INTRODUCTION. 17 



After correlating the data obtained by the above-named investigations 

 it is pretty certain that it will be possible to take each vibrator and trace 

 the effects produced upon it by the above changes. It is highly probable 

 that we shall also know something of the nature of the vibrating system 

 and the part that it plays in that complex body we call the atom. 



For instance, let us take the bands of uranyl nitrate. It was found 

 that the uranyl bands of an aqueous solution of the nitrate had shorter 

 wave-lengths than that of any other uranyl salt in water. The uranyl bands 

 of the nitrate in other solvents were farther towards the red than the bands 

 of an aqueous solution. Now, although the solvent has a great effect upon 

 the bands, nevertheless it seems quite certain that the N0 3 group has a 

 very considerable effect upon the vibrations of the uranyl group. If it 

 were possible to find the ratio e/ra for the vibrators in this case by the 

 Zeeman effect, it might be possible to find an approximate value for the 

 force exerted by the NO, group upon the vibrator. It seems quite certain 

 that this force differs for the vibrators producing different bands. The 

 measurements of the wave-lengths of the uranous bands are as yet very 

 few, yet they seem to indicate that for aqueous solutions of the urinous 

 salts the bands of the nitrate are farther towards the violet than the bands 

 of the other uranous salts. The values given for the phosphorescent bands 

 by E. Becquerel and by J. Becquerel indicate that the bands of the nitrate 

 are further towards the violet than those of the other uranyl salts. We 

 thus see that throughout these three spectra the NO, group exerts a 

 similar force upon the vibrators that are the cause of the bands. 



