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Chemistry. — '' Invusthjations on t/w Taiiipeniture-Coefjicients of 

 the free Molecular Surface-Energy of Liquids between — 80° 

 and 1650° C." XII. The SurJ-ace-Eneryy of the Isotropous 

 and Anisotropoua Liquid Phases of some Aromatic Azo:i'ii- 

 Compounds and of Anisaldazine. By Prof. F. M, Jaeger and 

 Dr. Jul. Kahn. 



^ 1. With the purpose of elucidating better the significance of 

 the temperature-coefficients of the free molecular surf'ace-energ}' ft 

 of liquids as a criterion for the degree to which these liquids are 

 associated, we have now extended our measurements to some of 

 these compounds which show more than one liquid phase and of 

 which all, with the exception of (he last, are optically anisotropous. 



There can hardly be a doubt any longer that these anisotropous 

 liquids should be considered really as (juite homogeneous liquid 

 phases of very peculiar molecular structure, while the mutual 

 relations of these anisotropous phases to the isotropous phase on the 

 one side and to the solid phase on the other, are quite analogous 

 to those commonly observed in the cases of polymorphism. 



The successive anisotropous liquids, which reveal themselves in 

 the case of some of these substances and which in the case of 

 enantiotropic transformations can exist within a proper, sharply 

 limited temperature-range, may be distinguished according to the 

 explanation givQ^n by the most probable hypothesis yet suggested, 

 by a motion of the molecules in "swarms", which decrease in com- 

 plexity after each higher transformation-temperature has been passed; 

 these molecules themselves probably have moreover an atomistic 

 structure, causing a general shape which is in one direction of space 

 considerably more elongated than in the two directions perpendicular 

 to the first. 



By this hypothesis it thus becomes highly probable, that the 

 isotropous liquid, which always appears at the highest transition- 

 point, will possess a much less complex structure than the foregoing 

 anisotropous liquids, — a supposition which will be found to agree 

 entirely with our usual ideas about the progress of a dissociation 

 occurring with increase of temperature. 



If the hypothesis accepted till now was right, that a smaller value 



of ^ than the normal of 2,2 erg stated by Eötvös, indicates an 

 at 



association, but that a larger value than 2,2 Erg pro degree points 



to a dissociation of the liquid, — we may expect here that the 



