Chalk – this animal Svyatogorsky chalk.
In the waters of the oceans, there are different kinds of tiny plants and animals. One is the single-celled creatures called ‘foraminifera’ with shell lime. Otmiraya, they sink to the ocean floor. Over time, a thick layer is formed of these shells. Of course, this takes millions of years. Gradually, this layer is cemented and turns into a soft limestone that we call chalk.
How not to get dirty with chalk?
To make school chalk does not stain hands, enough to dip it for a few seconds in the diluted 2-3 times the milk. After this procedure is no longer dirty chalk and writing is still good.
To chalk writing on the blackboard better
To chalk writing on the blackboard better, you need to wash the board, and then wipe with a sugar solution.
What better use of chalk in the school?
School chalk is 2 basic types – lumpy and pressed. Lump Chalk is now very rare. This makes sewing chalk chalky lumps mined in a quarry. This chalk can even be eaten. It can be useless, but in extreme cases is not harmful.
The main component is calcium carbonate chalk. Natural (lumpy) chalk does not contain any other ingredients. The basis for the pressed as chalk – no carbonate and calcium sulfate (CaSO4), which is derived from gypsum (CaSO4-2H2O). In the manufacture of molded crayons in gypsum powder added components such as limestone, starch, and sticking agents (PVA glue, BF, casein, stationery, etc.) Molded chalks also contain different kinds of dyes.
These facts explain the fact that during the use of chalk may appear dry skin of hands, arise bundle nail plate, cracking skin of hands.
Therefore, the best chalk for his daily use at school – is a natural (lumpy) chalk, which is more than 95% composed of calcium carbonate, safe for human health
What chalk is edible and what is not?
Some of us more than once observed unexpectedly coming strangeness in taste, especially in childhood. Sometimes it is quite reasonable children six to ten years suddenly begin to drag in the mouth “dirtiest” and not simply drag and targeted search for a specific substance. This may be chalk, clay, coal, even limestone pebbles on the beach, match heads or land.
Someone remembers with affection as a child in the village with my grandmother secretly ate plaster, someone longs for “sweet” Cretaceous Soviet era.
Some of us have kept the style, for example, chalk, and in adulthood. Accidentally found “brothers” out of habit, these people seriously discuss the taste differences between different brands of chalk, and argue about whether harmful health chalk from a store office supplies and any tastier. Many women notice a passion for chalk whitewash or during pregnancy.
All of these habits are not accidental. After all the chalk – a natural source of calcium. Addiction to all calcareous rocks, including clay also shows the lack of this trace element in the body.
In stores and pharmacies, you, unfortunately, can not find food of chalk. All that now offers the industry – chalk it as a dietary supplement for pets.
Building chalk have in any case it is impossible – it is the roughly treated material containing a lot of impurities and chemicals that are added to give it certain properties.
Stationery chalk too insecure – often for hardness it is mixed with gypsum. Natural color chalk white, so any colored chalk prior can be considered toxic because of the dye contained therein. An exception may be only children’s crayons – the child loves to try “to the tooth” all new producers and take into account this fact.
It is best to eat natural chalk, mined in open pits or extracted from the rock.
Chalk on Mars:
Chalk is found only in the world, and studies show – on Mars.
In three meteorites of Martian origin ALN 84001, Stick and Shergottite contains calcium carbonate and traces of gypsum.
Pasta was made of chalk …
Pasta, a word of Italian origin, which OBO Zn Chet not only pasta but the mass is used in the manufacture of artists pastel crayons to draw. Thus triturated chalk, coloring powder and liquid water-based adhesive to a homogeneous mass. From the resulting mass is then shaped pencils are dried.