116 DE. B. D. STEELE, DR. D. McINTOSH AND DK. E. H. AECHIBALD 



The average value of this coefficient is, according to EOTVOS, 2'27. From the 

 experiments of RAMSAY and SHIELDS it is 2-12, while BALY and DONNAN have found 

 that the liquefied gases oxygen, nitrogen and carbon monoxide give values very near 

 to 2, and this number has also been found by us for the three substances hydrogen 



bromide, iodide and sulphide. 



RAMSAY and SHIELDS have shown that for normal liquids the relation between 

 molecular surface energy and temperature is given by the equation 



in which t represents the temperature measured from the critical point and d is a 



small constant. 



From this equation it follows that the surface energy disappears at a temperature 

 d degrees below the critical point, and therefore the curve for a normal liquid, if 

 produced, should cut the temperature axis at this point. 



This is the case for hydrogen bromide, iodide and sulphide, for which, as will be 

 seen from Table XL, the value of d is 16'3, 157 and 0'2 respectively. 



ENERGY 



Fig. 7. 



The curves are shown in fig. 7, in which the critical temperature of each liquid is 

 indicated by an arrow. 



