Note 58 — Chapter IX · STRATIFIED ROCKS OF ORGANIC ORIGIN—ILLUSTRATIONS FROM VEGETABLE LIFE.
Reading edition
Carbonic acid gas contains two equivalents of oxygen to one of carbon, the chemical expression for the compound being CO2; carburetted hydrogen, which is the gas we employ in illuminating our streets and houses, contains four equivalents of hydrogen to two of carbon, and is chemically expressed by the symbols C2H4; water is composed of one equivalent of oxygen, and one of hydrogen, the symbolic form being HO.