Portrait of John Stewart MacArthur

People/scientist, engineer

John Stewart MacArthur

John Stewart MacArthur (1856–1920), scientist, engineer, from United Kingdom. Linked to gold.

The lucky break

With the Glasgow doctors Robert and William Forrest, he tested potassium cyanide as a solvent for gold in November 1886. British patents followed in October 1887 and July 1888.1,2,3

The downfall

In 1896 the Great Cyanide Case in the Pretoria High Court challenged the novelty of the patents. They were annulled in South Africa and then elsewhere, so he gained little from them.1,2,3

Legacy

After his 1890 demonstration on the Witwatersrand, recovery from complex ores rose from about 45 to 98 per cent and monthly gold output roughly doubled within two years. He later refined radium at Runcorn and Balloch.1,2,3

Story cards

Timeline

  1. 1887Cyanide process for gold developed in Scotland4
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Where next

People

Partner ofRobert Wardrop ForrestA chemist and two doctors who changed gold recovery.1Partner ofWilliam ForrestThe Forrest brothers backed his cyanide experiments.1

Mines

InspiredWitwatersrand main reef mines, 1886 to 1887Recovery on the Rand rose from about 45 to 98 per cent.1

Events

DiscoveredCyanide process for gold developed in ScotlandThree Glasgow experimenters found cyanide dissolves gold.1

Sources

  1. MacArthur papers: John Stewart MacArthur Balliol College Archives, Oxford
  2. Wikidata item Q6259177
  3. File pages and licence metadata for portraits (via the Commons imageinfo/extmetadata API) Wikimedia Commons
  4. Cyanide hazards to plants and animals from gold mining and related water issues (publication page) US Geological Survey

Pictures on this page: Jsmacarthur-X-007r.jpg, Elliott & Fry according to verso jsmacarthur-X-007v on flickr (Public domain).

From the Prospector Trails mining history dataset: each fact links to the source it was checked against. Figures are as the source gives them, in the money of their day. Not investment advice.

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Cover photos from Wikimedia Commons: Super Pit, Kalgoorlie by Kgbo, CC BY-SA 4.0. Pictures: Pangkalpinang. Mijn 3b. Een reeks koelies bezig met het transporteeren van grond, Europeana (Public Domain Mark 1.0); Mijnramp Bois du Caizier, Marcinelle, België. Schacht, Rossem, Wim van / Anefo / Europeana (Public Domain Mark 1.0); NASA's ASTER Shows Brazilian City After Dam Disaster, NASA/METI/AIST/Japan Space Systems, and U.S./Japan ASTER Science Team (Public domain (NASA media, no copyright)).