Popular Science Monthly/Volume 17/August 1880/Biographical Sketch of Frederick Wöhler
|←Fouque's Santorin and its Eruptions||Popular Science Monthly Volume 17 August 1880 (1880)
Biographical Sketch of Frederick Wöhler
By Charles Arad Joy
FREDERICK WÖHLER, the Nestor of German chemists, was born July 31, 1800, in the little hamlet of Eschersheim, near Frankfort-on-the-Main, in the house of the village pastor who was his uncle by marriage. How it happened that the mother was away from home at such an important period—for this was not her residence—is worthy of record, as it shows that there were heroic elements in the family for the son to inherit. The father held the office of equerry to the Elector of Hesse-Cassel in the early part of this century. This Elector is celebrated in history for the violence of his temper. He was one day visiting the royal stables in company with the equerry, and on this occasion was so particularly insulting and unreasonable that, endurance having ceased to be a virtue, Wöhler seized a horsewhip, and then and there gave his Royal Highness such a castigation as he had often enough richly merited, but doubtless never expected to receive. The equerry then jumped upon the back of the fleetest horse in the stables, and, accompanied by a groom who was to return the steed, soon put a safe distance between himself and the impending wrath of his sovereign. The august Elector, fearing ridicule, thought it wisest to let the matter drop, and never pursued the fugitive. It became necessary, however, for the family to make a hasty retreat from Cassel, and the wife took refuge in the house of her sister, where she remained until the birth of the subject of our sketch. The parents subsequently purchased a small estate at Rödelsheim, where they resided until 1812, when they removed to Frankfort.
Frederick's first instruction in writing, drawing, and later in French, was imparted by his father, who was a university-bred man of unusual intelligence. When he was about seven years old he attended the public school, and received, in addition, private lessons in Latin, French, and music. A fondness for experiments and for making collections early manifested itself, and was judiciously encouraged by his father and an intimate friend who had, in the capacity of private tutor to a nobleman, spent some time at the University of Göttingen, and had, while there, devoted special attention to the study of the natural sciences. This friend owned considerable chemical and physical apparatus, with which he exhibited experiments to the boy, and also allowed the youth to practice his skill, particularly with the battery, which was the great novelty of the day. In addition to these experiments, all sorts of minerals which presented any peculiarity of appearance were collected for future examination.
In 1814 Wöhler entered the high school (gymnasium) at Frankfort, where he prepared for the university. Among his teachers at the gymnasium were several men who afterward became renowned for their learning and special acquirements, namely, F. A. Schlosser, Grotifend, and Carl Ritter. The boy was faithful in his attendance upon the exercises of the school, and satisfactorily passed all of his examinations, but was not distinguished for much knowledge of the ancient languages; indeed, his passionate love of the chemical and physical sciences and his zeal in collecting minerals absorbed so much of his time and tempted him so frequently to neglect both the classics and mathematics that private tutors were occasionally necessary to coach him over difficult passages or knotty problems. He kept up a system of exchange of minerals with his fellow students, and with dealers, especially with Hermann von Meyer and with Herr Menge, in Hanau, to the latter of whom he carried many a bagful of hyalite collected by himself. An important influence was exerted upon the scientific bent of his mind by Dr. Buch, a very intellectual and learned man, who occupied himself largely with chemical, physical, and mineralogical studies, with whom Wöhler enjoyed for years a most instructive intercourse, and to whom he subsequently expressed his indebtedness for the first serious encouragement to pursue scientific studies. Dr. Buch had improvised a laboratory in his kitchen, where, on certain days, experiments were allowed. Among other things, aided by his young pupil, Dr. Buch analyzed some pyrites from Bohemia, in which he found the recently discovered element selenium, and published the result in Gilbert's “Annalen,” to the great satisfaction of Wöhler, who then, for the first time, saw his name in print. The two also prepared some cadmium, another new metal, from zinc-ore.
Wöhler afterward carried with him on a pedestrian tour to Cassel and Göttingen a specimen of what he had prepared, in order to show it to its discoverer, Professor Stromeyer, and to have him identify it as genuine. It was during this visit that he made the acquaintance of the celebrated Blumenbach, whose text-book of “Natural History” he had zealously studied. Blumenbach received the young student very cordially, and kindly showed him the curiosities of his natural history collection. He could hardly have anticipated that a few years later the young man would become his colleague at the university, as the successor to the lamented Stromeyer.
