346 



Sir W. Eamsay and Mr. F. Soddy. [Apr. 14, 



while important additional knowledge has been gained, namely, that 

 chloroformed calf vaccine, if originally of sufficiently high potency, 

 will, when prepared and stored under suitable conditions, retain for a 

 considerable time a high degree of potency, and this notwithstanding 

 that the extraneous organisms had been rapidly eliminated from it in 

 an early stage of its preparation. 



" Further Experiments on the Production of Helium from 

 Eadium." By Sir William Eamsay, K.C.B., F.E.S., and 

 Frederick Soddy, M.A. Eeceived April 14, — Eead April 28, 

 1904. 



The research, of which a preliminary account has already been given 

 in the ' Proceedings,' vol. 72, pp. 206 and 208, has been continued with 

 the view of ascertaining the volume of emanation produced in a given 

 time from a known weight of radium in the form of bromide, and 

 also the quantity of helium resulting from the spontaneous change of 

 the emanation. 



Owing to the minute quantity of material at our disposal, the 

 research has been a somewhat tedious one ; but we have succeeded in 

 obtaining fairly concordant measures of the volume of both emanation 

 and helium. The present paper gives a description of the apparatus 

 employed, the methods of experiment, and the quantitative relation 

 between radium and its products. 



The inactive nature of the emanation from thorium was the subject 

 of an investigation by Eutherford and Soddy. * They concluded 

 " that it is a chemically inert gas analogous in nature to the members 

 of the argon family." And they continue : " The speculation naturally 

 arises whether the presence of helium in minerals and its invariable 

 association with uranium and thorium may not be connected with their 

 radio-activity." The discovery was thus the subject of prediction. 

 It followed an attempt to obtain the spectrum of the emanation. 

 Thinking that the spectrum, if brilliant, might be observed by mixing 

 the emanation with a gas of simple spectrum, the first experiments 

 were made by mixing it with helium ; but it soon became evident that 

 the helium spectrum overpowered that of the emanation to such an 

 extent as to mask it entirely. And experiments on the removal of 

 gases not belonging to the argon group from the emanation convinced 

 us that its quantity was so small as to require special contrivances in 

 order to deal with it. All apparatus, consequently, was constructed 

 on a minute scale of capillary tubing, less than half a millimetre in 



* ' Phil. Mag.,' 1902, 6, vol. 4, p. 581. 



