595 



did not cause the direction of the iiiteiinolecular forces to deviate 



from the dii'ection 7-cqiiired L\y Nkwton ; an angle, namely, deviating 



1 

 from the ioininK line, of the vaUie can be exclnded: a deviation 



•I ^ 1020 



between the direction indicated in tne law of Newton, namely I he 



joining line, and the direction of attraction throngh the relative ether 



1 

 motion of 2 X 30 km. per sec. remains hcloin this amount of ; 



-^ ' 102G' 



the deviation, provided- there be one, amounts to less tlian 

 1 micron at a distance of J 00 1 i g h t - c e n t ii r i e s. 



Chemistry. — "Inrcstn/itt/ojis on tlw Tt'ntperature-CoefjicU'nts of 

 the Free Molecular Surface- Energy of Liquids from — 80' 

 to 1650° C.'" XIII. The Surface- Energi/ of position-isomeric 

 Benzene- Der ivalive.'< . By Prof. Dr. F. M. J.-iEGERand Dr. Jul. Kahn. 



(Communicated in the meeting of September 25, 1915) 



§ 1. For the purpose of inve.stigating the intluence of the clieniical 

 constitution of the liquids on the magnitude and on the temperature- 

 coefficients of tlie free surface-energy, we also made a series of 

 measurements with a number of benzene-derivatives, which are to 

 each other in relation of position-isomerides. The problem considered 

 seemed to us of yet greater importance, because i. a. in the already 

 previously mentioned paper of Fei'stet/), some position isomeridcs 

 were studied with this same purpose, and this author as a result 

 of his experiments concluded, that the surface-tensions of such 

 isomeric substances did not differ from each other in any appreciable 

 degree. His conclusion, founded only on a relatively small number of 

 data, seemed to us not too probable, judging from some experience 

 already gathered by us in the course of tiiese investigations: for the 

 ,(u-/-cur\'es, determined by the first of us in the cases of diiiietltjiJ- 

 resorcinol and dimethyl-hi/droquinone''), and also of mt'sityleiie and 

 pseudocumene'), appeared to be clearly different for the two pairs of 

 isomerides. 



Therefore it seemed of importance to extend such a comparison 

 of the magnitude of the surface-tension to a greater number of such 

 position-isomeric derivatives. 



1) Feustel, Drude's Annalen 16, 61. (1905). 



•Ï) F. M Jaeger, these Proceedings. 23, 357, (3914). 



:') F. M. Jaeger, these Proceedings, 23, 408, 409, (1914). 



