Rutherford and Radon

Rediscovery of the Elements Rutherford and Radon

transmutation of the elements. He was to be (1877–1956) he developed the “transformation acknowledged as the “leading explorer of the theory” which showed radioactivity was a vast, infinitely complex universe within the nuclear property. From thorium Rutherford III atom, a universe that he was the first to pene- observed a gaseous radioactive product, which trate.”3 he called “emanation”—he had discovered the Ernest Rutherford, the son of a flax farmer in element radon.2,3 New Zealand, gained his undergraduate train- The British method of developing explicit ing in his native country. In 1895 he moved to descriptive models to explain nature was per- England, where he attended Cambridge Univ- fect for the advance of nuclear chemistry at this ersity; he was entering the scientific scene in moment in history; Lord Kelvin (William Europe just as radioactivity was discovered in Thomson, 1824–1907) said he could not reason 1896 by Henri Becquerel (1852–1908) of Paris. “without making a visualizable picture” of the His first research involved hertzian (radio) phenomenon he wanted to describe. J. J. James L. Marshall, Beta Eta 1971, and waves, but he then moved on to the study of Thomson of the Cavendish Laboratory at Virginia R. Marshall, Beta Eta 2003, uranium rays with J. J. Thomson (1856–1940) at Cambridge was using the idea of charged cor- Department of Chemistry, University of Cambridge. Rutherford showed that these ion- puscles to explain cathode rays, and he viewed North Texas, Denton, TX 76203-5070, izing rays consisted of two main types, which the atom as a dynamic, moving mixture of pos- he called alpha and beta “for simplicity.”2 itive and negative charges. Scientists on the [email protected] In 1898 Rutherford took a post at McGill continent, by contrast, were not impressed by University, Montreal, Canada, while Marie and this “picture making” — the Curies, for exam- EDITOR’S NOTE: This installment of the Pierre Curie in Paris were discovering polonium ple, considered the British method as “childish, Rediscovery series is based in part on recent publi- (1898) and radium (1899). This new phenome- arbitrary, and English.”2 cations1 that appeared in the ACS Division of non of radioactivity mystified many, but From McGill University Rutherford moved History, used with permission, that deal with the Rutherford’s incisive mind and fertile imagina- to Manchester University in 1907 and then to historical controversy between Rutherford and tion allowed him to use atoms not only as use- Cambridge University in 1919. Scientists who Dorn regarding the discovery of radon (Figure 1). ful, but also as necessary, models to offer coher- would later become famous in their own right ent explanations. At McGill he came to under- flocked to these laboratories for training and Introduction. At the beginning of the 19th stand radioactive decay and he developed the collaboration— such scientists included century, John Dalton (1766–1844) proposed concept of “half-life”; with Frederick Soddy Frederick Soddy (who invented the term “iso- that the world was composed of atoms with specific masses. Even though there was no Figure 1. Two scientists in the literature associated with the discovery of direct evidence that such discrete particles actu- radon. Right: Ernest Rutherford (1871–1937), Macdonald Professor of ally existed, his theory was utilized throughout McGill University, Montreal, the 1800s. Using atoms as models, scientists Canada (portrait at the Dept. of refined these atomic masses and developed Physics, McGill University). theories of organic chemistry, stereochemistry, Rutherford first characterized ema- crystallography, ionic and covalent bonding, nation of a radon isotope (from and electrochemistry. The scientific community thorium) as a gas and an element, generally accepted the fact that chemistry and should be credited with the behaved as if atoms existed. But since no one discovery of radon. Left: Friedrich had ever seen an atom, some scientists could Ernst Dorn (1848–1916), still refute their existence, even into the 20th Geheimer Regierungs-Rat century; Ernst Mach denied them to his death 2 Professor of Friedrichs Universität, in 1916. Ernest Rutherford (1871–1937), how- Halle (Saale). (Portrait at the ever, did not doubt the existence of atoms for a University of Halle; photograph by the authors). He was the first to moment. He used them to explain the mysteri- observe emanation from radium specifically (the etymological source of ous phenomenon of radioactivity, which in turn the name “radon”), but his observations were subsequent to allowed him to determine their structure; even- Rutherford’s work. tually, he was even able to perform artificial

