150 



RESINS, BITTER PRINCIPLES, ETC. 



and with alkaline solutions at a temperature as low as the boiling- 

 point. 1 Both this and the foregoing acid form salts of ethyl when 

 boiled with alcohol. 



Gyrophoric acid, which is sparingly soluble in ether, yields 01 

 on decomposition with alkali, and turns red on exposure to ai 

 moniacal air. 2 



Parellic acid, which is only slowly coloured under the same 

 conditions. 3 



Ceratophyttin, which strikes a violet colour with ferric chloride 

 and blood-red with chlorinated lime. 4 



Patellaric acid, which, in alkaline solution, turns red when ex- 

 posed to the air. Ferric chloride colours it blue ; chlorinat 

 lime, blood-red. 5 



Evernic add yields orcin by dry distillation, is coloured dark- 

 red by ammoniacal air, but only yellow by chlorinated lime. 6 



Everninic add (oxyusnetinic acid ?) is also coloured yellow bj 

 chlorinated lime, but does not change when exposed to ammonij 

 cal air. 



Usnic acid behaves in a similar manner, but an alkaline solution 

 turns red on exposure to air, and the acid itself yields betaorcin 

 by dry distillation. 7 



Carbusnic acid 8 (is sparingly soluble in ether) gives no colour 

 reactions. 



Vulpinw add (chrysopicrin), which is more easily soluble in 

 bisulphide of carbon and chloroform than in ether, is obtainable 

 in yellow crystals and forms yellow salts with alkalies. Boiling 

 with baryta-water resolves it into alphatoluic acid, oxalic acid, 

 and methyl-alcohol. 9 It may therefore be placed in the group of 



1 Schunck, Annal. d. Chem. und Pharm. xli. 157, 1842 (Journ. Chem. Soc. 

 i. 71) ; liv. 261, 1845 ; Ixi. 64, 1847 ; Stenhouse, ibid. Ixviii. 57, 1848; cxxv. 

 353, 1863 (Journ. Chem. Soc. xx. 221) ; Hesse, cxxxix. 22, 1866. 



2 Compare Stenhouse, ibid. Ixx. 218, 1849. 



3 Compare Schunck, ibid. liv. 274, 1845 ; Strecker, Ixviii. 114, 1848. 



4 Compare Hesse, ibid. cxix. 365, 1861, 



5 Compare Weigelt, Journ. f. prakt. Chem. cvi. 28, 1869. 



6 Compare Stenhouse, ibid. Ixviii. 86, 1848 ; Hesse, ibid, xlvii. 297, 1861. 



7 Compare Knop, Annal. d. Chem. und Pharm. xlix. 103, 1843 ; Kochleder 

 and Held, ibid, xlviii. 1, 1843 ; Stenhouse, ibid. Ixviii. 97, 114. Knop and 

 Schnedermann, Journ. f. prakt. Chem. xxxvii. 363, 1843 ; Hesse, Annal. d. 

 Chem. und Pharm. cxvii. 343, 1861. 



8 See Hesse, ibid, cxxxvii. 241, 1866 ; Ber. d. d. chem. Ges. x. 1324, 187< 

 (Journ. Chem. Soc. xxxii. 896). 



9 Stein, Chem. Centralblatt, 556, 1864 ; 432, 1865. See also Spiegel, Ber. 

 d. d. chem. Ges. xiii. 1629, 1880. 



