Popular Science Monthly/Volume 84/January 1914/Chabaneau: An Early Worker on Platinum
|CHABANEAU: AN EARLY WORKER ON PLATINUM|
By Professor JAS. LEWIS HOWE
WASHINGTON AND LEE UNIVERSITY
NOT long since M. Louis Quennessen of Paris (head of the old house of Des Moutis & Co., platinum refiners) directed my attention to an early worker on platinum, Pierre-François Chabaneau, whose name has so far escaped the historians of chemistry that I think it is not even mentioned in any English or German work, and has only appeared in the last edition of Moissan's "Traite de Chimie Minèrale." More recently, through the courtesy of M. Quennessen, I have received a copy of an all but unknown memoir, "Notice sur Chabaneau, Chimiste Périgourdin," par M. Jules Delanoue, printed at Périgueux in 1862, portions of which appear to be of sufficient interest to put on record. This biographical sketch was written in 1857, though not published till five years later, and has for its purpose "to call to the attention of our citizens the useful work, too little known, of a modest man, who unquestionably deserves the first place among the distinguished men whom Périgord has given to the world."
It may be noted that Périgueux is the capital of the old province of Périgord (now in part Dordogne) in southwest France, and has an interesting history going back to the time when it was the old Gallic town of Vesunna, the capital of the Petrocorii. Numerous remains of Vesunna are still in existence, especially baths, temples, an aqueduct and fragments of the amphitheater, mostly dating from its Roman occupation. The most notable building of Périgueux is the cathedral of St. Front, belonging to the Byzantine period, which bears quite a close resemblance to St. Mark's at Venice. The town has undergone many vicissitudes, having been taken by the barbarians in the fourth century, the Saracens in the eighth, the Normans in the ninth, the English in the fourteenth, and later restored to the French. It was a stronghold of the Calvinists in the Huguenot wars, and at this time was nearly laid in ruins. In the midst of an agricultural region, it is perhaps best known for its truffles and chestnut-fed hogs, the latter being used in hunting for the former.
The early history of Chabaneau is a not unfamiliar one of precocity and hardship.
Behold now our young man in the streets of Paris, in the midst of the immense Babylon, without relatives, without friends, having neither experience of the world nor yet money! The six livres, which represented his whole fortune, had been expended in the purchase of a perruque, imperiously demanded by the customs of the times. He dared not return to his angry uncle, nor indeed had he the means for the journey. A kind Providence directed him to the abbe 1 La Bose, to whom he related his story and revealed the extreme embarrassment in which he found himself. The worthy abbé was greatly interested and offered to place him as professor of mathematics in the Jesuit college at Passy (just out of Paris), of which he was the director. The young theologian, whose studies had been confined to Greek, Latin and philosophy, was absolutely unacquainted even with arithmetic. He was greatly disappointed when he learned what his employment would be, but necessity compelled him to seize even this plank of safety; it was this or nothing. He unhesitatingly accepted the position, without venturing to acknowledge his complete ignorance of the subject he was to teach; he thought that perhaps by work and perseverance he might be able to fulfil his duties. He gave proof on this occasion of energy rare in one of his age, for he was only seventeen.
It is related of Jacques Amyot, the celebrated translator of Plutarch, that while he was a college servant, he was possessed of such a desire for knowledge, that he studied at night by the light of the fire. Young Chabaneau, whom chance and want compelled to teach others what he did not know himself, and who had great ambition to worthily carry out his task, passed the nights in preparation of the lessons for the following day. He hid his lamp, and then, when all the college world slept, lit it and worked till day. And so it was that, with indefatigable labor, aided by a powerful physical constitution, he made himself master of arithmetic, algebra and geometry. Nor did he stop with these studies; the passion for knowledge dominated him. He studied experimental physics, natural history and chemistry, that prodigious science which had just begun to give promise of the astounding wonders which have been realized in our day.
Just at this time was beginning the most active period in the work of Lavoisier, and it was the year before that he had presented to the Académie des Sciences his refutation of the supposed transformation of water into earth, in which the balance was used as an instrument of chemical research, and which soon led to the conception of the permanence of matter and later to the overthrow of the phlogiston theory. This work of Lavoisier could not fail to make a great impression upon such a mind as that of Chabaneau.
