Harz Mountains and Göttingen

Home , Eisleben, Goslar, Harz, Oker, Oker (Goslar), Rammelsberg

Rediscovery of the Elements The Harz Mountains and Göttingen

Figure 1. The Harz Mountains, stretching 100 kilometers from Eisleben (the birthplace of III Martin Luther) through Goslar (UNESCO World Heritage site for its historic mines), is located 80 kilometers southeast of Hanover, Germany. The two elements discovered in this region were cadmium and thallium.

James L. Marshall, Beta Eta 1971, and Virginia R. Marshall, Beta Eta 2003, Department of Chemistry, University of RIGHT: Figure 2. An ancient North Texas, Denton, TX 76203-5070, woodcut of the Oker manufacturing [email protected] region during its productive period of the 1800s (courtesy, Museum der The Harz Mountains. In central Germany lie Göttinger Chemie). Oker is a the Harz Mountains, a natural preserve and a suburb of Goslar which was active National Park (Figure 1). This region, which lies in the processing of silver, copper, astride of the boundary separating West and lead, and zinc. East Germany during 1949–1990, was a “no- man’s land” which served as a protected area allowing natural plants and wildlife to flourish. Today one may gain an appreciation for the mining industry in the Harz Mountains Another exhibit in the Rammelsberger beauty and expanse of the region by traveling (Figures 2, 3). The Rammselberg Museum in Museum provides a spectacular example of the narrow-gauge Brockenbahn (train) from Goslar (Figure 4) is an expansive network of goslarite (Figure 6). This mineral specimen has Wernigerode (the birthplace of Klaproth, the buildings holding elaborate exhibits of mining the typical appearance of cave formations, but discoverer of uranium;1f ) to the summit of equipment, uniforms and tools, and scientific instead of being composed of calcium carbon- Brocken, the highest peak of the Harz (1141 m) displays of the metals mined in the area. ate it was formed by the leaching of oxidized and the mythical home of witches in Goethe’s Zinc has played an important part in the his- zinc sulfides in the geological layers above to Faust. tory of Rammelsberg region. A special exhibit in form zinc sulfate stalactites and stalagmites. For over a millennium mining was wide- the Rammelsberg Museum describes the first The zinc ores of the Rammelsberg region are spread in the Harz; this region produced silver, published description of purified zinc (Note 1) particularly rich in cadmium, the element iron, lead, and zinc, and small amounts of cop- at Goslar by George Engelhard von Löhneyss immediately below zinc in the Periodic Table. A per and gold. Cadmium was a by-product of (1552–1625)2 (Figure 5). When the smelters of special exhibit in the Rammelsberg Museum the zinc industry in Goslar and was discovered silver and lead were operating, volatile zinc shows various hues of cadmium formulations by Friedrich Stromeyer (1776–1835) at the would sublime from the furnaces and condense used in dyes and paints, including the famous University of Göttingen, 50 kilometers to the in the gaps between the slate stones. This yellows of Vincent van Gogh’s (1853–1890) southwest. Tilkerode in the southeastern part of metal, described as “white as tin but harder,” paintings (Figure 7). the Harz provided the ores in which William could be scraped from the walls but was not Cadmium was discovered in 1817 by Crookes (1832–1919) discovered thallium in commercially valued because it was too brittle. Friedrich Stromeyer (1776–1835) at the London in 1861.1h However, it was soon discovered that when University of Göttingen.3 Stromeyer was not mixed with copper it made superior brass to the only a professor but also General Inspector of The Discovery of Cadmium. The Goslar previous recipe from tin and calamine (zinc sil- Pharmacies (Apotheken) throughout the region has historically been the center of the icates and oxides). Kingdom of Hannover (stretching from

4 THE HEXAGON/SPRING 2012 Figure 3. The present appearance of Oker. This manufacturing region lies at the foot of the Harz Mountains (far distance, to the right), the rich source of many metals and minerals. This northwestern portion of the Harz is sometimes called the “Classic Geological Square Mile” because of its continuous sequence of tilted geologic layers from the Paleozoic era to the present, 400 million years.

