February 2jrd, igo^.] PROCEEDINGS. xvii 



XIII. The excited or induced activity from radium left 

 behind where the emanation has been was shown by blowing 

 the latter out of the zinc sulphide tube, when a considerable 

 part of the luminosity remained. 



XIV. The original spectrum tube in which helium was first 

 observed in the gases from radium was exhibited. 



XV. An apparatus designed by the Hon. J. R. Strutt to 

 illustrate the charge carried away by the rays of radium was 

 exhibited. A sealed glass tube containing a radium compound 

 was supported by quartz inside a perfectly exhausted space, and 

 to its lower end gold leaves were attached. The latter con- 

 tinuously received a charge, diverged until they touched the walls, 

 and collapsed, going through a complete cycle every four minutes. 

 The apparatus had been continuously working for several months, 

 and constitutes a perpetual motion machine in its essential 

 characteristics. 



A hearty vote of thanks was passed to Mr. Soddy for his 

 lecture. 



Special Meeting, February 23rd, 1904. 



Professor W. Boyd Davi^kins, D.Sc, F.R.S., President, 

 in the Chair. 



The Wilde Lecture, " On the Evolution of Matter as 

 revealed by the Radio-active Elements," was delivered 

 by Mr. F. Soddy, M.A., of University College, London. 



Ordinary Meeting, March ist, 1904. 



Professor H. B. Dixon, M.A., F.R.S., in the Chair. 



• The thanks of the members were voted to the donors of the 

 books upon the table. 



Professor A. Schuster, Ph.D., F.R.S., read a paper, entitled 



" On the Rate at which Ions are generated in the 



Atmosphere," in which he described a method of observation 



which allowed him to determine the number of ions which 



-are constantly being formed in the atmosphere. All experiments 



