Angela Underwood, age 13, of Grand Forks, N.D., for her question:
JUST WHAT IS BORAX?
Borax is an important chemical compound of the element boron. Its chemical name is sodium borate or sodium tetraborate. Borax is a white, soft, many sided crystal that dissolves easily and quickly in water.
Borax crystals will clump together if they are exposed to moist air, much as salt crystals will.
Borax is best known for its use in washing powders, water softeners and soaps. It is also used a great deal in various medicines, for ointments and for eye washes.
Manufacturers also mix borax with clay and other substances to make enamel glazes for sinks, stoves, refrigerators and metal tiles.
Potters use borax to add strength to their products and to make a hard glaze for dishes. In addition, glassmakers mix borax with sand so that it will melt easily and give strong, brilliant glass. Glass cooking utensils and thermometers are also made from glass that contains borax.
Borax is sometimes used as a food preservative. It is also used in the textile industries, in tanning leather and in making paper. It is indeed a very versatile material.
Most of the world's supply of borax comes from Southern California. It has been estimated that there is more than a 100 year supply of borax in one California mine alone.
Borax may be taken from open pit mines, as in California's Mojave Desert. In these locations, miners strip away the covering ground to expose the borax bed. Workers then use dynamite to blast loose the solid borax. Large chunks of the material are then crushed and dissolved. The solution goes through many purification steps until borax crystals are obtained.
Borax is also obtained from dry lake beds. A solution is made and then allowed to stand in vats to separate the borax from the heavier salts, which sink to the bottom.
Kernite is 75 percent pure sodium borate. It was discovered in the Mojave Desert in 1926 and is today's major source of commercial borax.
Kernite is crushed and then dissolved in water. After the impurities are filtered off, it is allowed to recrystalize. This is a cheap and easy way to produce borax.
Tibet was the first important source of borax. Since the 1920s, however, the United States and California have produced most of the world's supply.
When borax crystals are heated in a loop of platinum wire, they swell because the water in them evaporates. When all the water is gone, a clear, glassy liquid remains. This liquid combines with many metallic oxides to produce borax beads of various colors.
In mineral and chemical analyses, the borax beads are used to detect the presence of certain metals. If cobalt is present, a dark blue bead appears. For copper, a light blue bead appears. The presence of nickel will produce a brown bead while manganese comes out amethyst.
Boric acid is made in the United States by treating borax with hydrochloric or sulfuric acid. It forms colorless, odorless crystals or a white powder that dissolves in water.