We hope to answer the question if this jump really exists by 
special experiments arranged for the purpose; we may, in the mean¬ 
time, consider that it does probably exist. What Curie found in the 
transformation of y iron to cf iron is analogous to the sudden change 
which we here assume to exist while the form of the law remains 
unaltered, and which can occur at the melting point or at a point 
of transformation to an allotropic modification. Weiss 1 ) has shown 
that this can be accounted for on the assumption that at this particular 
point di-atomic iron changes into tri-atomic. 
On the other hand we consider it probable that the law according 
to which the specific susceptibility increases with the temperature, 
viz: inverse proportionality to the square root of the absolute tem¬ 
perature at lower temperatures, gradually transforms into that of 
inverse proportionality (Curie’s law) at higher temperatures, and that 
each of these laws, therefore, may be but approximative to the 
same function over different ranges of values of the independent 
variable T. 
The supposition that the change of specific susceptibility with 
density is of no importance lies at the bottom of the assumption of 
the gradual transformation of Curie’s law into that of T *. If, on 
the other hand, we assume that this change is of importance, that 
e. g. when the internal pressure is considerable the molecules under 
its influence undergo not only a compression but also a lessening of 
their magnetic moments, then a region of great molecular compres¬ 
sibility in which the specific susceptibility should change both with 
the temperature and with the density should exist between the gaseous 
phase in which the specific susceptibility would be pretty well in¬ 
dependent of the pressure, and the liquid phase at lower temperatures, 
in which the molecules would not be appreciably affected by an 
additional external presence on aeeonnt of their already great mternjU 
pressure, and in which, therefore, the specific susceptibility would 
also be pretty well independent of the pressure. As regards the 
difference between the magnetic moment of the elementary magnets 
in the condition of saturated liquid and vapour and that at^normal 
or smaller density at the same temperatures, it is to ^ 
according to that representation, that this difference -U ch-ge wUh 
temperature in consequence of the change of density with temperature. 
The assumption can also be made that complex molecules are 
formed in the liquid state, and that these diminish fcemten«V of 
the elemental* magnets; in that case changes in suscephbil.ty of 
i) P. Weiss, loc. dt 
