“A History of Platinum and its Allied Metals”, by Donald McDonald and Leslie B. Hunt 9 The Partnership of Smithson Tennant and William Hyde Wollaston “A quantity of platina was purchased by me a few years since with the design of rendering it malleable for the different purposes to which it is adapted. That object has now been attained. ” WILLIAM HYDE W O L L A S T O N Up to the end of the eighteenth century the attempts to produce malleable platinum had advanced mainly in the hands of practical men aiming at its pre­ paration and fabrication rather than at the solution of scientific problems. These were now to be attacked with a marked degree of success by two remarkable but very different men who first became friends during their student days at Cam ­ bridge and who formed a working partnership in 1800 designed not only for scientific purposes but also for financial reasons. They were of the same genera­ tion and much the same background as the professional scientists of London whose work was described in Chapter 8, and to whom they were well known, but with the exception of Humphry Davy they were of greater stature and made a greater advance in the development of platinum metallurgy than their predecessors. Their combined achievements over a relatively short span of years included the successful production for the first time of malleable platinum on a truly com­ mercial scale as well as the discovery of no less than four new elements contained in native platinum, a factor that was of material help in the purification and treatment of platinum itself. The junior partner, who was in fact to carry most of the burden after the first few years, William Hyde Wollaston, kept meticulous records of his experiments and of his expenditure and later of his sales of platinum but these remained undiscovered for many years. A collection of his note-books and other manuscripts relating to his life and work, including brief drafts for an unwritten biography by his friend Henry Warburton, were eventually found in 1949 by the late L. F. Gilbert in the Department of Mineralogy and Petrology in the University of Cambridge and formed the subject of a paper of his in 1952 (1). In 147 © 1982 Johnson Matthey “A History of Platinum and its Allied Metals”, by Donald McDonald and Leslie B. Hunt Wollaston’s partner in the long investigations of native platinum. Smithson Tennant, became interested in the metal while still a student at Cambridge. This extract from his diary for October 4th 1784, when he was only 22. describes his visit to Lorenz Crell at Helmstadt and records the details of the Count von Sickingen’s method of rendering platinum malleable more recent years these note-books and papers, now in the care of the Library of Cambridge University, have been studied in more detail by Dr. M. C. Usselman (2), and by Dr. J. A. Chaldecott (3). Other note-books compiled by Tennant and in the same keeping have enabled Dr. A. E. Wales to publish valuable information on his part in the joint enterprise (4). This chapter therefore owes much to their respective publications, while the original author of this book also contributed a study of Tennant (5). Taking the older man first, Smithson Tennant (1761-1815) was born at Selby in Yorkshire, the son of a clergyman. In 1781 it was proposed that he should study under Joseph Priestley, now settled in Birmingham, but this did not materialise and instead he entered the University of Edinburgh to study chemistry under Joseph Black with whom he developed a close relationship and from whom he may very well have acquired his early interest in platinum. He moved to Cambridge in October 1782, first at Christ’s College and later at Emmanuel, and in 1785 while still an undergraduate he was elected a Fellow of the Royal Society. During the summer vacation of 1784 he made a journey through Denmark and Sweden, visiting mines and chemical plants and meeting Scheele and Gahn, and on his return journey visited Lorenz Crell at Helmstadt. The extract from his diary reproduced above shows that he was already interest­ ing himself in the problem of producing malleable platinum. In the following year he paid a visit to Paris to meet Lavoisier and then to Dijon where he was the guest of Guyton de Morveau, both of these men of course having been active only a few years earlier in working with platinum. (An amusing side light on these visits is to be found in a letter from Guyton de Morveau to Crell’s Chemische Annalen in 1786 (6 ). The writer refers to “one of my chemical friends the Englishman Herr Tennant”, to which Crell adds in a footnote: “I also have the pleasure of counting Herr Tennant among my chemical acquaintances”). In his la'ter period at Cambridge Tennant became friendly with his younger fellow student in medicine, Wollaston, who was at Gonville and Caius from 1782 148 © 1982 Johnson Matthey “A History of Platinum and its Allied Metals”, by Donald McDonald and Leslie B. Hunt until 1789 and who was particularly interested in the older man’s accounts of his visits to the leading chemists in Europe. Wollaston took up medical practice after leaving Cambridge, first in H unt­ ingdon and then in Bury St. Edmunds, but in 1797 he moved to a practice in London where his friends considered he would have greater scope for the high ability he had already shown as a physician. Tennant had already settled there four years earlier, also after a brief spell as a physician, work for which he found himself temperamentally unsuited. In this same year he presented a short paper to the Royal Society “ On the Action of Nitre on Gold and Platina” (7), quoting the earlier work of Lewis and Marggraf on the native metal before describing his own results on the corrosive attack on his more or less pure platinum. In 1799, Wollaston, by now devoting most of his time to scientific researches, purchased small amounts of platinum and began to study the most efficient means of its dissolution in varying formulations of aqua regia. By the end of the following year, undoubtedly stimulated by the similar leanings and knowledge of his friend Smithson Tennant and probably after much discussion of the problem, the two men entered into an informal and unpublicised partnership directed towards various chemically-based commercial endeavours, one of which was the production and marketing of malleable platinum, and Wollaston abandoned his medical practice. O n Christmas Eve 1800 they invested £795 in the purchase of the very large quantity of 5959 ounces of alluvial platinum from one Hutchinson of whom nothing is known but who was almost certainly a London agent connected with the Jamaican end of the smuggling trade from Cartagena. In the following February they bought a further 800 ounces from Richard Knight who had apparently not put his process to commercial use. The underlying reasons for their undertaking this joint enterprise, one that was to lead to long years of chemical research and frustration before success was achieved, goes back to their time at Cambridge but a sense of urgency was given them by the prospects opened up by the two publications referred to earlier, the Abbé Rochon’s paper that appeared in English translation in the first volume of The Philosophical Magazine in 1798 and Richard Knight’s paper read to the British Mineralogical Society in January 1800 and also published in The Philoso­ phical Magazine in the following month. An interesting and possible link is that just opposite Richard Knight’s establishment in Foster Lane was the Church of St. Vedast in which his parents had been married in 1766 and where the Rector from 1779 until 1815 was in fact Wollaston’s father, the Reverend Francis Wollaston, F.R.S. In any case it was becoming very clear that if a process that was technically sound could yield malleable platinum in quantity and at a reasonable price a handsome financial return might well be expected. Tennant was a wealthy man by inheritance. It has often been said that Wollaston needed to earn a living from his researches but Dr. Usselman in the course of a detailed review of one episode of Wollaston’s career has revealed that in 1799 his elder brother George had made him a present of securities valued at some £8000 (8), making it possible for him at the age of 34 to abandon the 149 © 1982 Johnson Matthey “A History of Platinum and its Allied Metals”, by Donald McDonald and Leslie B. Hunt medical practice he disliked and to devote the remainder of his career to the scientific pursuits he so much preferred. Wollaston had a great admiration for Tennant, who as we have seen had made personal contacts with several of the French and German workers on platinum and who may thus have influenced the choice of project, while his brilliant if rather erratic mind would have been of great value in the early years of the partnership. The Discovery of Iridium and Osmium Before we can consider Wollaston’s principal work, the laborious investigation of the means of producing malleable platinum in quantity and its success after five years of frustrating experiments, we have to turn to the parallel investiga­ tions carried out by him and by Tennant that showed the presence, unsuspected by the earlier workers, of four other elements in native platinum. It will be remembered that when crude platinum was dissolved in aqua regia there was always a black insoluble residue left.