His pupils made rapid progress; they wondered at the knowledge of the young professor, and the director, abbe" La Rose, did not cease from expressing his satisfaction. . . .
Chabaneau was now about twenty years old, an age when is often born the love of independence. He knew that the knowledge which he now possessed would suffice to supply all his material needs. He therefore resigned from his position in the college of Passy, after having expressed his most sincere thanks to his benefactor, and, taking lodgings in the Rue des Mathurins, within the city, opened after the fashion of that day a course of public lectures which met with great success.
Among the most assiduous of his auditors were the young sons of the Comte de Pena-Florida, whose father had sent them to France to complete their education, and also to procure several professors for a great college for the nobility which he purposed founding at Bergara.
Bergara was a small city in the Basque province of Guipúzcoa in northern Spain, and near the bay of Biscay. It afterwards came into some prominence as the place where the treaty was signed in 1839 between Spain and the Carlists of the Basque provinces. Of the subsequent history of the college I have been able to learn nothing.
The young nobles gained the affection of their professor and made him the most brilliant offers if he would accept the direction of the college founded by their father. For a long time Chabaneau resisted, but, finally yielding to the earnest solicitation of the young marquesses and other friends, he decided to exchange France for Spain. He immediately began the study of the Spanish language, and with such ardor that in a few months he felt that he had fully mastered it.
He remained three years at Bergara, devoted himself without relaxation to scientific study, and acquired such a reputation that the king, Charles III., wishing to locate him in Madrid, created for him a public Chair of Mineralogy, Physics and Chemistry, lodged him in one of his palaces, and granted him an annual stipend of 2,200 piasters ($2,400), a very considerable sum for that time.
The inauguration of his course took place in the presence of the king and all the court. This opening lecture had for its subject the utility and the future of science, and was so remarkable that a Spanish poet composed for the occasion an ode, dedicated to the learned professor. Impelled by the love of science and wishing to justify the high favor in which he was held by the king, Chabaneau continued with great earnestness his scientific work. As he desired to enter into relations with all the learned men of Europe and to profit by their work, he recognized the necessity of studying English, Italian, German, etc. So energetic was he in his language study that at the age of twenty-five he was master of no less than eight languages, living or dead.
Charles III. provided Chabaneau with a valuable library and a laboratory, considered at that day "magnificent." All the spare moments remaining from his public instruction were devoted to the study of physics and especially of chemistry. At this period Spanish America was sending to the mint at Madrid not only ingots of gold and silver, but also from time to time a mineral in the form of little white metallic grains, infusible and very heavy. The miners found it associated with gold and with diamonds (?) and called it platina, from its similarity to silver (plata in Spanish).
The government had no use for the platina and, fearing it might be used to debase the coinage, ordered (ineffectually) that it should be buried when extracted from the ore. Meanwhile in 1741, an Englishman named Wood gave the knowledge of platina to Europe; in 1750 Watson announced that it contained a metal hitherto unknown; in 1752 Scheffer, director of the Stockholm mint, and in 1754 Lewis in London, dispelled all doubt regarding the fact that a new metal actually existed. Baron von Sickingen proposed a method for its extraction from the ore.The new metal, platinum, thus obtained was in the form of a powder or sponge, which resisted fusion, even in the most powerful furnace, and was thus wholly useless in the arts. Chabaneau undertook the difficult task of obtaining platinum in metallic ingots, in spite of its infusibility. He recognized that this very infusibility would give great value to objects made of this new metal.
Several other chemists of the time had busied themselves with this same problem. The only hope of success appeared to be in alloying platinum with other metals, but this seemed to present insurmountable difficulties, owing in part to the impurity of the platinum ore, and also to the large amount of other metals necessary for its solution. It was early observed (von Sickingen says by Scheffer, who wrote in 1751) that a small amount of metallic arsenic caused platinum to fuse easily, but the ingot thus obtained was exceedingly brittle. Achard (1779) found that by heating this alloy for a long time at a high temperature the arsenic was gradually volatilized, leaving a mass of platinum in a malleable condition. While his communication to the Berlin Academy is entitled "Leichte Methode, Gefässe aus Platina zu bereiten," it was nearly ten years before practical application seems to have been made of the method, and though a letter appears in Krells Annalen in 1790 stating that platinum vessels can be bought cheaply of Jeanty in Paris, they were actually very rare and possibly never practically used until after the close of the century. Achard's method seems, however, to have been used industrially by Jeanty as late as 1820, though the method of Chabaneau, rediscovered by Knight and possibly independently by Cock also, came into general use in the first decade of the nineteenth century. The vessels made by Achard's method could never have been satisfactory, especially owing to the difficulty of completely removing the arsenic from the platinum.
