英文科學(xué)讀本 第三冊(cè)·Lesson 40 Paraffin Oil

Lesson 40 Paraffin Oil

Our lessons on coal-tar and naphtha, Fred, like a good many others, have led us farther than I thought they would, said Willie. "Who would have thought now that they had anything to do with paraffin oil?"

Does paraffin oil come from coal-tar and naphtha then? asked Norah.

No, said Fred, "not exactly. But teacher has been showing us today that there are a great many inflammable liquids very much like the coal-naphtha in their properties. Some of them are prepared by man, but most of them are got direct from the ground."

Petroleum or rock-oil is the commonest of these. It is obtained from springs in many parts of the world, but chiefly in America and Russia.

Teacher says that these oil springs in some places rise to the surface of the ground, but as a rule deep wells are sunk, and the oil is pumped up from them.

The petroleum as it comes from the earth is of a dirty greenish-yellow color and very thick and oily. In this state it is unfit for use. It is pumped from the wells into great tanks, whence it is sent along iron pipes to the refining factories to be purified.

A coarse rough oil very like this is obtained from peat, from various kinds of coal, and, as we have seen, from coal-tar.

In the refinery this coarse oil separates into a variety of different substances. There is first of all the clear liquid commonly called paraffin oil, for burning in lamps.

That which is obtained from petroleum or rock-oil is called kerosene.

Then, besides this, there is a beautiful, fine, white substance like wax, which is known as solid paraffin, and is largely used in making candles.

Lastly, that which is left forms a rough coarser kind of oil, which is used for oiling machinery.

Teacher explained to us how the paraffin oil burns in a lamp, said Willie. "The porous wick absorbs the oil, and the heat of the flame makes it evaporate. It is not the oil itself that burns, but the gas or vapor from it, just as the ordinary coal-gas burns in our gas-burners."

Teacher showed us that the oil itself will not burn. He thrust a burning match into some of it in a saucer. The oil did not take fire. It actually put out the match.

He told us that it is only when paraffin is allowed to get heated that there is any danger. When it is heated it gives off this gas, and the gas is very explosive when mixed with air.

He showed us another liquid called benzine, which is obtained by refining the coal-tar naphtha. He poured a small spoonful of this into a saucer and put a light to it, and it blazed up in a moment with a little bang.

He said it was the gas or vapor only in this case that exploded. But benzine is much more dangerous than paraffin, because it constantly evaporates with the heat of an ordinary warm day.

SUMMARY

Paraffin, petroleum, or rock-oil is an inflammable liquid, which is obtained from oil-springs in the ground. The coarse liquid, as it is pumped up, is purified, and made to yield paraffin wax, and refined oil for burning in lamps. Benzine is another inflammable liquid—even more inflammable than paraffin oil. It is made by refining coal-tar naphtha. An ordinary warm day will cause it to evaporate. It is the vapor, or gas rising from it, which takes fire and explodes, when it mixes with the air.