LIPPMANN, GABRIEL:
French physicist; born at Hollerich, Luxemburg, in 1845. After being educated at the Ecole Normale and in Germany, he went to Paris, taking the degree of D.Sc. in 1875. During his stay in Germany he had given special attention to electricity, and subsequently invented the capillary electrometer, an electrocapillary motor, etc. In 1891 he discovered the process of color-photography, which discovery he amplified in 1892. He prepared glass slides, which were covered with a very finely granulated bromid-of-silver solution, and which, when dried, were placed in a concave frame filled with quicksilver, giving a mirror-like surface to the solution. When the photograph is taken the light-rays form a wave of light in the solution in conjunction with the rays from the quicksilver-mirror, giving light "maxima" and dark "minima." These when reproduced give, by reflected light, a true picture in the original colors. However, the very long exposure necessary (about ten minutes) makes the process unsatisfactory. This discovery won him recognition. In 1883 he succeeded Briot as professor of physical mathematics at the Sorbonne, and in 1885 he became professor of experimental physics at the same institution. In 1886 he was elected member of the Académie des Sciences, succeeding Dessain. Lippmann has contributed many essays to the professional journals, and is the author of "Cours de Thermodynamique," Paris, 1886, and "Cours d'Acoustique et d'Optique," ib. 1888.
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