from The American Heritage® Dictionary of the English Language, 4th Edition
- n. A reddish crystalline compound, C14H5O2(OH)3, that is isolated from madder root for use as a biological stain and commercial dye.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. A red anthraquinone dye, extracted from madder, that is used as a biological stain
- n. A protein of the lipocalin family
- n. A brownish or deep red decorative glass used in ancient times
from the GNU version of the Collaborative International Dictionary of English
- n. A dyestuff resembling alizarin, found in madder root, and extracted as an orange or red crystalline substance.
from The Century Dictionary and Cyclopedia
- n. A red coloring matter, C14H5O2(OH)3, used in dyeing, extracted from madder and prepared artificially by the oxidation of artificial alizarin.
Good steam-reds were easily obtained by using receipts originally designed for extracts of madder (mixtures of alizarin and purpurin).
We may remark that purpurin has not been obtained by direct synthesis.
Schützenberger and Schiffert, the coloring matters of madder are alizarin, purpurin, pseudopurpurin, purpuroxanthin, and an orange matter, which M. Rosenstiehl considers identical with hydrated purpurin.
It was known that purpuroxanthin does not dye; that pseudopurpurin is very easily transformed into purpurin, and the uncertainty which was felt concerning hydrated purpurin left room merely for the hypothesis that Turkey-red is obtained by the concurrent action of alizarin and purpurin.
The same operations have also another end -- to transform the purpurin into its hydrate, which is brighter and more solid.
Experience with the madder colors shows that a mixture of alizarin and purpurin yields the most beautiful roses in the steam style, but it is not the same in dyeing, where the roses got with fleur de garance have never been equaled.
It is now known, thanks to the researches of Perkin, Schunck, Roemer, Graebe, and Liebermann, that in the manufacture of artificial alizarin there are produced three distinct coloring matters -- alizarin, iso or anthrapurpurin, and flavopurpurin, the two latter being isomers of purpurin.
The only dyes in this group which appear somewhat behind the rest in point of fastness are purpurin and alizarin maroon.