In spite of the regal luxury of his laboratory, Chabaneau found at that time in Madrid fewer resources than would to-day be offered by the most unpretentious laboratory in France. Chabaneau was obliged to prepare his own reagents and make his apparatus. Chemistry was still an empiric science and Lavoisier had only just begun to bring order out of chaos. Further, at this time no one could have suspected that in addition to gold, mercury, lead, copper, iron, etc., the platinum ore contained five more metals, osmium, iridium, palladium, rhodium and ruthenium, not discovered till 1803 and 1844. Chabaneau found himself contending with six metals where he supposed there was only one, platinum. Inevitable mistakes and innumerable disappointments naturally resulted. He had proved that platinum was malleable, yet occasionally he found it despairingly brittle (this was an alloy with iridium); he knew that it was infusible, incombustible and unoxidizable, yet he was stupefied to see it at times burn and volatilize (this was the alloy with osmium).
The Marquess of Aranda, appreciating the great interest attaching to the industrial use of a metal of which Spain possessed all the mines, came often to Chabaneau's laboratory, and often found him discouraged and busying himself on other investigations. At such times Aranda, a most genial and lovable character, would console him, encourage him, and in the end bring him back to that which Aranda considered his great task, the investigation of "white gold," as it was then called. Chabaneau would take up with new zeal his tantalizing work, and so passed days and nights, months and years. At last he succeeded in surmounting all difficulties, his wearisome task was rewarded by the discovery of a process by which the metal could be purified. The effectiveness of the method was verified by several repetitions. The enchanted Marquess had him carry it out on a large scale and came to the laboratory each day with increasing interest. Judge of his astonishment and horror when one day he found Chabaneau in a frenzy engaged in throwing out the door and windows his dishes, flasks and ores, as well as all the solutions of platinum which he had prepared with so much trouble and difficulty.
The Castillian imperturbability of the Marquess only redoubled the French fury of the young chemist. "Away with it all. I'll smash the whole business," he cried in a mixture of French and the patois of P€rigord. "You shall never again get me to touch the damned metal." And in fact he broke up all the apparatus of the laboratory.
Really this infantile fury was to some extent justifiable. No one knew then, and indeed few know now, that lime does not precipitate platinum in artificial light, but that in daylight the metal is completely precipitated by this reagent. Chabaneau, working with lime at night, had been enabled to precipitate all the other metals which were present in his solution, while his platinum was left unprecipitated and purified. Repeating the operation by day, platinum and all were thrown down, and he was completely at sea, without being able to suspect the reason.
Three months later, at the home of the Marquess of Aranda there appeared upon a table an ingot some ten centimeters cube, with a beautiful metallic luster; it was malleable platinum. The enthusiastic Marquess started to pick it up, but failed to move it. "You are joking," said he to Chabaneau, "you have fastened it down." "No indeed," said the professor, and he raised the little ingot easily, though it weighed some twenty-three kilograms. The Marquess had not thought that the light platinum sponge would thus appear as the heaviest of all (then known) metals.Chabaneau's discovery consisted in compressing the platinum sponge while hot at the moment of its formation, and then hammering it several times while at a white heat. Since platinum is infusible at the highest temperature of a furnace, it is easily recognized how difficult it had been to convert the pulverulent metal into an ingot. This infusibility is, however, only relative, since Deville has since succeeded in fusing the metal with the oxygen-hydrogen blowpipe; but this property, added to a resistance to the action of acids equal to that of gold, evidently entitles platinum to rank with the precious (noble) metals.
It is to be noted that there were two necessary conditions for the preparation of malleable platinum, either of which was useless without the other. First, the metal must be obtained from the ore in a pure condition, for unless separated not only from the base metals, but also from the largest part of the other platinum metals, the sponge can not be welded into a malleable mass; second, while at a high temperature the sponge of pure platinum is easily compressed into a malleable ingot, at low temperatures it has no coherence. Virtually this process, generally attributed to Knight, was in use almost exclusively until the last third of the nineteenth century.