Figure 6. Found in a nearby mine, this is a mag- nificent example of “goslarite” (ZnSO4-7H2O), also known as zinc vitriol. This 62x28-cm stalactite formation was found in the “Vitriolkammer” [“vitriol room”), a chamber dripping with sulfate solutions. It is believed that the “prongs” of zinc minerals (and/or sublimed zinc) gave rise to its modern name (Ger. antler’s prong = Zincke].

BELOW: Figure 5. In the Rammelsberg Museum a wall-size reproduction of an excerpt from Löhneyss’ 1617 treatise2 refers to “Zinck or Conterfeht” (see arrows) collected by the accidental sublimation of volatile metallic zinc onto the walls of the smelter. The name “Conterfeht” [counterfeit] was used because when zinc was blended with copper in the correct proportions, the color Figure 4. The Rammelsberg Mining Museum in Goslar (N51° 53.39 E10° 25.09) has a fascinating display changed to a golden hue. Alchemists sought the of equipment and exhibits describing the 1000-year history of the Goslar-Oker area; tours are also offered Rammelsberg zinc, which gave them much hope through the historic mines. — albeit false — for easy riches.

Göttingen to Hamburg, see Figure 1). Upon reports that zinc medicines were turning yellow upon heating, he initiated a study of medica- tions prepared at Salzgitter-Bad (15 kilometers north of Goslar) which were believed to be the source of the problem. This company preparing the zinc preparations was originally known as Gesellschaft Saline Liebenhalle,4 (Figures 8,9) named for the salt mined for centuries in the village. During the 1800s the company’s name was changed to Johann Ludwig von Unger’s Erban & Company, a Chemischen Fabrik which produced magnesia, tartaric acid, sulfur, zinc and ammonia compounds, oils and extracts, and other pharmaceutical products.5

