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MacArthur Collection

John Stewart MacArthur (1856-1920)


Born one of seven children in Glasgow in 1856, JSM left school at fourteen to begin work as an apprentice chemist with the Tharsis Sulphur and Copper Co.; it was while working on the recovery of previous metals from sulphur liquids that his attention was drawn by the problem of gold extraction. Meanwhile an interest in photography and photographic chemistry had brought him into contact with two Glasgow doctors, the brothers Robert Wardrop Forrest and William Forrest, and together they carried out a number of scientific investigations; in 1885 the trio acquired several samples of refractory gold ore and began to experiment.

By the 1880s the world’s gold industry was in a precarious state, and nowhere was the problem more acute than on the goldfields of South Africa. The rich surface zones were becoming exhausted and treatment of the unoxidised pyritic reefs below by the regular method of amalgamation yielded only 50% of its wealth. Vast tailings containing at least one ounce of gold per ton were accumulating, and there was no practical method of recovery.

A number of Scottish mineral extraction companies were active in the search for a cheap and effective solution. In 1884 a New York metallurgist, Henry Rennel Cassel, had interested a group of Glasgow businessmen in proposals for an electrolytic process, resulting in the flotation of the Cassel Gold Extracting Co; two years later Cassel was granted a patent which attracted a great deal of attention, but while Cassel himself achieved impressive results, others were unable to repeat his success, and shortly after Cassel disappeared.

Macarthur’s association with the Forrest brothers had by now crystallised into a formal syndicate, backed by the financier George Morton; even after he joined Cassel Co s Technical Manager to pursue the electrolytic idea, JSM continued to work with the research syndicate towards a chemical solution, on the understanding that Cassel Co would have first claim in any discovery. The essential work, however, had already been done: in November 1886 the syndicate had tested potassium cyanide as a possible solvent, but it was not until a year later that the results were fully appreciated; the MacArthur-Forrest process, which involved dissolving crushed ore in a weak cyanide solution and then precipitating the gold with zinc shavings, received its British patents in October 1887 and July 1888, the South African patent following twelve months later.

The Cassel Gold Recovery Co immediately set about disseminating and exploiting the new process: expeditions were sent out worldwide and subsidiary companies established to control licensing. The first gold production by the new process took place in Australia and New Zealand, but it was on the South African Rand that the MacArthur-Forrest patents had their most powerful impact. Here the ores proved particularly amenable to cyanide treatment and after JSM himself had demonstrated the process to skeptical mine owners in 1890, it was quickly adopted; within two years of its introduction the total weight of gold produced had risen from forty thousand to one hundred thousand ounces per month. Stagnation in the gold-mining industry was arrested; the new process had striking effects: instead of being able to refine only around 45% of metal from complex ores, as before, 98% extraction could be achieved.

The Cassel directors had decided to exploit the process on a royalty basis, but by 1892 the mine owners were unhappy about the difficulties of obtaining licenses and the percentage of royalty demanded. Initially the petitioned the Volksraad Chamber of Mines for a reduction in rates, but when lengthy negotiations failed they made a more serious attack on the validity of the MacArthur –Forrest patents themselves.

The ‘ Great Cyanide Case’ which opened in the Pretorian High Court in February 1896, centred on the claim that JSM’s ‘invention’ contained no novelty: that gold was soluble in a cyanide solution had been known for many years, and extraction processes employing this knowledge had already received patents- in America, for example, Cassel Co had been compelled to purchase one such patent. It was true that until the advent of the MacArthur-Forrest process no gold had been extracted by this method in a commercially viable way, but this commonsense argument held little sway in a court of law. The patents were annulled first in South Africa, then elsewhere, so that JSM and the Cassel Co ceased to benefit materially in any way from their discovery. The issue, however, was never cut and dried: an English Court of Appeal in 1895 found that the process did contain ‘novelty, invention and utility’ and even in South Africa a verdict could be obtained only by a majority, not by the unanimity, of the judges; elsewhere the situation was defused by government purchase of the patents.

JSM continued to travel extensively, working as a practising metallurgist. In 1911 he became interested in the new science of radium, establishing a refining works for the production of radium bromide (only the second in Britain), first at Runcorn, Cheshire, and later at Balloch on the banks of Loch Lomond, where he operated at JSM Ltd. From 1911 he concentrated on this pioneering work on refining radium on an industrial scale (most work on radium at this time was confined to the laboratory). The process was highly toxic, costly and time-consuming – raw materials were imported from the USA and Portugal to undergo approximately fifty operations, and JSM estimated that realistically one should not expect a yield of more than one grain per ten tons of ore. However, the new substance was in demand for the treatment of cancers and skin conditions, and JSM further envisaged its use in the manufacture of fertilizers and luminous paint. His work on the development of radium salt production continued until his death in 1920.

JSM was deprived of material reward by the greed of the mine owners and the mismanagement of his colleagues, although he did enjoy the recognition of his profession – he was, for example, the first recipient of the gold medal of the Institution of Mining and Metallurgy; and the world since has been rather grudging in its praise of the Glasgow pioneer, failing to acknowledge that in his work on the cyanide process and radium, JSM showed himself to possess both the vision of an innovator and the crucial ability o make the move from test tube to factory.

JSM died at Pollockshields, Glasgow, on 16 March 1920.


JSM was neither a Balliol nor an Oxford man; the papers were given to the college by his son, John Stewart MacArthur (1893-1970, Balliol 1919). The Rev. MacArthur’s association with the college was revived in his later years when he held two Balliol livings, South Luffenham and Huntspill. On his death he bequeathed the bulk of his estate to the college, including a number of shares in American and South African mineral extraction companies and a considerable holding in ICI, which had incorporated the old Cassel Co.

The collection, which concentrates almost exclusively on JSM’s earlier development of the cyanide process, reflects the practical nature of his work – although he did publish some material, JSM was first and foremost a working chemist and metallurgist, and, less successfully, a businessman. The papers were either loose or had been organised in small subject groups by JSM himself and by his son who continued to collect items and foster interest in his father’s work by lending out material. This structure has been maintained as far as possible in the present catalogue, in which material is arranged by chronology and subject.


J Gray and JA McLachlan. ‘A History of the Introduction of the MacArthur-Forrest Cyanide Process to the Witwatersrand Goldfields.’ Journal of the Chemical, Metallurgical and Mining Society of South Africa, June 1933.

David I Harvie. ‘John Stewart MacArthur: Pioneer Gold and Radium Refiner.’ Endeavour (13.4), 1989. There is a photocopy of this in the file on MacArthur (annex); Mr. Harvie also provided a typescript version of the article, kept with it.

David I Harvie’s entry on MacArthur in the Dictionary of National Biography: Missing Persons.

In 1994, Mr. Harvie kindly provided the Library with further in formation on MacArthur, in the form of a synopsis of his work on him; a photocopy of this is also in the MacArthur file.

A History of Technology. Vol. V: The Late Nineteenth Century (ed. C Singer et al), pp 95, 249. Vol. VI: The Twentieth Century part I. (Ed TI Williams), p 424.

- SA Baker 1989, rev. R Kemsley 1994-5

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