The (M-ystals are uniavial and negative. 



Tlie optically active components are so lii2,lily soluble that it was 

 impossible up to now, to obtain crystals snitable for measnrements. 



Abont the general conclusions, relating to the facts here described, 

 vid. Publication 1 (iMarch lïUo) on this same subject. 



Lnhoratonj for Inoiyanic and Physical 

 Chemistry of the University. 

 Groningen, March 1915. 



Chemistry. — " fnvestiyations on the Teinperature-Coeffi.cients of 

 tlie free Molecular Surface- Ene ryy of Liquids at Tempera- 

 tures from — 80° to l<i50° 6V' IX. Tlie Surf ace- Enercfy of 

 homologous Aliphatic Amines. By Prof. F. M. Jakger and 

 Dr. Jut,. Kahn. (Communicated by Prof. P. van Romburgh). 



(Communicated in the meeting of April !23, 1915). 



§ 1. During the continuation of our studies regarding the intluence 

 of special substitutions in the molecules on the specific and mole- 

 cular surface-energy of homologous compounds, our attention was 

 drawn to the fact, that the free surface-energy and its temperature- 

 coefficient in the case óf organic derivatives of thetrivalent nitrogen often 

 show remarkably low values. We therefore determined to study 

 systematically a greater tiumber of the homologous series of the 

 aliphatic amines in the way jireviously described. The results of these 

 investigations are communicated in the following pages. 



A single determination of the value of the free surface-energy of 

 carefully purified and dried anhydrous ammonia : NH, taught us 

 that with this mother-substance itself, even at lower temperatures, 

 the value of •/ is a relatively small one. 



We found at — 73° C. for the specific surface-tension of liquid 

 ammonia : about 37 Erg pro cm^ '1, a value considerably ditferent 

 from the sparsely published data in literature regarding the surface- 

 energy of this liquid. As we had at the moment no means of 

 maintaining constant lower temperatures for a longer time, we could 

 not for the present continue these experiments further ; however we 

 hope to be able to return to these researches later on. 



1) The radius of the capillar tube was : 0.04595 cm., the depth of immersion : 

 U.l mui. Tiie maximum pressure observed was: l.'ilO mm. of mercury of 0° G. 



