071 the Specific Weight of Chemical Compmmds. 185 



ber of assumptions would be necessary in the formulse for the 

 densities of salts than if we adopted the hydracid theory, as 

 the improbability of a theory increases with the number of 

 assumptions which it is obliged to make, and as that theory is 

 the most probable which makes fewest assumptions, Dr. Kopp 

 decides in favour of that of the hydracids. In a future com- 

 munication we may perhaps enter more fully into this subject. 



The densities of several hydrated oxides may be calculated 

 if we assume the water to have the atomic volume 78, and the 

 oxide to retain its primitive volume. 



In some hydrates of salts the volume of water must be 84'. 



Chloride of barium ... Ba Cl^ + 2 H^ O 



Sulphate ofiime 2Ca SO^ + H- O 



Gypsum iCa S O'' + 2 H^ O 



Sulphate of copper 



manganese 

 nickel... 



magnesia 



CuSO^ + 5HH) 

 MnSO^+ 5H3 

 NiS0^ + 7H-'0 

 ZnS0^ + 7H-0 

 MgSO'»+7H2 



Other salts require the atomic volume 96. 



f. , _, r NaC03+ lOH^O 



lime . 



Nitrate of copper 



magnesia, 



Sulphate of iron , 



soda 



Ca C 03 + 5 H= O 

 CuN-0'' + 3H=0 

 MgN20° + 4H=0 

 Fe S O^ + 6 H2 O 

 NaSO^+lOH^O 



Of the combinations of the metalloids with one another, we 

 may mention those of chlorine. In this group the atomic 

 volume of chlorine = 298. The volume of the metalloid com- 

 bined with it remains primitive. 



Chloride of sulphur 



carbon 



cyanogen . 

 phosphorubj 



