SPECIFIC GRAVITY AND DISPLACEMENT OF SOME SALINE SOLUTIONS. 117 



salt in 1000 grams of water may be looked on as being the result of two operations, 

 namely : (a) the dissolution of — gram-molecules of the salt in 1000 grams of water, 

 which produces the first increment of displacement ; and (b) the further dissolution of 

 -- o'ram-molecules of the salt in the solution formed, which produces the second incre- 

 ment of displacement. These increments of displacement are very seldom found to be 

 alike ; the second portion of salt dissolved generally produces a greater increment of dis- 

 placement than the first. In the case of solutions of such concentration that their specific 

 gravity can be ascertained by the use of the pyknometer without too great probability of 

 error, this feature is found to be general, and has often been held to be universal. One 

 of the principal motives f 07- making this research ivas to find out, by the use of the 

 more refined hydrometric method, if there is any point in the dilution of a saline 

 solution at which further dilution is accompanied by expansion, in place of contraction. 

 The general result of the work is to shoiv that in solutions having the concentrations 

 here used, ivhere ?w<l/16, cases of expansion 07i dilution are not uncommon. 



The following table gives the values of m for which the value of (c^A — n) is 

 positive and becomes negative for the next lower value of ni. That is, the value 

 (^dA — v) changes sign at some concentration lower than that indicated by m and 

 higher than that indicated by l/2m. 



T=19-5''C. 



MR 



KCl 



RbCl 



CsCl 



KBr 



RbBr 



CsBr 



KI 



Rbl 



Csl 





m 



1/32 



1/128 



1/256 



1/16 



1/32 



1/64 



1/16 



1/16 



1/32 





MROg 



m 



KCIO3 

 1/512. 



RbClOj 

 1/64 



CsClOg 

 1/32 



KBrOg 



1/32 



RbBr03 



1/64 



CsBiOj 



1/128 



KIO3 



1/16 



Rbl03 



1/32 



CSIO3 

 1/16 





MNO3 

 m 



LiNO, 



1/2 



NaNOg 

 1/32 



KNO3 

 1/32 



RbNOg 



1/128 



CsNOg 

 1/32 



Ba(N03)2 

 1/512 



Pb(N03)2 

 1/64 







T = 23-0°C. 



MR 



RbBr 



CsBr 



KI 



Rbl 



Csl 













m 



1/32 



1/8 



1/16 



1/16 



1/32 













MEO3 



RbNOj 



CSXO3 



















ni 



1/128 



1/128 





' 













T=15-0°C. 



MR 

 m 



MNO3 

 m 



KCl 

 1/32 



NaNOg 

 1/16 



NaCl 

 1/16 



KNO3 

 1/16 



Sr(N03)2 

 1/128 



Ba(N03)2 

 1/128 













§ 47. If we consider Table No. I, Class A, § 26, in which are recorded the results 

 of experiment on solutions of chloride of potassium having the concentrations specified 

 by the general expression mKCl-t- 1000 grams of water, we have, besides the weight of 

 the solution and its specific gravity, columns containing its displacement, A, and the 



