alkali without adding an excess of the latter, 

 and the solution just heated to the boiling-point, as in the case 

 of orsellic acid, then, on adding a strong acid, a mixture of 

 lecanoric and evernesic acids would be precipitated. But as 

 Mr. Stenhouse treated his evernic acid with an excess of 

 caustic potash or baryta, and boiled for some time, the leca- 

 noric acid would of course be decomposed. On treating 

 evernic acid with boiling alcohol also, I should suppose that 

 lecanoric aether would be generated, as well as evernesic aether. 



