editad by
JOHN H. WOTlZ Southern Illlndn Unlv.nlt)r Corbondal., 62901
The Naming of Fluorine William H. Waggoner University of Georgia Athens, Georgia 30602 No chemist who has worked with fluorine or many of its simple derivatives can fail to appreciate the vigor with which this element reacts. The literature is dotted with accounts of the agonies suffered by those investigators who either through ignorance or carelessness failed to respect the reactivity of fluorine. While modern safety practices are designed with this characteristic in mind, it is not wellknown that the destructive power of fluorine was recognized many decades ago and was the reason for a suggestion made by Andre Marie Ampere (1775-1836) concerning a proper name for this element. Henri Moissan (1852-1907) was the first to obtain elemental fluorine ( I ) by electrolysis in 1886, although hydrogen fluoride and its aqueous solution, hydrofluoric acid, were known much earlier. One reviewer has concluded ( 2 ) that H F was definitely known in 1720. A number of 18th centurv chemists investigated this substance which was commonly prepared by warming powdered fluorspar (CaFz) with sulfuric acid, but none was able to decompose it. The mineral fluorspar was described by Georgius Agricola (1494-1555) in 1529 and its use as a flux in metallurgy (3)was responsible for its name (from the Latin, fluoere, to flow). Carl Wilhelm Scheele (1742-86) ~uhlishedseveral papers on fluorspar and correctly concluded that it was the lime (calcium) salt of a ueculiar acid. This "fluor or fluoric acid" then became known in Lavoisier's new nomenclature system as "l'acide fluorique" and in accordance with his oxygen theory of acids was regarded as a compound of water with the oxide of the unknown element, fluorium. In letters to Humphry Davy (1778-1829) dated 1 November 1810 and 25 August 1812, Ampere suggested (4) that fluoric acid (HF) was like muriatic acid (HC1) in that it did not contain oxygen but was a binary compound of hydrogen with an unknown element similar to chlorine. Davy's replies, dated 8 February 1811 and 6 March 1813, respectively, were included as footnotes in a later paper by Ampere (5). In the first of these, Davy expressed the cautious view that perhaps there was some oxygen present "in silicated fluoric acid" (SiF4), but in the later letter he had a .~.~ a r e n t changed lv his mind and wrote that "Your inaeniws views respecting fluurine may he confirmed." It is interestinr to notc that sometime during the two-year - ~.e r i o d betwee; the two letters, Davy had chsnged his uomenclature also. Ampere had noted that current practice employed the names fluorique for the acid and fluates for the salts, analogous to l'acide muriatique and the muriates, or to l'acide chlorique and the chlorates. But it was precisely this latter usage to which he objected. Chemists agreed that both muriatique and chlorique acids contained chlore; they disagreed as to the amount of oxygen, if any, in the two acids.
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Davy demonstrated ( 6 ) that muriatic was a binary acid and was oxygen-free. Ampere believed that the acid called fluorique was similar but if this were the case, the name should be changed to make i t consistent with the chlorine system. He therefore suggested three different names for the unknown parent element; fluore (his first possibility), fluorure (his second suggestion but discarded as heing too difficult to pronounce), and phtore (his choice). The word phtore (from the Greek, @6prol, that which destroys or corrupts) was selected with full cognizance of the properties of the element in question. The binary acid would he named hydrophtorique and "if, as is quite probable, an acid formed of phtore and oxygen is discovered, it would he phtorique acide and its salts phtorates." Ampere's approach to the naming of acids was eventually adopted although his preferred name for the lightest halogen was not. For his part, Davy was unsuccessful in his attempts to isolate the parent element (7) but he did accept Ampere's first suggestion and called it fluorine. Considering the fact that Thomas Thomson (1773-1852) was so influential in developing the English chemical nomenclature, albeit he was not above arbitrarily changing terms and spellings to suit himself, his reaction to Ampere's proposals is interesting. In his popular textbook (8) Thomson noted: "Davy has given it the name of fluorine, which we shall accept. Ampere has given it the name of Phthorine, (Phthore) from the Greek word @6pos, destructive. But it is quite evident that this new name cannot be adopted. There would he no end to names if every person at pleasure could coin new ones. The reason assigned by him for contriving this new name, namely, that he was the original starter of the hypothesis, is not valid . . . . Davy informs us that Ampere himself originally suggested the term fluorine." Literature Cited (11 Moisan. H.. Compl. r e n d . 92.1549 118861; 93.202 (1886). (21 PartinSon. J. R.. Mem Monchrsrer L i t . Phil. Sic., 61.71 (19231. 131 Agricola. G., "Oe Re Metaiiica." ITranslatorr: Hoover. H. C., and Hoover. L. H i D w e r Puhiicatiunn. Ine.. New Yurk. 1950, p. 181 footnote. 14) .loubert.J.. (Amgeie, A. M I , Ann. Chim. Phva.. 16) 4.5 (1885). 151 Ammre,A.M.. Ann Chim. Phy,, (21 2.5 118161. 16) Davy. H., Phil Trons.. 100.231 118101. 17) Dsw, H., Phil. Trans. 103.265 11813); 104.62 118141. 181 Thomren. T.. "A System sf Chemistry of l n o r ~ a n i cBodies..'7th od.. Baldwin and Crads!ck, Londim. IR3l.uel. I. p. 89 footnoU.
