Percival Norton Johnson was the founder of Johnson Matthey, the United Kingdom's largest precious metals business. He specialized in the assaying and refining of precious metals particularly gold imported from Brazil, and he perfected a method of extracting the Palladium from the gold thereby improving the color. He became a Fellow of the Royal Society in 1846. He went into full partnership with George Matthey, a stockbroker, in 1851. His expertise in refining earned his business the appointment of Assayer to the Bank of England in 1852.