Carbon dioxide (carbonic anhydride or carbonic acid) is a colourless, poisonous, heavy gas - twenty-two times as heavy as hydrogen - composed of carbon and oxygen with 12 parts by weight of carbon and 32 of oxygen. It is the final product of the complete combustion of carbon. Carbon dioxide is present as about five percent of exhaled air. Carbon dioxide has been variously known in the past as carbonic dioxode, carbonic acid and fixed air.
Carbon dioxide acts as a narcotic poison when present-in the air to the extent of only 4 or 5 percent. It may be tested for by leaving a white precipitate when bubbled through lime-water. It is disengaged from fermenting liquors and decomposing vegetable and animal substances, and forms the choke-damp of mines. From its weight it has a tendency to subside into low places, vaults and wells, rendering some low-lying places, as the upasvalley of Java, and many caves, uninhabitable.
Carbon dioxide has a pleasant, acidulous, pungent taste, and aerated beverages of all kinds - beer, champagne, and carbonated mineral water - owe their refreshing qualities to its presence, for though poisonous when taken into the lungs, it is agreeable when taken into the stomach. This acid is formed and given out during the respiration of animals, and in all ordinary combustions, from the oxidation of carbon in the fuel. It exists in large quantity in all limestones and marbles. It is evolved from the coloured parts of the flowers of plants both by night and day, and from the green parts of plants during the night. During the day plants absorb it from the atmosphere through their leaves, and it forms an important part of their nourishment. Research Carbon Dioxide
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SciTech
Research Carbon Dioxide