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E GE ESIS O E EC OG A IME Y
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In his Wolcott Gibbs Memorial Lecture,Frank W. Clarke, who had studied under G ibbs from 1865 to 1869, commented on the advances in analytical chemistry made by Gibbs and his students at the Lawrence Scientific School (1):
t th t p rt nt f ll th l tr l t d t r n t n f pp r, n n v r ll d, h h f r t p bl h d fr G bb l b r t r . It tr th t G r n h t, , l d t h v d th th d h rl r, b t f r I n d v r, h f l d t p bl h t. G bb , th r f r , nt tl d t f ll r d t f r pr h h th pr n t r f n th r .
As discussed later, C. Luckow published this claim soon after the appearance of Gibbs account. A paper that marks the centenary of Gibbs' work on electrogravimetry does not men- tion Luckow, who may have originated the technique (2). Ol v r W l tt G bb Oliver Wolcott Gibbs (1822-1908) - he dropped the first name, Oliver, early in his career - was a scientist of wide were attributed to over-rapid deposition, resulting in a spongy interests (1). Apart from his contributions to analytical chem- deposit. This is difficult to wash free from impurities and also istry, his work on the ammonia-cobalt compounds and on oxidizes easily. phosphotungstic and other complex inorganic acids occupied Two points made by Gibbs were that, after removal of much of his career. He was very much a person-to-person copper, the solution contained any other constituents of the teacher, keeping in close touch with his comparatively few sample and that it was at least probable that nickel might be students. determined by electrolysis of an ammoniacal solution of its Results obtained by E. V. M'Candless, presumably one of sulfate. In two determinations of nickel in a commercial Gibbs' students, form the basis of the 1864 announcement of sample, M'Candless obtained results of 91.36% and 91.60%. the technique that later became known as electrogravimetry. The metal deposit was bright and coherent, thus upholding Actually, the very brief announcement, "On the Electrolytic Gibbs' prediction. What a pity that no nickel determinations Precipitation of Copper and Nickel as a Method of Analysis", were reported for the copper-free liquid from the coinage alloy is the sixth and final section (pp. 334-36) of Gibbs' paper, experiments! Then we should have had the first example of an which carries the general title "Contributions to Chemistry overall electrogravimetric analysis of a sample. from the Laboratory of the Lawrence Scientific School" (3). In 1865, C. Luckow, a chemist working for the Cologne- The other sections deal with purely chemical separations, such Mindener Railway, claimed that he had been determining as of chromium, manganese, cobalt, and uranium from various copper and silver by electrolysis since 1860 (4, . In view of other metals. subsequent events, there is no reason to doubt his claim. He The deposition of copper from solutions of the sulfate was entered his methodology in a competition organized by the carried out in a small platinum capsule connected to the nega- Mansfeld Ober-berg und Haien Direction in Eisleben. This tive pole of one or two Bunsen cells. The positive electrode company needed a rapid and reasonably accurate method for was a stout platinum wire that dipped centrally into the solu- the determination of copper in ores, etc. The prize went to a Dr. tion. Completion of deposition, taking one to three hours, was A. Steinbeck for a method that involved titration in ammonia- checked by testing a drop of the liquid with hydrogen sulfide cal medium with potassium cyanide as a final step. However, water. After washing and vacuum-drying over sulfuric acid, Luckow also received an award. The details of both methods the copper-carrying capsule was reweighed. Six results with were published by the company in 1869 (6). Originally an average close to the theoretical value and a standard devia- Luckow, like Gibbs, had used the rather slow deposition from tion of about 0.3% are quoted. sulfate medium; otherwise he might have won the competition. M'Candless then determined copper in copper-nickel coin- Progress by Luckow and by others soon increased the speed age alloy. Four of his results were within 0.05% of the and versatility of electrogravimetry. specified 87.50% of copper. Some abnormally high results Two major advances made by Luckow were his discovery 8 ll. t. Ch . ( 0 that deposition of copper from dilute nitric acid medium was determination of nickel (9-12), copper (9,10,12), cobalt advantageous and his introduction of a separate cathode, i.e., (9,10,12), lead, zinc and manganese (11), and mercury (13). one that was not also the solution container. He