GEBER. After all the research and criticism that have been expended on this the first and most interesting personage in the modern history of chemistry, little is definitely known about him, and about the origin of the works which pass under his name. It has been a very general tradition to regard Geber as an Arabian, but until the publication in recent years by European scholars of the works of Arabian historians and bibliographers, the pro-bable source of the tradition has not been known. It seems to be pretty generally believed that the Geber of Western Europe is the same as the person who is called in full Abu Musa Dschabir (or Jabir) Ben Haijan Ben Abdallah el-Sufi el-Tarsusi el-Kufi, who was reckoned the most illustrious of the alchemists by the Arabs, and who is mentioned in the Kitab-al-Fihrist (10th cent.), by Ibn Khallikan (13th cent.), by Haji Khalfa (17th cent.), and other writers. If this be correct, Geber must have flourished in the 8th century, for, according to Haji Khalfa, Dschabir Ben Haijan died in the 160th year of the Hegira, which corresponds with the year beginning October 19, 776 A.D. This date is incidentally confirmed by other writers, though there are difficulties arising from the date of his teacher Kalid Ben Jezid, and his patron Dschaafar ess-Sadik. His birthplace was Tarsus, or, as others say, Kufa; and he is said to have resided at Damascus and at Kufa. This account, though apparently the most trustworthy, does not agree with the statements of D'Herbelot, quoted seemingly from native sources, that Geber was born at Harran in Mesopotamia, was a Sabsean by religion, and lived in the 3d century of the Hegira. Nor does it agree with that of Leo Africanus, who in 1526 gave a description of the Alchemical Society of Fez, in Africa, and told how the chief authority of that society was a certain Geber, a Greek, that had apostatized to Mahometanism, and lived a century after Mahomet. Leo's story has circulated very widely, but its accuracy has been impugned by Reiske and Asseman, and the works of both Leo and D'Herbelot have been rejected as autho-rities by Wiistenfeld. Other writers have tried to show that Geber was a native of Spain, or at least lived at Seville, but this has probably arisen from confusing Geber the chemist with other persons of the same or similar name, From the doubt encircling the personality of Geber, some have gone the length of questioning whether such a person ever existed but in name, and this view has been again expressed by Steinschneider, who mentions " Abu Musa Dschabir Ben Haiyan, commonly called Geber, an almost mythical person of the earliest period of Islam, renowned as an alchemist." While Steinschneider here ex-hibits notable scepticism with respect to Dschabir's very existence, he exhibits equal credulity in his belief that this mythical Dschabir is identical with Geber. In the present state of the question there is no alternative but to accept the account given in the Fihrist, and admit the possibility of Dschabir and Geber being one and the same, Con-firmation of this view is to be sought in a comparison of the works ascribed to Geber with those bearing the name of Dschabir. The latter are divisible into two classes, those mentioned in Arabic bibliographies, and those existing in manuscript in European libraries. To Dschabir is assigned the authorship of an immense number of works on chemistry and many other topics besides. Titles of 500 of these are given in the Fihrist, and have been reproduced by Hammer-Purgstall, but nothing else is known about them. Haji Khalfa also enu-merates the titles of several alchemical works by Dschabir, and other works are mentioned by other writers. Again Arabic MSS. on alchemy bearing the name of Dschabir Ben Haijan exist at Leyden, at Paris, in the British Museum, and elsewhere ; but these have not been critically examined as to their date, age, authenticity, contents, &e. It is not known if they correspond with the lists already mentioned, or with the Latin MSS. or the printed versions. The Latin MSS. are contained in the Vatican, at Leyden, Oxford, and other places. Of these the Vatican MS. is the alleged basis of some of the printed editions: and the Bodleian MSS. have been described by W. H. Black, but no collation of the text of these writings for critical pur-poses has as yet been made. The oldest of the MSS. dates from the 14th century ; but if the works ascribed to Roger Bacon, Albertus Magnus, and others be genuine, Geber's name and writings must have been known and esteemed at a still earlier period. The works which purport to have been written by Geber, and which have been printed, bear the following names :—Summa perfectionis ; Liber investi-gationis, or De investigations perfectionis; De inventione veritatis; Liber Fornacum; Testamentum. None of the editions appear to contain the whole of these tractates ; there are usually found only two or three of them, but the English translation contains them all except the Testament, which is considered spurious by some writers. The printed editions of these works are very numerous, but they are all uncommon, and some of them are exceedingly rare. No approximately complete list is contained in any biblio-graphy, and very few writers have seen more than half a dozen at most. The most complete catalogue from personal inspection is given by Beckmann. It contains twelve editions, but that does not comprise nearly all those which are known. While some of the editions correspond exactly, being merely reprints, there are important differences among others, What light these variations may throw upon the origin of the text has never been investigated. A critical edition of the works with the various readings would be necessary before deciding that what is found in them is really Geber's, and dates back eleven centuries. It may be that some of the knowledge of chemistry credited to Geber was really interpolated at a later date. It is quite possible that the account given of the various acids, salts, and metals, and of the apparatus and operations, may have been modified or extended. But, on the other hand, the general theory that runs through the whole of the writings is in all probability original. The theory is that the metals are composed of the same elements, and that by proper treatment the less perfect can be gradually developed into the more perfect metals. This theory is very clearly, and one may even say logically, worked out, and it was the leading idea in chemistry down to the 16th century at least. In carrying out this theory prac-tically, certain materials were employed and were subjected to operations, and the knowledge acquired about them took shape by degrees. Though subsequent workers added to what was known, Geber's reputed works are so clear, so precise, so complete, that they differ in a most striking manner from the works of even the best writers in the later alchemical period, and make it difficult to account for their existence at all. Older writings there are none; subsequent writings as clear as Geber's do not appear until far more was known; the unsolved problem therefore remains, Who was Geber, and how does it happen that his works stand quite alone in chemical literature ?

The following are a few of the authorities which may be consulted :—Abulfeda, Annates Moslemici, Copenhagen, 1790, with Reiske's note; Beckmann, Geschichte der Erfindungen, 1803, v. 272 ; Black, Catalogue of MSS. bequeathed to the University of Oxford by Elias Ashmole, 1845 ; D'Herbelot, Bibliotheque Orientale, Paris, 1697 ; Haji Khalfa, Lexicon, ed. Fluegel, London, 1835-58 ; Hammer-Purgstall, Literaturgeschichte der Araber, Vienna, 1850 ; Ibn-Khallikan, Biographical Dictionary, by De Slane, Paris, 1843, vol. i. pp. 800-1; Kitab-al-Fihrist, ed. Fluegel, 1871-72; Kopp, Beiträge zur Geschkhte der Chemie, Brunswick, 1875, part iii.; Laboratory, 1867, vol. i. pp. 71-76; Leo Africanus, Africa, Descriptio, Leyden, 1632 ; Steinschneider, "Die toxicologischen Schriften der Araber," in Virchow's Archiv, Berlin, 1871, Bd. 52 ; Wüstenfeld, Geschichte der Arabischen Aerzte, Göttingen, 1840.

See also article ALCHEMY. (J. F.)