SPRING 2012/THE HEXAGON 5 III prototype ofallteachinglaboratories,” Giessen in1824which “may beregarded asthe Wöhler accepted apostattheGewerbeschule Berzelius inStockholm during1823–1824, may recall thatafterapostdoctoral stintwith cesium. (1811–1899), thediscoverer ofrubidiumand ebrated studentwas Robert Wilhelm Bunsen deceased Stromeyer. moved tothisuniversityin1836replace the Friedrich Wöhler (1800–1882) (Figure 11), who chemistry buildingat Wöhlerplatz isastatue of Masch-Strasse). with aplaque(N51°32.10E09°55.76, Untere- the homeofhisfamilyismarkedincity ratory ever. .ratory . ever. fortheteachingofchemistry” von Liebig(1803–1873)erected “the firstlabo- known. Despitewidespread beliefthatJustus chemical laboratory instructionare notwell Physics (Figure 10). building whichisnowtheDepartmentof Stromeyer conductedhisanalyticalwork ata from theLatinword forzincores (cadmia). nated. Henamedthenew elementcadmium southwestern Poland) were similarlycontami- fied thatzincpreparations from Silesia(now small ingotby reaction withcharcoal. Heveri- isolate thecadmium, from whichheobtaineda bonate toremove zincsulfide, hewas able to After extraction withaqueousammoniumcar- of solutionszincsaltswithhydrogen sulfide. was abletoseparate ayellow sulfideby reaction due toiron impuritiesorarsenic, butStromeyer oration ofzincpreparations was thoughttobe 6 laboratory in1806atGöttingen. Stromeyer actuallydeveloped thefirstteaching by the1840s. selenides, usedinceramics by1830andinpaints oranges, andreds ofcadmium/zincsulfidesand display ofmineral pigments, includingtheyellows, Figure 7. IntheRammelsberg Museumisthis Immediately totheeastof historic The contributionsthatStromeyer madeto Originally theundesired yellow discol- 1g Bunsen was anativeofGöttingenand h HEXAGON The 8 His mostcel- 1b readers 6 at 7 um preparation (Figure 13). also included, e.g., theoriginalmetallicseleni- tions from Wöhler’s research withBerzelius are Nernst, and others. Earlierchemicalprepara- Wöhler, Stromeyer, Otto Wallach, Walther Göttinger Chemie)boastshistorical displays of attractive museumofchemistry (Museumder Tammannstrasse, N5133.49E956.90), an new campusoftheUniversityGöttingen(4 organic chemicaltheory (Figure 12). At the most notablydisproved the “vital force” in Hildesheim, 25kmtothewest. tallest structure inthefigure). The pharmacywhichsoldthesezincmedicationswasin Wagenfeld in town isnamedforthesaltminedincenterofvillage(besideSt. Mariae-Jakobi Church, the which producedzincpreparations withthecadmiumimpuritiesdetectedbyStromeyer(seenextfigure). The on thehilltopbeyond, thechemicalindustrialcomplexofJohann LudwigvonUnger’s Erban&Company E10° 22.33)ofSalzgitter-Bad. Datingfrom1905, thispaintingshowstheeastpanorama ofthevillage, and Figure 8. This paintingwasfoundinthetownpubliclibrary (Stadbibliothek;11Marktplatz;N52°02.81 Río’s discovery ofvanadium inMexico aluminum, yttrium, andberyllium, verifieddel in Berlin1825where heprepared metallic 22.65). “Wohnstift” —anoldfolks’ homeonKurpark amGreif (“HealthparkoftheGriffin”)(N52°02.38E10° Figure 9. Today theChemischenFabrik ofUnger’s Erban&Companyisgoneandreplaced bya 1a , and the previous issueof h eeim. . .” the selenium Mountains forthepurposeofextracting from it acid manufactory at Tilkerode intheHartz[sic] lbs oftheseleniferous depositfrom thesulfuric Hofmann placedatmy disposalupwards of10 Crookes wrote “In theyear 1850Professor covery ofthalliumwas described. William ment. ..” ment. which was causedby thepresence ofanew ele- .denly abrightgreen lineflashedintoview. . spectral analysisoftheresidue in1861, “sud- “green twig.” Tilkerode, theoriginalsourceofthallium. 9 which hecalled “thallium” meaning THE HEXAGON/ 10 9 The HEXAGON As Crookes was pursuinga SPRING 2012 , 1h the dis- In Figure 10. This “Fachwerkhaus” (Ger. = medieval half-timbered building) served as the Chemical Institute since the latter part of the 18th century, and recently was transferred to the Physics Department of the University of Göttingen (N51° 31.82 E09° 56.19). This is where Stromeyer discovered cadmium and developed the first chemistry laboratory program.

Figure 11. The statue of Friedrich Wöhler at Wöhlerplatz (N51° 31.81 E09° 56.17), stands next to the old Chemical Institute (see next figure).

Figure 12. At the base of the statue of Wöhler is the chemical structure of urea inlaid in brick. Wöhler stated, “I can make urea without the use of kidneys, or either man or dog.” He prepared urea OC(NH2)2 by heating its inorganic isomer, ammonium isocyanate, NH4CNO. Wöhler’s famous organic laboratory was located immediately to the east (razed in 1977 and replaced by apartment buildings).

Figure 14. These rolling hills are the Tilkerode area (N51° Figure 13. This original sample of selenium in the 37.26 E11° 18.34), the Museum der Göttinger Chemie (4 historic site of silver and Tammannstrasse; N51° 33.49 E09° 56.90) dates lead mining, and the source from Wöhler’s days with Berzelius. The label of the thallium discovered reads, “Wöhler: selenium from the Gripsholm- by Crookes in 1861. Today sludge (of the sulfuric acid factory) prepared in the fields are lush with peas 1824 by Wöhler (in Stockholm). The glass flask and rye (“Erbsen und was blown by Berzelius.” Even though Berzelius Roggen”). The “-rode” suffix gets official credit for the discovery of selenium, it is common in the Harz, was his postdoc Wöhler who did the work. meaning “forest clearing” in the local dialect.

