James Watt's research in pneumatic chemistry involved the use of inflammable (H) and dephlogisticated (O) airs to create water.  In 1783, James Watt showed that water was composed of inflammable and dephlogisticated airs, and that the masses of gases before combustion were exactly equal to the mass of water after combustion.  Until this point, water was viewed as a fundamental element rather than a compound.  James Watt also sought to explore the use of different "factitious airs" such as hydrocarbonate in medicinal treatments as "pneumatic therapy" by collaborating with Dr. Thomas Beddoes and Erasmus Darwin to treat Jessie Watt, his daughter suffering from tuberculosis, using fixed air.