324 Scientific Intelligence. 



SCIENTIFIC INTELLIGENCE. 



I. Chemistky and Physics. 



1. Gases Occluded or JEvolved by Radium Bromide. — Dewae 

 and Curie describe some experiments made with 0*4 g of radium 

 bromide. The pure, dry salt was placed in a glass tube com- 

 municating with a small Geissler tube and a mercury manometer, 

 and a very perfect vacuum was produced in the apparatus. Dur- 

 ing three months gas was given off at the rate of l cc per month, 

 and an examination of the spectrum by means of the Geissler 

 tube showed only the presence of hydrogen and the vapor of 

 mercury. It is possible that a minute quantity of moisture was 

 introduced with the salt, and that this was gradually decomposed 

 under the influence of radium. 



The sample of radium bromide was then taken to England in 

 order to make other experiments with it, and there it was trans- 

 ferred to a vessel of fused quartz, where it was heated to fusion at 

 a red heat after the air had been exhausted by means of a mer- 

 cury pump. The gases given off in this operation were passed 

 through three U-tubes cooled with liquid air, which retained the 

 greater part of the radium emanation and the less volatile gases. 

 The more volatile gases collected in this way amounted to 2*6 CC ; 

 they had carried with them some of the emanation and were 

 radio-active and luminous. Dewar examined the spectrum of this 

 spontaneous light by means of a photographic spectroscope with 

 a quartz ^>rism and an exposure of three days, with the result 

 that three bands belonging to nitrogen were obtained. When 

 the gas was subjected to the electric discharge in a Geissler tube, 

 the spectroscopic bands of nitrogen were also obtained, and upon 

 condensing the nitrogen by exposure to the temperature of liquid 

 hydrogen a high vacuum was produced in the Geissler tube, and 

 the spark then indicated the presence of nitrogen, but nothing 

 else. 



The quartz tube containing the radium bromide which had 

 been fused and thus freed from occluded gases was then sealed 

 while exhausted, by means of the oxyhydrogen blowpipe, and 

 taken back to Paris. Then, twenty days after it had been sealed, 

 Deslandres illuminated the interior or" the tube by a Ruhmkorff 

 coil by the aid of small coatings of tin-foil applied to the exterior 

 of the ends of the tube, and obtained the complete spectrum of 

 helium, with no other lines, by means of a photographic spectro- 

 scope with a quartz prism. This result agrees with those of 

 Ramsay upon the production of helium by radium salts dissolved 

 in water, and it is interesting in showing that the presence of 

 water is apparently unnecessary for this production of helium. — 

 Comptes JRendus, cxxxviii, 910. h. l. w. 



2. Uranyl Double Salts. — Rtmbach, Burger and Grewe have 

 prepared a large number of these double salts, many of which 



