When caustic lime is added in sulfite waste liquor to pH_??_12, lignosulfonic acid (L.S) and the other organic matter (X) are precipitated together.
Conditions of precipitation (amount of CaO, concentration of L.S in S.W.L., temperature etc.) and the composition of precipitate were studied.
Among nonlignin substances, we found five kinds of sugar, mannonic acid, xylonic acid and four acidic substances which are under investigation. The content of X in the product increases with concentration of L.S. in S.W.L.