By slow degrees Wöhler obtained more correct ideas of chemistry, and abandoned the doctrine of phlogiston, in which, without fairly comprehending it, he had at first believed. Dr. Buch's rich library was always open to him, and he was not, as formerly, confined to Hagen's old “Experimental Chemistry,” which had been used as a text-book by his father. Chemical experiments now became a passion with him, they absorbed his mind by day and night; his room at home was transformed into a laboratory full of glasses, retorts, washing-bottles, and minerals — everything in the greatest confusion. No coal-hod in the kitchen was safe in his sight, and it remains a wonder to the present day that he did not set the house on fire or poison some of the family by his operations in the kitchen! The breaking of a flask of chlorine at this period nearly suffocated him, and some severe burns by phosphorus suggested greater caution. He was particularly interested in experimenting with the voltaic battery, and succeeded in constructing one with one hundred small pairs of plates, with which he repeated Sir Humphry Davy's experiment of the isolation of potassium. All his efforts were now concentrated upon an attempt to prepare potassium in a chemical way, according to the method proposed by Curadeau. An old graphite crucible, which Bunsen, the director of the mint, gave to him, served as furnace, and, armed with a bellows loaned by the same person, the experiment was tried in the laundry, with his sister as assistant to blow the bellows. Great was his rejoicing when he perceived the balls of metal in the gun-barrel attached to the retort, and the sister was hardly less gratified at the result of their combined efforts. But the young chemist carried on other studies, to the detriment of his Latin and Greek. He constantly had instruction in drawing, to which his father, who himself drew well, attached much importance. He learned to draw from Nature, and his sketch-book always accompanied him on his excursions in the neighborhood and on the Rhine; he even tried painting in oil, and etching, for which he received much encouragement from the painter Morgenstern.
A rich present of antique Roman coins, which a friend of his father made him, increased his desire to collect similar ones to such a degree that he succeeded in getting together all of the coins of the Roman emperors in their order of succession; Roman urns, lamps, legion-stones, which at that time were still found in the ancient Roman encampments of the neighborhood, were also collected, and aroused in him much interest in Roman history. He likewise commenced to occupy himself with German literature, and to make himself acquainted with the poets of the last century, in which studies a young artist, his drawing master, was his guide. He was too young to appreciate the great political movements of the time, yet he always remembered with interest having seen Napoleon I. during his triumphal entry into Frankfort, and later the passage of the allied troops and Cossacks. His father bestowed particular care upon his son's physical development, and upon his strengthening of a naturally weak constitution by regular exercise, riding, fencing, swimming, and boating.
At Easter, 1820, when he had nearly completed his twentieth year, Wöhler graduated at the gymnasium and entered the university. Partly in accordance with his own inclination, and partly because favorable circumstances promised him success, it was decided that he should study medicine.
He spent his first year at the University of Marburg, where his father had also studied, and where many of his father's friends could befriend and guide him. He attended the lectures on botany, zoölogy, mineralogy, physics, and anatomy, and began during the winter to perform dissections. But chemistry continued to be his favorite study, and, much to the disgust of his landlord, he transformed his parlor into a laboratory, and occupied himself with the study of sulphocyanic acid and cyanogen compounds in general. He discovered iodide of cyanogen, for to him at least it was a discovery, as he was not aware at the time that Davy had previously prepared it. In the joy of his heart he communicated the discovery to Wurzer, the Professor of Chemistry at Marburg, to whom it was also new, but, instead of receiving commendation, he was reprimanded for neglecting his medical studies to carry on original investigations. After spending one year at Marburg, Wöhler went to Heidelberg, filled with enthusiasm for Leopold Gmelin, who became his most cherished friend and master. He wished to attend Gmelin's lectures on chemistry, but was told by that professor that it was superfluous, and he accordingly abandoned the idea, and thus secured more time for work in Gmelin's laboratory and for intimate personal intercourse with this amiable and learned man.
