54 . Prof. R. A. Lehfeldt on the 



Carbon tetrachloride-Benzene. 

 A (Carbon tetrachloride) = 152-70. B = 77-46. 



z. 



y- 



I 



n- 



log q. 



log*. 



p. 



Pa- 



Pb- 

 258-9 



0181 



101 



04-3 



•054 



2-9450 



7-0508 



273-6 



14-7 



•326 



•374 



•19-7 



•233 



1-6346 



1-7763 



2800 



65-2 



2148 



•543 



•580 



•376 



•41-2 



0-0748 



01402 



2940 



121-1 



172-9 



•793 



•80-5 



•66 



•677 



0-5833 



0-6157 



303-4 



205-3 



981 



•90-6 



•909 



•830 



•835 



0-9840 



0-9995 



306-5 



255-8 



50-7 



Carbon tetrachloride-Toluene. 

 A=152-70. B = 91-37. 



z. 



y- 



i 



n- 



log?. 



log*. 



p. 



Pa- 



Pb- 



011-7 



0-270 



007-3 



0-18-1 



71222 



75681 



1054 



19 



864 



•24 6 



•46-7 



•163 



•34-4 



7-5136 



1-9426 



122-8 



422 



80 6 



•345 



•59 7 



•240 



•470 



1-7216 



01706 



1400 



65-8 



742 



•47-4 



•71-2 



•350 



•59-7 



7-9548 



3930 



1580 



94-3 



63-7 



•641 



•82-8 



•51-7 



•74-2 



0-2519 



6825 



198-9 



147-6 



51-3 



•80-2 



•91-9 



•70-8 



•87-2 



6076 



10550 



2420 



2110 



310 



It is difficult to say what is the degree of accuracy of these 

 results, but certainly less than the accuracy of the vapour- 

 pressure measurements, chiefly because some of the condensed 

 vapour clings to the condensing-tube, and it is not certain 

 that what is collected quite fairly represents the whole. 



These results are also expressed by the curves on fig. 4. 

 Considering first, then, two pairs of normal liquids, we see 

 that the relation log £ = log k-\- r\og q, where k and r are 

 constants, satisfactorily represents the phenomena. That is 

 the relation proposed in the previous paper for mixtures of 

 benzene with methyl and ethyl acetates, and in all these cases 

 it appears to be correct within the limits of error of experi- 

 ment. But Margules has quite rightly pointed out (loc. cit. 

 p. 1266) that when r<l (as it usually is) the equation leads 

 to infinite values of dp/B? when £ = or ?=1, i.e., the 

 vapour-pressure curve would start and end vertically. That 

 deduction I had overlooked, and it is obvious from the curves 

 on fig. 2 that the vapour-pressure curve does not behave 

 in that way. The relation given cannot therefore hold 



