contained in the Roccella tinctoria. 263 



The filtered fluid gave a slight flocculent precipitate on the 

 addition of alcohol, but none with lime and baryta water or 

 sulphuric acid. On evaporation it left a clear brown syrup, 

 which soon changed into a crystalline mass, having a sweetish 

 bitter taste. It contained besides picro-erythrine, to which it 

 owed its bitter taste, a quantity of orcine, which was detected 

 in the following manner : — A part of it was dissolved in boil- 

 ing water, and during the boiling a quantity of magnesia was 

 introduced into it. After filtration the fluid was evaporated 

 to dryness. It left a brown mass, which no longer became 

 crystalline on standing. The picro-erythrine had entered into 

 combination with the magnesia, and on treating the mass with 

 aether in the cold, a yellowish-brown fluid was obtained, which 

 on evaporation gave crystals of orcine, recognisable by its 

 well-known properties. The dark brown viscid mass obtained 

 from the mother- liquor of the ery thric acid left on being burnt 

 a considerable quantity of ashes, consisting of sulphate of 

 soda, chloride of sodium, oxide of iron and carbonate of mag- 

 nesia, with a trace of carbonate of lime. 



The lichen, after being extracted with boiling water, had 

 lost its grayish-white colour and become green. It was dried 

 and then treated with boiling alcohol. The alcohol acquired 

 during the process a dark emerald-green colour. It was 

 strained through cloth while still hot. On becoming cold it 

 deposited a green flocculent substance, which was separated 

 by filtration. The green colour of this substance could not 

 be removed by washing with cold alcohol. On drying it be- 

 came dark green and coherent, but when powdered it was 

 light green again. This substance is a kind of fat; it cannot 

 be fused without being decomposed. When heated on plati- 

 num foil it melts to a brown fluid, giving off at the same time 

 a strong smell of burning fat, and burns without leaving any 

 ashes. Heated in a tube closed at one end it melts and gives 

 a brown, oily sublimate, which soon solidifies, but without 

 becoming crystalline. It is left behind on evaporating its al- 

 coholic solution as an amorphous green mass. It is precipi- 

 tated from its solution in alcohol by water, and also by an 

 alcoholic solution of acetate of lead. It is insoluble in boiling 

 muriatic and dilute sulphuric acids. Concentrated sulphuric 

 acid dissolves it. Boiling nitric acid, even if dilute, destroys 

 its green colour and makes it yellow. If treated with con- 

 centrated nitric acid, it is dissolved and decomposed with an 

 evolution of nitrous acid ; by degrees there collect on the 

 surface of the fluid yellow oily drops, which solidify on cool- 

 ing. It is very little soluble in boiling caustic ley, and inso- 

 luble in ammonia. The dark green fluid from which this. 



