• Webster's Revised Unabridged Dictionary
    • n Purpurin (Chem) A dyestuff resembling alizarin, found in madder root, and extracted as an orange or red crystalline substance.
    • ***
Century Dictionary and Cyclopedia
    • n purpurin A red coloring matter, C14H5O2(OH)3, used in dyeing, extracted from madder and prepared artificially by the oxidation of artificial alizarin. Its application in dyeing is similar to that of alizarin. In commerce it is known as alizarin, yellow shade (of red), the true alizarin giving blue shades of red.
    • ***


In literature:

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