January 22, 1897.] 



SCIENCE. 



139 



for the Advancement of Science at its 

 Toronto meeting in August, 1897, was re- 

 ceived and accepted with thanks. 



The following gentlemen were elected to 

 membership : Prof A. B. Macallum, M. B., 

 Ph.D., Toronto University ; Prof W. S. 

 Carter, M. D., University of Pennsylvania ; 

 L. B. Mendel, Ph.D., Yale University. 



The following ofift-cers were elected : Coun- 

 cil: R. H. Chittenden, Yale, President ; F. 

 S. Lee, Columbia, Secretary and Treasurer ; 

 H. P. Bowditch, Harvard ; W. H. Howell, 

 Johns Hopkins ; W. P. Lombard, Michigan. 

 Frederic S. Lee, 



Secretm-ij. 



Columbia University.. 



ELECTRIFICATION OF AIR BY RONTOEN 

 RAYS* 



To test whether or not the Eontgen rays 

 have any electrifying effect on air, the fol- 

 lowing arrangement was made. 



the other end two holes were made, one in 

 the middle, through which passed a glass 

 tube (referred to below as suction pipe) 

 of sufficient length to allow the end in the 

 lead cylinder to be put into any desired 

 place in the cylinder. By means of this, 

 air was drawn through an electric filter* by 

 an air pump. The other hole, at a little 

 distance from the center, contained a second 

 glass tube by which air was drawn through 

 India rubber tubing from the open-air quad- 

 rangle outside the laboratorJ^ 



In one series of experiments the end of 

 the suction pipe was kept in the axial line 

 of the lead cylinder at various points 10 

 cm. apart, beginning with a point close to 

 the end distant from the Eontgen lamp. 



In every case the air drawn through the 

 filter was found to be negatively electrified 

 when no screen or an aluminium screen 

 was interposed between the Eontgen lamp 

 and the near end of the lead cylinder. The 



A lead cylinder 76 cm. long, 23 em. di- 

 ameter, was constructed ; and both ends 

 were closed with paraffined cardboard, 

 transparent to the Eontgen rays. Outside 

 the end distant from the electrometer (see 

 diagram) a Eontgen larapf was placed. In 



*Eead before the Eoyal Society of Edinburgh, 

 Monday, December 21, 1896. From proof-sheets 

 of Nature, contributed by Lord Kelvin. 



t The Eontgen lamp was a vacuum vessel with an 

 oblique platinum plate (Jackson pattern). 



air was found not electrified at all, or very 

 slightly negative, when a lead screen was 

 interposed. 



When the Eontgen lamp was removed 

 or stopped, and air was still pumped 

 through the filter, no deflection was ob- 

 served on the electrometer. This proved 

 that the air of the quadrangle was not 

 electrified sufficiently to show any deflec- 



* Kelvin, Maclean, Gait, Proc. E. S., London, 

 March 14, 1895. 



