Thomas Graham FRS FRSE DCL (20 December 1805[1][2] – 11 September 1869) was a Scottish chemist known for his pioneering work in dialysis and the diffusion of gases.

There he developed a strong interest in chemistry, studying under Professor Thomas Thomson, who was impressed and influenced by the young man.

[8] In the former case, Graham deduced that when measured repeatedly under the same conditions of pressure and temperature, the rate of diffusive mixing of a gas is inversely proportional to the square root of its density, and given the relationship between density and molar mass, also inversely proportional to the square root of its molar mass.

In applied areas, Graham also made fundamental discoveries related to dialysis, a process used in research and industrial settings, as well as in modern health care.

[6] He also proposed the association theory which claimed that the substances such as cellulose or starch that we now know are polymers are composed from smaller molecules hold together by unknown forces.