DISCUSSION OF THE RESULTS. 139 



in figs. 15, 16, 17, and 26, the conductivities in fig. 27, the reflectivities in 

 fig. 30, and the hydrates formed by cadmium nitrate in fig. 54. 



None of the halogen salts of cadmium has any appreciable hydrating 

 power. It will be recalled in this connection that the halogen salts of cad- 

 mium give, in general, abnormal results in aqueous solution. They have 

 abnormally small conducting power for the electric current; not as small 

 as the corresponding salts of mercury, but much smaller than those of zinc, 

 which in turn have much less conductivity than the halides of metals of 

 the calcium magnesium group. 



In the light of this abnormal behavior of the halogen compounds of cad- 

 mium, it is not surprising that the chloride has such small hydrating power, 

 notwithstanding the fact that it can crystallize with two molecules of water. 

 The nitrate of cadmium shows very considerable hydrating power, as 

 would be expected from its water of crystallization. 



The sulphate of cadmium conducts itself in a manner analogous to the 

 other sulphates already studied. 



The chloride, nitrate, and sulphate of manganese were studied. The results 

 are recorded in tables 55 to 57. The freezing-point data are plotted in 

 curves, fig. 31, the conductivities in fig. 32, the refractivities in fig. 33, and 

 the hydrates in fig. 49. 



The results are perfectly normal in terms of the conceptions that we have 

 earlier developed. The hydrating power of the chloride and nitrate is what 

 would be expected from their water of crystallization, and the behavior of 

 the sulphate is strictly analogous to the other sulphates already studied. 



The chloride, nitrate, and sulphate of nickel were brought within the scope 

 of this investigation. The results that were obtained are given in tables 58 to 

 60. The freezing-point lowerings are plotted as curves in fig. 34, the conduc- 

 tivities in fig. 35, the refractivities in fig. 36, and hydrates in figs. 50 and 51. 

 The hydrates formed by nickel chloride and nitrate are complex, as would 

 be anticipated from their water of crystallization. The complexity increases 

 with fair regularity from the most concentrated to the most dilute solutions. 

 The results for the cobalt salts are strictly analogous to those for the 

 salts of nickel. They are given in tables 61 to 63. The freezing-point lower- 

 ings are plotted as curves in fig. 37, the conductivities in fig. 38, the refrac- 

 tivities in fig. 39, and the hydrates in figs. 50 and 51. 



Since the results with the salts of cobalt are so closely analogous to those 

 with the salts of nickel, it is not necessary to discuss them in any detail. 



The chloride, nitrate, and sulphate of copper were used. The results are 

 given in tables 64 to 66. The freezing-point lowerings are plotted in fig. 40, 

 the conductivities in fig. 41, and the refractivities in fig. 42. The hydrates 

 formed by copper chloride and copper nitrate are plotted as curves in figs. 49 

 and 52, respectively. 



