462 Scientific Intelligence. 



(3) The influence of the character of the metal surface is negli- 

 gible. 



(4) The potential of the charged plate is dependent upon : 

 (a) The capacity with which the plate is connected ; — the 



quantity of electricity, that is, the product of capacity and poten- 

 tial is smaller for the greater potential, that is for smaller capac- 

 ity. If we assume that this is due to the conductivity of the air, 

 one can assume that the quantity of electricity is constant. 



(h) The time of exposure to the rays. The potential increases 

 with the time of exposure up to 20 sec. and then remains con- 

 stant. 



(c) On the nature of the rays. Hard rays exert a stronger 

 influence than weak rays. 



(d) On the nature of the metals ; the potential is greater the 

 greater the atomic weight, and the more the metal is electronega- 

 tive. The influence of atomic weight is more notable with the 

 hard rays ; the position of the metals in the electromotive series 

 has greater effect in the case of the weak rays. 



(e) On the surrounding gas. The potential is greater in air 

 than in C0 2 . 



(5) Secondary rays tend to neutralize the charges. This phe- 

 nomenon explains the discordant results obtained by various 

 observers. — Ann. der Physik, No. 11, 1905, pp. 140-171. J. t. 



7. Emission of Negative Corpuscles by the Alkali Metals. — 

 Elster and Geitel discovered that even the light emitted by 

 a glass rod heated to a dull red heat was sufficient to cause 

 rubidium to emit corpuscles. Professor J. J. Thomson shows 

 that rubidium and the liquid alloy of sodium and potassium give 

 out corpuscles in the dark. This result leads Professor Thomson 

 to speculate upon probable differences of temperature between 

 the interiors of bodies and their surfaces arising from the explo- 

 sion of atoms. — Phil. Mag., Nov. 1905, pp. 584-590. j. t. 



8. A New Method of showing the Presence of Neon, Krypton, 

 and Xenon. — S. Valentiner and R. Schmidt depart somewhat 

 from the method of Dewar, by which, using the singular occlu- 

 sion power of charcoal at low temperatures, Dewar showed the 

 presence of neon, hydrogen and helium. Valentiner and Schmidt 

 exhaust the spectrum tube and connected apparatus ; then admit 

 a large quantity of argon, submit this argon to the occlusion 

 action of charcoal at the temperature of liquid air. By this 

 process neon is left in the spectrum tube ; and the quantity can 

 be suitably increased by varying the pressure and amount of 

 exhaustion. Suitable modifications of this method of employing 

 argon as a basis and the occluding power of charcoal at different 

 low temperatures enabled the authors to show the presence of 

 krypton and xenon. — Ann. der Physik, No. 11, 1905, pp. 187-197. 



J. T. 



9. The Mechanical Properties of Catgut Musical Strings ; a 

 Correction by J. R. Benton (communicated). — I have to correct 



