102 Proceedings of the Royal Irish Academy. 



turns a light brownish yellow coloiu- on standing and a yellowish-brown 

 coloav on being gently heated. On warming a fairly concentrated solution 

 of it in alkali it turned red in colour, but the colour did not alter to 

 brown on further heating. The alkaline solution decolourises potassium 

 permanganate in the cold. 



The substance was recrystallized from acetone, and dried at 110° C. before 

 analysis : — 



0-1030 substance gave 0-2084 CO, and 0-0394 H,0, 

 corresponding to C 53-85 and H 4 25. 



This analysis agrees with the formulae C31H32O2,, or CnHicOm, which 

 require C 53-7, H 4-2. 



It is rather difficult to identify this substance with any known similar 

 compound. 0. Hesse Journ. f. pr. Chem. (2), 62 (1900), pp. 430-477) found 

 in this lichen a compound which he named cuspidatic acid, melting at 218° C, 

 easily soluble in ether, alcohol, and acetone, giving a blue-violet colour with 

 ferric chloride, and having the composition C1GH22O1,,- lljO (requiring for 

 '-'leH-jjOiy- G 51-31, H 5-88), though Hesse does not lay much stress on the 

 correctness of this formula. It does not seem very likely that our substance 

 is identical with this one, since i^ is not soluble in ether and has got a different 

 decomposition-point. It is, however, evident from its behaviour that our 

 substance is very similar, and probably related chemically, to scopuloric and 

 salazinic acid. 



The probable chemical relationship between these three substances is also 

 indicated by the formula of the cuspidatic (?) acid from Ramalina cuspidata. 

 If we take as the formula for this acid CmHs.Oo,,, this difi'ers from the 

 formula OjuHjiOio for salazinic acid by four CHOH radicals ; while if we 

 consider the formula CuUisOiu, then salazinic acid, OnHuOo would, be 

 anhydro-cuspidatic (?) acid. 



Further Treatment of the Lichen . 



As in the case of Rccmalina scopuloritni, it was considered unnecessary to 

 examine the lichen further after extraction with acetone. 



Dyeing Ejrperiraents. 



This lichen does not dye wool such deep shades as either of the other two 

 lichens ; the colour of the wool after boiling for six hours with an equal weight 

 of the lichen was only a light brown. It was found that its chief acid 

 constituent (cuspidatic (?) acid) when boiled with wool imparted similar 

 shades to the wool, and is consequently the chief tinctorial constituent of 

 the lichen. 



