The Colouring Matter of Red Roses. 



195 



his generosity in supplying me with sufficient material enabled the work to 

 be successfully accomplished. 



For the isolation of the anthocyan pigment, the methods used by 

 Willstatter and Nolan, in their investigation of the "Kosa Gallica," were 

 adopted, while the examination of the flavonol pigment was carried out on 

 somewhat similar lines to that used by Dr. Everest in his examination of the 

 viola. 



Experimental. 



Isolation of the Anthocyan Pigment. 



100 grm. of the petals (which had been first air-dried in the shade, at 

 room temperature, and finally over concentrated sulphuric acid), were 

 allowed to stand in a closed vessel, with about 300 c.c. of methyl alcohol, 

 containing 2 per cent, of concentrated hydrochloric acid (to prevent pseudo- 

 base formation), for about twenty-four hours; the mass was then pressed, to 

 obtain as much extract as possible, and the residue treated with a further 

 ■quantity of methyl alcoholic hydrochloric acid. After standing some hours, 

 this was filtered, with suction, and as the extraction was still incomplete, the 

 residue was again extracted with the same solvent. The residue after 

 filtering and washing possessed but a pale pink colour, and further extraction 

 was deemed unnecessary. The filtrates and washings were united ; they 

 possessed a fine, deep red colour, with a bluish-violet tinge at the edge of the 

 solution. The combined filtrates and washings were poured into about three 

 times their volume of ether, well agitated, and allowed to stand for some 

 hours. Practically all the anthocyan pigment separated out as a dark brown, 

 gummy mass, from which the supernatant solution could be readily decanted. 



The crude anthocyan pigment was redissolved in methyl alcoholic hydro- 

 chloric acid, and reprecipitated with ether (about two and a half times 

 the volume of the alcoholic solution). After standing some hours, to allow 

 precipitation to be as complete as possible, the ether-alcohol solution was 

 •decanted off and the precipitate allowed to stand for twenty-four hours in 

 contact with a mixture of methyl alcohol and glacial acetic acid (to remove 

 impurities capable of being hydrolysed or acetylated), and finally collected on 

 ■a filter, washed with a small quantity of methyl alcohol (containing 1 per cent, 

 hydrochloric acid), and air-dried. 



The dark brown powder thus obtained was dissolved in boiling water, an 

 equal volume of ethyl alcohol (containing 3 per cent, hydrochloric acid) added, 

 and the solution allowed to cool ; the colouring matter separated out in the 

 form of dark brown leaflets, possessing a golden reflex. These were collected 

 and air-dried. For identification purposes the anthocyanin chloride thus 



