122 



derixed for an ideal gas, e. g. from Boltzmann's entropy principle, 

 cf. Snppl. N". 24:n § 4, or from the virial theorem. Conversely it 

 necessarily follows from this, that in Fig. 2 the ^q, ^-curve at the 

 small densities must change its direction to one parallel to the ^-axis, 

 as is clearly indicated by the point o = 0.08. 



In conclusion we will return for a moment to the assumption 

 rigidly adhered to in this paper, viz. that the presence of the nitrogen 

 molecules does not exert any influence on the distribution of the 

 rotatory energy of the oxygen molecules. The following mechanism 

 would be in accordance with this supposition : the oxygen molecules 

 behave at a collision (at least with the nitrogen molecules) as rigid 

 smooth spheres, they carry a (magnetic) doublet (or have according 

 to Snppl. N^ 32^ § 7 a magnetic moment in consequence of a 

 rotation about an axis of small moment of inertia with zero-point 

 energy in the temperature region considered); the nitrogen molecules 

 have a structure such that they do not exert a directive force on 

 the oxygen molecules. The ol:)ject of this suggestion is, however, no 

 other than to show that tlie assumption mentioned above is not an 

 impossible one. 



Chemistry. — ''The Al/olropi/ of Otdmiuni. 111". By Prof. Ernst 

 (V)HKN and W. D. Hki,dkrman. 



The ekctronwiive behaviour of Cadiniuin. 



1. The (Hlatometric ineasurements made with caduiiuni which had 

 been deposited clecti'olytically. had shown ') that this material is a 

 moditication which is not stable at room temperature. This corre- 

 sponds with the result found I)y Ernst Cohkn and E. Goldschmidt') 

 in their investigations on the electrolysis of solutions of tin salts. 

 When such a solution is electrolysed below 18° C. there is not 

 formed grey tin as might be expected, but the modification which 

 is metastable at this temperattire is deposited. 



In the following pages we give an abbreviated account on the 

 investigations we have carried out in order to identify the product 

 which is formed duriug the electrolysis of solutions of cadmium salts. 



2. Some years ago Hulktt ') described "a low voltage standard 

 cell", represented by the following scheme : 



1) These Proc. p. 54. 



2) Zeitschr. f. piiysik. Chemie 50, 225 (1905). 



») Trans. Americ. Elecliochem. Society 7, 353 (1905). 



