Thomas Graham was born on December 10, 1805 in Glasgow, Scotland. His father, a successful textile manufacturer and merchant, insisted that Graham become a minister in the Church of Scotland. Instead, he studied at Glasgow University beginning in 1819. He was only 14.

Graham studied under Thomas Thomson, a chemist, and developed a strong interest in science and chemistry. As he persisted with his scientific studies, Graham’s father refused his son financial support. In order to support himself, he wrote and taught at the university. He graduated from Glasgow University in 1824 and spent two years doing research with professor T.C. Hope in Edinburgh. By 1826, he had earned his master’s degree.

In 1829, Graham became a Mechanics Institution lecturer. In 1830, he returned to Glasgow University as the chemistry chair. Also in 1829, Graham published a paper on the diffusion of gases. He investigated the rate at which different gases diffused through porous barriers. He also studied the effusion of gases, which is the movement of gases through small openings. He discovered through this work that the rate of diffusion and effusion of a gas is inversely proportional to its mass as long as temperature and pressure remain constant. Today, this is known as Graham’s Law of Effusion.

Graham became a professor at the newly founded University College, London in 1837 and became a Fellow of the Royal Society in 1836. He remained the chair at University College until 1855 when he became the Master of the Mint. He held this position for the next fourteen years. He disliked the official role and was more suited to scientific research.

Around 1860, Graham focused his study on liquids, solutions, and colloids. He discovered that liquids diffuse and found that gelatin, glue, and starch diffuse very slowly. He called these substances colloids and distinguished them from crystalloids, which diffuse quickly. He found that the colloids particularly diffused slowly through a membrane and developed dialysis as a way to separate particles of different sizes.

Graham was honored for his work in chemistry. He was a member of the Institute of France. He was a founding member and president of the Chemical Society of London and of the Cavendish Society. He was offered the presidency of the Royal Society but declined due to his poor health. Graham died on September 16, 1869 at the age of 64.