22 THE HEXAGON/SUMMER 2010 Figure 4. Map of McGill area of Montreal, Canada. Rue [street] University which leads northwest into the university is a continuation of Interstate 10. Macdonald Physics Building (the old Physics Building), where Rutherford performed his work, then Macdonald- Stewart Library, now called the Shulich Library (Engineering and Science), 809, rue Sherbrooke Ouest—N45° 30.30 W73° 34.49. Rutherford Building (Modern Physics Building), which holds the Rutherford Musum, 3600 rue University—N45° 30.41 W73° 34.72. Figure 2. Near the Roddick Gates on Rue “1” = James McGill statue, close to Roddick Gates—N45° 30.25 W73° 34.54. Sherbrooke in Montreal, Canada, is this statue of “2” = Otto Maass Chemistry Building, modern chemistry building, 801, rue Sherbrooke Ouest—N45° James McGill (1744–1813), whose bequest was 30.31 W73° 34.46. responsible for the founding of McGill University “3” [in inset] = Rutherford home during 1900–1907, then No. 152 Rue Sainte Famille Street, now 3702 in 1821. The plaque at the base is inscribed in Rue Sainte Famille (corner of Rue Ste Famille and Rue Basset)—N45° 30.75 W73° 34.58. both English and French. McGill won his fortune “4” [in inset] = Rutherford Building (Modern Physics Building)—for reference in the inset, same as above. in the fur trade and went on to other enterprises in property. He was born in Glasgow, Scotland, “Photographs.” The creator of the museum was museum (Figures 7 and 8). In the alcove outside and was educated at the University of Glasgow, Dr. Ferdinand Terroux, a student of Rutherford the museum is a bust and plaque in honor of where a plaque exists in his honor recognizing his at Cambridge University, who came to McGill Rutherford (Figure 9), and inside the Otto achievements in Canada. (See next figure). in 1931, where he became professor of physics. Maass Chemistry Building is a plaque devoted Dr. Terroux established the museum in 1967 to Soddy (Figure 9). tope”), Niels Bohr (who first described the after he assembled Rutherford’s apparatus and quantized atom), Otto Hahn (who discovered equipment, which had been in storage for An incorrect ascription of radon’s discovery. atomic fission), Henry Moseley (who discov- many decades. The modern museum reputedly In the literature Friedrich Ernst Dorn is com- ered atomic numbers from his X-ray research), houses the world’s best collection of Rutherford monly, but incorrectly, ascribed as the discover- Georg von Hevesy (who discovered hafnium), apparatus. Two figures presented here show er of radon; for example, presented for decades James Chadwick (who discovered the neutron), only a meager sampling of the richness of the in the Handbook of Chemistry and Physics is this and Hans Geiger (famed for his eponymous statement: 4 a,c “The element [radon] was discov- counting device). Rutherford was a giant in his ered in 1900 by Dorn, who called it radium ema- field and was mourned at his premature death nation.” This error has been repeated countless at the age of 66 at Cambridge.2,3 times in subsequent articles, books, and web sites. In fact, Dorn did not first give the name of Rediscovering Rutherford in McGill. “emanation” to the phenomenon (much less Rutherford’s Nobel Prize in 1908 was given in “radium emanation”); he did not have the recognition of his work at McGill University faintest idea of the nature of the phenomenon, (Figures 2,3), an English-speaking university and he certainly did not realize that it might be in the center of Montreal, Canada (see Figure a new element (Note 1). 4). The building where Rutherford and Soddy What was the source of the error? Here is performed their work, then called the the story: Macdonald Physics Building (Figure 5), still A difficulty in assigning proper credit of stands (Figure 6). radon’s discoverer was recognized by Nearby is the Rutherford Physics Building, Partington5 who identified an erroneous cita- where a beautiful and complete Rutherford tion by George Charles de Hevesy Museum has been established which in fine (1888–1866).6 In Hevesy’s paper, an incorrect detail describes the experiments performed at Figure 3. In the Cloisters of Glasgow University is reference was given to Dorn’s original paper 7 McGill University. The exhibits include cases this plaque (N55° 52.26 W04° 17.33) devoted to where radium was observed to produce an demonstrating “The Nature and Properties of McGill. Nearby (200 meters northwest; N55° emanation; this faulty reference was copied ␣-rays,” “Emanations from Thorium and 52.37 W04° 17.45) is a plaque commemorating into all subsequent works of reference until Radium,” “Excited Radioactivity,” “Ionization the site where Soddy, who earlier was a postdoc- Partington corrected the error 44 years later.5 Studies,” “Heating Effectings of Radiation,” toral fellow for Rutherford in McGill University, In the meantime, Dorn’s paper apparently was “The Radium Decay Series,” “Measurement originated the term “isotope” in 1913 at a dinner not widely read and its exact contents were lost Techniques,” “Various Documents,” and party held by his parents-in-law. in time (Note 2).

