446 
of the electric conductivity power, the temperature coefficient thereof, 
the flow-pressure, the hardness ete., a method which, for instance, 
has led to such excellent results in the system Mg-Cd'); in that 
system the criterion of the three-phase tension is again unsuitable 
owing to the small value of vapour tension in that system. 
The investigation of the three-phase tension in mixed crystal systems 
can therefore open new points of view in systems where up to the 
present one has concluded to the absence of compounds and may 
perhaps lead in other cases to a decision. One might think here of 
the difference, in the case of optical antipodes, between pseudo- 
1) Compare Urasorr. Z. f. anorg. Chem. 73, 31 (1912). 
