Uranium Radiation and Electrical Conduction produced. 109 



capillary canal about one half millimetre in diameter, the 

 absorption of water is as great as 18 per cent, of the volume 

 contained per hour. In finely porous rock correspondingly 

 larger absorptions are to be anticipated. Again, the tempera- 

 tures and pressures given in the above experiments would be 

 more than reached by a column of water penetrating a few 

 miles below the earth's surface. Finally, the action of water 

 on silicates will be accelerated in proportion as higher 

 temperatures are entered with increasing terrestrial depth. 

 Eventually, therefore, heat must be evolved more rapidly than 

 it is conducted away. 



With the above proviso, one may reasonably conclude that 

 the action of hot water on rock within the earth constitutes a 

 furnace whose efficiency increases in marked degree with the 

 depth of the seat of reaction below sea-level. 



Brown University, 

 Providence, U.S.A. 



VIII. Uranium Radiation and the Electrical Conduction pro- 

 duced by it. By E. Butherford, M.A., B.Sc, formerly 

 1851 Science Scholar, Coutts Trotter Student, Trinity 

 College, Cambridge ; McDonald Professor of Physics, 

 McGill University, Montreal*. 



THE remarkable radiation emitted by uranium and its 

 compounds has been studied by its discoverer, Becquerel, 

 and the results of his investigations on the nature and pro- 

 perties of the radiation have been given in a series of papers 

 in the Comptes Rendus^. He showed that the radiation, con- 

 tinuously emitted from uranium compounds, has the power 

 of passing through considerable thicknesses of metals and 

 other opaque substances ; it has the power of acting on a 

 photographic plate and of discharging positive and negative 

 electrification to an equal degree. The gas through which 

 the radiation passes is made a temporary conductor of electri- 

 city and preserves its power of discharging electrification for 

 a short time after the source of radiation has been removed. 



The results of Becquerel showed that Bontgen and uranium 

 radiations were very similar in their power of penetrating 

 solid bodies and producing conduction in a gas exposed to 

 them ; but there was an essential difference between the two 

 types of radiation. He found that uranium radiation could 

 be refracted and polarized, while no definite results showing 



& 



* Communicated by Prof. J. J. Thomson, F.K.S. 



t C. R. 1896, pp. 420, 501, 559, 689, 762, 1086 ; 1897, pp. 43S, 800. 



