Roebuck, John

SUBJECT AREA: Chemical technology

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b. 1718 Sheffield, England

d. 17 July 1794

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English chemist and manufacturer, inventor of the lead-chamber process for sulphuric acid.

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The son of a prosperous Sheffield manufacturer, Roebuck forsook the family business to pursue studies in medicine at Edinburgh University. There he met Dr Joseph Black (1727–99), celebrated Professor of Chemistry, who aroused in Roebuck a lasting interest in chemistry. Roebuck continued his studies at Leyden, where he took his medical degree in 1742. He set up in practice in Birmingham, but in his spare time he continued chemical experiments that might help local industries.

Among his early achievements was his new method of refining gold and silver. Success led to the setting up of a large laboratory and a reputation as a chemical consultant. It was at this time that Roebuck devised an improved way of making sulphuric acid. This vital substance was then made by burning sulphur and nitre (potassium nitrate) over water in a glass globe. The scale of the process was limited by the fragility of the glass. Roebuck substituted "lead chambers", or vessels consisting of sheets of lead, a metal both cheap and resistant to acids, set in wooden frames. After the first plant was set up in 1746, productivity rose and the price of sulphuric acid fell sharply. Success encouraged Roebuck to establish a second, larger plant at Prestonpans, near Edinburgh. He preferred to rely on secrecy rather than patents to preserve his monopoly, but a departing employee took the secret with him and the process spread rapidly in England and on the European continent. It remained the standard process until it was superseded by the contact process towards the end of the nineteenth century. Roebuck next turned his attention to ironmaking and finally selected a site on the Carron river, near Falkirk in Scotland, where the raw materials and water power and transport lay close at hand. The Carron ironworks began producing iron in 1760 and became one of the great names in the history of ironmaking. Roebuck was an early proponent of the smelting of iron with coke, pioneered by Abraham Darby at Coalbrookdale. To supply the stronger blast required, Roebuck consulted John Smeaton, who c. 1760 installed the first blowing cylinders of any size.

All had so far gone well for Roebuck, but he now leased coal-mines and salt-works from the Duke of Hamilton's lands at Borrowstonness in Linlithgow. The coal workings were plagued with flooding which the existing Newcomen engines were unable to overcome. Through his friendship with Joseph Black, patron of James Watt, Roebuck persuaded Watt to join him to apply his improved steam-engine to the flooded mine. He took over Black's loan to Watt of £1,200, helped him to obtain the first steam-engine patent of 1769 and took a two-thirds interest in the project. However, the new engine was not yet equal to the task and the debts mounted. To satisfy his creditors, Roebuck had to dispose of his capital in his various ventures. One creditor was Matthew Boulton, who accepted Roebuck's two-thirds share in Watt's steam-engine, rather than claim payment from his depleted estate, thus initiating a famous partnership. Roebuck was retained to manage Borrowstonness and allowed an annuity for his continued support until his death in 1794.

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Further Reading

Memoir of John Roebuck in J.Roy. Soc. Edin., vol. 4 (1798), pp. 65–87.

S.Gregory, 1987, "John Roebuck, 18th century entrepreneur", Chem. Engr. 443:28–31.

LRD