Kekule's ''Sausage" Formulae Oswald J. Walker 3 Mannicotts Welwyn Garden City, Herts AL8 7BW, UK The origin of what are sometimes known as Kekule's "sausage" formulae is prohahly not well-known and is worthy of heing recorded again (1). These formulae played an important part in KekulB's development of the closed ring structure of benzene, first published by him in 1865 in Volume 53.Number 1, January 1976 1 27
French and Belgian journals (2). In 1866 these papers were published again in German in the Annalen (3). and the whole theory was reproduced in the second volume of Kekul8's "Lehrbuch der Organischen Chemie" (6). In the publications of 1865 and 1866 KekulB still made use of his own rather cumbersome symbolism which he had first employed in the first volume of his Lehrbuch published in 1861 (4). According to this scheme the symbol used for an element was made to represent its valency. Thus hydrogen was shown as a single circle, oxygen as a fusion of two, and carbon as a fusion of four circles, as seen in the left-hand column of symbols below
Carbon
1-(
By 1865 Kekul6 had simplified these symbols to the forms shown in the right-hand column, the length of the symbol heing proportional to the valency. These symbols are frequently referred to as Kekule's "sausage" formulas, and the author of this nickname is thought to have been, Kolbe. Actually Kolhe called them "roll" formulas (5)."Kekul6 gab den Atomen die Form uon
28 1 Journal of Chemical Education
Semmeln" (Semmel = roll, loaf [of bread]). Kolhe went on to speak of these formulas, referring to the original form, as "Zwei-, Drei-, und Vierback iihnliche Gestalten, deren Wulste je eine Affinitiit representieren". A mis-reading of the word Wulste (bulges) as Wurste (sausages) probably accounts for the erroneous appelation attributed to Kolbe. In KekulB's original publications of the henzene theory (2-4, 6) we find these "roll" symbols used extensively to represent henzene and its derivatives. I t is not generally realized that Kekul6 himself made very little use of the convenient plain hexagon symbol for henzene in his puhlications. In the parts of his Lehrhuch that dealt with the aromatic compounds, apart from the section where he fully described his henzene theory, we find only two pages that contain benzene rings, and here they are used in conjunction with the earlier "roll" symbols. After the publication of his henzene theory Kekul6 wrote about thirty papers dealing with aromatic substances. The henzene hexagon was used in only four or so of these papers and even there only to a limited extent. Literature Cited (1) Walker, 0. J., "Annals of Seicnee IV: 1939, p. 31. (21 Kckul6,A.,Bull. Soc. Chim.. 3.98 (186Sl;Rull. Acod R. Bdg, 19,551 (18651. (31 Kekul6.A.Ann.. 137.129(1966). ( 4 ) Kekul6, A,. "Lohrbuch der Organixhen Chemie." Val. I. F. Enke P"b1.. Edsngen.
1861.p. 169. (6) Kolhe, H . . J pmkl. Chem.. 24,375 (18811. (6) Kekul6. A.. "Lohrbuch der Organischcn Chemie."Vol. 2, F. Enke Publ., Edangen,
1866.
