AIR

From Philosopedia

AIR

Along with water, air is one of Earth’s treasures. Both water and air are shockingly taken for granted by most. Air is colorless, odorless, and tasteless. It envelops Earth. It is a gaseous mixture, mainly nitrogen (approximately 78%) and oxygen (approximately 21%), with lesser amounts of argon, carbon dioxide, hydrogen, neon, helium, and other gases. Freethinker Joseph Priestley (1733-1804) in 1774 was the first to announce that he had isolated oxygen; however, Carl Wilhelm Scheele (1742-1786) had discovered oxygen in 1772 but not publicized his findings. The fact that the gas is a component of the atmosphere was finally and definitely established by Antoine Laurent Lavoisier (1743-1794)—he disproved the earlier theory of phlogiston, and his Traité él´mentaire de chimie (1789) contained the ideas which set chemistry on its modern path. Most aquatic animals use a respiratory organ called a gill to obtain oxygen by breathing water. Most other animals use a nose.

In Australia, scientists have found that a newborn mouse—a marsupial called the Julia Creek dunnart—gets its oxygen through its skin. Its offspring are among the smallest newborn mammals known, about one-sixth of an inch long and weighing slightly more than half an ounce. The young mouse’s skin is hairless and rich in blood, providing a convenient means for gas exchange. For mice up to about four ounces in weight, respiration through the skin exceeded that through the lungs. But as the mice grew more, the lungs took over.

(CE; Nature, March 1999)