350 History of Luminescence 



The transparency of quartz was an important discovery, of great 

 value today for experiments with ultraviolet light. 



Thus began the career of Edmond Becquerel who was to lead the 

 study of phosphorescence and related luminescences for many years. 

 The combination of the Becquerels, father and son, and Jean Bap- 

 tiste Biot could hardly have been a more celebrated one, although 

 Edmond Becquerel was only nineteen years old at this time. Biot 

 had been professor of physics at the College of France since 1800 

 and professor of astronomy of the Faculty of Sciences at Paris since 

 1809. He was a man of very wide interests in the natural sciences, 

 perhaps best known for studies on polarized light, which led to a 

 method for the analysis of sugars. A. C. Becquerel, a professor and 

 director of the Museum of Natural History in Paris had a long and 

 distinguished career in physics, especially in the fields of electricity, 

 magnetism, and electrochemistry. 



The outline of E. Becquerel's research presented above, and sub- 

 sequent discussion of contemporary workers are not intended to 

 detract from the importance of the huge amount of experimentation 

 on phosphors carried out in the latter part of the century. In fact 

 the later research is too voluminous to be reported in detail; in 

 many respects it did fill in where Becquerel had pioneered. The 

 names of E. Wiedemann and G. C. Schmitt of Erlangen, or P. Lenard 

 and V. Klatt of Heidelberg on phosphorescence, of G. G. Stokes of 

 Cambridge and E. Lommel of Munich on fluorescence, and of W. 

 Crookes and P. Lenard on cathodoluminescence deserve the same 

 historical acclaim as that of Becquerel, and their pioneering dis- 

 coveries will be found in subsequent pages of this book. 



An immediate consequence of the Becquerel publications was 

 stimulation of research on phosphorescence in Italy by C. Matteucci 

 (1842) and in the United States by former members of the American 

 Philosophical Society, the famous Joseph Henry (1797-1878), pro- 

 fessor of natural philosophy at the College of New Jersey (Princeton, 

 N. J.) from 1832 to 1846, and J. W. Draper, professor of chemistry 

 at New York University. Draper's work is considered in the next 

 section. 



Joseph Henry's studies on electromagnetic induction and his 

 prestige as the first Secretary of the Smithsonian Institution have 

 served to conceal an earlier work, " On Phosphorogenic Emanation," 

 presented in 1841, and published in the Proceedings of the Ameri- 

 can Philosophical Society for 1843. By this term Henry referred to 

 the discovery of Becquerel and Biot (1839) that something pro- 

 duced in an electric spark, which caused luminescence of phosphors 

 in the air, was cut off by glass but would act through quartz, i. e.. 



