Description and references
The root of Alkanna tinctoria Tausch, Boraginaceae. Habit. Asia Minor, Hungary, Greece, Mediterranean
region. Constit. Alkannin (the coloring principle) and
tannin. Extraction of roots: Betrabet, Chakravarti, J. Indian Inst. Sci. 16A, 51 (1933); C.A. 28, 1038 (1934); Majamdar,
Chakravarti, J. Indian Chem. Soc. 17, 272 (1940); C.A. 34, 6262 (1940).
Derivative
Alkannin paper.
Nomenclature
Anchusin paper; Boettger's paper. Properties
White paper impregnated with a 1% alc tincture
of alkanet root and dried. A blue paper can be made from the red
paper by treating the latter with a 1% Na2CO3 soln. This paper acts nearly like litmus paper. Alkalies = green
or blue; acids = red. pH: 8.0 red; 10.0 blue.For coloring wines, cosmetics, confectionery. Alkannin
paper as indicator.
Astringent.