Nearly all the time which his medical studies left him he devoted to chemistry, and even toward the close of his course, when practical medicine became very absorbing, he still continued to spend several hours daily in the laboratory. He resumed his researches on sulphocyanic acid at Heidelberg, and commenced those on cyanic acid, the results of which, at Gmelin's solicitation, were published in Gilbert's “Annalen.” It was of great service to Wöhler at this time that Gmelin and Tiedemann were engaged upon their physiological researches, thus encouraging him to a similar line of study. He enjoyed to a high degree the esteem of Tiedemann, and owes to this excellent man the kind encouragement to pursue physiological researches, which proved so important in Wöhler's future career. Wöhler was one of the competitors for the prize offered by the medical faculty for a thesis on the “Migration of Matter into Urine,” and had the good fortune to be successful. Among other things, it was shown by this research that plant-alkalies, in their transformation through the blood, are changed into carbonates. In September, 1823, Wöhler passed the university examination, and received the degree of Doctor of Medicine and Surgery, “nec non artis obstetriciæ.”
Immediately after leaving the University of Heidelberg it was Wöhler's intention to visit the larger hospitals of Europe, as a further preparation for the practice of his profession, but Gmelin advised him to abandon the uncertain practice of medicine and to devote himself solely to chemistry, for which specialty he had shown such decided inclination and talent. Acting upon this advice, Wöhler wrote to Berzelius for permission to study in the laboratory at Stockholm, and received from the great Swedish chemist the following answer: “Any one who has studied chemistry under the direction of Leopold Gmelin has very little to learn from me; but, nevertheless, I can not forego the pleasure of making your personal acquaintance, and will therefore cheerfully accept you as the companion of my labors. You can come whenever it is agreeable to you.” Armed with this permission, Wöhler at once made preparations for the journey. As his means were limited, he decided to take a sailing vessel from Lübeck, but when he reached that port he found that there was only a small craft in the harbor destined for Stockholm, and that it would be six weeks before she would sail. Of this delay he says, in a sketch furnished to the Berlin Chemical Society in 1875: “I could hardly have endured the loss of time had I not cultivated the acquaintance of Menge, the Icelandic traveler and genial mineral-dealer, in whose collections I could satisfy my fondness for minerals. I had already made his acquaintance in Frankfort, where I had exchanged specimens with him, and where he on one occasion introduced me to Goethe, who came to buy a fine specimen of copper azurite from Chessy.”
Menge introduced him to Kindt, the principal apothecary in Lübeck, for whom he formed a lasting friendship, and with whom he resided the last three weeks of his stay in town. To occupy his time while waiting for the ship to take in cargo, Wöhler undertook, in company with Kindt, to prepare some potassium according to the method proposed by Brunner. Instead of a wrought-iron retort, they made use of one of the bottles in which mercury is furnished to commerce, while a bent gun-barrel served as the neck of the retort. He obtained such a rich supply of potassium that he was able to take a large quantity to Sweden, which afterward proved of great importance in Berzelius's experiments on the isolation of silicium, boron, and zirconium. It was also in Lübeck that Wöhler met for the first time Mitscherlich, who was returning from a visit to Berzelius. At last the ship set her sails, and on the 23d of October, 1823, started for Travemünde, where he took passage on the 25th. After a very stormy passage the vessel dropped anchor at Dalarö, a small port situated on the rocky coast, whence, to avoid a long sea-voyage, he decided to go by land to Stockholm. The officer of the guard who examined his passport, on hearing that he was going to study with Berzelius, declined to accept the usual fee, saying he “had too much respect for science and his celebrated countryman to take money from one who, in the pursuit of knowledge, had undertaken so long a journey.” Wöhler arrived at Stockholm at night, and early the next morning could hardly restrain his impatience to call upon the great master.
Berzelius had an official residence in the Academy of Sciences, and a medical student, whose acquaintance he had casually made, showed the way. We will let Wöhler himself describe his first interview: “With a throbbing heart I stood before Berzelius's door and rang the bell. A well-dressed, dignified gentleman, with florid and healthy complexion, let me in. It was Berzelius himself. He welcomed me very cordially, informed me that he had been expecting me for some time, and wished me to tell him of my journey — all this in the German language, with which he was as familiar as with French and English. When he conducted me into his laboratory I felt as if I were in a daze, doubting whether I found myself in reality in these classic walls and in the fulfillment of all my dreams. He took me the first day to the institute, where he gave his lectures to medical students, but which were attended by officers of the army and several of his friends, and which I regularly visited afterward to accustom my ears to the language. This afforded me opportunity to admire his calm and clear delivery, and his skill in performing experiments. In this institute was also the laboratory for medical students, which was presided over by Mosander.” The following day Wöhler at once set to work. He was provided with a platinum crucible, a balance with weights, and a wash-bottle, but had to furnish his own blowpipe, the use of which Berzelius strongly recommended. He was at that time the only pupil, as Mitscherlich, Henry and Gustavus Rose, had preceded him, and Magnus was his successor. The laboratory consisted of two common rooms, with very simple accommodations. There were neither furnaces, nor ventilators, nor water, nor gas. In one of the rooms were two pine tables, at one of which Berzelius had his place, while Wöhler worked at the other. There were the usual cases for reagents, a glass-blowing table, a water-trough, under which stood a pail, and where the cook Anna came every day to wash the soiled vessels. This cook was a famous character, and ruled over the establishment with despotic sway. As she was one day cleaning some vessels, she remarked that they smelt strongly of oxidized muriatic acid. “Look here, Anna,” said Berzelius, “thou must not call it oxidized muriatic acid any longer, but chlorine that is better.”
