400 Scientific Intelligence. 



days, on heating, the hydrogen spectrum reappeared. After 

 eight da}'s, on repetition of the heating, the hydrogen lines again 

 appeared. Further examination was prevented by the breaking 

 of the tube. 



The folio wing experiment with cleveite led to a totally different 

 result. In a combustion tube 0*3 g. of cleveite with S0 4 KH was 

 strongly heated and the tube flushed with hydrogen until no 

 helium lines could be seen. The tube was then exhausted as far 

 as possible. After three days, perhaps, there was a trace of the 

 helium spectrum ; but repeated heating and pumping disclosed 

 in fourteen days no trace of helium. This experiment was 

 repeated without S0 4 KH with the same result. 



In marked contrast to this experiment was the following : 

 About 40 mg. RaBr 2 were so strongly heated in a highly exhausted 

 quartz tube that the substance resublimed in a cooled end of the 

 tube. The tube was flushed with hydrogen and exhausted, and 

 on the following day the substance was again resublimed ; no 

 trace of the helium spectrum was seen. In six weeks, however, the 

 helium spectrum could be readily produced in the tube. These 

 experiments appear to the author to dispose of the theory of 

 occlusion. 



They point out that there may be a possibility of the forma- 

 tion of a helid. Instead of pure RaBr 2 we may be dealing with 

 a mixture of this substance with a small quantity of a hypothet- 

 ical helid. However this may be, they conclude that there is no 

 doubt of a connection between the radium emanation and helium. 

 — Ann. der Physik, No. 10, 1905, pp. 905-1008. j. t. 



9. Blondofs " Emission pesante" — M. R. Blondot published in 

 the Comptes Rendus issues of 1904 two papers on a phenomenon 

 analogous to the so-called N-rays, to which he gave the name 

 " emission pesante." A preparation of calcium sulphide becomes 

 more luminescent under the influence of this emission. Blondlot 

 states that he has not only observed this increase in luminescence, 

 but also an effect of the magnetic field on the emission. Rudolf 

 F. Pozdena has made an exhaustive examination of the effects 

 claimed by Blondlot and cannot find any evidence of the new 

 emission if the observer does not conduct the experiments him- 

 self. The phenomenon is a subjective one and may arise in the 

 anatomy of the retina of the eye by a species of autosuggestion 

 leading to a "Will to believe." — Ann. der Ihysik, No. 6, 1905, 

 pp. 104-131. J= t. 



10. Diffusion of Nascent Hydrogen through Iron. — A. 

 Winkleman has conducted a long series of experiments upon 

 this subject with the following conclusions : 



The nascent hydrogen being formed on the outside of a hollow 

 iron cylinder which was closed at the bottom and connected at 

 the other end with an air pump, the iron cylinder serving as a 

 cathode in a suitable electrolytic cell, it was found : 



(1) The quantity of gas diffusing from the outside to the inside 

 of the cylinder was independent of the pressure inside the cylin- 



