Another effective method of preparing crystals is to dissolve the chemical in a suitable solvent, like water, rubbing alcohol, or mineral spirits. This method is especially useful for chemicals in the salt family, like table salt, Epsom salts, Alka-Seltzer, and baking soda. Salts will usually decompose when heated, leaving a tarlike mess. However, when dissolved in water or alcohol, these salts will slowly recrystallize as the solvent evaporates to form colorful crystalline patterns. Many chemicals can form different types of crystals, depending on whether they are melt- recrystallized or recrystallized from solution.
Some chemicals recrystallize almost immediately, while some take hours, days, or even weeks.
The chemicals listed in the accompanying table are easily obtained, and will recrystallize in a reasonable amount of time to yield beautiful photomicrographs. Several examples of photomicrographs of household chemicals are illustrated. The majority of microscopes use a tungsten-halide bulb as a light source. These bulbs emit a very bright light with a wavelength spectrum centered in the 3200 K color-temperature range. There are a wide variety of films available that reproduce this color balance correctly.