34 BULLETIN 448, U. S. DEPARTMENT OE AGRICULTURE. 
have been removed. The precipitate may then be dissolved in hydro- 
chloric acid of 10 or 15 per cent strength. After whirling again in 
the centrifuge to separate the lead chlorid thrown out of the solu- 
tion, the clear red liquid is shaken out once or twice with amyl 
alcohol to remove various extractives soluble in this substance. It 
may then be boiled for a short time, by which means the glucosid 
is hydrolyzed, the derived coloring matter, or anthocyanidin, being 
produced. This may now be extracted and obtained in fairly pure 
solution by shaking out with amyl alcohol. The anthocyanidins, 
according to Willstaetter, 1 are oxonium bases, containing also acidic 
phenolic groups. They are not very readily soluble in amyl alcohol 
though relatively more so than in aqueous liquids. 
The coloring principles of saffron and of Persian berries also consist 
chiefly of glucosids, though the lead salts of these are relatively more 
soluble. These glucosids also are readily hydrolyzed by boiling with 
acid, but the change in case of saffron is attended with destruction of 
much coloring matter, at least when the hydrolysis is carried out in 
the ordinary manner, with free access of air. Berberine is said to be 
the only common natural basic coloring matter and it is seldom, if 
ever, found in food products. 
By extraction from neutral solutions with ether, the leaf pigments 
(identical or similar colors are also found in -egg yolk, 2 fats and oils, s 
carrots, and tomatoes 4 ) are taken up. They are removed from this 
solvent by washing with dilute alkali. 
Coloring matters of alkanet, annatto, turmeric, and of the red dye- 
woods (sandalwood, camwood, and barwood) are very readily and com- 
pletely extracted hj ether from slightly acid solutions. The flavone 
coloring matters of fustic, of Persian berries (after hydrolysis), and 
of quercitron, also the coloring matter of brazilwood and the green 
derivatives formed from chlorophyll by alkali treatment, are taken up 
in very large proportion by ether from slightly acid solutions. 
The coloring matters of logwood, of archil, of saffron, and of cochi- 
neal are extracted in relatively small amount by ether from slightly 
acid solutions, but are largely taken up by amyl alcohol. 
Caramel and the anthocyans constituting the red coloring matters 
of most common fruits are extracted in relatively small proportion 
by amyl alcohol from acid solutions. Ammoniacal cochineal (car- 
mine) is similar, but the ordinary coloring matter is readily re-formed 
by standing with hydrochloric acid. 
iSitzb. kgl. Preuss. Acad. 12 (1914), 402^*11. For further papers by Willstaetter and coworkers see 
Liebig's Ann. 408 (1915), 1-158. 
2 Willstaetter and Escher, Zeit. Physiol. Chem. 76, (1912), 214. 
s See Palmer and Eckles, Mo. Sta. Research Bui., Nos. 9, 10, 11, 12. 
* Willstaetter and Stoll, Untersuchungen ueber Chlorophyll, Berlin (1913). 
