 Rubian was obtained from the water extract of madder root by adding bone–charcoal and extracting the bone–charcoal with ethanol.Rubian was an uncrystallisable gum, hydrolysable by acids or an enzyme contained in the madder root to give alizarin and a sugar.Rubian was actually a mixture of glycosides of di and trihydroxy anthraquinones of which a major component was ruberythric acid which is an alizarin 2–b–primeveroside.