SPRING 2012/THE HEXAGON 7 III “valence.” “atomicity”) whichhasledtoourmodernterm posed theterm “quantivalence” (instead of tematic namesforthealkanes nation. Hofmannpromoted themodernsys- Hofmann rearrangement andHofmannelimi- work withaminesledtotheeponymous from thedestructivedistillationofcoal. His tar, originallyawaste liquidproduct derived work onanilinesanddyes, derived from coal Hofmann isprobably bestremembered forhis ing 1845–1864before returning toGermany. Crookes attended), remained atthatpostdur- “aromatic” forcoaltarderivatives. in 1846(Figure 16). meters northwestof Tilkerode), firstappearing area inthemid-1800swere inOker(65kilo- acid manufacturiesthatexistedintheHarz Bel). the tetrahedral carbonofvan’t Hoffand Le were developed laterwiththe1874conceptsof blue, Cl=green. C =black, H=yellow, O= “fiery” red, N= “dye” Hofmann choseisthesameasthatusedtoday: olefins andacetylene. The color scheme even proposing amodelforunsaturation in organic structures andmultivalent atoms— constructed from “croquet balls” toexplain dimensional ball-and-stickmolecularmodels Atoms” (April7, 1865), where heusedtwo- Institution “On theCombiningPowers of delivered afamouslecture attheRoyal College ofChemistry in London the firstDirector ofthenewly formedRoyal Liebig attheUniversityofGiessen. Hofmann, (1818–1892) hadstudiedunderJustus von pyrites from Falun (175kilometersnorthwest). Sweden, sulfuric acidmanufactory atGripsholm, brown mud” depositedinaleadchamberhis selenium in1817(Figure 13)inthe “golden- and whendidHofmann procure the Tilkerode the Harz) Bleikammerschlamm (lead-chambersludgein was discovered by Crookes inaHarzer source ofCrookes’ “seleniferous deposit” Tilkerode (Figure 14)andwere certainlythe 8 deposit.” Hofmann, theproviderof“seleniferous obtained from Hofmann. (Note2) produced theseleniferous sludgethatCrookes that Okeristheclearchoiceforsite nor didsmeltersofany kind. “Schwefelsäurefabrik”) factory (German: “Vitriolfabrik” or Tilkerode proved thatasulfuricacidmanu- (Figure 15), butavisitby theauthorsto The finaltantalizing questionremains, how The Germanliterature verifiesthatthallium It istruethatselenium-richores aboundin 19 1e 11 17 — just asBerzeliushaddiscovered just — a residue from theroasted iron August Wilhelm vonHofmann Before returning toGermany, he 18 (Three-dimensional models 11,13a Local scholarsagree never existed there — 13 The onlysulfuric 15 14 and coined (the school 16 He pro- 9,13 13a 12 nessmen” gists, andphysicians; industrialistsand busi- ers andmineoperators; apothecaries, drug- quently associatedwith “agricultural-landown- at Wippra (6kilometerssouth). Tilkerode bythe Tourist Museum is oneofmanyerected in astonishing range ofacquaintenances” industry, maintained closecontactwiththe sulfuricacid for hisacquisitionofthesample. Specifically, he industrial site. the subject, mentioningOker asaprimary Eskebornite” (CuFeSe source forthe mineral shut down1862. Eponymous to Goldschachtca. 