94 Proceedings of the ttoyal I?'ish Academy. 



The latter was removed as completely as possible by washing repeatedly 

 with small quantities of ether, and examined separately. 'J'here was then left 

 a small amount of the substance (a), which was reorystallized from alcohol. 

 It forms colourless prismatic needles, melting at 191-192° C. soluble in ether 

 and alcohol. Its alcoholic solution reddens litmus, and gives a blue-violet 

 colour with a trace of ferric chloride ; a few drops of ferric chloride give 

 a cherry-red colouration. Its alcoholic solution gives no colouration with 

 bleaching powder. The substance dissolves in caustic potash, forming a pale 

 yellow-coloured solution which is not altered in colour by gentle heating. 

 When this soli;tion is acidified with hydrochloric acid, a white substance is 

 precipitated. The potash solution readily decolourises potassium perman- 

 ganate in the cold. 



The general behaviour of this substance (i.e. melting-point, ferric chloride 

 reaction. &c.) points to its being identical with stereocaulic acid, which was 

 found by Zopf in Parmelia saxatilis (Liebig's Annalen, 295 (1897), p. 222), 

 but the amount of the substance available was insufficient to permit of an 

 analysis of it being made. 



2. Extraction with Acetone. — The lichen after being extracted with ether 

 was e.xtracted with acetone in a Soxhlet apparatus as long as any solid 

 matter was removed (about two days). During the process a white crys- 

 talline solid separated from the solution. ' 



The extract, when cooled, deposited a discoloured white solid, and the 

 dark-coloured mother liquor on concentration gave further quantities of this 

 substance. The white solid was washed repeatedly with acetone to remove 

 dark oily matter, and the washings were mixed with the dark substance 

 extracted by ether and examined separately. 



On trying to purify this white substance it was found that it was not 

 readily soluble in any of the ordinary solvents, but it dissolved most easily, 

 yet very sparingly, and on heating onlj', in acetone, alcohol, or glacial acetic 

 acid. It was noticed that prolonged heating with alcohol or glacial acetic 

 acid tended to decompose it, the solution becoming yellow or brown-red in 

 colour. On evaporating these coloured solutions to dryness, brown or brownish- 

 red non-crystalline solids were obtained. Finally, it was found that acetone, 

 although the substance was not so soluble in it as in glacial acetic acid, was 

 the most suitable solvent, apparently not decomposing the substance, to any 

 "reat extent at least. 



O 



It was found also that the crude substance contained a small amount of 

 another white, microcrystalline solid which could be extracted from it by 

 acetic ester, 'i'his solid melted at ab(jut 215''C. (not sharply); its alcoholic 

 solution gave a brownish-red colouration with ferric chloride ; it was soluble 