Berzelius was at this time engaged upon his beautiful researches on hydrofluoric acid, silicium, boron, and zirconium. It was most instructive for Wöhler to follow these researches and note the methods pursued by the great Swedish chemist. After a hard day's work in the laboratory, Wöhler generally spent his long evenings in studying the Swedish language, and in translating Berzelius's treatises for Poggendorff's “Annalen.” Sometimes Berzelius would retain him at his house, and entertain him with stories of Gay-Lussac, Thenard, Dulong, Wollaston, H. Davy, and other scientific celebrities, with all of whom he corresponded, and whose letters he preserved in separate portfolios. He permitted Wöhler to read his correspondence with these celebrated men, and also to peruse his journal of a visit to Paris and London. When the weather became more moderate and the days grew longer, Wöhler made short excursions to the mines, factories, and mineral deposits of the neighborhood of Stockholm, on some of which occasions he was accompanied by Berzelius. The first analysis which Berzelius gave Wöhler to make was that of a new zeolite. In reality he performed the work himself, in order to show his method and all the manipulations peculiar to himself. “Afterward,” says Wöhler, “he gave me a mineral called lievrite to analyze, which, as a test of my perseverance, I had to repeat till the results were uniform. If I had been hasty and the results did not agree, he would say, ‘Doctor, that was quickly but badly done.’” Besides mineral analyses Wöhler prepared selenium and lithium, and repeated his experiments on hydrocyanic acid, which Berzelius had highly commended in his “Jahresbericht,” and which he thought had contributed largely to establish the accuracy of the new chlorine theory. After the work in the laboratory ceased, Berzelius had promised Alexander Brongniart and his son Adolph, the botanist, to be their companion and guide on a geological journey through Sweden and Norway. Wöhler was invited to join this party, and gladly accepted the invitation. As the Brongniarts were not to arrive in Sweden before the middle of July, Wöhler improved the interval by making an extensive tour to a number of celebrated mines and quarries where he gathered a rich store of rare minerals to send to his German friends. He finally joined Berzelius at Skinskatteberg, the estate of Hisinger. The venerable and hospitable Hisinger, so well known for his contributions to the geology and mineralogy of Sweden, and also for the liberality with which he had supported Berzelius during the commencement of his studies, lived here, a very rich man, on a princely estate, surrounded by magnificent forests, gardens, and mines. The party spent a week here most delightfully, examining and testing minerals with the blowpipe and visiting mines. While they were waiting for the arrival of the Brongniarts, a traveler brought the news that Sir Humphry Davy was in Götheborg, and that he hoped to meet Berzelius before he left this part of the country. In the mean time the Brongniarts and Hans Christian Oersted arrived, but, being impatient, could not await the arrival of Davy, and continued their journey. Berzelius and Wöhler staid behind, and, in a few days, Davy's arrival was announced, and Berzelius at once waited upon him at his hotel. “The meeting of these two men,” says Wöhler, “was very cordial”; and he adds, “Davy addressed some encouraging words to me when I was presented to him as a young chemist.” Davy returned to England, while the rest of the party continued their journey to Norway. While at Christiania they encountered the Crown-Prince Oscar, then Viceroy of Norway, and, not being able to escape in time, were detected by the Prince, who stopped the procession, and called Berzelius to his carriage and asked him to dinner. Here was a dilemma; but Berzelius contrived to procure the necessary court costume, and to answer the summons to the royal presence.
