268 Mr. Schunck on the Substances 



flame. The fluid in the retort was neutralized with sulphuric 

 acid and evaporated to dryness. The residue was treated 

 with alcohol, which on evaporation gave crystals of orcine. 

 Its products of decomposition with alkalies are therefore the 

 same as those of lecanoric aether. Its analysis gave the fol- 

 lowing results : — 



I. 0*5380 grm. gave 1*1965 carbonic acid and 0*2970 

 water. 



II. 0*4085 grm. gave 0*9095 carbonic acid and 0*2260 

 water. 



These numbers correspond to the following composition : — 



Calculated. I. II. 



38 equivs. Carbon . 2850*0 61*45 60*65 60*72 

 23 ... Hydrogen 287*5 6*19 6*13 6*14 



15 ... Oxygen . 1500*0 32*36 33*22 33*14 

 4637*5 100*00 100*00 100*00 

 Its rational formula is C 14 H 18 14 + C 4 H 5 O. It is there- 

 fore formed from erythric acid by the substitution of 1 equi- 

 valent of oxide of ethyle for 1 equivalent of water. 



Picro-erythrine. 



This substance is a product derived from erythric acid. 

 To it must be attributed the highly bitter taste of all the ex- 

 tracts made of the lichen, whether aqueous or alcoholic. In 

 its properties, however, it agrees strictly neither with the 

 erythrine-bitter of Heeren nor the amarythrine of Kane. It 

 approaches nearest to the telerythrine of the latter, according 

 to the description given by him of that substance. It is a 

 product of the action of water on erythric acid. If pure ery- 

 thric acid, as prepared by the process described above, be 

 treated with boiling water for a short time, it dissolves, the 

 fluid acquires a bitter taste, and on cooling deposits no ery- 

 thric acid. On evaporation it yields a brownish, viscid mass, 

 leaving a taste between bitter and sweet. This mass, after 

 some time, becomes crystalline. It may then be treated with 

 cold water, which leaves the picro-erythrine behind white and 

 pure. I have described above how it may be obtained as a 

 secondary product in the preparation of erythric acid. In 

 operating on the plant with boiling water much more is ob- 

 tained of it than of erythric acid. On extracting the lichen 

 also with boiling alcohol, a considerable quantity is found in 

 the extract. Picro-erythrine has the following properties. It 

 has a strong but not disagreeably bitter taste. It is soluble in 

 water, alcohol and aether. Its solubility in aether distinguishes 

 it from Kane's amarythrine and telerythrine, which are insolu- 

 ble in that fluid. It does not dissolve readily in cold water, but 



