Ryax and O'Riokdan — Tinctorial Constituents of some Lichens. 99 



The substance when crystallized from acetone forms yellow prismatic 

 needles melting at 197-199° C, readily soluble in ether, acetone, and 

 chloroform. 



The colour, crystalline form, and melting point of this substance resemble 

 those of d-usnic acid which has been found in this lichen by Zopf (Liebig's 

 Annalen, 352 (1907), pp. 1-44), and which occurs in many other lichens 

 (0. Hesse; Ber. d. Dtsch. Chem. Ges. 30 (1897), pp. 357-366; Liebig's 

 Annalen, 284 (1895), p. 157. As d-usnic acid is very strongly dextro- 

 rotatory in chloroform solution, a solution of our substance in chloroform 

 was examined polarimetrically and found to be strongly dextro-rotatory, 

 lience, there is no doubt that it is d-usnic acid. 



Extraction ivith Acetone. 



The lichen after extraction with ether was extracted for about ten hours 

 with acetone. The solution was brown in colour, and on cooling deposited a 

 white substance, which was treated in a similar manner to the salazinic 

 acid from Parmelia sciMdilis. The amount of this white substance obtained 

 was about 3 per cent, of the weight of lichen taken. 



This substance resembles salazinic acid very closely. When recrystallized 

 from acetone it forms microcrystalline needles turning brown about 225° C. 

 and dark brown about 250° C, with signs of softening, but not melting up to 

 265° C. It is insoluble in ether, slightly soluble in acetone, but more so than 

 salazinic acid, and slightly soluble in alcohol. Its alcoholic solution turns 

 blue litmus red, and gives a violet-red colour with ferric chloride (more 

 violet than that given by salazinic acid) ; it gives no colour with bleaching 

 powder. 



It dissolves in alkali in the cold, forming a pale yellow solution which 

 turns yellowish- brown on standing five or ten minutes, and red to brown on 

 warming. A cold, concentrated solution in alkali gi\'es a red precipitate on 

 acidification with hydrochloric acid ; the brown solution obtained on warming 

 with alkali gives a brown precipitate on acidification. The alkaline solution 

 decolourises potassium permanganate readily in the cold. 



The substance itself assumes a light terra-cotta colour on contact with 

 concentrated sulphuric acid, in which it dissolves, forming an orange-coloured 

 solution. 



On heating in a test-tube the substance turns brown, and finally black, 

 giving a white sublimate which condenses on the sides of the tube. On 

 cooling this sublimate appears to consist of small concentrically arranged 

 masses of crystals which decolourise a drop of permanganate readily in the 

 cold. 



R.I. A. PROC, VOL. \XXnl., SECT. B, [^] 



