1903.] and the production of Helium from Radii' m. 207 



4932, 4713, and 4472. There were also present three lines of ap- 

 proximate wave-lengths 6180, 5695, 5455, that have not yet been 

 identified. 



On two subsequent occasions the gases evolved from both solutions 

 of- radium bromide were mixed, after four days' accumulation which 

 amounted to about 2'5 c.c. in each case, and were examined in a 

 similar way. The D 3 line of helium could not be detected. It may 

 be well to state the composition found for the gases continuously 

 generated by a solution of radium, for it seemed likely that the 

 large excess of hydrogen over the composition required to form 

 water, shown in the analysis given by Bodliinder* might be due 

 to the greater solubility of the oxygen. In our analyses the gases 

 were extracted with the pump, and the first gave 28'6, the second 

 2 9 '2 per cent, of oxygen. The slight excess of hydrogen is doubtless 

 due to the action of the oxygen on the grease of the stop-cocks, 

 which has been already mentioned. The rate of production of these 

 gases is about 0*5 c.c. per day for 50 milligrams of radium bromide, 

 which is over twice as great as that found by Bodliinder. 



4. Production of Helium ly the Radium Emanation. 



The maximum amount of the emanation obtained from 50 milligrams 

 of radium bromide was conveyed by means of oxygen into a 

 U-tube cooled in liquid air, and the latter was then extracted by the 

 pump. It was then washed out with a little fresh oxygen which was 

 again pumped off. The vacuum tube sealed on to the U-tube, after 

 removing the liquid air showed no trace of helium. The spectrum 

 was apparently a new one, probably that of the emanation, but this 

 has not yet been completely examined, and we hope to publish 

 further details shortly. After standing from the 17th to the 

 121st inst. the helium spectrum appeared, and the characteristic lines 

 were observed identical in position with those of a helium tube 

 thrown into the field of vision at the same time. On the 22nd the 

 yellow, the green, the two blues and the violet were seen, and in 

 addition the three new lines also present in the helium obtained from 

 radium. A confirmatory experiment gave identical results. 



We wish to express our indebtedness to the Research Fund of the 

 Chemical Society for a part of the radium used in this investigation. 



* ' Ber.' (loc. cit.}. 