500meters, length ca. 1300meters. Distance tunnel]. Beganin1784, total Eskeborner gallery[horizontal “Former mineentrance. Old over byforest. The signreads: are nowallfilledinand taken held Crookes’ thallium. The mines of theselenium-richores which 38.01 E11°19.13wasthesource Goldschaft minecomplex(N51° Figure 15. The Eskeborner- Harz (1846). includes theproductionoflead, copper, andsilver, andthenthefirstmajorsulfuricacidmanufactoryin the Hütterwer Harz, thenthemodernnameHarz-MetallGmbhin2001. The longhistoryofthissmeltersite sludge. This manufactory, datingfrom1527, wasoriginallytheFrau-Marien-Saigenhütte, later(1968)the E10° 29.09), thesiteofanoldsulfuricacidworkswhichprobablyfurnishedCrookes’ seleniferous Figure 16. These historicsmeltingladlessitoutsidetheHarzMetalsinOker(6Hüttenstrasse; N51°54.05 Continent, Chemistry, Hofmanntraveled frequently tothe deposit? As Director oftheRoyal Collegeof 15 22 writing aseriesofreview articleson 20 — all affording all muchopportunity — and “with amazingenergy andan 23 Unfortunately, itisunknown 2 ).sign The 21 he fre- confirm thediscovery ofterrestrial helium. the Georg-August-Universität Göttingen, and head oftheInstitute ofInorganic Chemistry at Herbert Roesky, retired Professor andprevious Acknowledgments. Next issue: Grateful acknowledgmentisgiventoDr. story! appears thatwewillnever knowthecomplete nondescript gray soot(Figure 17), andit how Hofmannlaidhishandsonthissampleof THE HEXAGON/ Crookes usesspectral analysisto SPRING 2012 much earlier. Silver and lead ores from 14. R. G. Williams and A. Barrett, Imperial Tilkerode were transported to the smelters of College. A Pictorial History, 1988, Imperial Mägdesprung and its suburb Silberhütte as College Archives, London. early as 1693 (15 kilometers to the west; see 15. A. S. Travis, Endeavour, 1992, 16(2) (New 13b Figure 1). A minor Vitriolfabrik was estab- Series), 59–63. lished at Silberhütte, perhaps as early as the 16. Hofmann used the term “aromatique” in a late 1700s,28 but it ceased production in 1832 — letter to J.-B. Dumas, referring to the long before Hofmann, originally studying law homologous carboxylic acid series: A. W. and languages at the University of Giessen in Hofmann, Comptes rendus, 1855, 41, 1836, was attracted to chemistry and won his 718–720. doctorate with Liebig in 1841.15, 22 By 1845 the rich selenium content of the Tilkerode ores had 17. A. W. Hofmann, An Introduction to Modern been established by the blowpipe method of Chemistry, 1865, Walton and Maberley Berzelius,29 giving one reason to collect lead- (London), 168–169. chamber residues to procure quantities of this 18. A. W. Hofmann, Proc. Roy. Instit., 1865, 4, element. (A major sulfuric acid factory was 401–420. 13b again started up at Silberhütte in 1885; today 19. R. B. Grossman and J. Chem. Ed., 1989, this community is well-known for its fireworks 66(1), 30–33. factory, Pyrotechnik Silberhütte). 20. Justus von Liebig und August Wilhelm Figure 17. This display in the Science Museum of References Hofmann in ihren Briefen Nachträge South Kensington, London, includes (1) 1845–1869, 1988, E. Heuser, ed., “Seleniferous deposit from the sulfuric acid cham- 1. J. L. Marshall and V. R. Marshall, Bionomica-Verlag, Mannheim. bers of Tilkerode in which Crookes first noticed the The HEXAGON of Alpha Chi Sigma, (a) 2004, 21. J. J. Beer, J. Chem. Ed., 1960, 37, 248–251. existence of a new element”; (2) “Residue left on 95(2), 24–28, (b) 2004, 95(3), 46–50, (c) 2005, distilling crude selenium from the deposit and 96(4), 4–8, (d) 2006, 97(2), 24–29, (e) 2007, 22. C. Meinel, Angew. Chem. Int. Ed. Engl., 1992, which was shown to contain thallium.” Tilkerode 98(4), 70–76, (f) 2008, 99(2), 20–24, (g) 31, 1265–1282. never had a sulfuric acid manufactory; hence the 2008, 99(3), 42–46; (h) 2011, 102(4), 62–67. 