This journey to Norway was one of the bright periods in Wöhler's history, and he always recalls it with pleasure to his pupils whenever they ask him for the recital. Finally, in September, 1824, Wöhler took leave of Berzelius, and returned to the Continent. He stopped at Göttingen on his way to Frankfort, where he made the acquaintance of Hausmann, who subsequently became his much-valued friend and colleague. During a visit, which he immediately afterward made to Gmelin and Tiedemann, and in accordance with their advice, he decided to apply for the position of docent at the University of Heidelberg. While preparing to habilitate himself at the university, he enjoyed the intimate friendship of Dr. Buch and of the celebrated astronomer Summering, who was then much occupied with observations on the sun's spots, and with experiments on the concentration of alcohol through membranes. Wöhler undertook at this time the translation of Berzelius's “Jahresbericht,” which Christian Gmelin, of Tübingen, Berzelius's first German pupil, transferred to him, as he himself could no longer continue it. Wöhler was the more willing to undertake this translation, as the sale of the book promised to defray by degrees the expense of his Swedish journey. It was while thus engaged at the University of Heidelberg, in 1824, that Wöhler first made the acquaintance of his life-long friend Justus von Liebig. The meeting of these two men took place at Frankfort. By a singular coincidence they had been working in the same direction on cyanogen compounds, and there was a slight scientific misunderstanding between them; but all this was at once dissipated when they met for personal explanation, and the two young men formed a friendship which continued unbroken to the time of Liebig's death. Finding that their ideas ran in parallel directions, instead of opposing each other, they decided to work together, and for many years they kept up frequent correspondence, met regularly for consultation, and spent their vacations together among the mountains. Liebig's hospitable home in Giessen and Munich became the headquarters for Wöhler, Buff, Kopp, and others, and here were subsequently planned many of the scientific researches which have so greatly enriched our chemical literature. When Liebig and Wöhler first met, the former was not twenty-one years of age, and the latter was only twenty-four; and yet both had become renowned already for their important discoveries. It is no disparagement to Liebig to say that the acquaintance with Wöhler was of inestimable value to him. The young man needed the quiet, thorough, and solid character of Wöhler to check his own too vivid imagination, and prevent him from jumping too hastily to conclusions. Liebig was quick and impulsive, Wöhler was slow and sure, and the two characters worked admirably together, the one supplementing the other. In after-years they were so much together that it would be difficult to say how far any investigation was absolutely original with either of them. They compared notes on all occasions, and it was especially Liebig who hesitated to publish until he had subjected his paper to the cool criticism of his friend. No envy and no jealousy appear to have cast a shadow upon their friendship, and the large accumulation of letters in Wöhler's hands testifies to the tribute of respect and affection which Liebig showed toward one who could have been a most dangerous rival.
Wöhler's career took an unexpected turn during the winter of 1824-'25. The Gewerbeschule was at that time founded in Berlin. It consisted of but one class in the beginning, to which Henry Rose gave instruction in chemistry. Rose, Mitscherlich, and especially Leopold von Buch, recommended Wöhler for the chair of chemistry in the newly founded institution. To the two former he had been introduced by Berzelius, while Leopold von Buch had previously made his acquaintance while he was a student at the University of Marburg. The young student had made such an impression on Von Buch that he became his devoted friend and patron. Wöhler had found a new variety of harmotome (Phillipsite) in a basalt-quarry near Marburg, and, as Von Buch had in the last century published a notice of this mineral, the new variety greatly interested him, and he was also pleased to find a young man so well versed in mineralogy. When the question of the new position in Berlin was pending, Von Buch wrote a long and characteristic letter to Wöhler in which, with sprightly humor, he described the society and the chief personages of Berlin of that day, and endeavored to persuade the young chemist to select the Prussian capital, in preference to Heidelberg, as a place of residence. Wöhler did not long hesitate, and in March, 1825, removed to Berlin, where he was at once installed, under Director Kloeden, as teacher of chemistry and mineralogy. At first he only took the position on trial for a year, on a salary of three hundred dollars and a modest apartment. By degrees the institution grew in importance, and Wöhler's salary was very much increased, and a fine dwelling was assigned to him; and in 1828, by royal decree, he was raised to the rank of professor. It was at about this time that he was married to his first wife who was the daughter of a wealthy banker of Cassel. The young professor now entered upon a prosperous career. His residence at the capital of Prussia, the great resources which were at his command, the constant scientific intercourse with the favorite pupils of Berzelius, Mitscherlich, Henry Rose, Gustavus Rose, and particularly with his intimate friend Magnus, and the opportunity of meeting with other shining lights of the day, could not fail to exert an inspiring and instructive influence.
