WORK OF J. N. PEARCE. 



75 



(see fig. 30). The total combined water passes through a minimum at 0.05 normal 

 and then increases rapidly with increasing concentration (see fig. 31 and table 58). 



Table 5S. Nickel Nitrate Data for Freezing-point and Conductivity Measurements, 



Specific Gravity, and Hydrates. 



Amer. Chem. Journ., 33, 574 (1905). 



Before going farther it will be interesting to note the great similarity between the 

 salts of cobalt, copper, and nickel which we have just studied. Solutions of the 

 same concentrations were used in all five salts. 



Reference to figs. 27, 29, and 31, will show at a glance the close relation between 

 the amounts of water held in combination by these salts, whether they are chlorides 

 or nitrates. We are not surprised at this, since, with the exception of copper 

 chloride, all crystallize with 6 molecules of water. In fact, we found it impossible 

 to put more than two curves on one sheet, so closely did the values agree. From 

 the minimum in the most concentrated solutions studied, the magnitude of the 

 hydrating power is a linear function of the concentration. In other words, each 

 hydrate has its own definite composition, which varies with every concentration. 



The curves representing the hydration per molecule (figs. 26, 28, and 30) show 

 the same striking similarity. They are almost asymptotic with the two coordinates. 

 The hydration per molecule decreases very rapidly, for the very dilute solutions, to 

 approximately the same concentration, when they become nearly constant for 

 further increase in concentration. 



