9i 

 value of -- appears beyond doubt to be smaller than with mono- 



01 



methylamine. 



Finally the increase of the surfaoe-energy by substitution of H- 

 atoms also appears here, as formerly stated, to be appreciably greater 

 if substitution occurs by unsaturated, than by saturated hydrocarbon- 

 radicals : a comparison of the data for allylamine on the one side, 

 and of propyl-, and isopropylamine on the other side, soon convinces 

 of the truth of this. 



Lastly we may draw attention here to the data regarding the 

 formamide, which are also reproduced among those of the derivatives 

 of trivalent nitrogen. Although this compound does not possess more 

 than a single C-atom, the value of ft nevertheless appears here to 

 be much greater than e.g. for {CH,)N^H^, demonstrating the special 

 influence of the strongly electronegative oxygen-atom, and more 

 especially of the unsaturated carbonyl-radical, in a perfectly clear way. 



Moreover this liquid, which in several respects shows some ana- 

 logy with the strongly dissociating solvents, appears to possess a 



d,u 

 very small temperature-coefficient — : on an average about 0.89 Erg. 



per degree. It would be of interest to study the behaviour of inorganic 



salts if dissolved in this liquid, with respect to the electric current. 



In analogy to the case of water, one would be inclined to conclude 



dfi 

 in this case from the exceptionally small value of — -, that the liquid 



at 



formamide might be highly associated. 



Laboratory for Inorganic and 

 Groningen, April 1915. Physical Chemistry of the University. 



Chemistry. — "The Allofropy of Sodium." I. By Prof. Ekn.st 

 CoHKN and Dr. S. Wolff. 



(Communicated in the meeting of Api'il 23, 1915). 



1. Some time ago Ernst Cohkn and G. dk Bruin') relying on 

 the determinations by Ezer Griffiths ') of the true specific lieat of 

 sodium, proved that this metal shows ailotropy and that the sub- 

 stance known hitherto as "sodium" is a metastable system in con- 

 sequence of the simultaneous presence of «- and ^i-sodium. 



1) These Proc. 23, 896 (1915). 



-) Proc. Roy. Soc. London 89, (A) 501 (1914), 



