285 



dn 

 In the case of the alcohols and umter, the values of — are 



at 



remarkably small; also in the case of the nlcohoh a regular increase 



with growing molecular weight is observable -. 



Öfi 



While in the case of mater the value of — is J ,0 Erg per degree, 



01 



it is for CH,OH: 0,67 Erg per degree, 

 for C,H,OH: 0,94 Erg per degree, 

 and for C„H^OH: 1,10 Erg per degree. 

 On later occasions other regularities of this kind will be pointed out. 



Groningen, Holliad, June 1915. 



Lnhoratory for Physical and Inonjanic 

 Chemistry of the University. 



Chemistry. — "Investigations on the Teuiperature-Coefficients of 

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

 aiid 1650° C." XI. The Surface- Tens ion of homologous 

 Triglycerides of the fatty Acids. By Prof. F. M. Jaeger and 

 Dr. Jul. Kahn. 



^ 1. In the following we give the measurements made with 

 the neutral ethers of glycerol and the fatty acids. The information 

 about the surface-energy of the simple fats and its tem|ieraturc- 

 coefficient must be considered of high importance for practical reasons, 

 because it allows conclusions to be made about the corresponding 

 values for I he natural fats, tlio^e being mixtures of the simple fats. 

 The temperature-coenicient of ft appears furthermore to have very 

 exceptional values for some of these derivatives which may be con- 

 sidered as a fact in many respects also of interest from a theoretical 

 point of view. 



Finally we give here again some measurements of the specidc 

 surface-energy x and its temperature-coefficient, for natural butter 

 and for margarine, which measurements were made with the 

 purpose of finding out, if a reliable criterion could perhaps be 

 obtained for the discrimination of pure natural butter from that 

 which had been adulterated by vegetable fats. Although the temperature- 

 coefficient of / in the case of margarine evidently differs from that 

 for natural butter, we think these differences too slight to fomul 



