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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 lihalfa 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 Drschabir 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, rise. 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 11th 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 ; Libcr investi- gatiom's, or De investigatione mrfectionis; De inventione om’latis; Liber Fornacmn; 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 bibliography, 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 practically, certain materials were employed and were subjected to operations, and the knowledge acquired about them toolr 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 :—-ibulfeila, Anlzalcs Jloslcmici, Copenhagen, 1790, with Reiskc's note; Beckrnaun, Gcschiclrlc dcr lirfimlungcn, 1803, v. 272; Black, Catalogue of Illb'b'. bcqiwatllcd to the University of Oxford by Elias Aslunolc, 1845 ; D'Herbclot, Bibliulhcque ()n'entale, Paris, 1697; llaji lihalfa, Lea-icon, cd. Flucgel, London, 1835-58 ; llzmimer-Purgstall. Literalurgcschichlc dcr Aral/or, Vienna, 1850 ; Ibn—lihallikan, Biographical Dictionary, by De Slanc, Paris, 1843, vol. i. pp. 800—1; Kiiab-al-Fihrisf, ed. Flucgcl, 1871—72; Kopp, Bcitra'gc cur Geschichte dcr (Jimmie, Brunswick, 1575, part iii.; Laboratory, 1867, vol. i. pp. 71—76; Leo Africanus, African Dc- script-io, Leyden, 1632; SteinSchneidcr, “ Die toxicologiselu-n Schriften der Amber," in Yirchow’s Archir, Berlin, 1571, Ed. 5‘2; VViistcnfcld, Gcschichtc dcr .lrabischcn .lcrztc, Gettingen, 1840. See also article Alchemy.

(j. f.)

GEBWEILER, in French Gael/Miller, a town of the German imperial province of Alsace-Lorraine, in the district of Upper Alsace, situated about 13 miles south of Colmar, at the mouth of the Blumenthal or “ Vale of Flowers.” It communicates by a branch line with the railway between Strasburg and Basel. Among the principal buildings are the Roman Catholic church of St Lcodgar, dating from the 12th century, the Evangelical church, the synagogue, the town-house, and the old Dominican convent now used as a market and concert-hall. The spinning, weaving, bleaching, and dyeing of cotton is the chief industry, but wOollcn goods and silk ribbons, as well as machinery, are also manu- factured. Gebweiler is mentioned as early as 774. It belonged to the religious foundation of Murbach, and in 1759 the abbots chose it for their residence. At the French Revolution of 1789, however, the chapter house was laid in ruins, and though the archives were rescued and removed to Colmar, the library perished in the devastation. Population in 1871, 11,104; in 1875, 11,622.

 

Leaf-tailed Gecko (Phyllurus platurus).

GECKO, the Common name applied to all the species of

G'ecl'olirlw, an extensive family of lizards belonging to the Paehyglossze, or “ thick—skinned " sub-order of Gray. The geckoes are small creatures, seldom exceeding 8 inches in length including the tail. With the head considerably flattened, the body short and thick, the legs not high enough to prevent the body dragging somewhat on the ground, the eyes large and almost destitute of eyelids, and the tail short and in some cases nearly as thick as the body, the geckoes altogether lack the litheness and grace characteristic of most lizards. Their colours also are dull, and to the weird and forbidding aspect thus produced the general prejudice against these creatures in the countries where they occur, which has led to their being classed with toads and snakes, is no doubt to be attributed. Their bite was supposed to be venomous, and their saliva to produce painful cutaneous eruptions ; cven their touch was thought sufficient to convey a dangerous taint. It is needless to say that in this instance the popular mind was misled by appearances. The geckoes are not only harmless, but are exceedingly useful creatures, feeding on insects and worms, which, owing to

the great width of their oesophagus, they are enabled to