Flavine, an extract of quercitron bark, formerly largely employed as a yellow dyestuff. Its value varied greatly with the manner in which the extract is made. It is usually obtained by boiling the bark with water and then adding sulphuric acid, which precipitates the dyestuff as a yellow powder. Various "mordants" may be employed with it, different colours resulting according to the mordant employed. With aluminium or tin mordants a fine yellow results; iron salts give a grey to black colour; and by the use of mixtures of iron and aluminium salts different shades of orange may be obtained.