To keep coloured alumn crystals from breaking, or losing their colour, place them under a glass shade with a saucer of water; this will preserve the atmosphere moist, and prevent the crystals getting too dry.
If crystals be formed on wire, they will be liable to break off, from the expansion and contraction of the wire by changes of temperature.
TO CRYSTALLIZE CAMPHOR.
Dissolve camphor in spirit of wine, moderately heated, until the spirit will not dissolve any more; pour some of the solution into a cold glass, and the camphor will instantly crystallize in beautiful tree-like forms, such as we see in the show-glasses of camphor in druggists’ windows.
CRYSTALLIZED TIN.
Mix half an ounce of nitric acid, six drams of muriatic acid, and two ounces of water; pour the mixture upon a piece of tin plate previously made hot, and, after washing it in the mixture, it will bear a beautiful crystalline surface, in feathery forms. This is the celebrated moirée metallique, and, when varnished, is made into ornamental boxes, &c. The figures will vary according to the degree of heat previously given to the metal.
CRYSTALS IN HARD WATER.
Hold in a wine-glass of hard water, a crystal of oxalic acid, and white threads will instantly descend through the liquid, suspended from the crystal.