Mining engineer and metallurgical chemist John Stewart MacArthur was born in Glasgow and started his apprenticeship as a chemist in 1871 with the Tharsis Sulphur & Copper Co, who had offices at 136 West George Street and 53 Renfield Street and works at Charles Street, St. Rollox and 160 Garngad Road.

In 1881 while working on the recovery of precious metals from copper liquors his attention was directed to the extraction of gold from ores.

In 1885 he entered into partnership with Dr Robert W Forrest and Dr William Forrest who provided him with a small room in their surgery at 319 Crown Street, Gorbals to conduct his research.

Also in 1885 the Cassel Gold Extracting Co., was formed to extract gold from ore using the Cassels Patent. MacArthur published an article in the Chemical Industries Magazine of 1885 on the issue of gold extraction which brought him to the attention of the industry.

The Cassel Company had failed to get any results from their own process and turned to MacArthur for help and he eventually joined the Cassel Gold Extracting Co., as technical manager in 1886. However, MacArthur and the Forrest brothers had discovered that they could use a weak solution of potassium cyanide to dissolve the gold from ores. They informed Cassel’s of their discovery and the process was tested at their works. The successful results from testing 15 tons of ore from the New Zealand Crown Mines proved that the process of extraction was commercially viable and a contract was drawn up with the New Zealand company to erect a plant in New Zealand. The gold mines of South Africa were targeted next and with such success that it increased the value of the Rand and opened a new chapter in the history of the world’s gold production.

The cyanide process, discovered on the south side of Glasgow, spread all over the world and is said to have created a new source of wealth. In 1911 John Stewart MacArthur began to manufacture radium compounds in Runcorn but subsequently moved his production to Balloch.

During the First World War he produced radium for medicinal purposes and for luminous paint for the military. The entire output was purchased by the Government. He became a member of the Institution of Mining and Metallurgy in 1892 and in 1902 was awarded the institutions gold medal in recognition of his work in the introduction and development of the cyanide process. He was also an original member of the Society of Chemical Industry.

He died at his Knowe Terrace home on 16th March 1920.

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