William Cookworthy

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William Cookworthy (1705—1780) was an 18th century Quaker scientist and entrepreneur, with wide-ranging interests. He was the first person in Britain to discover how to make hard paste porcelain, and he discovered and exploited china clay deposits in Cornwall.


William Cookworthy was born on 12 April 1705 in Kingsbridge, Devon, the eldest child of William Cookworthy, a Quaker weaver. His father died when he was 13. At the age of 15 he was taken on by Sylvanus Bevan, a London apothecary, but because he could not afford the apprenticeship fees he never qualified as an apothecary himself. Around 1726 he came to Plymouth, where he lived for the rest of his life, and set up as a manufacturing chemist under the name of Bevans and Cookworthy. In 1735 he married Sarah Berry, with whom he had five daughters, but she died ten years later. He died on 17 October 1780.[1]

Chemist and mineralogist

Following the death of his wife Sarah, Cookworthy's brother Philip took over the daily running of the business, and William devoted much of his time to his work as a chemist. He was in correspondence with others in the field, and had a wide reputation, earning him the designation of "the great Cookworthy". He devised his own pharmaceutical preparations, but was more particularly known for his work in assaying. He convinced himself of the value of dowsing as a method of detecting mineral deposits, though his demonstrations were not always successful.[2]


Cookworthy was the first person in Britain to work out the correct proportions of kaolin and petuntse (china clay and china stone, both derivatives of granite) in making hard paste porcelain, and a method of producing an attractive glaze. He discovered suitable deposits of the two materials on a site in Cornwall, and took out a patent for his discoveries. Together with another Quaker, Richard Champion, he set up a company which produced porcelain in Plymouth from 1768 to 1770 and in Bristol for a longer period. He withdrew from this in 1773. The manufacture of porcelain proved uneconomic, due partly to the high cost of producing sufficient heat and partly to the high proportion of seconds and complete failures. When the West Midland china manufacturers acquired his patent, it was for the sake of using the glazing method he had developed.[3]

Quaker and mystic

The death of his wife Sarah in 1745 not only led to Cookworthy's reducing his involvement in business, it also produced a spiritual crisis, which eventually gave new life to his Quakerism and led to him being recognised as a minister. His work in this capacity was largely confined to Devon and Cornwall. It was probably he who initiated the Plymouth agitation against Quakers dealing in prize goods. Plymouth's trade had suffered considerably because of its development as a naval base, but merchants were able to take advantage of the auctioning of prize vessels and their contents brought in by navy ships and privateers. Cookworthy pressed the view that Quaker merchants engaging in this were behaving wrongly, as they were profiting by war, and the view was eventually accepted.[4]

He did not remain in an orthodox line of Quakerism, but started to read widely. This resulted in his translating and publishing foreign works which chimed with his developing mystical sense. The first was Muralt's L'instinct Divin recommandé aux hommmes (although he thought that part of it would have been better omitted), and it was followed by some works of Emanuel Swedenborg. These activities in no way reduced his standing among Quakers, which was high.[5]


  1. Fox, H. The story of William Cookworthy. Cookworthy Museum. 1972. ch 5
  2. Selleck, A D. Cookworthy: A man of no common clay. Barron Jay. 1978. ch 2
  3. Selleck. ch 3
  4. Wyatt, M. Quakers in Plymouth: A Friends' Meeting in context. Quacks. 2017. ch 3; Selleck ch 5
  5. Selleck. ch 4