Write a method to separate a mixture of sand and potash alum.
A mixture of sand and potash alum is separated by filtration followed by evaporation. The mixture contains two constituents, i.e., potash alum and sand.
Mix both the constituents thoroughly with water so that potash alum gets dissolved in water. However, sand, being insoluble in water, will not get dissolved in it. On filtering the liquid, the solid that is left behind will be the sand, and the liquid will be a solution of potash alum. Potash alum can now be re-crystallized by heating the solution gently. In the process, all the water gets evaporated leaving behind potash alum.