In 1848 Young left Tennants', and in partnership with his friend and assistant Edward Meldrum, set up a small business refining the crude oil. The new oils were successful, but the supply of oil from the coal mine soon began to fail (eventually being exhausted in 1851). Young, noticing that the oil was dripping from the sandstone roof of the coal mine, theorised that it somehow originated from the action of heat on the coal seam and from this thought that it might be produced artificially.