GRAHAM, THOMAS. - GRAHAM'S LAW OF EFFUSION.

On the Motion of Gases. Received June 18, - Read June 18, 1846. (+) On the Motion of Gases. Part II. Received JJune 21, - Read June 21, 1849.

(London, Richard and John E. Taylor, 1846 a. 1849). 4to. No wrappers as extracted from "Philosophical Transactions" 1846 . Pp. 573-631 a. 3 engraved plates + 1849. Pp. 349-391. Clean and fine.

First appearance of the papers in which he announced his famous Law of Effusion. Graham's Law shows the relationship between the molar or molecular mass of a gas and the rate at which it will effuse. Effusion is the process of gas molecules escaping through tiny holes in their container. He showed experimentally that the ratio of the rates of effusion of two gases is equal to the square root of the inverse ratio of their molecular masses or densities and the effusion rate of a gas is inversely proportional to the square root of its molecular mass.

Thomas Graham, the Scottish Chemist, first president of the Chemical Society of London, and one of the chief founders of physical chemistry. He formulated Graham's Law of diffusion relating the rate of diffusion of gases to their densities, discovered and named the process of dialysis used for separating colloids from crystalloids, studied the three forms of phosphoric and arsenics acids that led to the developpement of the concept of polybasic acids, a major contribution to inorganic chemistry.

Order-nr.: 46340