284 Mr. William Sutherland on the 



The agreement here is excellent, as will be seen more clearly 

 if we compare bodies not having equal shrinkage, as K and 

 Li, for which we get the 10 7 fjup 2 difference 20, the cA" 1 diffe- 

 rence *90 with a ratio 22, or K and XH 4 , for which the two 

 differences are 12 and 1*05 with a ratio 11. 



The agreement above is a verification of the theory of the 

 compressibility of solutions, here barely outlined, and the 

 equation 



W.<lv£-*& =32(cA-i- c A r i) 



when A a = A& nearly constitutes a second method of getting 

 values of cA~ 1 ; but we will not use it, as it adds no bodies to 

 our list. It suffices to have partly verified the principles on 

 which the first method is founded by their application to quite 

 another physical phenomenon, and especially the principle 

 involved in the remarkable equation 



X- 1 = (W" 1 + nAr^&l + n) . 



With the values in Table XXXIII. and that for LiCl, namely, 

 *83, we can obtain the value of cAr 1 for any salt whose con- 

 stituents are to be found in the table,, or we can if we like use 

 the actual values in Tables XXX, and XXXI.; we can then cal- 

 culate M 9 /cA-\ which is proportional to M% or Wl = GWfcAr 1 , 

 where C is a constant. To connect the values of M 2 / thus 

 found with those previously given absolutely in Table XXV., 

 we must find the value of C/c, which we can proceed to do in 

 the following manner : — 



We have seen (Section 14) that we had better regard the 

 molecule of water as doubled relatively to that of ordinary 

 liquids, and as we have shown that the molecules are paired 

 in ordinary liquids the molecules are doubly paired in water ; 

 but it was suggested that the second pairing of the pairs was not 

 attended with any alteration in the parameter of molecular 

 force, and that the only effect of the second pairing was to make 

 the radius of the molecular domain of water 2^ as large as if 

 water were an ordinary liquid. And, again, in the case of 

 solutions the surface-tensions have been measured at about 

 15° C , whereas for comparison with our previous work they 

 ought to have been measured at 2T c /3, which for water is about 

 150° C. At this temperature the value of the surface-tension 

 of water reduces, according to Eotvos, to about *6 of its value 

 at 15° C. Hence the equation, which treating water as an 

 ordinary liquid and at 15° we wrote a w =Wwi/ c , ought for 

 double pairing and at 150° to become '6a w = W'2zw%/c, and 

 similar statements hold for the equation for u ; so that values 



