64 AET. 10. — K. IKEDA : STUDIES ON THE 



%' ill the brackets is the empirical molar fraction of acetone 

 in the gas phase, determined by means of the index of refrac- 

 tion. Unfortunately the method is not an exact one for gaseous 

 mixtures so readily condensible. The other values are those 

 calculated by Cunaeus by means of the following equation given 

 by VAN DEK Waals : 



J dP ^ x-x' 

 ~P d{l-x) ~ x'{l-x') 



As the equation is deduced thermodynamically (see Continuität 

 etc., 2, 137) it must be applicable irrespective of the chemical 

 complexity of the liquid phase. The values so calculated deserve 

 therefore more confidence, and these will be employed in the 

 following calculation. 



Two of the data on the total pressure are doubtful. I mean 

 those corresponding to x = 0.490 and x = 0.844. In the original 

 paper the numbers in the brackets are given. When an xP 

 curve is drawn with the other six data we get quite a regular 

 curve ; these two values, however, deviate very far from the 

 curve. Hence they have been replaced by the numbers in the 

 column. I believe I am not making too free with the data 

 given, particularly in view of the remark of Roozeboom. 



As is well known, ethyl ether is a substance very nearly 

 normal, while acetone has been demonstrated by Ramsay and 

 Shields to be associated, though its vapour density corresponds 

 to the simple formula CaHoO. Hence in the gas phase of the 

 system there are only two chemical species C^HeO and (C2H5).,0, 

 while ill the liquid phase there are at least three, i.e. CgH^O, 

 (CoHcO)-;, and (C2H,5)20. Under the supposition that there is 

 only one polymer of acetone the mode of calculation developed 

 above may be applied to this case. 