Wöhler always considered it peculiarly fortunate that he was here able to make the personal acquaintance of Alexander von Humboldt, and to have the privilege of listening to his intellectual conversations, and of attending his celebrated lectures on Cosmos. In the year 1828 Von Humboldt was made President of the German Association of Naturalists, and opened the session with a most finished and brilliant discourse, and, though crowded with work, he still found time during the meeting of the Association to collect around him a choice circle of specialists, and in particular to show much attention to Berzelius, who was at that time on a visit to Berlin. Von Humboldt gave a breakfast in honor of Berzelius, which was remarkable for the number of celebrated men who were present at it. After the breakfast a drive was arranged to Humboldt's country-seat at Tegel. Here the host exhibited the art-treasures of his brother William, and afterward the whole party drove to the quarry of Rüdersdorf, where geology was discussed by the learned company. On this occasion, Wöhler has reported that it was very interesting to watch the contrast between Humboldt's well-known inexhaustible powers of conversation and Berzelius's quiet demeanor. Wöhler, being the youngest and slightest in stature, had a seat in a dog-cart between Humboldt and Berzelius. While on the way to the quarry, in the midst of one of Humboldt's harangues, Berzelius turned to Wöhler and said in Swedish: “O Lord, how this man does talk! I can't stand it much longer!” Wöhler was greatly embarrassed for fear that Humboldt would overhear the remark, but, as he kept on talking, this anxiety vanished.
This was, perhaps, the most prolific period of Wöhler's life, for at this time he published his famous researches on aluminum, glucinum, yttrium, and, in association with Liebig, on cyanogen, cyanic and uric acids. Gay-Lussac had proposed the question in the early part of the century whether, when cyanogen was treated with alkalies, a cyanic acid might not be produced, and it was in answer to this question that Wöhler published his first paper in Gilbert's “Annalen” in the year 1822. It was at the same time that Liebig, then a boy in years, had gone to Paris to show Gay-Lussac what he had done in the same direction; and it was Humboldt who aided the boy chemist in Paris, just as he did Wöhler in Berlin in later years. Subsequently, as we have seen, Wöhler and Liebig made common cause of this investigation, and published their researches together. But the most important research of Wöhler falls in the year 1828.
This was the artificial production of urea. This investigation forms an epoch in the history of chemistry. Previous to this time the so-called organic world and the functions of vital force were believed to constitute a realm by themselves. Berzelius had said distinctly in his great text-book that we should never be able to imitate the products of vital force in our laboratories. We could destroy and could build up material things, but to imitate the vital forces would always be impossible. Wöhler, at the age of twenty-eight, overthrew this theory and created a revolution in the domain of chemistry. He made a breach through what appeared to be an impenetrable wall, and this opening has gone on increasing ever since, until it would appear as if, in a few years, no wall would be left standing. Berzelius's estimate of the value of the research on artificial urea is given in a most genial letter which he wrote to Wöhler in January, 1831, and which has recently been published in Germany. Wöhler had found in a mineral what appeared to him to be the oxide of an unknown metal, and he sent a specimen of the strange substance to Berzelius with an interrogation-mark. The new substance proved to be oxide of vanadium, and the fact that Wöhler narrowly escaped discovering it led Berzelius to write the following letter, which we translate entire:
Notwithstanding the great advantages which his position offered in Berlin, and the favorable prospects open to him in the future, Wöhler was constrained, for domestic reasons, to resign his professorship in 1832, and to remove to Cassel, where his wife's family resided. For several years he held no official position, and occupied himself with the translation of the third edition of Berzelius's text-book of chemistry, and with the yearly reports. He spent some time with Liebig, at Giessen, where the two friends completed their important research on the oil of bitter almonds. The large supply of arsenical nickel which had accumulated as an incidental product at the prussian-blue factory in Cassel led Wöhler to invent a method by which the nickel could be economically separated, to be subsequently used in the manufacture of German silver. The process succeeded so well that extensive nickel-works were established, yielding many thousand pounds for exportation to Birmingham. He, at that time, proposed nickel as a suitable metal for coinage, but no attention was paid to the suggestion. While Wöhler was residing at Cassel, a Gewerbeschule, similar to the one in Berlin, was founded, and he was appointed to a position corresponding to the one he had held in Berlin, and was one of the three officials upon whom devolved the organization of the new institution. Afterward Professors Buff and Phillips were added to the corps of teachers. Wöhler's duties as professor at the Gewerbeschule naturally directed his attention to technical chemistry, and in the autumn of 1833, in company with his intimate friend Magnus, he made a journey to France and England, to visit laboratories and chemical works, and on this tour had the opportunity to become personally acquainted with the most eminent living scientists of that period. In March, 1836, Professor Stromeyer having died the previous year, Wöhler was called to Göttingen as Professor of Chemistry and Pharmacy, Director of the Laboratories, and Inspector-General of all the Apothecaries of the Kingdom of Hanover. His place in Cassel was supplied by Professor Robert Bunsen, who previous to that time had been a docent at Göttingen, and at the present time is the renowned teacher at the University of Heidelberg. Wöhler could not at first refuse the post of Director of the State Apothecaries, and for twelve years traveled over the kingdom at great inconvenience and loss of time; he finally resigned this branch of the service, and gained more time for research. He has been seven times elected Dean of the Medical Faculty, until he declined a further nomination.
