Oxygen
2 of the 6 encyclopedias on this shelf carry an entry for Oxygen. Both are reproduced below, so you can see where they agree and where they differ.
The Encyclopedia of Founding (1892)
This gas was obtained by Dr. Priestley in 1774 from red oxide of mercury exposed to a burning lens, and again in the following year by the Swedish chemist Scheele. With regard to the importance of this great discovery Prof. Liebig observes: "Since the discovery of oxygen the civilized world has undergone a revolution in manners and customs. The knowledge of the composition of the atmosphere, of the solid crust of the earth, of water, and of their influence upon the life of plants and animals, was linked with that discovery. The successful pursuit of innumerable trades and manufactures, the profitable separation of metals from their ores, also stand in the closest connection therewith. It may well be said that the material prosperity of empires has increased manifold since the time oxygen became known, and the fortune of every individual has been augmented in proportion." Eight ninths of water consist of oxygen; it forms one fifth of air and about one half of silica, chalk, and alumina, which three constitute the chief substances of the earth's surface. It is absolutely essential for the support of animal life. In mechanical combination with nitrogen it forms the atmosphere surrounding the globe, and is given off by all growing plants when under the influence of sunlight. Its chemical affinities for other elementary substances are very powerful, combining with all except fluorine. Owing to the intensity with which many of these combinations takes place, this gas has the power of supporting combustion in an eminent degree. It is tasteless, colorless, inodorous, and has hitherto resisted all attempts to liquify it. Combustion is nothing more than a chemical union of the oxygen of the air with the combustible body or some of its elements. We make the fire hotter by bringing more air in contact with the fuel. See COMBUSTION; FLAME, etc.
Aiton's Encyclopedia (1910)
oks'i-jen, an elemental gas, without color, taste, or odor. Its most prominent characteristic is its power to burn up many substances, that is to say, to unite with them and give off heat and light during the process. Substances which burn or unite with oxygen are said to be combustible. Burning bodies obtain oxygen usually from the air. If the air is shut off burning ceases. Oxygen was discovered by Priestley in 1774, and was named by the chemist Lavoisier. It is the most abundant element in the world. It forms one-fifth of the air, eight-ninths of the water, and from forty-four to forty-eight hundreths of the solid crust of the earth. It enters into combination with other elements to make up the structure of all plants and animals. Animals breathe air that the blood may absorb oxygen. Animal heat and energy are supplied by the action of oxygen. A combination of oxygen with another element is called an oxide. Thus we have mercuric oxide, zinc oxide, silver oxide, oxide of iron, etc. A dioxide is a compound with a double quantity of oxygen. Carbon dioxide , for instance, is a union of carbon with a double quantity of oxygen. The rusting of iron is the slow formation of an iron oxide. It is interesting to know that under a pressure of fifty atmospheres and a temperature of--119 degree. C., oxygen becomes a pale, steel-blue liquid, and that it may be frozen into a white solid. See Ozone ; Water ; Air ; Sand ; Sugar ; Fire
What Has Changed in the Last Century
The chemistry here still holds: oxygen is about 21 per cent of air, eight-ninths of water by weight, and the most abundant element in the earth's crust. Two claims have fallen. The 1892 account says oxygen "has hitherto resisted all attempts to liquify it," though Cailletet and Pictet had in fact liquefied it in 1877 — a fact Aiton's has caught up with by 1910, correctly giving the pale blue liquid; and its statement that oxygen combines with everything "except fluorine" ended with the synthesis of oxygen difluoride in 1929. Since then oxygen has gained three known isotopes (1929), lost its long job as the standard for atomic weights when carbon-12 replaced it in 1961, and acquired a history: the Great Oxidation Event, the arrival of free oxygen in the atmosphere from photosynthesising microbes roughly 2.4 billion years ago.
Written for this edition, 2026.