SUMMER 2010/THE HEXAGON 23 III original discovery paper beganwithareference toRutherford’s 58.22). Onceinhand, 29.33E11° the 37 (N51° Academy ofSciences], Emil-Abderhalden-Str. Naturforscher Leopoldina[LeopoldGermany ed thejournalinDeutsche Akademie der traveled toHalle(Saale)(Figure 10)andlocat- cle andotherassociatedliterature, theauthors To obtainacopy ofthisobscure arti- research. local gatheringstopresent theirrecent readings ofcolleaguesasthey metininformal Scientific SocietyofHalle”], whichrecorded the forschenden Gesellschaft(Halle) insular journal well; (1874–1949) toproduce anemanationas observed by André-Louis Debierne difficult tostudy. (Actiniumwas later Universität Halle-Wittenberg].” [Friedrichs Universität, nowtheMartin-Luther stances available locally at ourInstitute taken asecondlookatotherradioactive sub- adopted theapproach ofRutherford andhave . Ihave the sameproperties asthorium... substances (suchasuranium) didnotexhibit . Rutherford saidthatotherradioactive scope... ton, hastheproperty ofdischarging anelectro- pounds, even afterbeingfiltered through cot- stream ofairover thoriumorcom- rium: “Rutherford noticedthatasweeping sequential studentdissertations no more on “emanation,” exceptfortwo incon- process.” (Insubsequentyears Dornpublished apparently concerned “a physico-chemical the emanation, exceptthatthephenomenon makes nospeculationregarding thenature of a universallyvalid relation.” Inhis paperDorn the amountofmoisture, [but]Ihave notfound the emanationandsecondary activityupon me thatthere isastrong dependencebetween of moisture andheatonactivity: “It appearsto study, Dorn examined principallytheinfluence enon ofthorium, butthatradium did. Inhis “emanation”nium didnotdisplay the phenom- tus, andfoundthatindeeduranium andpolo- explicitly usingRutherford’s designofappara- muth). Dornrepeated Rutherford’s procedure, barium), andpolonium(cruderadioactive bis- rium, radium (intheformofcruderadioactive pastiche ofexperimentscovering uranium, tho- tigate withits “long” half-lifeof3.823 days. shorter half-lifeof 3.96seconds its half-lifeofabout55.6seconds, radioactive substances”], Emanation” [“Theradiated emanationfrom Radioaktiven Substanzen Ausgesandte radon (Rn-222) 24 220) The isotopethatemanatedfrom thorium(Rn- Dorn’s paper The originalpaperofDorn, “Die Von Dorn hadstumbledontotheisotopeof 10 11 previously observed by Rutherford, with this isotope, Rn-219, hadaneven 10 7 that was theeasiesttoinves- 8 Abhandlungen derNatur - continued withanelaborate of theemanationfrom tho- 7 was publishedinthe [“Treatises ofthe 9 ). 4b ). 4b was more 4b hnmnnmgtb omo “phosphores- phenomenon might beaformof note toRutherford, Mme. Curie thought the non) stated, in thefirsteditionofherthesis, Mme. Curie(thefirsttonoticethephenome- ly was by Rutherford andtheCuries. By1903 not contemplatedseriouslyby Dorn, itcertain- . inaform hitherto unknown.” consider theemanationasradioactive energy . . which carriestheradioactivity. . . . [Insteadwe] ies generate anemanationorgaseousmaterial “Mr. Rutherford suggeststhatradioactive bod- charitable organizations, oftendirectly toRutherford himself. The viewisnorthwest. (1831–1917) wasatobaccomagnatewhodonatedgeneroussumsofmoneytoMcGillUniversityandother appearance ofthe buildingatthetimeofRutherford. The benefactorSir William ChristianMacdonald Figure 5. The MacdonaldPhysics Building, builtin1893, fiveyearsbefore Rutherford arrived. This isthe northwest. ings (thebuildingtotheleftisBurnsideHall, servingAtmosphericandOceanicSciences). The viewis As iscommoninallurbansettings, thishistoricsitehasbecomesurroundedandcramped byotherbuild- visit. Itwasthenbeingremodeled, andtodayservesastheSchulichLibrary forEngineeringandScience. Figure 6. This wastheappearance oftheMacdonaldPhysics Buildingin2000, atthetimeofauthors’ Although thenature oftheemanationwas 13 In aprivate 12b cotton orwater, butalsothrough chemicalbar- unscathed through aphysical barrier suchas to showthatnotonlydidtheemanation pass he andhiscolleagueFrederick Soddy were able radioactive particles, stray dust, etc. also depositionofgaseousions, depositionof that includednotonlyphosphorescence, but attacked theproblem, considering explanations molecules ofair.” that they were “centers offorce attachedto vague descriptionswere offered, forexample, cence.” 