ELECTRICAL CONDUCTIVITIES, ETC. 75 



An examination of the preceding tables shows the following relations. The halo- 

 gen salts of lithium are all dissociated to just about the same extent, the sulphate in 

 the more concentrated solutions very much less. 



The salts of sodium with the common mineral acids are all dissociated to just 

 about the same extent, and slightly greater than the corresponding salts of lithium. 

 This applies also to the sulphate in the more concentrated solution. Potassium salts 

 of the common mineral acids show just about the same dissociation. The potassium 

 salts of these acids are, in general, slightly more dissociated than the corresponding 

 sodium salts. 



The salts of ammonium are even slightly more dissociated than those of potassium. 

 This points strongly to the correctness of the theory that ammonium hydroxide is a 

 strong and not a weak base. Salts of strong bases are more dissociated than those of 

 weak bases. The fact that ammonium hydroxide has small conductivity and is yet 

 a strong base has been satisfactorily explained by Hantzsch. When ammonia is 

 dissolved in water only a little ammonium hydroxide is formed, and this is strongly 

 dissociated. Most of the ammonia in the presence of water remains there as ammo- 

 nia and does not form the hydroxide with water. This explains the small conductivity 

 of an aqueous solution of ammonia. 



That ammonium hydroxide is a strong base is in keeping with the fact that ammo- 

 nium salts of strong acids are so little hydrolyzed. Only the salts of comparatively 

 weak bases with strong acids are appreciably hydrolyzed. 



Salts of calcium, strontium, barium, and magnesium are dissociated to approxi- 

 mately the same extent, but considerably less than the corresponding salts of the 

 alkali metals under the same conditions of dilution and temperature. Salts of zinc 

 are dissociated somewhat less than those of magnesium. This applies especially to 

 the halogen salts, which were not studied in this work because of the ease with which 

 they break down with water. 



The halogen salts of cadmium are dissociated less than those of any other known 

 metal except mercury. What this means we do not know. The comparatively 

 small dissociation of the cadmium halides is seen from the above table. The halides 

 of mercury are scarcely dissociated at all, the aqueous solutions of these salts being 

 practically nonelectrolytes, not conducting the current to any appreciable extent. 

 The salts of manganese, nickel, and cobalt have approximately the same dissociation. 

 These substances are dissociated to j ust about the same extent as the corresponding 

 salts of calcium, strontium, barium, and magnesium. The same applies to the salts 

 of copper. Lead salts show considerably less dissociation. 



The salts of aluminium and iron are quaternary electrolytes, each molecule dis- 

 sociating into four ions. The percentage dissociation, which, on account of hydroly- 

 sis can be taken only as an approximation, is much less than that of the salts of 

 calcium, strontium, barium, magnesium, manganese, nickel, and cobalt. 



