Substance* in the Solid State and in Aqueous Solution. 415 



A, of molecules of water have necessarily equal densities. We 

 shall be pardoned the following calculations : — 



Densities 19°*5/19°'5, calculated from Kremers's 

 experiments. 



A. 



Srl 2 . 



PbN 2 6 . 



50 



1-2919 



1-2926 



100 



1-1516 



1-1519 



200 



1-0773 



1-0774 



300 



1-0391 



1-0391 



Among Thomsen's experiments the following is to be 

 found: — 



PbN,O 6 + 200H 2 O, dlS / 18°= 1-0771. 



Conclusion. 



It is possible to form groups of substances of which the 

 densities are equal when A = A'. For instance, this is the 

 case for the homonymous salts of Fe, Ma, and Cr. We call 

 the following salts homonymous: — 



RS0 4 ; RC1 2 ; RN 2 6 ; &c. 



The same holds good for the homonymous salts of Cu, Zn, 

 Ni, and Co. 



The following Table H contains several experiments (which 

 have already been published) referring to this last case. 



Table H. 

 Solutions with Equal Densities. 



Thomsen's experiments. t = 



= 18°. 



A 



Dissolved , , 0/ , 

 substanee. | 



Mean. 



200 

 200 



ZnS0 4 1-0455 

 CuS0 4 10444 



10449 



Nicol's experiments. 



207 

 207 

 207 

 207 



ZnS0 4 

 0uSO 4 



coso 4 



NiS0 4 



104367 

 104268 

 1-04304 

 104296 



104308 



For two substances which possess the same v tbe values of 

 a, a! are inversely proportional to the molecular weights a, a' . 



