Читать книгу Henley's Formulas, Recipes and Processes (Applied Chemistry) - Various - Страница 119

—A solution of tannin, prepared from a bark or from commercial tannin, is precipitated with limewater, the lime being added until the solution just turns red litmus paper blue. The supernatant liquid is then decanted, {39} and the precipitate is dried without artificial heat. The resulting calcium tannate is then mixed, according to the purpose for which the adhesive is intended, with from 1 to 10 times its weight of dry casein by grinding in a mill. The adhesive compound is soluble in water, petroleum, oils, and carbon bisulphide. It is very strong, and is applied in the form of a paste with water.