u — 

 1 — 



436 



kT 



T { 1 liv\ { 1 hv\ 



—kT\ 1 + '-\^ k\ T -\ ^ =:/.(T-f A). 



1 hv, V <5 kTj \ ^ Q k J ^ ^ ' 



6 kT 



As further bj h^'pothesis — is proportional to U, the following 



/ 

 relation is obtained 



— =C(r+A) or x(^4-^)=C', which is the relation found 



X 

 empirically e.g. for anhydrous manganese sulphate above nitrogen 

 temperatures. That for other substances, like crystallized manganese 

 sulphate above nitrogen temperatures, Curie's law was found appro- 



ximately fulfilled, is obviously due to a small value of Zi, or of — . 



u 



By means of formulae (1) and (2) the value of — was calculated 



kT 



kT 

 for a series of values of — ; it the underlying suppositions are correct, 



— must have the same relationship to T for a paramagnetic sub- 



U kT ^ , ... J 



stance as —^^ to — . The comparison of the two functions is made 



kl' hv^ 



by means of logarithmic diagrams^); in the one diagram the abscissae 



kT U 



were loq — and the ordinates loq -y,, in the other log T and 



' hv^ " kT 



log —y respectively. For nearly all the substances examined the curves 



could be made to coincide with sufficient approximation. The shift 

 along the axis of abscissae required to produce coincidence gives 



the value of — for the substance under consideration. 



k 



Subjoined in the two tables are the results obtained for two of 



the substances. At the head of the table is found the value of — - 



k 



which has to be assumed for the particular substance to bring about 



the closest coincidence of the two curves. The first column gives 



the absolute temperature T, the second the observed values of x. 



Starling from any one of the observed values, the values for the other 



temperatures may be calculated by means of (1) and (2). The fourth 



') Gomp. H. Kamerlingh Onnes and W. H. Keesom. Malli. Enz. V 10, Leiden 

 Cuaim. Sirppl N". ïi;i, ^ 33. 