14 This “radioactive energy” was baffling; THE HEXAGON/ 15 Rutherford vigorously SUMMER 2010 14 Eventually Figure 7. This was Dr. Montague (Monty) Cohen, curator of the museum, now deceased (29-01- Figure 9. Left: Bust of Rutherford in the alcove of the Rutherford Physics Building. Right: Plaque devoted to 2002). In this photograph, Monty is standing Soddy is in the Otto Maass Chemistry Building. Soddy has sometimes been described as “Rutherford’s before the exhibit concerning Rutherford’s discov- great discovery in McGill.” ery of radon, which is “Case B” of the museum. Chemical Abstracts), “emanation” with the accomplishment is summarized by Oliver chemical symbol Em, radon with Rn, thoron Sacks in Uncle Tungsten:21 with Tn, actinon with At, and of course “radi- The Curies (like Becquerel) were at first um emanation”—and generally a reader of inclined to attribute [radium’s] “induced the literature wasn’t sure whether one was radioactivity” [in everything around them] to dealing with the general element or with a something immaterial, or to see it as “reso- specific isotope. In 1923 the International nance,” perhaps analogous to phosphorescence Committee on Chemical Elements noted10 or fluorescence. But there were also indications that “the Committee has found it necessary to of a material emission. They had found, as early modify the nomenclature of several radioactive as 1897, that if thorium was kept in a tightly elements. . . Radon replaces the names radium shut bottle its radioactivity increased, returning emanation and niton.” to its previous level as soon as the bottle was The proper recognition of the “true discover- opened. But they did not follow up on this er” of an element has not always been straight- observation, and it was Ernest Rutherford who Figure 8. In one of his pioneering researches, forward. The recent play Oxygen, for example, first realized the extraordinary implication of Rutherford first demonstrated the prodigious skillfully demonstrates how claims of element this: that a new substance was coming into amount of heat generated by radioactivity. Using discoveries may be ambiguous.19 The criteria being, being generated by the thorium; a far this differential air calorimeter (where two flasks used in such claims have evolved over the years more radioactive substance than its parent. were connected by a manometer), a known mass — for example, in pre-Lavoisier times chlorine Rutherford enlisted the help of the young of radium is inserted in the right flask and a resis- has been credited to Scheele in 1774 on the chemist Frederick Soddy, and they were able to tance wire in the left flask. The heat was adjusted basis of his description of a crude mixture, even show that the “emanation” of thorium was in in the resistance wire on the left so that xylene in though its true nature was first recognized in fact a material substance, a gas, which could be the manometer (indicating relative pressure in the 1810 by Davy, who gave it its present name.12a isolated. . . . Soddy [wrote later]. . . “I remember two flasks) is balanced by equally heated air in During the 1800s, a blend of increasingly rigor- quite well standing there transfixed as though both flasks. The amount of heat generated by the ous criteria was demanded, including isolation stunned by the colossal impact of the thing and radium (1 gram) was calculated to be 110 gram- of the element, recognition of it as an element, blurting out. . . . ‘Rutherford, this is transmuta- calories/hour, enormously greater than that gener- determination of its relative atomic mass, and tion. . . .’ Rutherford’s reply was . . . ‘For Mike’s ated in chemical reactions. Rutherford expanded acquisition of spectroscopic data. Thomas sake, Soddy, don’t call it transmutation. They’ll this experiment to separate out the contributions of Thomson (1773–1852), who wrote the compre- have our heads off as alchemists.’ ” gamma radiation (using lead shielding) and ema- hensive History of Chemistry in the early 19th For the next Rediscovery article, we will visit nation (by purging of the flasks). century, reminded us that “For it is not the man Rutherford’s laboratory in Manchester, England, who forms the first vague notion of a thing that where he discovered the atomic nucleus, and where riers such as P2O5, sulfuric acid, lead chromate, really adds to the stock of our knowledge, but Henry Gwyn-Jeffreys Moseley (1887–1915) for- heated magnesium, and even “platinum heated he who demonstrates its truth and accurately mulated the concept of atomic numbers. to incipient fusion”;16 and that it obeyed Boyle’s determines its nature.”20 By 1900 rigid criteria law, could be condensed out, and thus behaved were in practice for a claim of the discovery of just like a gas.17 By 1903 they could claim that an element—and by these criteria it is clear that Acknowledgments. the “emanation” must be matter in the gaseous Rutherford owns the credit for radon. The authors are indebted to Professor state.18 By the next year Mme. Curie herself Montague Cohen, curator of the Rutherford agreed with Rutherfords’s conclusions.15 Legacy of Rutherford in McGill. Rutherford’s Museum at the Department of Physics, McGill By 1920 the literature was filled with a realization that the radioactive process involves University, for his hospitality and for valuable mélange of names for the radioactive gaseous transmutation of the elements introduced the information regarding the careers of Ernest element, including “niton” with the chemical scientific world to 20th century nuclear chem- Rutherford and Frederick Soddy. Sadly, symbol Nt (niton was the “official” entry in istry. The importance and excitement of this Professor Cohen passed away in 2002. We are

SUMMER 2010/THE HEXAGON 25 A biography various solutionsandgelatin. IIIradium emanationdiffusedinto where hisreaction vesselsstoodwhile on thestairsleadingtobasement, 57.88). Heperformedhisstudies E11° 29.20 nation fromradium (N51° Germany, where Dorndetectedema- Wittenberg), Halle, Sachsen-Anhalt, the Martin-LutherUniversitätHalle- Friedemann-Bach-Platz, (asof1933, Building ofFriedrichs Universität, Figure 10. Physikalisches Institut Oliver Sacks’ gravely misreported itscontents: xlnto a ie yDr... [He] explanation was givenby Dorn... Heilbron. recognized inthebiography by John L. had notread Dorn’s publication well-known authorof correct 1900 article was citedas of radon. rect sequenceofevents regarding thediscovery physics. X-rays, andvariousotherelectrical-mechanicalstudies, developinganimpressive reputation inapplied liquid crystals, thebiologicaleffectsof geophysical studies, mathematics, “Renaissance Man” whopublishedin voluminous which are carefully researched, suchasthe Rutherford by John Campbell, noted intheearliercompletebiography of the discovery ofradon toDornwas briefly credit toRutherford. The incorrect ascriptionof on nteWkpdawbst o “Radon.” found onthe Wikipedia websitefor ascriptions ofDorn’s “discovery ofradon” is Note 2. For acentury thereference toDorn’s 26 Dorn” Wikipedia websiteentry for “Friedrich Ernst It isgratifying tonotice, however, thatthe Notes. true discoverer ofradon. proclaim specificallythatRutherford was the Rutherford, andwhoperhapswas thefirstto the lifeofNobelLaureate Ernest furnished importantclarifyingdetailsregarding life ofErnestRutherford, whohasgraciously Christchurch, New Zealand, anexpertonthe Campbell oftheUniversityCanterbury, Leopoldina. Also