Dictionary.net

(Prepared by evaporating solution of potass to dryness in an iron vessel.) This preparation is generally run into cylindrical moulds, covered with paper, and kept in well-corked vessels. It is powerfully escharotic, and is used for forming issues, curing strictures, &c.

A caustic prepared by evaporating liquor potassae till water ceases to escape, drying the residue on a warm stone, and breaking into pieces when cold.