предыдущая главасодержаниеследующая глава



The early alchemists1 spent most of their time trying to change common metals such as lead into gold. Many people laughed at the idea. The alchemists had no clear notion of what they were doing. They simply tried all sorts of strange "recipes" and hoped to make the change take place by magic.

Now the scientists know that the alchemists were not entirely wrong. For it is possible for certain metals to change into others. The discovery and study of radium showed that this is true. The alchemists would be unhappy, however, because radium, which is thousands of times more expensive than gold, goes through a series of changes and becomes common lead.

Radium is one of the simple substances, or elements, that scientists call radioactive. Radioactive elements change all by themselves into other elements. As they do so, they send out powerful rays. These rays can go through many substances that light cannot go through. The rays from radium, for instance, can go through flesh and be used to treat such diseases as cancer.

A common use of radium is in paint. Paint containing very tiny amounts of this element is used on the hands of clocks and watches to make them glow in the dark. Chemicals in the paint give out frashes of light when hit by rays from the radium.

Carelessly used radium can cause terrible burns. Supplies of it must be kept in special containers with thick lead walls.

Pure radium is a white metal. It is very heavy. But there is so little of it that no one has ever been bothered by its weight. Only a few pounds have been produced in the whole world.

Radium was discovered by the French scientists Pierre and Marie Curie. The story of their work is one of the really exciting chapters in the story of science.


1) What did the early alchemists spend most of their time on?

2) Is radium one of the radioactive elements?

3) What is a common use of radium?

4) What can carelessly used radium cause?

5) Whom was radium discovered by?


1. alchemists - алхимики


"He is the salt of the earth1." "He is not worth his salt2." Both of these are common sayings. They show that salt is an important substance. It is even more important today than in the past.

At times salt has been used as money. The word salary comes from sal, the Latin word for "salt". The Roman soldiers used to be paid partly in salt.

The Arabs used to believe that eating another person's salt meant that you would do him no harm. It was a bad sign if anyone refused to eat salt when he was a guest. In some parts of Africa it is still good manners, when you meet a friend, to let him lick your cake of salt.

There are superstitions about salt, too. Spilling salt is supposed to bring bad luck. But the person who spills the salt can keep the bad luck away if he throws a little over his left shoulder. Another superstition is that you can catch a bird if you sprinkle a little salt on its tail.

Salt is something which everyone has to have. We cannot live without it. Of course, most of us like the taste of salt, too.

Sea water has salt in it. But most of the salt we buy comes from deep in the ground. It comes from layers of rock salt there. The layers were formed when salty seas of long ago evaporated. Later, the salt was covered with other rocks.

It is not hard to get salt from the layers of rock salt underground. Mines can be dug down, and the salt taken out in blocks. Or water can be forced down through pipes to the salt and then pumped up again. The salt that has been dissolved in the water can easily be taken out of it.

Most of the salt we buy is in tiny crystals. Under a microscope they look like tiny cubes of glass.

Chemicals made from salt are used in the manufacture of rubber, and steel, and dyes, and drugs. Chemicals from salt are used to soften water and to bleach cloth. They help in scouring wool and making leather. The list could go on and on. A great many of our factories of today would be forced to shut down if there were no more salt.


1) How has salt been used at times?

2) What does the word "salary" come from?

3) Are there any superstitions about salt?

4) When were the layers of rock salt formed?

5) How are chemicals made from salt used?


1. "He is the salt of the earth." - Таких хороших людей, как он, мало.

2. "Не is not worth his salt." - Он никчемный человек.

предыдущая главасодержаниеследующая глава

© GENLING.RU, 2001-2021
При использовании материалов сайта активная ссылка обязательна:
http://genling.ru/ 'Общее языкознание'
Поможем с курсовой, контрольной, дипломной
1500+ квалифицированных специалистов готовы вам помочь