more saltpeter is added, and if the whole is heated and allowed to cool without being stirred, then the superfluous saltpeter will not settle on the bottom in the form of a powder, but will form in clustering hexagonal prisms on the bottom and on the sides. If powdered saltpeter is dissolved in water and then put in a warm place, then the water will evaporate and the residuum of saltpeter will be precipitated in the form of hexagonal crystals.
If common salt is dissolved in water and the water is heated and allowed to evaporate, then the residuum of salt is precipitated also, not in the form of a powder, but in cubes. If saltpeter and salt are dissolved together, the residuum of the two substances do not combine, but each is precipitated in its own form: the saltpeter in prisms, the salt in cubes.
If lime or any other salt or any other substance is dissolved in water and the water is evaporated, each substance is precipitated in its own peculiar way: one in triangular prisms, another in octagonal, another in brick-like forms, another in stars—each in its own way. These figures are different in all solid substances. Sometimes they are large and are found like stones in the ground; sometimes they are so small that they are invisible to the naked eye; but still each substance has its own form.
If, when water is saturated with saltpeter and the figures begin to form, the edges of the figure are broken with a needle, then again in the same place there will be deposited new atoms of the saltpeter, and the broken edge will be repaired just exactly in its own proper form—in hexagonal prisms. It is the same with salt and with everything else. All the infinitesimal atoms move and take their places where they are needed.
When water becomes ice, the same phenomenon takes place. A snowflake comes flying down; no figure can be seen in it. But as soon as it lights on anything moist and cold, on a pane of glass, or on fur, its form may be discerned. You can see a little star or a little plate. On the window-panes the vapor does not
