Decant it into a tall tank and let it rest for several hours, when most of the impurities will settle' to the bottom, and, after decanting the glue, the bottoms may be added to the next boiling. If a large quantity of glue solution is to be treated, the heat contained in it, will be sufficient to keep it fluid; but for a small quantity a jacketed pan must be used for clarifying. The addition of a very small quantity of alum to the glue solution is beneficial, as it coagulates the flocculent matter and renders it heavier. For gelatine, moist alumina would be suitable as a clarifying agent, or inert white powders, such as china clay or French chalk; these substances should be stirred into the gelatine solution and allowed to settle out. Experiments on the lines indicated should be tried on a small scale first.