[1] Writing in the Geographical Journal, March 1894, on “Evolution of Indian Geography,” he says: “The plants of Indian and African coal measures are without exception identical, and among the few animals which have been found in India one is indistinguishable from an African species, another is closely allied, and both faunas are characterized by the very remarkable genus group of reptiles comprising the Dicynodon and other allied forms (see Manual of Geology of India, 2nd ed. p. 203). These, however, are not the only analogies, for near the coast of South Africa there are developed a series of beds containing the plant fossils in the lower part and marine shells in the upper, known as the Uitenhage series, which corresponds exactly to the small patches of the Rajmahál series along the east coast of India. The few plant forms found in the lower beds of Africa are mostly identical with or closely allied to the Rajmahál species, while of the very few marine shells in the Indian outcrops, which are sufficiently well preserved for identification, at least one species is identical with an African form. These very close relationships between the plants and animals of India and Africa at this remote period appear inexplicable unless there were direct land communications between them over what is now the Indian Ocean. On the east coast of India in the Khasi Hills, and on the coast of South Africa, the marine fossils of late Jurassic and early cretaceous age are largely identical with, or very closely allied to each other, showing that they must have been inhabitants of one and the same great sea. In western India the fossils of the same age belong to a fauna which is found in the north of Madagascar, in northern and eastern Africa, in western Asia, and ranges into Europe—a fauna differing so radically from that of the eastern exposures that only a few specimens of world-wide range are found in both. Seeing that the distances between the separate outcrops containing representatives of the two faunas are much less than those separating the outcrops from the nearest ones of the same fauna, the only possible explanation of the facts is that there was a continuous stretch of dry land connecting South Africa and India and separating two distinct marine zoological provinces.”
ETHYL, in chemistry, the name given to the alkyl radical C2H5. The compounds containing this radical are treated under other headings; the hydride is better known as ethane, the alcohol, C2H5OH, is the ordinary alcohol of commerce, and the oxide (C2H5)2O is ordinary ether.
ETHYL CHLORIDE, or Hydrochloric Ether, C2H5Cl, a chemical compound prepared by passing dry hydrochloric acid gas into absolute alcohol. It is a colourless liquid with a sweetish burning taste and an agreeable odour. It is extremely volatile, boiling at 12.5° C. (54.5° F.), and is therefore a gas at ordinary room temperatures; it is stored in glass tubes fitted with screw-capped nozzles. The vapour burns with a smoky green-edged flame. It is largely used in dentistry and slight surgical operations to produce local anaesthesia (q.v.), and is known by the trade-name kelene. More volatile anaesthetics such as anestile or anaesthyl and coryl are produced by mixing with methyl chloride; a mixture of ethyl and methyl chlorides with ethyl bromide is known as somnoform.
ETHYLENE, or Ethene, C2H4, or H2C:CH2, the first representative of the series of olefine hydrocarbons, is found in coal gas. It is usually prepared by heating a mixture of ethyl alcohol and sulphuric acid. G.S. Newth (Jour. Chem. Soc., 1901, 79, p. 915) obtains a purer product by dropping ethyl alcohol into syrupy phosphoric acid (sp. gr. 1.75) warmed to 200° C., subsequently raising the temperature to 220° C. It can also be obtained by the action of sodium on ethylidene chloride (B. Tollens, Ann., 1866, 137, p. 311); by the reduction of copper acetylide with zinc dust and ammonia; by heating ethyl bromide with an alcoholic solution of caustic potash; by passing a mixture of carbon bisulphide and sulphuretted hydrogen over red-hot copper; and by the electrolysis of a concentrated solution of potassium succinate,
(CH2·CO2K)2 + 2H2O = C2H4 + 2CO2 + 2KOH + H2.
It is a colourless gas of somewhat sweetish taste; it is slightly soluble in water, but more so in alcohol and ether. It can be liquefied at −1.1° C., under a pressure of 42½ atmos. It solidifies at −181° C. and melts at −169° C. (K. Olszewski); it boils at −105° C. (L.P. Cailletet), or −102° to −103° C. (K. Olszewski). Its critical temperature is 13° C., and its specific gravity is 0.9784 (air = 1). The specific gravity of liquid ethylene is 0.386 (3° C.). Ethylene burns with a bright luminous flame, and forms a very explosive mixture with oxygen. For the combustion of ethylene see [Flame]. On strong heating it decomposes, giving, among other products, carbon, methane and acetylene (M. Berthelot, Ann., 1866, 139, p. 277). Being an unsaturated hydrocarbon, it is capable of forming addition products, e.g. it combines with hydrogen in the presence of platinum black, to form ethane, C2H6, with sulphur trioxide to form carbyl sulphate, C2H4(SO3)2, with hydrobromic and hydriodic acids at 100° C. to form ethyl bromide, C2H5Br, and ethyl iodide, C2H5I, with sulphuric acid at 160-170° C. to form ethyl sulphuric acid, C2H5·HSO4, and with hypochlorous acid to form glycol chlorhydrin, Cl·CH2·CH2·OH. Dilute potassium permanganate solution oxidizes it to ethylene glycol, HO·CH2·CH2·OH, whilst fuming nitric acid converts it into oxalic acid. Several compounds of ethylene and metallic chlorides are known; e.g. ferric chloride in the presence of ether at 150° C. gives C2H4·FeCl3·2H2O (J. Kachtler, Ber., 1869, 2, p. 510), while platinum bichloride in concentrated hydrochloric acid solution absorbs ethylene, forming the compound C2H4·PtCl2 (K. Birnbaum, Ann., 1868, 145, p. 69).