The Fairy-Land of Science · Lecture VIII, part 3 · Part 8: Lecture VIII: The history of a piece of coal
24. What coal gives us, and the plants that did their work
Goal: Your child can explain that pressing and heat turned old plants into coal, and can list some things people get from coal.
You'll need
- A soft pencil and a sheet of paper
- Two or three slices of soft bread and a heavy book
- Science notebook and pencils
What's in the book
Pages 186 to 192. The swamp sank under the sea and was covered with sand, then rose for a new forest, layer after layer; the coal fields of England; how weight and heat turned peat to hard coal; pencil lead pressed from graphite dust; making coal-gas in a clay pipe; paraffin, dyes and sweet flavors from coal-tar; and the plants of long ago that did their work without seeing what good it would do.
The lesson, step by step
Hook question
SayThe plants of the coal forest lived quietly, died and were buried for ages. Did they do any good?
Let your child think. Buckley's answer comes at the end.
Read together
Read page 186.
Such is the history of how the coal which we now dig out of the depths of the earth once grew as beautiful plants on the surface.
Then read or tell pages 187 and 188: hundreds of feet of rock pressed the peat for ages, and heat from deep inside the Earth baked it. Coal that flames still has the plant oils and gas in it; hard coal has lost them.
Try it: squash it
Press the slices of bread flat under the heavy book for a few minutes. The soft, puffy bread becomes a thin, hard layer.
SayThat is what weight did to the peat.
Scribble with the pencil. Buckley explains that pencil "lead" is carbon (graphite) dust pressed hard into sticks, just as coal is pressed carbon.
Watch only: gas from coal
Watch only: don't try this at home. Buckley packed powdered coal into the bowl of a clay tobacco-pipe, sealed it with clay, and heated it over a spirit-lamp:
I have brought a tobacco-pipe, the bowl of which is filled with a little powdered coal, and the broad end cemented up with common clay.
Gas came out of the stem and burned. This uses hot flames and a burnable gas. Look for a video of a teacher doing it. Gas made this way once lit the streets of whole cities.
Gifts from coal
Read page 190.
Thus from coal we get not only nearly all our heat and our light, but beautiful colours and pleasant flavours.
Buckley lists lamp oil, dyes (mauve, magenta and violet) and flavors for candies, all from coal-tar. Then read page 192, her lesson from the coal plants:
These saw no results during their own short existences, they only lived and enjoyed the bright sunshine, and did their work, and were content.
Tell it back and check
Your child tells the whole history of a piece of coal, from swamp to fire. Then ask:
1. What turned soft peat into hard coal?
2. Name two things people got from coal.
3. What did Buckley say we can learn from the coal plants?
What we know now
Burning coal gives off carbon dioxide and smoke. Too much carbon dioxide in the air warms the Earth's climate, so today many countries use less coal and more sun, wind and water power. Coal still holds sunlight from 300 million years ago, just as Buckley said.
Afterwards
Notice it this week: look for layers in rocks, road cuttings or cliffs. Notice where your home gets its heat and electricity, and ask a grown-up what powers them.
Tip
Buckley ends with lines from Tennyson's In Memoriam. They are lovely read aloud, even if your child doesn't follow every word.
Answers to the book's problems
1. The great weight of rock above pressing it for a very long time, and heat from inside the Earth. 2. Any two: heat, gas for lights, lamp oil (paraffin), dyes, flavors for sweets, power for engines, railways and ships, and for making iron. 3. To do our work faithfully and be content, even if we can't see what good it will do; it may help others long after.
Worked out for this site from the scan. If a number in your copy differs, trust the book.