“A History of Platinum and its Allied Metals”, by Donald McDonald and Leslie B. Hunt 8 The Professional Scientists of London and their Societies “Platinum is a most valuable metal; as it is not oxidisable nor fusible under common circumstances, and only with difficulty com­ binable with sulphur and not acted upon by common acids, it is admirably adapted for the uses of the philosophical chemist." HUMPHRY DAVY The thirty year period from 1790 until 1820 was a vital and productive phase in the development of both pure and applied science. Lavoisier’s chemical revolu­ tion had cleared the minds of chemists, his definition of an element had opened the way to the discovery of many more, and methods of analysis, if still rather simple, had become established. The chemical industry began to expand while the scientific study of mineralogy was aiding in the development of mining and metallurgy. At the same time there existed a body of scientists, particularly in London, who were interesting themselves in technology and who were able to secure an income for themselves from their professional work by lecturing, by editing and publishing, by the manufacture of chemicals or by the making of scientific instruments. These men tended to associate into groups or small societies for joint experimentation and discussion. They were particularly interested in the metals recently discovered including titanium, molybdenum, tungsten and niobium, and although it would be a considerable overstatement to say that they were particularly concerned with platinum they none the less took an active interest in its properties and its fabrication and from their activities stemmed several important advances. The Leading Role of William Allen One of the first to engage in lecturing was Bryan Higgins (1741—1818) at his School of Practical Chemistry in Greek Street, Soho, started in 1774, and from which developed the Society for Philosophical Experiments and Conversations, 133 © 1982 Johnson Matthey “A History of Platinum and its Allied Metals”, by Donald McDonald and Leslie B. Hunt Allen's laboratory at Plough Court in the early nineteenth century. A successful pharma­ ceutical business was carried on here and a school of young research assistants was built up. Meetings of both the Askesian Society and the British Mineralogical Society were also held here from 1796 until 1807 when the members took part in the founding of both the Geological Society and the London Institution founded in 1794. Another very active organisation was the Physical Society of Guy’s Hospital, recognised as an important meeting place for scientists from its foundation in 1771 until the middle of the nineteenth century. In 1792 the young William Allen, the son of a Quaker silk manufacturer who disliked his father’s business, entered the famous Plough Court Pharmacy, established in 1715 in Lombard Street in the City of London by Joseph Gurney Bevan, a leading member of the Quakers. He began at once to attend the lectures given by Bryan Higgins and to devote his spare time to studying “ the new system of chemistry” and in 1794 he also became a member of the Physical Society at Guy’s Hospital. In that year Bevan retired, being succeeded by Samuel Mildred who took Allen into partnership but retired in 1797, leaving the business in Allen’s charge (1). Next door to the pharmacy there worked a printer named James Phillips who had two sons William (1775-1828) and Richard (1778-1851). The elder was establishing himself as a mineralogist, while the younger Richard became apprenticed to Allen at Plough Court. In the same neighbourhood there lived William Hasledine Pepys, the son of a cutler and maker of surgical instruments, and it was these very young men who took the initiative in forming the Askesian 134 © 1982 Johnson Matthey “A History of Platinum and its Allied Metals”, by Donald McDonald and Leslie B. Hunt Society in March 1796, the name being taken from the Greek word for exercise or training. They appointed an older man, Samuel Woods, a woollen draper also of Lombard Street, as president and were soon joined among others by Alexander Tilloch, the founder in 1798 of The Philosphical Magazine, and later by two distinguished surgeons, Astley Cooper (1768—1841) and William Babington (1756-1833). The latter, an older man than most of the members of the Askesian Society and resident apothecary at Guy’s Hospital, had tried to melt platinum in 1797, writing in his lecture notes preserved there: “The most violent fires are insufficient to melt it though its parts may be made to cohere together into a solid button by the strong heat of a wind furnace. ” (2) Meetings were held fortnightly at Plough Court and a collection of apparatus was assembled. In December 1798 Allen wrote in his