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There are such substances, which are called isomorphic: they crystallize the same, despite the different composition. The crystals of one such substance is able to grow in a saturated solution of another: so as if the crystal in the crystal. If it is cut, the cut will be geometric pattern.

The most affordable among isomorphous substances alum, crystalline double sulfate with the General formula M M(SO4)2*12H2o will Use their three varieties: dark purple cromakalim KCr'(SO4)2*12H2O, green salesonline NH4Fe'(SO4)2*12H2O and colorless potassium КАl(SO4)2*12H2O.

In an enamel or glass dish, pour water, pour any alum (one species) and heat, stirring with a glass or wooden stick, but not to boil. When the salt has dissolved, add another portion of the same alum and again heat. When the solution becomes saturated quickly filter it through cotton swab placed in a glass or enamel funnel, rinsed with boiling water. If the funnel is cold, can cause premature crystallization and the crystals will clog the funnel.

Jar with a solution of alum cover and leave to cool slowly. At the bottom will fall out of the small crystals. If they're going to grow together, heat the solution, adding a little water, and again cool. The crystals remove, drain, put into a test tube and close the tube. Just cook the other crystal of alum. Saturated solutions save! In order not to confuse them, stick on the banks of the label.

Select one crystal of each species, tie a thin thread (for example, from nylon stocking) and dip everyone in your solution. Banks keep away from drafts; cover them with paper covers.

About a week crystals will increase markedly. Swap them. If you start to hang in each Bank, two of the crystal, there will be even more alternating colors. To avoid confusion, to the ends of the threads attach labels and record in your lab journal, how long and in what solution are crystals.

Correct alum crystal has the shape of an octahedron, but we do not need a perfect crystal. On the contrary, the prichudlivee form, the more interesting the picture on the cut. At the same time you can grow crystalline aggregates - Druze choose to seed already fused crystals. If they began to ramify during growth, not correct them; moreover, you can control the growth of faces. Lubricate the face with vaseline, and it will cease to grow, wash off the vaseline with acetone and the face will grow again.

The finished crystal cut wet rough thread; this work requires accuracy and patience. The cut surface trim emery paper and Polish on wet Whatman paper in a circular motion.

Depending or how the selected section plane as in the crystal layers and what is their thickness, you get a variety of geometric patterns. The Druze options even more. Cut crystal pattern immediately cover with a clear varnish (good nail Polish), otherwise it will fade and crumble into powder.

Much easier to manufacture the pattern of the crystals of ammonia-ammonium chloride. However, it is colorless, but the picture reminds you... However, let's not get ahead of ourselves.

USEPA ammonium chloride in warm water and mixing thoroughly, prepare a saturated solution. Take the glass plate or mirror, wash the surface with a brush, apply it prepared solution. Let the vinyl solution slowly cooled in air, and that it is not exposed to dust, you can hide it in the closet. A few hours later the water will evaporate and the glass pattern is formed. You don't even need to look to understand what it resembles: frosty pattern on the winter window.

This experience, of course, it is best to put the New year. Warm faux frosty pattern is not threatened, but the water must be kept away...

O. Holguín. "Experiments without explosions"
M., "Chemistry", 1986


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