1862.] 267 



water, alcohol, and ether, it was impossible to purify it. The oil 

 was agitated with metallic mercury, to remove free iodine, then 

 washed with water, dried over chloride of calcium, and redistilled. 

 The quantity obtained in this manner was extremely small. The 

 specimen examined was almost colourless, and boiled at 90 C. The 

 residue in the retort contained another oil, boiling, with rapid de- 

 composition, at a much higher temperature. Analysis furnished the 

 following results : 



0-3615 grm. substance gave 0-3630 CO a and 0-1870 Aq, corre- 

 sponding to 27'39 Carbon and 5' 75 Hydrogen per cent. 



These numbers approximate to those which iodide of propyl or 

 iodide of butyl should furnish ; but owing to the very small quantity 

 of substance at my disposal, I was unable to subject this curious oil 

 to a thorough examination. 



Tribrom* beta-orcin . 



I have ascertained that when bromine is added to an aqueous 

 solution of beta-orcin, a brominated derivative is formed, which 

 crystallizes in needles. It is but slightly soluble in water, very 

 soluble in alcohol and ether. It is perfectly similar in its properties 

 to tribromorcin, derived from ordinary orcin, and most probably re- 

 sembles it in constitution. Unfortunately the small amount of beta- 

 orcin in my possession prevented me obtaining the tribrom-beta-orcin 

 in sufficient abundance to submit it to analysis. 



In the present state of our knowledge, the following equations will 

 serve to throw light upon the constitution of a few of the more im- 

 portant lichen-derived compounds : 



(1) "When alcohol is boiled with erythrin, the following reaction 

 takes place : 



C 56 H 30 28 + 2C 4 H 6 2 =C 24 H 16 O u + 2C 20 H 12 O 8 + 2HO 

 Erythrin. Picroerythrin. Orsellinic ether. 



(2) When erythrin is boiled with alkalies, the following transfor- 

 mations ensue : 



(a) C M H 30 28 + 2HO=C 24 H 16 O u -f 2C 1G H 8 O 8 



Erythrin. Picroerythrin. Orsellinic acid. 



The picroerythrin is then transformed into erythroglucine, orcin, and 

 carbonic acid, and the orsellinic acid into carbonic acid and orcin : 



u 2 