diary: “I am making great progress in chemical experiments - fused platina with oxygen on charcoal.” (3) At a meeting held in the Askesian Society’s room on April 2nd 1799 attended by Allen, Pepys, Tilloch, Richard Knight, the son of a London ironmonger who became an instrument maker, and William Lowry, the engraver and geologist, it was resolved that “those present do form themselves into a Society under the Denomination of the British Mineralogical Society. ” (4) The number of members was not to exceed twenty and was to be confined to those able and willing to undertake the chemical analysis of mineral substances. It was felt that the absence in England of any school or college of scientific minerology such as the École des Mines established in France in 1783 could be remedied by the collective activities of the members in applying science to mining and metallurgy. Before the end of the year the founders were joined by William Phillips, Charles Rochemont Aikin and his brother Arthur, the latter becoming president of the society. Other members included Dr. Babington, Richard Phillips and Robert Bingley, the Assay Master at the Royal Mint, while William Henry of Manchester, Charles Hatchett and Richard Kirwan were among those elected corresponding members. Bingley had already conducted a series of experiments on platinum and particularly on its separation from gold in the course of normal assaying. These he described in a long letter to Charles Hatchett (5) in which he wrote: “That it is a source of great satisfaction to be able compleatly to separate two metals which have so many properties in common, and by such means as are not in the least destructive to gold. ” Meetings were held fortnightly at Plough Court, reports being read on the analyses of minerals, and on January 9th 1800 a paper was read by Richard Knight (1768-1844) entitled “A New and Expeditious Process for Rendering Platina Malleable” (6). The author, who displayed to the meeting a specimen of his malleable metal, opened his remarks in these words: 135 © 1982 Johnson Matthey “A History of Platinum and its Allied Metals”, by Donald McDonald and Leslie B. Hunt At a meeting of the British Mineralogical Society on January 9th 1800. Richard Knight, the son of an THE ironmonger ill the City of London and a competent analyst and instrument m aker, read a paper describing his PHILOSOPHICAL MAGAZINE. method of producing malleable platinum. His principal advance lay in a more forceful compression of the sponge while hot. There is no evidence TEBRVART 1800. that Knight made more than two or three pieces of apparatus from his platinum, but it is likely that his paper I. A ttr.u nnd rxptJitLnu Proctft for rendtr'mg PlaJm* served to arouse the interest of mal treble. By Mr. Richard K n i s h t , Mtmbrr t f Wollaston and Tennant whose major tbr Bntijb Miiuralogital Socttj. CommtuvcaUd by A t contribution is described in the next Author. chapter 1 HE many peculiar advantages which platina in a mal­ leable (late poffelTes over every other metal for the fabric»!- tion of a variety of inllruments and utenfils particularly ufeful for the purpofes of chemiftry, together with the extreme difficulty of procuring it, being hitherto only to be obtained from Paris, o f a very indifferent quality, and at a price, equal to that of gold, firft induced me to turn m y attention to th* fubjeft. After having repeated a variety of experiment^ 'from the different writer« on thit fubftance, without effeft, I at length completed a procefs, the fucoefs of which baa fully anfwered my expeQations. By the procefs which I follow 1 am able to reduce any quantity if crude platina to a perfectly malleable (late, entirely free from impurity, and capable of being wrought into any form whatever. As thik is a circumilance of con&derable importance to (he chemical world, and the advantages which may refult from it to fo* ciety in general are perhaps incalculable, I would co nfid # myfel{deferving of cenfure, could I allow any motive whatever to induce me to withhold it from the public. By fending it for publication in • work of fuch exttnfiv* circuJatiso as the Vol. VI. B Wiil*. “The many peculiar advantages which platina in a malleable state possesses over every other metal for the fabrication of a variety of instruments and utensils particularly useful for the purposes of chemistry, together with the extreme difficulty of procuring it, being hitherto only obtained from Paris, of a very indifferent quality, and at a price equal to that of gold, first induced me to turn my attention to the subject. After having repeated a variety of experiments, from the different writers on this substance, without effect, I at length completed a process, the success of which has fully answered my expectations.