The king, who spent some of his leisure moments dabbling in science, often came to Chabaneau's laboratory and assisted in his experiments. He was very proud to have such a discovery made in his capital, and caused a commemorative medal to be struck in platinum. He also gave Chabaneau a life pension of 2,800 piasters ($3,000), in addition to his annual stipend of 12,000 livres, but the pension was granted only on the express condition of residence in Spain, and was to be forfeited should Chabaneau leave the kingdom. The letters-patent bear the date of 1783, and thus establish the priority of Chabaneau's discovery officially and in an incontestible manner.
Chabaneau was for some time engaged in preparing large quantities of malleable platinum. Then his patron, Marquess d'Aranda, having been appointed ambassador to France (1787), he was prevailed on to accompany him to Paris, in order to convert under his auspices some of the new metal into ornaments for the crown. Jeanetty, goldsmith to the court of France and a very able man, had been commissioned for this work, and he sought vainly to discover the process used by Chabaneau. He did, however, discover another method (alloying with arsenic) and employed it with such success that he founded in Paris a manufactory for platinum ware, which prospered down to 1820. At present the method of compression while hot, without alloying, is used, and that of Jeanetty has been abandoned.
It was only two years after this memoir was written that Deville and Debray perfected the method first proposed by Hare in 1838 of fusing platinum in the flame of the oxygen-hydrogen blowpipe. The memoir is somewhat misleading regarding the process of Jeanty (or Jeanetty), for while it is true that he did for many years manufacture platinum crucibles and other vessels by his method, it was early in the century entirely supplanted by the compression method, and it is doubtful if much practical application was ever made of it.
It is then to Chabaneau that belongs all the honor of having first discovered and employed on a large scale the only method which is in use to-day for preparing a metal, so valuable for chemistry and the arts, and yet no contemporary writer has recorded the claim of our modest compatriot to the glory of this discovery. I apply to him the term modest, for in spite of all our entreaties he could never be persuaded to put forward his just claims. But to-day, as we have before our eyes the letters-patent of the Spanish government, bearing the date of 1783 and testifying to the discovery made by Chabaneau, we come to lay claim for him to the honor of priority, and to preserve his memory, ungratefully forgotten by his contemporaries.
About 1790 Chabaneau published a large work on the natural sciences in the Spanish language, which was to have been followed by several others, but which was complete as far as regards his specialty. This work, which demanded bo much research, night work, and fatigue of every kind, gravely affected his health, and the court physicians prescribed a return to his native air and a period of complete repose. This rest and our climate affected him so favorably that in a few months his health was wholly regained, and he determined to renounce his pension of 15,000 francs in order to dwell in his fatherland and to end in this quiet retreat, in the bosom of his family, a life, hitherto passed among strangers in the midst of the most assiduous labors.
Retiring to the country, near Nontron, he sought to live obscurely, but the jury of the central schools of France besought him to accept the chair of physics and experimental chemistry in the École Centrale of Périgueux. The subjects were so seldom taught at this period that Chabaneau felt it the duty of a good citizen to accept the modest position. His course of lectures, which lasted two years, was printed at the expense of the administration, and published in the year VII by Canler at Périgueux.
On the suppression of the central schools he was offered a chair of chemistry at Paris, and his permission was sought to translate and publish his great work; but, well determined this time to live in his quiet retreat, he refused all these propositions, desiring only to live in solitude and to enjoy the repose so needed and so welcome after all his labors.
He died in January, 1842, at the age of 88, and left no descendant bearing his name. He lived tranquilly, isolated from the world, on his country-place of Clara, near Nontron, dividing his time, like a sage of antiquity, between rural pursuits and philosophical study.
We knew him only in his declining years, but he was then a fine-looking old man, with pleasing and regular features, bearing much resemblance to those of our good and lamented Béranger. His conversation was charming and always instructive. Friend and contemporary of Volney, of Cabanis, of Lavoisier, he was nourished upon their ideas and imbued with their spirit, and they were pleasingly reflected in his conversation.
Thus ends the story which has happily rescued for us from oblivion the life and work of one of the gifted early workers in chemistry. That his name had been forgotten is doubtless chiefly due to his own modesty, but in part also to the fact that his labors were largely carried on in Spain, and his only important published work was in that language. Whatever may be the reason, the atmosphere of Spain has never been conducive to the development of science.