We may remark that purpurin has not been obtained by direct synthesis.
"Scientific American Supplement, No. 286" by Various
Benzo purpurine 4 B, 3 lb.
"The Dyeing of Cotton Fabrics" by Franklin Beech
Purpurin (red coloring-matter), 44.
"Rugs: Oriental and Occidental, Antique & Modern" by Rosa Belle Holt
These chemists isolated two compounds which they named alizarin and purpurin.
"Coal" by Raphael Meldola
Madder contains two closely allied colouring matters, namely, alizarin and purpurin.
"Encyclopaedia Britannica, 11th Edition, Volume 8, Slice 8" by Various