"Instead of the bowl of the pipe with its pinchof coal-dust, they have large, strongly-built, closed chambers called retorts, made of firebrick and iron, each one holding nearly a quarter of a ton of coal.
"Instead of the stem, they have long iron pipes, and instead of the little glass tube, they haveenormous iron gas-holders, many times bigger than our school."SUMMARY
To make coal-gas, the coal is heated in closed retorts, and the gas and smoke are allowed to pass away by long pipes, into great receivers, to be puri?ed. The cinders left from the burning are coke.
Lesson 35
More about the Fish
"I want you to think again about the fish and its breathing, Norah," said Fred. "It gets its air from the water. Now it is quite clear that it cannot get as much air in this way as lung-breathing animals can. We live and move about in an ocean of air itself. Now just tell me how you feel when Will and I give you a good long "pepper" with your jumping-rope.""I get out of breath and very hot; I breathe veryrapidly," said Norah.
"That"s quite right," said Fred. "You then breathe in more air than usual. Our bodies are always warmer or colder according to the amount of air we breathe in.
