to Convert a Liquid into a Solid.
Dissolve about half a pound of sulphate of soda in a pint of boiling water, and after it has stood a few minutes to settle, pour it off into a clean glass vessel. Pour a little sweet oil upon the surface, and put it to stand where it can get cold, and where no one will touch it. When cold, put in a stick, and the fluid, previously clear, will at once become opaque, and begin to crystallize, until at length there is a solid crystalline mass.