1904.] On the Production of Helium from Radium. 347 



diameter. Approximate measurements of the scale of the apparatus 

 in centimetres are given in the sketches. 



Fig. 1 gives a sketch of the first apparatus, which was soon 

 abandoned ; suffice it to say that an attempt was made to accumulate 

 the emanation in A, which contained a solution of several grammes 



Tig. 1. 



of impure chloride, obtained from very impure carbonate, and to 

 examine its spectrum in the U-tube B, made of capillary tubing, with 

 electrodes of platinum as shown. The spectrum was that of carbon 

 monoxide and dioxide. 



Experiment 1. — A brief description of this experiment has already 

 been given.* Twenty milligrammes of radium bromide was dissolved 

 by admitting water boiled in vacuo to the crystals in the bulb A 

 (fig. 1), which had previously been freed from air with the pump. 

 The bromide, as a letter from the seller informed us, had been 

 prepared in the solid state about months. The evolved electro- 

 lytic gas containing the emanation was collected through the pump 

 and introduced into the apparatus, of which a sketch is given in fig. 2. 

 Before this was done, the whole apparatus had been exhausted, and 

 washed out with oxygen several times, admitted through the gas- 



* Loc. cit., p. 206. 



