The Principles of Leather Manufacture
CHAPTER XIX.
_THE CHEMISTRY OF THE TANNINS._
Sources of tannins -- General qualities of tannins -- Chemical constitution -- Catechol- and pyrogallol tannins -- Catechins -- Tendency of Catechol tannins to darken with light -- “Physiological” and “pathological” tannins -- Presence of mordant colouring matters PAGE 294