Note 7 — LECTURE II. GRAVITATION—COHESION.
Reading edition
Page 55. Crystallisation of Alum.—The solution must be saturated—that is, it must contain as much alum as can possibly be dissolved. In making the solution, it is best to add powdered alum to hot water as long as it dissolves; and when no more is taken up, allow the solution to stand a few minutes, and then pour it off from the dirt and undissolved alum.