23. A. W. Hofmann, Chem. News, 1877, 35, seleniferous ore was processed elsewhere, most 2. G. E. von Löhneyss, Bericht vom Bergwerk, 118–119. certainly at Oker in the Harz region. 1617, Part 5, Zellerfeld, 83. 24. G. Agricola, De Re Metallica Libri XII, 1556, 3. F. Stromeyer, Ann. Phys., 1818, 30, 193–210. Frobenius, Basel, H. L. and L. H. Hoover, Dr. Günther Beer, Director of the Chemistry 4. H.-H. Emons and H.-H. Walter, Alte Salinen English translation with notes, 1912, Museum. The two furnished much information in Mitteleuropa, 1988, VEB Deutscher Verlag London, 1950 edition, Dover, New York, (both published and unpublished) regarding für Grundstoffindustrie-Leipzig, 145. 409. Stromeyer, Wöhler, and the history of cadmi- 25. Paracelsus, Liber mineralium II, c. 1570. um. The authors are indebted to Dr. Dieter 5. W. Vershofen, Die Anfänge der Chemisch- Klaus, Museum Schloss Bernburg, Germany; Pharmazeutischen Industrie, 1. Band, 1958, 26. J. R. Partington, A History of Chemistry. Andreas Karcher, Verwalter der Tilkerode (cura- Berlin [u.a.] Dt. Betriebswirte-Verl., 62–63. Vol. 2. 1961, Macmillan, London, 726. tor of Tilkerode Area; erected park signs, e.g., 6. I. Remsen, Nature, 1894, 49(1275), 531–535. 27. J. Masefield, The Travels of Marco Polo, the Figure 15); and Heinz Mente (“best historian of 7. R. E. Oesper, J. Chem. Ed., 1927, 4(12), 1461– Venetian, 1908, E. P. Dutton, N.Y., 71. the Harzgerode/Silberhütte region” and author 1476. 28. The Silberhütte Vitrolwerk is not listed in of Harzgerode in alten Ansichten, 1992, 8. G. Lockemann and R. E. Oesper, J. Chem. main compilations, e.g., Liste von Europäische Bibliothek) for furnishing mine Ed., 1953, 30(4), 202–204. Hüttenwerken in Deutschland, http://de.wiki- and Vitriolwerk information for the Harz pedia.org/wiki/, but is mentioned in archival region. 9. W. Crookes, Chem. News, 1861, 3, 193–194; literature, e.g., B. H. Voigt, Neuer Nekrolog reprinted in W. Crookes, Phil. Mag., 1861, 21 der Deutschen, Vol. 1, Friedrich-August Notes (4th series, no. 140, April), 301–305. Schmidt, 1824, 74. Note 1. The first reference to “zinck” specifi- 10. W. Crookes, 1861, Chem. News, 3, 303. 29. J. J. Berzelius, The Use of the Blowpipe in cally as a metal was in 1556 by Agricola 11. J. Fieser, Nebenmetalle, 12. Band, “Die Chemistry and Mineralogy, 1845, J. D. 24 (1494–1555) and in a (ca. 1570) publication Metallischen Rohstoffe,” 1966, Ferdinand Whitney, trans., Ticknor & Co. (Boston), 98. questionably attributed to Paracelsus Enke, Stuttgart, 173. 1c, 25 (1493–1541). Although Andreas Sigismund 12. J. E. Jorpes, Bidrag Till Kungl. Svenska Marggraf (1709–1782) is credited in 1746 with Vetenskapsakademiens Historia VII. Jac. ______the first laboratory preparation of metallic 1d, 26 Berzelius, 1966, translated by B. Steele, zinc, descriptions of metallic zinc in the East Almqvist and Wiksell, Stockholm. 61–63. Just a reminder that you can find out more and Europe appeared previously. Perhaps the about the “Rediscovery of the Elements” first European reference to zinc was by Marco 13. Personal communication, (a) Dr. Dieter Polo27 during his journey through Persia (1272) Klaus, Museum Schloss Bernburg, series, by Brothers Jim and Jenny Marshall, at: where it was called “tutty” or “Tutia.” Germany; (b) Andreas Karcher, Tilkerode, http://www.jennymarshall.com/rediscovery.htm Note 2. Actually, there had been a Germany and Heinz Mente, Harzgerode, Vitriolfabrik even closer to Tilkerode — but Germany.

SPRING 2012/THE HEXAGON 9