Solutions of Volatile Substances. 217 



r\. tt (solvent). p. $(calc). £ (obs.). 



CC1 4 in toluene 0-181 93-0 1054 0072 0073 



Toluene in CC1 4 0"872 3102 242-0 0680 0-708 



(A = carbon tetrachloride ; B = toluene.) 



CC1 4 iu benzene 0054 2709 2736 0-045 0043 



Benzene in CC1 4 0-835 3102 306-5 0825 0830 



(A = carbon tetrachloride ; B = benzene.) 



Unfortunately no sufficiently dilute solution of toluene in 

 CC1 4 was measured ; that quoted contained (as may be seen 

 from the value of £) 29'2 per cent, of the dissolved body, and 

 it appears that the range of applicability of the formula is here 

 exceeded : otherwise the agreement is good. 



The mixtures containing alcohol, on the other hand, show- 

 maxima of vapour-pressures, and on this account the 

 departure from the formulae for dilute solutions is much more 

 marked, and it is not possible to apply equations (i.) and (ii.) 

 when the amount of dissolved body exceeds a very few per 

 cent. The numbers are : — 



i\. 7r (solvent). p. £(calc). £ (obs.). 



Alcohol in benzene 0-281 270-9 3504 0070 0-088 



Benzene in alcohol 0-668 219-5 3150 0958 0-886 



(A = alcohol ; B = benzene.) 



Alcohol in toluene 0-591 93-0 199-5 0-123 0-138 



Toluene in alcohol 0902 219-5 233-5 0959 0-946 



(A = alcohol ; B = toluene.) 



Temperature, throughout = 50° O. 



The quantity of dissolved substance in the liquid is less 

 than that calculated, in each of the four alcohol mixtures. It 

 is easy to show that for them the formula (i.) or (ii.) is less 

 accurate than in the case of normal liquids, for a mixture in 

 nearly equal parts may be looked upon either as a solution of 

 A in B or of B in A. If it be calculatad. accordingly the 

 results will of course differ, since the solution is not by any 

 means dilute ; but whilst in the case of the normal liquids 

 the disao-reement of the two results is small, in the alcohol 

 mixtures it is egregious. 



East London Technical College, 

 March 1899. 



