Gas
Collier's New Encyclopedia (1921)
in chemistry, a substance possessing the condition of perfect fluid elasticity, and presenting under a constant pressure a uniform rate of expansion for equal increments of temperature, but when reaching its maximum density behaving like a vapor. All gases can be condensed into liquids by cold and pressure. Some of the elements, as oxygen, hydrogen, nitrogen, chlorine, and probably fluorine, are gases at ordinary temperatures. Atmospheric air is a mechanical mixture of 77 parts by weight of nitrogen, and 23 of oxygen, or 79 volumes of nitrogen mixed with 21 volumes of oxygen. Gases are formed by the dry distillation of animal and vegetable substances, which yield carbon dioxide, carbon monoxide, ammonia, nitrogen, hydrogen, sulphur dioxide, hydrogen sulphide, and hydrocarbons. The gas of commerce is carburetted hydrogen (CH4). Its frequent disengagerment in coal mines with resultant explosions, generally fatal to many lives, miners to give it the has caused the name of fire-damp. In parts of the world it issues from crevices or holes in the strata in so moderate and continuous a stream, as to burn with a huge jet instead of exploding. It was discovered in the United States about 1845, and is known as natural gas. Gas wells abound in Ohio, Indiana, Pennsylvania, and the West. This natural gas serves the purposes of illuminating and heating. The GAS GAS COCK SUPPLY PIPE RUBBER BAG GAS INLET PIPE INLET VALVE GAS SUPPLY OF OTTO GAS ENGINE ignition of carburetted hydrogen may be seen in any coal fire. It has been discovered that giant jets of apparently. similar gas flames exist in the sun, and are one main source of its light and heat.
What Has Changed in the Last Century
Collier's 1921 account still describes air as simply "77 parts by weight of nitrogen, and 23 of oxygen" — leaving out argon, which Rayleigh and Ramsay had identified in air in 1894, and the neon, krypton and xenon Ramsay found soon after; modern figures give about 78% nitrogen, 21% oxygen and 0.93% argon by volume. The claim that "all gases can be condensed into liquids by cold and pressure" survives, but helium proved the awkward case: liquefied by Kamerlingh Onnes in 1908, it will not freeze under cooling alone and needs applied pressure to solidify. Most decisively, the closing remark that "giant jets of apparently similar gas flames" light the sun is now wholly superseded: the sun shines by nuclear fusion of hydrogen into helium, worked out in the 1930s by Bethe and others, not by combustion. On the commercial side, the manufactured coal gas the entry treats as "the gas of commerce" has almost entirely given way to natural gas, now shipped worldwide in liquefied form.
Written for this edition, 2026.