Q. What is carbon?
A. The solid part of fuel. It abounds also in all animal bodies, earths, and minerals.
Q. Mention some different species of carbon.
A. Common charcoal, lamp-black, coke, black lead, and the diamond, are all varieties of carbon.
Q. What is hydrogen?
A. An inflammable gas. The gas used in our streets, is only the hydrogen gas driven out of coals by heat.
Q. What are the peculiar characteristics of hydrogen gas?
A. Though this gas itself will burn, yet a candle will not burn when immersed in it; nor can an animal live in it. Hydrogen gas is the lightest of all known substances.[7]
[7] Hydrogen gas may be made thus:—Put some pieces of zinc or iron filings into a glass: pour over them a little sulphuric acid (vitriol), diluted with twice the quantity of water; then cover the glass over for a few minutes, and hydrogen gas will be given off.