Compounds of Short-lived Radioactive Elements. 125 



so that the velocity observed is only an average, and is less 

 than the velocity would be if they were charged all the 

 time. 



In conclusion, it may be said that the results obtained on 

 the ionic velocities, coefficients of diffusion and conductivities 

 of salt vapours in flames, seem to agree with the view that 

 the positive ions consist of metal atoms having charges about 

 three times the charge on one hydrogen ion in solutions. At 

 the same time it must be pointed out that the possible error 

 in the determinations of all these quantities is large; so that 

 it is possible, but I think improbable, that the charge per ion 

 is in reality equal to that on one hydrogen ion. 



In a previous paper I gave reasons for believing that the 

 positive ions due to salt vapours in flames are atoms of the 

 metal. The arguments used in that paper are independent 

 of the value of the charge carried by each ion so long as all 

 the atoms when ionized carry the same charge. It has been 

 suggested by Langevin that these ions are hydrogen atoms. 

 This suggestion depends entirely on calculations of the ionic 

 velocity by means of the formula lc = e~k\mv. This formula 

 cannot be relied on to give the velocity within a factor of at 

 least two or three, partly owing to our ignorance of the true 

 values of X and partly because the formula itself is unreliable. 

 No suggestion has been made as to how hydrogen ions are 

 produced by salt vapours ; and moreover the experiments 

 made to determine the ionic velocities cannot be explained 

 satisfactorily on the view that the ions are hydrogen atoms. 

 Also salt vapours produce enormous conductivity in flames 

 which contain no hydrogen. The increases of current ob- 

 served in the determinations of the ionic velocities are nearly 

 proportional to the conductivities due to the salt vapours, 

 which shows that the ionic velocities measured are not those 

 of a few special ions produced by some secondary reaction, 

 but are the velocities of the majority of the ions due to the 

 salts which must be formed from the salts, and therefore 

 cannot be hydrogen. 



IX. On the Existence of Chemical Compounds of Short-lived 

 Radioactive Elements. By Hans Schrader, PhD* 



Introduction. 



THE short-lived radioactive transformation products of 

 radium, thorium, and actinium, which are included 

 under the name of active deposits, do not differ funda- 

 mentally in their physical properties from the elements of 

 * Communicated by Prof. E. Rutherford, F.R.S. 



WIS 



