752 



^ -*i 3= 0,00073 ') 0,00093 ') 



1 d*; 



^ -^ = 0,001585') 0,0011763') 



V dl), 



1 dv 



= — 0,000139 O —0,0000783^) 



V dp 

 Tliis yields for ether 



1 dn 



— --^ = — 0,01075 + 0,0088 = — 0,00195 



and for benzene 



1 dii 

 ^ r= — 0,01853 + 0,01462 = — 0,00391 



Theoretically we should find according- to equation (5): 



1 dv 1 



_- ' =: — = ^. 0,00183. 



1 d>j 

 Accordingly there is not even agreement in the sign of - j-. When 



we, however, take into consideration that the value found is the 



difference of two values which are each about five times the value 



of the amount sought, and that they are very inaccurately known, 



1 d»i . , . , 



it is not excluded that — ^ is in realitv negative. P^ven in tlie 



I dv 

 value of — r — an error of 4"/, is by no means excluded, and the 

 V dpi 



1 ö»i 

 error in the determination of - ^ will without doubt be many 



1] OpT 

 1 ri 



times larger than that in — ^^ — . On the other hand it is of course 



V dpT 



a 

 been found by different ialion of the empiiical formulae of the form: r, = --, — r » 



in which Thorpe and Rodger, Phil. Trans. Royal Soc. of London 185 p. 397, 

 A. 1894 comprise their observations. 



') According to Warburg and Sachs. Ann. d. Phys. u Ghera. 22 p. 521. A. 1884. 

 The pressure is expressed in kg. per cm^, 



2). According to Amagat 1893, extrapolated for 0° and 1 atm. from the values 

 given in the Recueil de constantes physiques. 



3) According to Kopp. 1847. Borrowed from the "Recueil etc.". 



*) According to Sdchodski 1910, extrapolated for 0° and 1 atm. from the values 

 given in the "Recueil etc.". 



") According to Rontgen 1891, extrapolated for 0° and 1 atm. from the values 

 given in the "Recueil etc.". 



