KEY AND INDEX 



University of Berlin; 1867, perpetual secretary 

 Berlin Academy of Sciences. He made a special 

 study of animal electricity, and laid the founda- 

 tion for all our knowledge of this subject. In- 

 vented the method for reading table messages 

 by light deflected from a mirror attached to the 

 needle of a galvanometer. 



Dufay, Charles Francois de Cisternay, ii, 267. 

 Born at Paris, 1698; died at Paris, 1739. French 

 chemist. Destined for the army, he paid more 

 attention to science, and soon abandoned mili- 

 tary service to devote himself to chemistry. 

 1733, was made member of the Academy of 

 Sciences, and pursued anatomy, botany, astron- 

 omy, mathematics, and mechanics as well as 

 chemistry. Noted for his researches in the phe- 

 nomena of phosphorescence and the properties 

 of caustic soda. Made many surprising discov- 

 eries in electricity. Made many experiments in 

 the double refraction of crystals. Through his 

 efforts the Jardin des Plantes was greatly im- 

 proved and developed. 



Dujardin, Felix, iv, 124. Born at Tours, 1801 ; 

 died at Rennes, 1860. French zoologist. Studied 

 Tours and Paris. Became Professor of Zoology 

 in the Faculte de Rennes. Made a special study 

 of worms and insects. 



Dumas, Jean Baptiste, iv, 128. Born at Alais, 

 1800; died at Cannes, 1884. French chemist. 

 Was apprenticed to an apothecary in Geneva. 

 Went to Paris and studied chemistry. Professor 

 of Chemistry in the Athenaeum, later at the Sor- 

 bonne. Made a specialty of organic chemistry; 

 and made many valuable researches for the de- 

 termination of atomic weights. Also occupied 



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