Text What is a diamond?

If you had a piece of putty and wanted to make it hard, what would you do? You’d squeeze it and press it, and the more you squeezed and pressed, the harder it would become.

Diamonds were made in the same way by nature. A hundred million years ago, the earth was in its early cooling stages. At that time, there ex­isted beneath the ground a mass of hot liquid rock. This was subjected to extreme heat and pressure. Carbon which was subjected to this pressure be­came what we called “diamonds”.

The word “diamond” comes from the Greek word adamas, which means “unconquerable”. A diamond is truly unconquerable, for nothing in the world can cut it – except another diamond!

The first records we have of people deliberately looking for diamond indicate that this happened in India. Diamond mining as an industry started there more than 2,500 years ago!

Diamonds were prized from the very beginning. In fact, before the fifteenth century, diamonds were still so rare that only kings and queens owned them.

Today, the capital of the diamond empire is j South Africa where, in 1867, important sources of diamonds were discovered by accident. A poor farmer’s child found a pretty stone. A shrewd neighbor who recognized it as a gem diamond bought it, and when he sold it, diggers of all ages and nationalities flocked to the scene.

Within a year, three great diamond fields were found and the city of Kimberly, the center of a great diamond empire, was born.

The only difference between an industrial dia­mond and any other kind of diamond is that the industrial diamond is of an inferior grade. If it were of perfect quality, beautiful in color and without a flaw, the diamond would, of course, be used in jew­elry, where it brings higher prices.

It may seem astonishing to you that something as precious as a diamond is used in industry at all, but the diamond has been called the “emperor of industry”!

So three fourths of all diamonds that are found don’t go into jewelry at all. They are used in indus­try. And they are used because of their extreme hardness. For instance, about 20 per cent of all in­dustrial diamonds are mounted in drills and used by mining companies to drill through rock.

Diamonds are crushed to dust and this diamond dust is used in making diamond-grinding wheels. These wheels sharpen certain tools and also grind lenses. Other diamonds are used in dies. Without diamonds, some of our most important industries would have to shut down.

Ex.1 Think and answer.

1 How does putty material change of pressed and squeezed?

2 How did the Earth look like a hundred million years ago?

3 Where did the word “diamond” come from?

4 How hard are the diamonds?

5 Where did the diamond mining industry start?

6 What is City of Kimberly famous for?

7 What does the price of a diamond depend on?

8 What is the difference between an industrial and any other kind of diamonds?

9 Why is the diamond called “the emperor of industry”?

10 What are diamond-grinding wheels used for?

Text What is platinum?

Platinum is a metal – but what an amazing metal it is! It is grayish white in color, and its name comes from the Spanish plata and means “little sil­ver”.

Platinum is harder than copper and almost as pliable as gold. You could take a single ounce of platinum and stretch it out into a fine wire that would reach from New York City to New Orleans, Louisiana. A cube of platinum measuring a foot each way would have a weight of more than half a ton! Platinum is almost twice as heavy as lead.

Platinum is usually found in ores often mixed with the rare metals palladium, rhodium, iridium, and osmium, which are called “platinum metals”. Occasionally, it is found with metals such as gold, copper, silver, iron, chromium, and nickel. It is found in the form of small grains, scales, or nug­gets.

Large deposits of platinum were first discovered in South America in the eighteenth century. For a great many years it was considered quite useless, and so it was cheap. Then, when people began to find how useful this metal could be, and since it is quite rare, the price went up to the point where that cube of platinum mentioned above would have been worth $2,500,000.

What makes platinum especially useful is that it resists oxidation, acids, and heat. The melting point of platinum is about 3,190 degrees Fahren­heit! For most purposes, platinum is mixed (alloyed) with one of the other “platinum metals” or with silver, gold, copper, nickel, or tin.

While the chief use of platinum is for opened or closed, in laboratory weights, in instruments for exact measurement of temperatures, and for fus­es in delicate electric instruments.

Ex.1 Think and answer.

1 What is the word "platinum" derived from?

2 What color is platinum?

3 How hard is platinum?

4 How heavy is platinum?

Text What is water?

When scientists wonder whether there is life on other planets, they often ask this question: “Is there water there?” Life as we know it would be impossible without water.

Water is a tasteless, odorless, colorless compound that makes up a large proportion of all living things. It occurs everywhere in the soil, and exists in varying amounts in the air.

Living things can digest and absorb foods only when these foods are dissolved in water. Living tissue consists chiefly of water. What is water made of? It is a simple compound of two gases: hydrogen, a very light gas; and oxygen, a heavier, active gas.

When hydrogen is burned in oxygen, water is formed. But water does not resemble either of the elements which compose it. It has a set of properties all its own.

Water, like most other matter, exists in three states: a liquid state, which is the common form; a solid, called “ice”; and a gas, called “water vapor”. In which one of these forms water shall exist depends ordinarily on the temperature.

At 0 degrees centigrade, or 32 degrees Fahrenheit, water changes from the liquid to the solid state, or freezes. At 100 degrees centigrade, or 212 degrees Fahrenheit, it changes from the liquid to the gaseous state. This change from liquid, visible water to the invisible water gas is called “evaporation”.

Thus, if a piece of ice is brought into a warm room, it starts to become liquid or melt. If the room is warm enough, the little puddle of water formed from the melting ice finally disappears. The liquid is changed into water vapor. When water is cooled, it expands just before it reaches the freezing point.

Water as it occurs in nature is never pure in the true sense. It contains dissolved mineral material, dissolved gases, and living organisms.