PROXIMATE PRINCIPLES OF SOME OF THE LICHENS. 
85 
the ether is decomposed, and a gas is emitted which burns with the flame charac- 
teristic of alcohol. The potash when examined contained no orcin. There is every 
reason therefore to regard this substance as an ether. 
I. 0*2482 grm. ether prepared with absolute alcohol and dried in vacuo, gave with 
chromate of lead 0*5740 carbonic acid and 0*1600 water. 
II. 0*2774 grm. ether prepared in the same way, gave 0*640 carbonic acid and 
0*1 71 water. 
III. 0*373 grm. ether prepared with potash and alcohol, gave 0*859 carbonic acid 
and 0*228 water. 
IV, 0*2617 grm. ether prepared with potash and alcohol, gave 0*604 carbonic acid 
and 0*1635 water. 
Calculated numbers. 
I. 
II. 
III. 
IV. 
22 C 
1681*570 
63*30 
63*07 
62*92 
62*80 
62*94 
14 H 
174*713 
6*58 
7*15 
6*88 
6*79 
6*93 
8 0 
800*000 
30*12 
29*78 
30*20 
30*41 
30*13 
2656*283 
100*00 
100*00 
100*00 
100*00 
100*00 
Cjg Hg O 7 -I-C 4 H 5 O, the formula derived from these analyses, is exactly that which 
the evernesic ether ought theoretically to have, and which I am strongly inclined to 
think this substance most certainly is. It is no doubt somewhat singular that when 
an attempt was made to form the evernesic ether directly, by boiling evernesic acid in 
absolute alcohol saturated with muriatic acid gas, it totally failed. Still I am inclined 
to regard the substance above described as evernesic ether, as it certainly cannot be 
evernic ether, as might naturally have been expected, seeing that evernic acid was 
the acid employed in its formation ; for its mother-liquors always contained orcin, 
thus showing that the evernic acid had been decomposed ; and when the evernesic 
ether was fused with dry potash, it yielded no orcin, which evernic acid always does 
when similarly treated. It is clear therefore that the ether could not contain any 
evernic acid. The only probable explanation of this enigma appears to be that 
evernic acid does not form an ether, and that evernesic ether is only procurable 
when evernesic acid is generated in contact with alcohol. 
On Orcin and its Preparation . 
It is a remarkable circumstance that, so far as we know, orcin is always one of the 
products when any of the colouring principles of the lichens which yield red dyes 
with ammonia are subjected to particular operations. We have seen that this is the 
case with the principles of the different varieties of Roccella tinctoria, with those of 
the various kinds of Lecanora, and with that of the Evernia Prunastri. When the 
colouring principles of these lichens are destructively distilled, or are boiled with 
alkalies, or even with pure water or alcohol, orcin is always one, though by no means 
the only product. This circumstance is characteristic of this whole class of bodies. 
