М. М. Кутепова The World of Chemistry Мир

Read the text again and entitle it. Then divide the text into logical parts, give titles to all of them thus making a plan.

Write out all the sentences, expressing the main idea(s) of each logical part and translate them into Russian.

Condense the sentences of the text where possible.

Write an abstract to the text in your own words using the plan and the sentences you've written out and condensed.

Remember: 1. An abstract is an introduction of a reader into the matter.

2. 
   An abstract is much more shorter than a summary.
   
3. 
   Points in an abstract are more generalized than in a^ summary.
   

6. 
   Revise the grammar and lexical material to Units 6 and 7 and translate the following text into Russian without a dictionary:
   

THE ORIGIN OF COAL
Carbon compounds are very abundant in nature. All organic substances are carbon compounds, and dead animals or plant matter, once exposed to the air, decay very rapidly owing to the oxidation brought about by the agency of bacteria. The gaseous products of this process of decay escape into bacterial decomposition, and have become trapped or fixed in rock. Coal and petroleum are supposed to be the result of this failure of nature’s cleaning system.
When plant matter from the great prehistoric forests came submerged in swamps and bogs, the supply of air was limited, and complete oxidation was, therefore, impossible.
These beds of dead plant matter gradually became covered with deposits of sand and mud, so that the pressure above them became very


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great, the beds of plant tissue being pushed deeper into the hotter zones of the Earth’s crust. As a result of this terrific compression, water is believed to have been pressed out of the plant remains and the chemical changes taking place resulted in the loss of hydrogen and hydrogen compounds such as methane (marsh gas).
The final result, after thousands of years, was coal: a material containing a high percentage of carbon. Different varieties of coal, dependent on the pressure involved, may be formed. The process of coal formation is generally believed as follows:
plant matter -> peat (29%C) -> lignite (43%C) -> bituminous coal (64%C) -> anthracite (87%C).
The percentages of carbon given above are average values from the analysis of a large number of coals, but the gradual increase in carbon content is clearly shown. If the pressure of the rock has been so great that all the hydrogen has been expelled, graphite is formed. Coal is not found, therefore, in the oldest rocks since the pressures involved would have expelled (удалили бы) all hydrogen from the original plant tissue. The theory of the biological origin of coal may be represented by the following diagram:
atmospheric carbon dioxide photosynthesis -> sugar starch -> cellulose —> (plant tissue) -> wood -> coal.
Thus, the solar energy stored by plants during the process of photosynthesis millions of years ago is liberated as heat energy in the combustion of coal today.

7.