150 RESINS, BITTER PRINCIPLES, ETC. 



and with alkaline solutions at a temperatui-e as low as the boiling- 

 pomt.i Both thia and the foregoing acid form salts of ethyl when 

 boiled with alcohol. 



* Gyrophoric add, which is sparingly soluble in ether, yields orcin 

 on decomposition with alkali, and turns red on exposure to am- 

 moniacal air.' 



Parellic acid, which is only slowly coloured under the same 

 conditions.^ 



CeratophylUn, which strikes a violet colour with ferric chloride 

 and blood-red with chlorinated lime.* 



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

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

 lime, blood^red.* 



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

 red by ammoniacal air, but only yellow by chlorinated lime.* / 



Evernink add (pxyusnetinic acid 1) is also coloured yellow by 

 chlorinated lime, but does not change when exposed to ammoniar 

 cal air. 



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

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

 by dry- distillation.^ 



. Carbusnie add* (is sparingly soluble in ether) gives no colour 

 reactions. 



Vvlpink 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 barytarwater resolves it into alphatoluic add, oxalic acid, 

 and methyl-alcohoL^ It may therefore be placed in the group of 



^ Sohunck, Annal. d. Chem. und Pharm. xli. 157, 1842 (Joum. Chem. Soc. 

 i. 71) ; liv. 261, 1845 ; bd. 64, 1847 ; Stenhouae, ibid. Ixviii. 57, 1848; oxxv. 

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



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



' Compare Sohunck, ibid. liv. 274, 1845 ; Strecker, Ixviii. 114, 1848. 



^ Cbmpaore Hesse, ibid. cxix. 365, 1861. 



" Compare Weigelt, Joum. f. prakt. Chem. cvi. 28, 1869. 



' Compare Stenhouse, ibid. Ixviii. 86, 1848 ; Hease, ibid, xlvii. 297, 1861. 



' Compare Knop, Annal. A. Chem. und Pharm. xUx. 103, 1843 ; Bochleder 

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

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

 Chem. und Pharm. oxvii. 343, 1861. 



s See Hesse, ibid, cxxxvii. 241, 1866 ; Ber. d. d. chem. Ges. x. 1324, 1877 

 (Joum. Chem. Soc. xxxii. 896). 



' Stein, Chem. Centralblatt, 556, 1864 ; 432, 1865. See also Spiegel, Be' 

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



