w 



404 Dr. A. D. Fokker on the Electric Current from 



content = 40 per cent, of saturation. How much gas will be 

 dissolved in an hour ? 



t = QQ minutes, 



= 60(l-r^') = 60(l-^- 222 ) = 60(l--8009) = 60x-1991 



= 11*8 per cent, saturation* 



Hence after an hour the water will have risen to 51*8 per 

 cent, of saturation. 



These equations can also be used to calculate curves 

 showing the rate of solution in water of the different gases 

 under different conditions, and as an example the curves for 

 oxygen between 0° C. and 30° C. have been calculated in 

 percentages of saturation, and are shown in fig. 9. It is 

 noteworthy that when expressed in percentages of saturation, 

 the curves for the three gases lie very close to each other,, 

 those for oxygen and nitrogen being practically identical. 



The authors desire to express again their indebtedness to 

 Dr. Hacket (Lecturer in Physics in this College) for the 

 interest he has taken in this investigation, and the valuable 

 assistance he has generously given in the mathematical 

 treatment of the subject. 



Chemical Department, 

 Royal College of Science for Ireland. 



XXXIX. On the Contributions to the Electric Current from 

 the Polarization and Magnetization Electrons. By Dr. A- 

 D. Fokker {Leiden)*. 



AX important question in the electronic theory of matter 

 is the evaluation of the electric current due to the 

 motion of the electrons of electrically neutral atoms. To 

 Minkowski the idea is due to put the question as a variation 

 problem of a current by small virtual displacements, in a 

 manner to be described hereafter. Born has worked out this 

 idea after Minkowski's death |. 



* Communicated by the Author. Abstract from a paper offered to the 

 Kon. Akad. v. Wetcnsch. at Amsterdam. 



t Hermann Minkowski — Max Born, Erne Ableitung der Grundgleicli- 

 an yen fur die elektromagnetischen Voryiinye in beweqten Korpern, Math. 

 Ann. lxviii. p. 526, 1910. 



