From the alizarin-potassium thus obtained the alizarin is set free by the aid of hydrochloric acid.
Wash the alizarin thus separated, dry it81 by simple exposure to air, and purify it by repeated crystallisation out of alcohol.
Industrially, it ranks next to indigo and alizarin in importance as a natural dye stuff.
This is filtered off from the alizarin lake, heated to boiling, and acidified with hydrochloric acid.
On wool, the colour is so extremely fast to light and to milling that it may well serve as a substitute for alizarin.
In addition to alizarin, other anthracene derivatives are of industrial importance.
alizarin only stains the untreated woollen, whilst the piece treated with alumina is dyed red, and that with iron, purple.
This is alizarin, the coloring matter contained in the madder root.
Magenta was also a substantive colour, but alizarin was certainly not one of this class.
In the roots three coloring matters are obtained: alizarin and purpurin, which are both red, and xanthin, which is yellow.
alizarin a·liz·a·rin (ə-lĭz'ər-ĭn)
An orange-red crystalline compound used in making dyes and as an indicator.