LIPPMANN, GABRIEL (1845-1920, French physicist, was born at Hollerich, Luxembourg, on Aug. 16, 1845. He was educated at Paris and was sent by the Government on a scien tific mission to investigate the methods of teaching science in Germany. Later he held the following posts: "maitre de Con ferences" in the Sorbonne (1878-83), professor of mathematical physics in the faculty of Science, Paris (1883-86), and finally professor of experimental physics and director of the research laboratories which were transferred to the Sorbonne; he retained this post until his death. Lippmann's name is generally asso ciated with his researches in colour photography and with the invention of the capillary electrometer. In 1881 he described a method of colour photography which depended on interference; later, experiments were carried out under Lippmann and the method improved. While at Heidelberg he saw an experiment in which a drop of mercury covered with sulphuric acid contracted when touched with an iron wire. This led to the invention of the
Lippmann capillary electrometer, which depends on the polariza tion and surface tension of a mercury-sulphuric acid surface. Lippmann was an able inventor in other directions ; he com pared the times of two pendulums of nearly equal period, he tried to eliminate the irregularities of pendulum clocks and worked on the measurement of time. He invented a coelostat for photo graphing an appreciable area of the sky, an astatic galvanometer, an electric connection which was independent of applied pressure and a seismograph which gave directly the acceleration of the earth. He also wrote a paper on the induction of resistance-free circuits. This was verified later by Kammerlingh Onnes.
Lippmann received many honours. He was elected F.R.S. in 1908, president of the Paris academy of science (1912), and was awarded the Nobel prize for physics in 1908. He died on July 31, 1921, on board ship.