What is written on the blackboard? Detailed answer

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What is written on the blackboard? Detailed answer

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What is written on the blackboard?

Gypsum.

School "chalk" is not chalk at all. Chalk is made up of calcium carbonate, as are coral, limestone, marble, human and fish skeletons, eye lenses, scale in kettles, and indigestion pills like Rennies, Setlers, and Tams.

Gypsum is made up of calcium sulfate. Someone will object that, well, you might think, there is little difference, but although both are very similar in appearance, in fact they are completely different and do not even consist of the same chemical elements.

On the other hand, many substances that seem completely different are actually made up of the same chemical elements. Take, for example, carbon, hydrogen and oxygen. Combined in different proportions, they give different things like testosterone, vanilla, aspirin, cholesterol, glucose, vinegar, and alcohol.

Technically known as hydrated calcium sulfate, gypsum is one of the most widely used materials in the world. Gypsum has been mined for 4000 years - the plaster inside the Egyptian pyramids is made from gypsum - and today it is used in a huge range of industrial processes, the most common of which is ordinary building plaster.

About 75% of all gypsum produced in the world is used for the manufacture of plaster and other building products: drywall, tiles and the so-called "Paris", or building gypsum (plaster of Paris). Gypsum is a key ingredient in cement and is used in the production of fertilizers, paper and textiles. A typical new American home contains more than seven tons of this material.

Building gypsum is called "Parisian" because in Paris itself and around it, especially in Montmartre, clay contains rich deposits of gypsum.

In nature, gypsum is also found in the form of alabaster - a snow-white, translucent material that goes to statues, busts and more.

Alabaster can be painted almost any color, and heating can even make it look like marble. Powdered alabaster has traditionally been considered a remedy for pain in the legs. In the old days, it was common to pick out a piece from a church statue to prepare a healing ointment.

As ironic as it sounds, the word "gypsum" itself comes from the Greek gypsos, which means "chalk".

Author: John Lloyd, John Mitchinson

Random interesting fact from the Great Encyclopedia:

Who and where managed to survive and not become disabled after his brain was pierced by an iron rod?

In 1848, an American railroad worker, Phineas Gage, suffered a work injury when a metal rod pierced the frontal lobes of his brain, entering through his left cheek and exiting near the top of his head. Less than an hour later, Gage came to his senses, and then, with the help of colleagues, went to the surgeon, calmly arguing about the hole in his head. The wound developed an infection, but the worker recovered and lived another 12 years. His memory, speech, perception were not disturbed, only his character changed - he became more irritable and lost his inclination to work.

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James Bond fans are familiar with two super spy movies called Casino Royale: one is an unofficial parody of 1967, the other is a 2006 movie with Daniel Craig. And in that, and in another film there is, of course, a casino in which there is a croupier. However, if it comes to someone's mind to shoot another remake in a few years, then there may no longer be a piano or a croupier.

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