Digester, PAPIN'S, is a strong boiler with a closely fitting cover, in which articles of food may be boiled at a higher temperature than 212° (100° C.). As its name implies, it was invented by Papin (q.v.), and a common form is the Autoclave, fig. 1, where the lid can be turned round under clamps or ears, and thus be rendered steam-tight. Another form is given in fig. 2, where a portion of the side is removed to exhibit the interior. The lid, A, is fastened down by a screw, B, and the steam generated in the boiler is allowed to escape at a stopcock, C, or by raising the weighted valve, D. The increased pressure to which the contents of the boiler are exposed causes the boiling-point of the water to rise to 400° (204° C.), and occasionally higher. The digester is of great value as a means of preparing soups of various kinds, and especially in the extraction of gelatin from bones.