104 Proceedings of the Rnyal Iruh Academy. 



tinctorial properties. Further, owing to its occurrence on rocks associated 

 with Parmelia saxatilis and the Rainalinas, we considered an examination of 

 physcione and its demethylation product desirable. 



GoUecticm of the Lichen for Examination. 



This lichen, which is very widely distributed, and often occurs in common 

 with Pai'melia saxatilis, Ramalina scopulorum, and U. cuspidata on the same 

 rocks, was collected from rocks on the seashore about a mile and a half south 

 of Skerries, Co. Dublin. 



Extraction of Physcione. 



About -50 grams of the lichen were extracted at a time with chloroform 

 in a Soxhlet apparatus, until all the physcione had been removed. The 

 solution, on cooling, deposited the physcione as a yellow solid, which was 

 washed with chloroform to free it from a dark-coloured oily matter with 

 which it was mixed, and then recrystallized from benzene. It consists of 

 yellow needles, melting at 207-208' C, and dissolves in alcohol, ether, 

 acetone, chloroform, or benzene. In alkalis or ammouia it dissolves, forming 

 red solutions, from which a yellow solid is reprecipitated by addition of acids. 

 Its solution in concentrated sulphuric acid has a deep purple-red colour. 



Wool, or wool mordanted with alumina, is scarcely affected when boiled 

 with a dilute alcoholic solution of physcione, so that this substance, as well as 

 the lichen from which it was extracted, can scarcely be regarded as a dye. 



Demethf/lation of Physcione. 



A small quantity of physcione was dissolved in ten times its weight of 

 concentrated sulphuric acid ; tlie solution was heated to 160^ C, and kept at 

 that temperature for half an hour. Tlie product was cooled and poured into 

 water. The dark-coloured solid was filtered, washed with water, dried and 

 extracted with boiling benzene. On evaporating the filtrate, frangula-emodin, 

 consisting of brownish-red crystals melting at 245-249° C, was obtained. 



When its solution in dilute alcohol \vas boiled for an hour with unmor- 

 danted wool, the latter acquired a duU orange-yellow colour, while wool 

 mordanted with alumina under the same conditions was dyed a bright orange- 

 yellow shade. 



