Classification of fuels

The principal fuels used at present for making steam are coal, coke, wood, charcoal, peat, mineral oil, natural and artificial gas. All kinds of fuel may, in fact, be virtually subdivided into three classes: solid, liquid and gaseous. All coals seem to be derived from vegetable origin and their differences appeared as a result of the varying conditions under which they were formed. Anthracite coal consists almost entire­ly of carbon and inorganic matters; it contains little or no hy­drocarbon at all. Some varieties appear to approach graphite in their characteristics and are burnt with difficulty unless at first mixed with other coals. Good anthracite is hard, compact and lustrous. It burns with very little flame unless it is moist, and gives a very intense fire, free of smoke. Even when carefully used, it is liable to break up at high temperatures and, in this way, the fine pieces may be lost with the ash. Semianthracite contains some hydrocarbon, is less dense than anthracite, ignites at once, and burns readily with a short flame. Bituminous coals contain a large and varying percents of hydrocarbons or bituminous matter. Their physical properties and behavior, when burning, vary widely so that classification is difficult, though at least three kinds may be distinguished: dry bituminous coals, caking bituminous coals and, at last, long-flaming bituminous coals. The latter has a strong ten­dency to produce smoke; some do and some do not cake at all while burning. Charcoal is made by charring wood; it is no longer used for making steam but is widely applied for special metallurgical purposes.

Lesson 12

Part 1

The gerundial constructions

The gerund and the words relating to it form gerundial constructions that usually begin with a preposition, a possessive pronoun or a noun. Gerundial constructions can be of two types:

1. Dependent gerundial constructions;

2. Absolute gerundial constructions.

Dependent gerundial constructions

Dependent gerundial constructions are constructions which don’t have a word denoting a doer before gerund. These gerundial constructions are translated into Russian by a subordinate clause and gerund itself is translated by a predicate, e.g.:

This polymer differs from that one by having absorption properties - Этот полимер отличается от того тем, что он обладает адсорбционными свойствами.