The Widening of Interest in Platinum and Its Properties
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“A History of Platinum and its Allied Metals”, by Donald McDonald and Leslie B. Hunt 7 The Widening of Interest in Platinum and its Properties “The Value of this new metal is not measured solely by its scarcity, but since it has been possible to render it perfectly malleable it is possible to begin to recognise the eminent qualities that it possesses." JA N INGEN-HOI SZ The last few chapters have recounted the intensive and progressive work of a small group of men, leading gradually up to the achievements of the seventeen- eighties in France and Spain. We now come to a rather less progressive period, disturbed by revolution and war, but one in which the interest in platinum nevertheless spread more widely throughout Europe with the gaining of experience of its properties and uses. There were several factors to account for this. One was the intense interest being taken in experimenting with magnetism and static electricity and especially in the effects of passing “the electric fire” through wires of various metals. Another was the considerable increase during the last two decades of the eighteenth century in the number of scientific journals that began publication, these not only giving a more speedy account of researches than the older transac tions of the academies but also encouraging much correspondence from country to country, as well as reproducing papers from one to another, while a third was an increase in the travelling of scientists from one capital city to another and their discussions and occasionally evenjoint experimentation. One other interesting example indicative of the increased interest in platinum is contained in a memoire written by A. F. Fourcroy in 1785 immediately after his election to the Académie des Sciences. The great French navigator J. F. de La Pérouse was about to embark on his voyage round the world and the Académie had been asked for advice on the work to be undertaken. Fourcroy included in his suggestions the remark that “ new sources of platinum would be especially valuable” (1). Unfortunately La Pérouse and his crew were later all lost in the South Pacific and nothing was ever heard of any search he might have made for platinum. 109 © 1982 Johnson Matthey “A History of Platinum and its Allied Metals”, by Donald McDonald and Leslie B. Hunt The Influence of Jan Ingen-housz The most fascinating figure of this phase of activity was Jan Ingen-housz, a Dutchman by birth but an inveterate traveller and a pioneer in the field of plant physiology. As a very young m an he was encouraged by Sir John Pringle, then the chief medical officer of the British Army, who had met the family during his service in the Low countries in the War of the Austrian Succession. Ingen-housz took his M.D. at Louvain and then studied physics at Leyden under Musschen- broek, the inventor of the Leyden jar. After a brief period at the University of Edinburgh he settled as a physician in his native Breda until 1765 when, on the advice of Pringle, now the leading figure in London medical circles, he came over to establish his own practice there (2). Here he met Priestley and Benjamin Franklin and worked with William Watson at the Foundling Hospital in the early days of inoculation against smallpox. W atson’s interest in both electricity and platinum may well have prompted Ingen-housz to pursue these matters further, but in 1768 he was chosen by Pringle, and with the approval of George III, to go to Vienna to inoculate the children of the Empress Maria Theresa. This led to an appointment as court physician with a handsome salary which he used in part to set up a laboratory and to cultivate his taste for experimentation in physics and chemistry. In Vienna he entertained a number of distinguished visitors, including Maria Theresa’s son the Emperor Joseph II, as well as visiting scientists. He was elected a Fellow of the Royal Society in 1769 and in one of his early papers, dated November 1775 (3) he described several experiments on platinum and its magnetic properties, following this with an account of his melting the metal in a narrow glass tube into which he “ directed five or six electrical explo sions from three very large jars.” He concluded: “ By this experiment it should seem as if platina (which hitherto could never be melted by common fire by itself, but only in the focus of a very strong burning glass such as was a little while ago m ade at Paris) were equally fusible if not more so than iron, by electrical fire.” Thus Ingen-housz was the first to melt platinum by means other than a burning glass. Between 1775 and 1782 he sent no fewer than nine papers to the Royal Society, although most of these concerned the respiration of plants, and he became a respected member of the scientific communities of Vienna, Paris and London. The greater part of the years 1777 to 1779 he spent in London, where he delivered the Bakerian lecture to the Royal Society, dealing with electrical phenomena and supporting Franklin’s “One-fluid” theory (4). He remained in Vienna from 1780 until 1788, continuing the work on plant respiration that made him famous but also experimenting on platinum. During the visit to Vienna by the Count von Sickingen in 1784 Ingen-housz was shown the Count’s method of rendering platinum malleable and they collaborated in a further experiment with the electric discharge, using a piece of wire provided by 110 © 1982 Johnson Matthey “A History of Platinum and its Allied Metals”, by Donald McDonald and Leslie B. Hunt The title page of the first volume of researches published by Ingen-housz in F’aris in 1785 and dedicated to his friend Benjamin Franklin. This NOUVEL. LES included a detailed account of the work on platinum carried out b> the Count \on Sick ingen and by the Abbe EXPÉRIENCES Rochon. with both of whom he had E T collaborated, followed by a description of his own experimental work on the OBSERVATIONS melting of a platinum wire by means of an electric discharge from a Ley den jar SUR DIVERS OBJETS while the wire was surrounded by oxygen. His suggestions for the DE PHYSIQUE. cladding base metals with platinum are also gi\ en P ar J e a n INGEN-HOUSZ, Confeiller Aulique, 8c Médecin du corps de Leurs Majeftés Impériales & Royales, Membre de la Société Royale de Londres, &c. Êcc. A PARIS, C h ez P. T h é o p h il e I U r r o is !e jeune. Libraire, quai de« Auguftms , n° ï 8. M. D C C. L X X X V. A v e c A î p î o b î i i o s , n P r i v i l è g e d u R o i . Sickingen. In a letter to his friend Jacob van Breda of Delft he described their experiment, and also included it in his major publication (5, 6). “A wire of platinum of the thickness of a large knitting needle was surrounded by a steel wire of which the point was very sharp; we raised the steel wire to incandescence by means of a Leyden jar inside a flask of good quality dephlogisticated air. The steel wire burned and to all appearances communicated the flame to the platinum . which was found to be in perfect fusion and had lost neither its colour nor its malleability. This experiment demonstrates that platinum is a true metal endowed with all the qualities that make the other metals useful in the arts and trades; that it can be melted; that the melting destroys none of its valuable properties, and in consequence it only remains for us to take advantage of it, to see it in commerce and to find a less expensive method for melting it. ” His work on platinum continued when he received a gift of six pounds of the native metal from the Marquis de Santa Cruz and at the same time obtained 111 © 1982 Johnson Matthey “A History of Platinum and its Allied Metals”, by Donald McDonald and Leslie B. Hunt information about the work of Chabaneau in Spain. Going to Paris in July 1778 to study Lavoisier’s new chemistry he wrote that he found the chemists there were not taking very much interest in research on platinum. “ 1 did what I could to awaken the interest of some of the best chemists of my acquaintance and encouraged them to take up afresh their work on this metal that they had almost abandoned. I succeeded in drawing them out of their inactivities: among others M. Pelletier, whose talents and learning are well known, having resumed his researches, soon succeeded in taking a large step forward.” During this visit to Paris (which was brought to an abrupt end by the storm ing of the Bastille on July 14 1789) he made contact, as we have seen in Chapter 5, with Janety and with the Abbé Rochon while he also collaborated with Pelletier in preparing malleable platinum from the sal-ammoniac precipitate: “One should ram it and press it into a red-hot-crucible and then strike it with a blow of a pestle, or one forges it with a hammer while hot and I have made from it several objects, among others a medal which was very successful. ” Ingen-housz’s own account of his work on platinum is bound up with reports of a number of other of his many researches in a book written for publication in French in 1781 (6).