and the Surface- Tension of Solutions. 493 







Table XIV. 







LiCl. 



LiBr. Lil. 



LiN0 3 



Li 2 S0 4 



NaCl. 



NaBr 



713 



368 254 



486 



673 



•581 



340 



67 



63 56 



56 



72 



61 



56 



Nal. 



NaN0 3 . Na 2 SO, 



1. Na 2 C0 3 



KOI. 



KBr. 



EX 



258 



437 516 



681 



500 



331 



256 



54 



52 66 



82 



56 



54 



51 



KN0 3 



K 2 S0 4 . K 2 00 3 . CaCl a . 



SrCl a . 



BaCl a . 



383 



478 



564 



400 



330 



272 



47 



66 



72 



56 



60 



60 



The ratios in the second row have values between 47 

 and 82, and in each series they diminish in the order car- 

 bonate, sulphate, chloride, bromide, iodide, and nitrate ; and 

 although the compounds of the dibasic acids do not separate 

 themselves from the others by any distinct gap, yet if on 

 account of what we have seen in connexion with surface- 

 tension we set them apart, the ratios for the rest lie between 

 47 and 67 with a mean value 57, which is close to the value 

 for 12 out of 15 of the compounds ; or, in other words, the 

 relative values of (M 2 %)i, calculated on dynamical principles 

 from the experimental compressibilities of solutions, agree 

 within the limits of experimental error with the relative 

 values given by the Kinetic Theory of Solids for 12 out of 

 15 substances of the types NaCl and MgCl 2 . 



For the five values of compounds with dibasic acids, the 

 mean is 72, which is larger than the 57 for the other com- 

 pounds, a result in striking contrast to that of Table VII., 

 where the corresponding ratio in connexion with surface - 

 tensions came out for compounds with the dibasic acids only 

 half of the value for other compounds. This discrepancy 

 shows that the equation (21) is not a complete statement of the 

 facts of the compressibility of solutions ; instead of saying that 

 (1/^p 2 - l/fi 1 p 1 2 )p 2 + 2/^ 1 p 1 2 is equal to 2 1 A 2 (Z 2 / Wl 2 )§/(iA ] 2 A 2 )* 

 we should say that amongst compounds of the types NaCl 

 and MgCl 2 it is proportional to it, and also in the type 

 Na 2 C0 3 it is proportional to it, but with a different factor 

 of proportionality. We can see that this is true in another 

 way, because if equation (21) were strictly correct then 

 10~ 4 M ] /At 1 p 1 2 (M 1 2 / 1 )* for water ought to have a value differing 

 from that of the ratios above by the factor 2 1 A 2 /( 1 A l9 A 2 )* 5 

 which we have seen from surface-tensions cannot be much 

 different from 1 ; now (M^l^i for water being about 2*4, 

 10~ 4 M 1 //i 1 p 1 2 (M 1 2 / 1 )*=16 ; which is only about a quarter of 



Phil. Mag. S. 5. Vol. 40. No. 247. Dec. 1895. 2 M 



