ERDMANN, JOHANN EDUARD (1805-1892), German philosophical writer, was born at Wolmar in Livonia on the 13th of June 1805. He studied theology at Dorpat and afterwards at Berlin, where he fell under the influence of Hegel. From 1829 to 1832 he was a minister of religion in his native town. Afterwards he devoted himself to philosophy, and qualified in that subject at Berlin in 1834. In 1836 he was professor-extraordinary at Halle, became full professor in 1839, and died there on the 12th of June 1892. He published many philosophical text-books and treatises, and a number of sermons; but his chief claim to remembrance rests on his elaborate _Grundriss der Geschichte der Philosophie_ (2 vols., 1866), the 3rd edition of which has been translated into English. Erdmann's special merit is that he does not rest content with being a mere summarizer of opinions, but tries to exhibit the history of human thought as a continuous and ever-developing effort to solve the great speculative problems with which man has been confronted in all ages. His chief other works were: _Leib und Seele_ (1837), _Grundriss der Psychologie_ (1840), _Grundriss der Logik und Metaphysik_ (1841), and _Psychologische Briefe_ (1851). ERDMANN, OTTO LINNE (1804-1869), German chemist, son of Karl Gottfried Erdmann (1774-1835), the physician who introduced vaccination into Saxony, was born at Dresden on the 11th of April 1804. In 1820 he began to attend the medico-chirurgical academy of his native place, and in 1822 he entered the university of Leipzig where in 1827 he became extraordinary professor, and in 1830 ordinary professor of chemistry. This office he held until his death, which happened at Leipzig on the 9th of October 1869. He was particularly successful as a teacher, and the laboratory established at Leipzig under his direction in 1843 was long regarded as a model institution. As an investigator he is best known for his work on nickel and indigo and other dye-stuffs. With R.F. Marchand (1813-1850) he also carried out a number of determinations of atomic weights. In 1828, in conjunction with A.F.G. Werther (1815-1869), he founded the _Journal fur technische und okonomische Chemie_, which became in 1834 the _Journal fur praktische Chemie_. He was also the author of _Uber das Nickel_ (1827), _Lehrbuch der Chemie_ (1828), _Grundriss der Waarenkunde_ (1833), and _Uber das Studium der Chemie_ (1861). EREBUS, in Greek mythology, son (according to Hesiod, _Theog._ 123) of Chaos, and father of Aether (upper air) and Hemera (day) by his sister Nyx (night). The word, which signifies darkness, is in Homer the gloomy subterranean region through which the departed shades pass into Hades. The entrance to it was in the extreme west, on the borders of Ocean, in the mythical land of the Cimmerians. It is to be distinguished from Tartarus, the place of punishment for the wicked.