84 Scientific Intelligence. 



ous observers have obtained results varying from 100 to 134 in 

 the same terms. The material used consisted of l*0523g. of radi- 

 um-barium bromide, corresponding to -795 lg. of radium. The 

 method used was that previously employed by Angstrom for the 

 same purpose. It consisted in placing the radium in a calorimeter, 

 and keeping a second, exactly similar, calorimeter at the same 

 temperature by an electrically heated wire of known resistance. 

 The elevation of temperature thus produced in the calorimeters 

 amounted to 5 -5° C. At first only 40 per cent of the expected 

 heating was produced, probably on account of the escape of some 

 emanation before the beginning of the experiment, but this 

 increased from day to day. The radium employed was in equi- 

 librium with its decomposition products of short period, but its 

 contents of the products from radium D to radium F was uncer- 

 tain. — Monatshefte, xxix, 853. h. l. w. 



6. Positive Rays. — W. Wien arranged an apparatus which 

 enabled him to transmit the canal rays some distance through a 

 capillary tube which was exhausted by means of charcoal and 

 liquid air to a low vacuum. He concludes from his observations 

 that the particles in the canal rays which are least influenced by 

 a magnetic field are those which carry the light emission. More- 

 over, the condition of equilibrium of particles of equal weight — 

 which may be destroyed by a magnetic field — reasserts itself dur- 

 ing the length of path of the rays. The length of this path 

 increases with higher potentials. — Physik. Zeitschrift, No. 22, 

 Nov. 1, 1908, pp. 765-767. J. t. 



7. Spectral Intensity of Canal Pays. — The observers of the 

 Doppler Effect in canal rays in hydrogen agree that the displace- 

 ment observed is a band which is separated from the hydrogen 

 line by a space showing no band. J. Stark and W. Stenberg 

 select the method of viewing the hydrogen line at right angles 

 to the direction of the canal rays, in order to determine its 

 changes in intensity. No Doppler effect of course is seen, but 

 the photometric measures indicate the changes in velocity of the 

 positive particles. They state that the intensity of the canal 

 rays depends upon their velocity. They also find a minimum 

 intensity in the Doppler effect. — Ann. der Physih., vol. xxvi, 

 1908, pp. 918-926. . J. T. 



8. Canal Rays. — J. Stark discusses the bearing of modifica- 

 tion of the electromagnetic theory of light upon the phenomena 

 of canal rays, especially Planck's theory of electrical resonators, 

 and Einstein's discussion of lichtquantenhypothese, and believes 

 that this latter hypothesis must stand or fall with further observa- 

 tions of the canal r&ys.—Physik. Zeitschrift, No. 22, Nov. 1, 

 1908, pp. 767-773. j. t. 



9. Potential Measurements in the dark Cathode Space. — W. 

 Westphal has confirmed Prof. J. J. Thomson's theory that the 

 cathode rays are due to impacts of positive particles impinging 

 through the cathode space upon the cathode, and shows, also, 

 that measurements of this potential by means of sounding wires 