used a platinum This last determination was described by Frank W. Clarke, the foil that was about 2-1/2 in. long and 1-1/4 in. wide. This was author of the Gibbs Memorial Lecture (1). bent into a cylinder and a stout platinum wire was attached. The Some of the later developments that extended the scope and anode, a flat platinum wire spiral of diameter to fit into the speed of electrogravimetry have recendy been reviewed (14 ,15). bottom electrolysis beaker, had a vertical extension to carry a One of these was the mercury cathode, developed by Edgar binding post, and a stand with an arm carrying a screw Fahs Smith and his students (14). The publication of Smith's connector held the cathode with its lower edge close to the book in 1890 (16) evoked a short note from Gibbs (17). This anode. concerns a paper that Gibbs had read before the National Luckow also examined the electrolytic behavior of a number Academy of Sciences in 1885. The note states that the of other metals, especially those likely to accompany copper in experiments that he made on metal deposition on a mercury technical samples (6). By suitable adjustment of the medium, cathode were purely qualitative, and that Luckow subse- he achieved simultaneous deposition of copper on the cathode quently applied the same process to the estimation of zinc (18). and lead, as lead dioxide, on the anode. Three years after the first communication from the Eisleben f r n nd t laboratories, another described some developments, including an improved platinum electrode system (7). The cathode, now . . W. Cl r , "W l tt G bb M r l t r ", Trans. of conical form, was slotted, so that oxygen arising from the Chem. Soc., 0 , 95, 2 2. anode could pass to the exterior of the cathode. In a sense, this 2. . Sz b dv r , "W l tt G bb nd th C nt n r f was the ancestor of the gauze-type electrodes that permit free El tr r v tr ", J. Chem, Educ., 64, 41, 666 66 . circulation of the solution. The actual aim was, however, to . W. G bb , " tr z r Ch d b r t r d r overcome a problem that occurred in the analysis of copper r n S nt f S h l", . Anal. Chem., 864, , 2 6 samples that contained much iron. With a simple cylindrical Amer. J. Set. Arts, 86 , 89, 8 6 . cathode a dark coloration, caused by reduction of iron along 4. C. , "U b r El tr M t ll An l ", Dinglers with the copper, appeared in the oxygen-starved region around Polytech. J., 86 , 177, 2 2 , 2 6 02. the outside of the cathode. By the summer of 1869, the . . Sz b dv r , History of Analytical Chemistry; r n: laboratory was able to determine copper in all samples that Y r , 66, p. 4. were free from antimony, arsenic and bismuth, which precipi- 6. M n f ld h n Ob r b r nd tt n r t n n E l tate on the copper deposit arid blacken it. b n, "U b r t n d K pf r h lt S h f rn n h In 1880, Luckow wrote a partially-reminiscent paper con- pr rt n M th d n", . Anal. Chem., 86 , 8, 4 th l tr cerning the use of the electric current in analytical chemistry r t t n b n n p. 2 . (8). He recalled the accounts that he had published in 1865 (4) . M n f ld h n Ob r b r nd l tt n r t n n E l and pointed out the advantages of electrodeposition. One of b n, "U b r d t n d K pf r nd n r nd r r M t ll these was that the process can run unattended, e.g., overnight. f l tr l t h W ", . Anal. Chem., 8 2, 11, 6. Following a survey of the electrochemical behavior of solu- 8. C. , "U b r d An nd n d l tr h n Str tions of various acids and salts, Luckow referred to some of the n d r n l t h n Ch ", . Anal, Chem., 880, 19, . then recent investigations by others. Examples included the . . Wr ht n, " tr z r nt t t v n t n d r M t ll f El tr l t h W ", . Anal. Chem., 8 6, 15, 2 06. 0. G. . S h d r, " r l tr l t h n t n d l nd K b lt ", Berg-u.-Hiittenmann. Z., 8 , 6, , , t d n . r n , . Anal. Chem., 8 , 16, 44 0. . A. h , " r l tr l t h n t rn n d M n n , l , n nd l ", Compt. Rend., 8 , 85, 226 22 . 2. W. Ohl, " l tr l t h t n v n K b lt, l, K pf r nd d r n rth l n d r n l t h n Ch ", Z. Anal. Chem., 8 , 18, 2 . . . W. Cl r , " r l tr l t h t rn n d Q lb r nd d C d ", Amer, J. Sci. Arts, 8 8, 16, 200 20 . 4. . M. b n n, " rr n fr Ind tr : Ed r h S th t t n An d nd bl C p M r r C th d ", n . . l tr d rr n nt f r l tr d p t n St nd M. . Orn , d ., Electrochemistry, Past and Present, Bull. Hist, Chem. 7 (1990) 19
A r n Ch l S t : W h n t n, .C., 8 , pp. 4 8 468. . . . St , " nr I. S. S nd ( 8 44 , A W ll b r d t r", n . . St nd M. . Orn , d ., El tr h tr , t nd r nt, A r n Ch l S t : W h n t n, .C., 8 , pp. 46 4 6. 6. E. . S th, El tr h l An l , h l d lph , 8 0. . W. G bb , " t n th El tr l t t r n t n f M t l A l ", A r. Ch . ., 8 2, , 0 . 8. C. , Ch . t. 88 , , 8 t d n E. ntz, . An l. Ch ., 1886, 2 , 4.