In 1860 Wöhler was made permanent Secretary of the Royal Hanoverian Academy of Sciences, to succeed Hausmann, and this position he continues to hold at the present time, attending to all the duties of correspondence with the punctuality of a young man, recalling his intimate friend Dumas, who at the same age holds a similar post in the French Institute.
In 1873 the fiftieth anniversary of Wöhler's doctorate was celebrated with great pomp by the students of the university, and on the 31st of July, 1875, being the fiftieth year of his active career as a teacher, and the seventy-fifth of his age, addresses and congratulations were poured in upon him from all parts of the world. During the current year, on the occasion of the eightieth anniversary of Wöhler's birth, the demonstrations of honor and rejoicing will be general at all of the seats of learning in Europe and America, and a presentation of a gold medal will be made to him to commemorate the interesting event. In the course of a long and distinguished career, the universities, learned societies, and sovereigns of Europe have vied with each other in conferring honors upon Wöhler. He received the Order of Merit from Prussia, the highest title of dignity from Hanover, and was elected one of the eight foreign associates of the French Institute, and the Emperor Napoleon made him an officer of the Legion of Honor; and so many decorations and diplomas have been presented to him that the mere catalogue would fill a page. The principal published works of Wöhler have been his translations of Berzelius's “Yearly Reports,” and Berzelius's “Text-book of Chemistry”; also “Grundriss der Unorganischen Chemie und der Organischen Chemie”; “Mineral Analyse mit Beispielen,” etc. These books have passed through numerous editions, and latterly the “Organic Chemistry” has been edited by Professor Fittig, formerly Wöhler's assistant at Göttingen. During the last fifty years Wöhler has published in Gilbert's, Poggendorff's, and Liebig's “Annalen” more than two hundred and fifty different papers on chemical subjects, or an average of five every year. Although these contributions have been of great importance to the progress of the science, the crowning glory of Wöhler must be sought in the influence he has exerted as a teacher of chemistry. During the last forty-four years his laboratory at Göttingen has been the workshop in which great numbers of students have been taught how to conduct original researches, and many of these pupils have become professors all over the world. All of those who took their degrees must have presented an original thesis; and in nearly every instance, although the student performed the physical labors of the research, the suggestion, the topic, and the method came from Wöhler. It is difficult to measure the importance of such a life, or to express in fitting terms the gratitude we owe the man. All who have had the privilege of nearer relations to him have learned to love him as a man, revere him as a teacher, and respect him for the profundity of his knowledge.
Professor Wöhler has been twice married. His first wife died many years ago, leaving a son and daughter. His only son now resides near Göttingen, and is a wealthy landed proprietor; the daughter by the first marriage is the wife of the Burgomeister of Göttingen, and has children and grandchildren, so that Wöhler lives to see several great-grandchildren gather at his family board. By his marriage to the wife who still survives there have been three daughters, all living, two of whom are married, one residing in Hamburg and the other in London. The venerable man is surrounded by family and friends, with an ample fortune to provide for every want. He has ceased to deliver lectures or to impart instruction in the laboratory, but maintains the liveliest interest in all questions of the day, and in his private correspondence displays the vigor and playfulness of his youth.