Oxygen
Collier's New Encyclopedia (1921)
in chemistry, symbol 0; at. wt. 16; a dyad element existing in the free state in the atmosphere, and in combination in the ocean. İt forms about one-fifth of the former and eightninths of the latter. It is also present in the great majority of substances forming the earth's crust, and is the most abundant of all the elements. It was discovered in 1774 by Scheele in Sweden and Priestley in England independently, but the name was given by can be printed Lavoisier some time after. It obtained pure by heating black oxide of manganese, or a mixture of this oxide with potassic chlorate in a retort, and collecting the gas over water. When , di- pure it is without color, taste, or smell. the sustaining principle of animal River It is phenomena of , life and of the ordinary the influence of cold North- combustion. Under and high pressure it has been reduced OXYHYDROGEN BLOWPIPE. An pre- apparatus in which hydrogen is burnt When hycentered in a stream of pure oxygen. Dairy drogen burns in air or oxygen, water is and produced. When combustion takes place gloves, in pure oxygen, a very high temperature Pop. results, stated by Bunsen to be 2,844 ° C. This temperature is capable of fusing highly refractory substances, and boileven of of bringing platinum to the ing point. The The original "limelight" was produced by directing an oxyhydrogen flame against lime. For industrial uses, the oxyhydrogen blowpipe has been almost entirely superseded by the oxyacetylene burner, which depends on similar principles, acetylene being substituted for hydrogen. celebrated
What Has Changed in the Last Century
The chemistry Collier's set out in 1921 is still sound: oxygen is the most abundant element in the earth's crust, about a fifth of the air, and eight-ninths of water by weight. What has moved is scale and method. Nobody now heats black oxide of manganese for industrial oxygen; since the Linde and Claude air-liquefaction plants of the early 1900s it has come from the fractional distillation of liquid air, and after the basic oxygen steelmaking process spread in the 1950s the world began consuming it by the hundreds of millions of tonnes, alongside its use in hospitals and as liquid oxygen in rocket propellant. The flat "at. wt. 16" also dated quickly: heavy isotopes oxygen-17 and oxygen-18 were identified in 1929, and in 1961 chemists abandoned oxygen as the standard of atomic weight in favour of carbon-12.
Written for this edition, 2026.