The American chemist Theodore William Richards (1868-1928) ushered in a new age of accuracy in chemistry by determining the atomic weights of many elements.

Theodore W. Richards was born on Jan. 31, 1868, in Germantown, Pa. His father, William Trost Richards, was a prominent landscape and marine artist; his mother, Anna Matlock Richards, was a poet and a woman of great cultivation. Until he entered college, his education was at home under his mother's direction. At age 14 he entered Haverford College as a sophomore, uncertain whether to become an astronomer or a chemist. He had defective eyesight, however, and by the time of his graduation he had decided on a career in chemistry.

In 1885 Richards entered Harvard as a senior and the following year was granted the bachelor's degree. Two years later he was awarded the doctorate with a dissertation on the atomic weights of hydrogen and oxygen. He won...