A blue jasper case for an Argand lamp. An Argand lamp was a new type of oil lanp which produced a much brighter light. It was invented by Swiss Scientist Ami Argand (1750-1803). The cylindrical base held the oil resevoir and a glass chimney sat above this.
Wedgwood had met Argand and he worked with fellow industrialist Matthew Boulton in Birmingham to make the lamp cases. Boulton made the metal parts needed for the lamp.