John T. Stock is Professor Emeritus in the Department of Chemistry of the University of Connecticut, Storrs, CT 06269 and is especially interested in the history of chemical instru- mentation and the history of electrochemistry.
"BETWEEN TWO STOOLS": KOPP, KOLBE AND THE HISTORY OF CHEMISTRY r nn K lb
Alan J. Rocke, Case Western Reserve University immediately to work on revisions for a second edition; he died 45 years later, the revision still incomplete. When Liebig left Hermann Kopp (1817-1892) and Hermann Kolbe (1818-1884) Giessen, new literary duties were added - principal editor of were two outstanding German chemists during the period in Liebig'sAnnalen der Chemie, and, with Will, managing editor which German chemistry rose to a position of prominence in of the annual Jahresbericht der Chemie. He continued these Europe (l). Although I know of only five surviving letters duties even after his transfer to Heidelberg. from Kopp to Kolbe and only one letter draft from Kolbe to Shortly after his arrival in Heidelberg he was asked by the Kopp - a document which we reproduce below - they must have Bavarian Academy of Sciences to write a history of modern been well acquainted for four decades. They may have first chemistry in Germany, as part of a project to commission two gotten to know each other when Kolbe was working as a newly dozen disciplinary histories in a series entitled Geschichte der minted Ph.D. with Robert Bunsen (1811-1899) at Marburg, Wissenschaften in Deutschland. The initiator of this project and Kopp was Privatdozent and then Ausserordentlicher Pro- was Leopold von Ranke (1795-1886), one of the founders of fessor at nearby Giessen, during the years 1842-1845. After modern critical historiography, whose goal was to write his- Kolbe became Bunsen's successor in 1851 (Bunsen having tory "wie es eigentlich gewesen ist", that is, without thematic, been called to Heidelberg), he maintained relations with all of didactic, or rhetorical coloration. Kopp had been strongly the Giessen chemists and visited them not infrequently. Upon influenced by this German objectivist historiographical move- Justus Liebig's transfer to Munich in 1852, Kopp and Heinrich ment as early as the 1840s (2). Will became Liebig's joint successors; the following year they The result of this contract emerged in the early 1870s as Die divided up their duties, Will taking experimental chemistry Entwickelung der Chemie in der neueren Zeit. (3). Kopp did and the directorship of the laboratory, with Kopp becoming not, however, succeed in making this a history of German professor of theoretical chemistry. In 1863 Kopp was called to chemistry, despite (as he wrote Liebig in January 1871) numer- Heidelberg, becoming a colleague of Bunsen; he remained ous attempts to follow Ranke's national program (4). In his there for the rest of his life. preface, dated April 1873, he took the offensive; he averred Kopp's life work was investigating the relationships be- that science, being international by nature, can only be written tween physical and chemical properties of chemical com- from an internationalist perspective (5). The work was indeed pounds; he has rightly been regarded as one of the founders of aggressively international. The first two-thirds of the long the discipline of physical chemistry. But he was also active in crucial final chapter, covering the development of theories of a literary sense right from the beginning of his career - indeed, molecular constitution during the most recent period (1840- his first love as a student had been philology. His classic four- 1860), scarcely mentioned a German name - until he intro- volume Geschichte der Chemie was complete by his 30th duced the development of structure theory by August Kekuld birthday. The first edition was quickly sold out, and he began (6). In effect, Kopp found Ranke's critical historiography