30 Mr. W. Sutherland on Weak Electrolytes and 



These data are represented by the equations 



(A + pA 2 /2)//) 1 p 2 p = 0-0999 + 0-0457> 1 



from 2 h = to 05 . . (15) 



= 0-1224 + 0-509(0-25 -pjpa) 



from p 2 = 0'5 to 1, . . (16) 



the values of (A + pA' 2 /2)/p 1 p 2 p given by these having been 

 entered in the last line in Table II. Even in a 1 per cent, 

 solution o£ acetic acid only about 1 per cent, of the acid is 

 ionized, so that within the limits of Table II. we do not look 

 for any appreciable effect of ionization on A. Up to jh = 0*10 

 the small irregularities in (A + p&?/2)/p 1 p 2 p are due to the 

 want of sufficient refinement in the experimental data, the 

 value of A for ^,=0*01 being obtainable correct only to 

 1 part in 10. But at the other extreme whenp 1 >0 , 9 there 

 is a progressively increasing discrepancy between the results 

 of (16) and experiment, reaching 14 percent, when jd 1 = 0'98. 

 To obtain the limiting value of A/p 2 when p 2 is small, that is, 

 p ] — 1 nearly, the following three equations have been found 

 to summarize Table II. more accurately than (15) and (16) 

 do, namely : 



(A + p A 2 /2)/ Pl p 2 p = 0-1000 + 0'0U Pl 



fromp 1 = 0to0'5 . . (17) 



= 0-1011 + 0-0U Pl + 0-3(0-25 -pfr) 



from pi = 0-5 to 0-77 . (18) 



= 0-1227 + 0-044^ + 2-39 (pi-0-77) 2 



from Pl = 0-77 to 1. . (19) 



When p 1 = 0*769 the acetic acid and water are to one 

 another as CH 3 COOH to H 2 0, the mixture beino- one of 

 maximum density and maximum viscosity, though not of 

 maximum contraction. It is probable that here the relations 

 between acetic acid and water are such as give a relative 

 minimum of potential energy helping to determine the 

 chemical state of the water. I think that when ^ = 0*77, 

 for n molecules of (CH 3 COOH) 2 there are n of hydrol and 

 ??/2 of dihvdrol, so that the mixture might be denoted by 

 (CH 3 COOH) 2 +'H 8 + i(H 2 0) 2 , the reasons being that there 

 is good evidence that at 15° C. acetic acid is (CH 3 COOH) 2 , 

 and that the contraction A given by (18) and (19) for 

 p 1 z=0'17 is 0-0294, while that deduced from the formula just 



