TRANSACTIONS OP SECTION A. 541 



J. G. Davidson (' Phys. Zeit.' 8, p. 658), ' Wirkungen des ultravioletten Lichtes.' 

 Me. Marie Sadzewicz (' Acad. Sci. Cracovie Bull.' 5, p. 497), ' On the so-called 



Photoelectric Fatigue of Metal Plates.' 



J. A. Crowther (' Camb. Phil. Soc. Proc' 14, p. 340), ' On the Fatigue of Metals 



subjected to Radium Rays.' 



1908. 



H. Dember (' Phys. Zeit.' 9, p. 188), ' Empfindlichkeitsanderung lichtelektrischer 

 Zellen.' 



V. L. Chrisler (' Phys. Rev.' 27, p. 267), ' Effect of Absorbed Hydrogen and of 

 other Gases on the Photoelectric Activity of Metals.' 



1909. 



H. S. Allen (' Proc. Roy. Soc' A, 82, p. 161), ' The Photoelectric Fatigue of 

 Zinc. II.' 



E. Miiller (' Deutsch. Phys. Gesell. Verh.' 1, p. 72), ' Lichtelektrische Unter- 

 suchungen an Alkalinietallen.' 



J. A. Fleming (' Proc. Phys. Soc, London,' 21, p. 469; ' Phil. Mag.' 17, p. 286), 

 ' Photoelectric Properties of Potassium Sodium Alloy.' 



E. Bloch (' C. R.' 149, p. 1110), ' Sur l'effet photoelectrique de Hertz.' 



E. Cohnstaedt (' Phys. Zeit.' 10, p. 643), ' The Water-skin and Surface Processes 

 connected therewith.' 



R. A. Milhkan and G. Winchester (American Physical Society, Washington, 

 April 26, 27 ; Abstract in ' Phys. Rev.' 29, p. 85), ' The Absence of Photoelectric 

 Fatigue in a very High Vacuum.' 



W. Hallwachs (' Abh. d. naturwissensch. Gesellsch. Isis in Dresden,' 1, p. 65). 



R. Ladenburg (' Jahrbuch der Radioaktivitat,' 6, p. 425), ' Die neueren Forsch- 

 ungen iiber die durch Licht- und Rontgcnstrahlen hervorgerufene Emission negatives 

 Elektronen ' (with Bibliography). , 



1910. 



E. TJlhnanu (' Ann. d. Phys.' (4) 32, p. 1), ' Ueber die lichtelektrische Ermiidung 

 des Zinks.' 



E. Bloch (' Le Radium,' 7, p. 125), ' Recherches sur l'effet photo-electrique de 

 Hertz.' 



H. S. Allen (' Ann. d. Phys.' (4) 32, p. 1111), ' Ueber die lichtelektrische Ermiidung 

 des Zinks.' 



5. On the Recoil of Radium B from Radium A. 

 By Dr. W. Makower, Dr. S. Russ, and E. J. Evans. 



The first experiments by Russ and Makower were made to determine whether 

 RaB is electrically charged when it recoils in vacuo from RaA, and, if so, 

 the sign and magnitude of the deflection. A number of experiments, in which 

 the RaB was passed through a strong electric field maintained between two 

 brass electrodes made it clear that RaB is positively charged in these circum- 

 stances. Further experiments were therefore made, in which RaB recoiling 

 in vacuo from a wire coated with RaA was caused to pass between two 

 brass plates, 1'17 mm. apart, kept at a difference of potential which varied 

 in different experiments from about 1,000 volts to 2,000 volts. The RaB sub- 

 sequently fell upon a brass strip. After an exposure of ten minutes to the 

 radiation the brass strip was removed, and the distribution of activity over 

 the strip was tested by mounting it on a movable platform and bringing 

 successive portions of the strip under a rectangular window made of aluminium 

 leaf cut in a sheet of lead forming the base of an a -ray electroscope. The 

 window was 3 mm. long and 1 mm. wide. The magnitude of the deflection thus 

 found was of the order of magnitude to be expected if RaB carries the atomic 

 charge of electricity and if its atomic weight is 214, as is to be expected on the 

 transformation theory of radio-active processes. 



Experiments were also made by Makower and Evans on the magnetic deflec- 

 tion of RaB when it recoils. The radiant matter was made to pass in vacuo 

 through the field of a powerful electro-magnet, and then to fall upon a brass 

 1910. N N 