acknowledgedisDr. John the Deutsche Akademie derNaturforscher ments attheuniversitylibrary and archives of sites inHalleandforprocuring pertinentdocu- Wittenberg, forguidingusabouttheimportant Chemie, Martin-LutherUniversitätHalle- Kolbe (retired) oftheInstitutfürPhysikalische also grateful toDr. MonikaPlassandDr. Alfred , Note 1. An exampleofthemany incorrect 22 1901 , 155(orsometimes 115)insteadofthe 22b 2 Uncle Tungsten has beencorrected, givingproper , 23 Modern treatises oftheelements 24 Encyclopedia oftheElements of Dorndescribesa , 1–15. Itisclearthat Weeks, the Abh. Naturf Discovery oftheElements 3 , 21 chronicle thecor- 3 and laterwas 25 . “The correct 7 Ges. (Halle) when she 23 or 22a , , , make thismistake? A possiblesource ofthe lished atHalle! Why shouldsomany sources Rutherford in1902, volume 23, year 1901. Dorn publishednothingonemanationpriorto 8. E. Rutherford, 7. E. Dorn, . G. vonHevesy, 6. . J. R. Partington, 5. tury, includingDorn’s 1990biography ume atHallelabeledv. 22, year 1900alsocon- pri problem was suggested[Dr. MonikaPlass, .J. L. Marshalland V. R. Marshall, 1. References. inal publication ly toanincorrect citedyear intheauthor’s orig- tains v. 23, year 1901(alsoleadingunfortunate- 3. J. Campbell, J. L. Heilbron, 2. . For example, (a) 4. citations forDorn’s article . ” Onecantrace erroneous um emanation... of radium isagas. This was atfirstcalledradi- showed thatoneofthedisintegration products vate communication 1–14. Gesellschaft (Halle) and Physics 1913 300. N. Holmes, H. (c) Company, BocaRaton, FL, B-33;(b)B-298; 1984 Press. Explosion ofAtoms 29(2) Chem. New Zealand. 1999 ibid , , The ChemicalRubberPublishing , AAAS Publications, Christchurch, , 112–114. 10 , (a) , ed.-in-chief, C. D. Hodgmanand , 198–221. Abhandlungen derNaturforschenden 2003 1a , 64thed., ed.-in-chief, R. C. West, ). A careful search reveals that Rutherford. ScientistSupreme Philos. Mag 26 Ernest Rutherford andthe 1941 , Jahrb. Radioakt. Elektron. Nature throughout the20thcen- 28(2) CRC HandbookofChemistry , , ] thattheboundvol- 1901 2003 , CRC, Cleveland, Ohio, 7 beginning even with , 76–83;(b) , 1957 , , Oxford University 23 ., 1900 , 1–15. , 179 , 24 5.Ser., 49 , 912. Bull. Hist. 2004 pub- , , , , 6 E. Rutherford andF. Soddy, 16. 17. E. Rutherford andF.17. Soddy, 24. Per Enghag, 23. (a)http://en.wikipedia.org/wiki/Radon, (b) 22 E. Rutherford andF.18. Soddy, 15. E. Rutherford, 4 E. Rutherford, 14. M. S.13. Curie, J. R.12. Partington, 1 A. Debierne, 11. F. W. 10. Aston, G. P. Baxter, B. Brauner, A. 26. E. Rutherford andH.26. T. Brooks, M. E. Weeks, 25. 21. O. Sacks, T. Thomson, 20. 19. Mag. Debierne, A. Leduc, T. W. Richards, F. Soddy, Emanation desRadiums,” (Feb. 15), 411–414. 867–874. and G. Urbain, published by Rutherford. tations beyond explanationsalready and gelatins, respectively, withnointerpre- “emanation” insolutions the diffusionof Universität). These dissertationsdealtwith Inaugural Dissertations, Friedrichs wasserhalitige Gelatine,” “Über DiffusionvonRadiumEmanationin 1903 Sons). p 70–94(alternatepublisher:C. Scribner’s Soc. London. University Press, New Haven, CT, Ch. III, Yale “The RadiumEmanation,” Halle (Saale), Wissenschaftliche Beiträge 1990/33(O32), Luther-Universität Halle-Wittenberg am Ausgang des19. Jahrhunderts Institute inHalle—DiehalleschePhysik 100 Jahre GebäudedesPhysikalischen Weinheim, Germany, 1147, 1189. 2004 /Friedrich_Ernst_Dorn. Knopf, New York, 282. 1903 161–192. (Nov. 13), 235–236. (b) 942. Macmillan, London, Vol. 4, Education, Easton, PA, 785. 7th ed., Vol. II, 96. edition, ColbornandBentley, London, 1975 2001 Oxygen . F. Wallstabe, 9.“Untersuchungen überdie , 1902 , 6.Ser., 5, , Wiley-Verlag GmbH&Co. KGaA, , 6.Ser., 5 , Arno Press, N.Y., reprint of1830-31 ,Wiley-VCH, Weinheim,FRG. THE HEXAGON/ , C. Djerassi andR. Hoffman, , 1968 5.Ser., 4 Uncle Tungsten , Chem. News. J. Ind. Sci. 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