230 



SCIENCE PROGRESS 



been modified slightly to allow the substitution of silica for glass 

 bulbs. It will be described in its present form. The apparatus 

 is shown in fig. i. 1 



The bulb i is, if of silica, joined to the rest of the apparatus 

 by means of a ground silica-glass joint at h; if of glass, it is 

 directly joined at h. The bulb is half filled with the solution, 

 which is to undergo treatment, by means of a second side tube, 

 not shown in the figure ; this is then sealed off. The whole 



TO PUMP 



Fig. i. 



apparatus is evacuated. The emanation, and hydrogen and 

 oxygen, obtained from radium bromide solution in the manner 

 already explained (p. 73), are transferred as usual through the 

 inverted siphon a into the burette c, and there exploded ; the 

 excess of hydrogen and the emanation are admitted to the bulb. 

 This is then cooled to — 185 by means of liquid air, and the 

 hydrogen pumped off as completely as possible through the tap 

 f. Mercury is allowed to rise just above the ground joint h, 

 and acts as a seal, preventing any leakage. In most cases more 



1 Figs. 1 and 2 are reproduced from the Transactions of the Chemical Society 

 by kind permission of the secretaries. 



