252 IOWA ACADEMY OF SCIENCE 



Bopius (Beibl. z. d. Ann.. 28, 723), Dependence of the conduc- 

 tivity on the degree of illumination. 



Kom (Compt. Rend., 138, 1190), Picture Telegraphy. 



Marc (Zeits, f. anorg. Chemie, 37, 459), The effect of light and 

 temperature on selenium. 



Nutting (Phys. Zeits., 4, 201), The reflection coefficient of 

 selenium. 



Euhmer (Mechaniker, 11, 265), New Selenium apparatus. 



1904 



Amaduzzi (Phys. Zeits., 5, 647), Selenium. 



Berndt (Mechaniker, 1904, p. 97), Selenium cells on carbon. 



Berndt (Phys. Zeits., 5, 121), Some observations on selenium 



cells. 

 Berndt (Phys. Zeits., 5, 289), the action of selenium cells on a 



photographic plate. 



Berthier (Beibl. z. d. Ann., 28, 876), The photo-electric proper- 

 ties of selenium. 



BUtz (Nachr. d. Gott. "Wiss. Ges., 1904, p. 18). 



Chabot (Phys. Zeits., 5, 1904, 103 and 168), New rays or a new 

 emanation. Also Phys. Zeits., 5, 517 and 584. 



Agostini (Phys. Zeits., 5, 121), The electrical properties of 

 selenium. 



Davis (Nature, 70, 506), Is selenium radioactive. 



Kom (Phys. Zeits., 5, 113), New sending and receiving ap- 

 paratus for distance photography. 



Kom (Phys. Zeits., 5, 164), Receiving apparatus for distance 

 photography. 



Kom (Monograph printed by S. Hirzel press, Leipzig), Elec- 

 trical distance photography and similar things. 



Nisco (Eclair, e'ectric, 30, 1904), Photometer. 



Pfund (Phil. Mag., 7, 26), Studies with selenium cells. 



Eeiff (Mechaniker, 1904, p. 75, 86 and 100), Transmission of 

 pictures and writing by the Korn method. 



Buhmer (Elektroteeh. Zeits., 25, 1021), Selenium and its tech- 

 nical applications. 



