I. Read and translate the text

SALT

Salt is one of the most common materials. Chemically, salt is a compound of sodium and chloride. The common salt we use at home is produced in various ways: from sea water or the water of salt lakes, from salt springs, and from deposits of rock salt.

A gallon of ordinary sea water contains about a quarter of a pound of salt. Some salt lakes such as the Dead Sea or Great Salt Lake contain even larger percentages of salt.

Beds of rock salt are found in various parts of the world and are sometimes hundreds of feet thick. They were probably formed by the evaporation of ancient seas whose bottoms were later covered by layers of mud and sand. Salt springs may have been formed by the filtering of water through these beds of rock salt.

Most commercial salt is made from rock salt. Wells are drilled down to the salt beds. Pure water is pumped down to the rock salt through a pipe. The water dissolves the salt. The brine or salt water is forced up to the surface through anther pipe.

After the salt has been brought up in the form of brine, it is evaporated by steam in open pans or in vacuum pans until it forms grains. Table salt has a very fine grain. Salt today has many uses in industry, such as in the manufacture of glass, soap, and leather.

Vocabulary

compound – соединение

spring – источник

deposit – месторождение

ordinary – обычный

thick – толстый

evaporation – испарение

mud – ил, грязь

brine – соляной раствор

II. Answer the questions

1. What is salt chemically?

2. What salt do we use at home?

3. How much does a gallon of ordinary sea water contain?

4. What lakes contain even larger percentages of salt?

5. Where are beds of rock salt found?

6. How are salt springs formed?

7. What is pumped down to the rock salt through a pipe?

8. What does table salt have?

III. Make up your own sentences with the vocabulary

IV. Complete the sentences

1. Chemically, salt is …

2. salt lakes such as …

3. … are found in various parts of the world.

4. and are sometimes hundreds of feet thick.

5. Salt springs may have been formed by …

6. Pure water is pumped down …

V. Agree or disagree with the statements

1. The common salt we use at home is produced in only one way - from sea water.

2. A gallon of ordinary sea water contains about a quarter of a pound of salt.

3. Most commercial salt is made from sea water.

4. Table salt has a very fine grain.

VI. Retell the text

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I. Read and translate the text

SOIL

If the surface of the earth were not covered with soil, man would perish. Without soil, plants could not grow and human beings and other animals would have no food.

Soil is the loose, powdery earth in which plants grow. It is made up of very small pieces of rock and decayed plant and animal materials. The small pieces or particles of rock were once parts of larger rocks. The plant and animal materials come from plant and animal bodies.

No rock is so hard that it cannot in time be broken into pieces. Glaciers push great piles of rocks ahead of them as they move along and this pushing and grinding help crumble the rocks.

Water with chemicals in it will dissolve and wear away some kinds of rocks. Changes in temperature often help break rocks into small pieces. The heating and cooling of rocks may cause cracks to appear. Water gets into cracks, freezes, and cracks the rocks even more. Even plant roots may cause rocks to break.

Sometimes the seeds of trees fall into cracks in rocks, the seeds sprout, and as the roots of the plant grow, they help split the rock. Wind also helps crumble rocks by hurling sand against the rocks. But this is only the beginning of soil-making. To make real soil the sand or fine particles of rock must have “humus” added to it. Humus is an organic material that comes from plants and animal bodies. The bodies of almost all dead land plants and animals become a part of soil, through the work of bacteria.

Bacteria cause the plants and animals to decay and make the soil fertile. Earthworms and many kinds of insects help to make soil rich. The richest layer of soil is at the top and is called topsoil. The next layer is called – subsoil, it contains rocks. The layer beneath is bedrock, which is under the soil everywhere.