Malleable Platinum

At the start of the nineteenth century, platinum was refined in a scientific manner by William Hyde WoUaston, resulting in the successful production of malleable platinum on a commercial scale. During the course of the analytical work, WoUaston discovered paUadium, rhodium, indium, and osmium. Ruthenium was not discovered until 1844, when work was conducted on the composition of platinum ores from the Ural Mountains. 

Frenchman P. F. Chabeneau, and subsequently in London by W. H. Wollaston/ who in the years 1800-21 produced well over 1 tonne of malleable platinum. These techniques were developed because the chemical methods used to isolate the metal produced an easily powdered spongy precipitate. Not until the availability, half a century later, of furnaces capable of sustaining sufficiently high temperatures was easily workable, fused platinum commercially available. 

Sobolcvsky A process for converting native platinum to malleable platinum by pressing and heating. Developed by P. G. Sobolevsky in Russia in the 1820s. 

When you see Dr. Wollaston give him a thousand compliments from me and then ask him if it would be possible to have a little malleable platinum, not separated from its natural alloy with palladium, rhodium, etc, to make a crucible. The crucibles I have bought recently from Cary are of a metal noticeably purer than those which I formerly had, and for that very reason infinitely more susceptible to attack by other substances (5). 

Compression of the hot, spongy metal before cold-working is the novel feature of Knight s method and it represents an important advance in the history of platinum metallurgy. However, even the improved process failed to give consistent results. Knight never produced malleable platinum himself, nor did anyone else who used his published procedure. 

The criticism is correct when it accuses Wollaston of retarding the progress of investigation into the production of malleable platinum, for that was his prime motive for secrecy. He was well aware that his process was not novel enough to be patented, and could easily be mastered by a good chemist. As Berzelius wrote after learning of the process (23) ... 

The usual method of blowpipe analysis was to direct the flame on to a small portion of the material on a charcoal block. The substance under investigation was often mixed with sodium carbonate, borax, or microcosmic salt (sodium ammonium phosphate). When the material was heated alone or with sodium carbonate, it often yielded decomposition products with a characteristic appearance and borax or microcosmic salt fused to a glass to which the unknown material might impart a characteristic colour. After Wollaston had introduced a method of producing malleable platinum in 1800, a platinum wire was frequently used to support the material in blowpipe analysis, particularly in the production of glassy beads with borax and microcosmic salt. 

He was associated with Smithson Tennant in a process for malleable platinum (see p. 703) which Wollaston published shortly before his death, afte a long and painful illness, a tumour of the brain. 

Jeanety used a process tried by Marggraf (Vol. II) and investigated by Achard, of fusing platinum with arsenic and then driving off the arsenic by ignition, when malleable platinum remained, from which Achard made the first platinum crucible. Jeanety s process was described in some detail by Pelletier and Berthollet and Pelletier. Pelletier used phosphorus instead of arsenic, and Mussin-Pushkin used mercury. 

By December, 1800, he haul formed a financial partnership with Smithson Tennauit for the production of chemical commodities, notably malleable platinum, and his scientific achievements over the next two deceides would place him in the upper echelon of Europe s scientific elite. Wollaston s talent for doing science on a scale much smaller tham normal was a trait which often impressed his conten x>raries. William Bramde, for exan le, wrote... 

We also know that Wollaston had, in partnership with Smithson Tennant, invested heavily in the purchase of crude platina ore in late 1800, and from 1801 to 1805 he perfected the techniques of powder metallurgy that led to the production of malleable platinum in 1805 (28). Only when the processing of platinum became regularized about 1810 did Wollaston turn his attention again to electrochemistry, once more in connection with a small, demonstration device. 

Discovery Natural platinum has been known since antiquity and became well known in New Granada in South America in the 18 century. It was, however, an alloy of different platinum group metals, PGMs. Pure and malleable platinum was prepared by W. H. Wollaston in the first decade of the 19 century. 

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