1898 - Science

Science

Polish-born French physical chemist Marie (Marja) Curie (née Sklodowska), 31, and her husband, Pierre, 39, isolate radium, the first important radioactive element (see uranium, 1896). Married 3 years ago, they have endured extreme poverty, have earlier discovered a highly radioactive and dangerous element which they called polonium, after Marie's native land, and have now detected radium while extracting pure substances from pitchblende ore (see 1904).

Physicist Wilhelm Wien analyzes the positive rays emanating from the anode in an energized Crookes tube and finds that the particles have a mass-to-charge ratio more than 1,000 times larger than that of the electron (see 1897; Wien, 1893). Since the ratio of the particles is also comparable to the mass-to-charge ratio of the residual atoms in the discharge tubes, scientists suspect that the rays may actually be ions from the gases in the Crookes tube.

Physicist Philipp Lenard constructs a cathode-ray tube with an aluminum window that permits cathode rays to pass into the air (see Lenard, 1890). Now 36, he uses a phosphorescent screen to demonstrate that the rays decrease in number as the screen is drawn away from the CR tube and disappear entirely at a distance. His experiments show that the power of substances to absorb cathode rays depends not on their chemical nature but rather on their density, and that this absorption decreases as the velocity of the rays increases. Lenard will prove next year that cathode rays are created when light strikes metal surfaces, a phenomenon that will come to be called the photoelectric effect.

Mathematics teacher Johann Jakob Balmer dies at Basel March 12 at age 72, having made the first discovery of the simple mathematical relationship between the frequencies of light emitted by hydrogen (see Bohr, 1913).

The word photosynthesis is introduced to denote the process by which plants synthesize carbohydrates from carbon dioxide, water, and inorganic salts, using sunlight for energy and chlorophyll as a catalyst (see Ingenhousz, 1779; von Sachs, 1862).