[citation needed] He began to study medicine at University of Edinburgh in 1795, taking his medical in 1807, but ill-health[a] interrupted his practice as a physician, and he devoted his time mainly to chemical research, especially with regard to gases.

One of his best-known papers (published in Philosophical Transactions of the Royal Society, 1803) describes experiments on the quantity of gases absorbed by water at different temperatures and under different pressures.

His other papers deal with gas-analysis, fire-damp, illuminating gas, the composition of hydrochloric acid and of ammonia, urinary and other morbid concretions, and the disinfecting powers of heat.

His Elements of Experimental Chemistry (1799) enjoyed considerable vogue in its day,[4] going through eleven editions in 30 years.

He was elected a Fellow of the Royal Society in February 1809, having been awarded their prestigious Copley Medal in 1808.