212 PROPERTIES OF ELECTRICALLY CONDUCTING SYSTEMS 



monia with the nuclear atom. What characterizes these compounds in 

 particular is their stability. Similar relations may exist in the case of 

 other salts which show a pronounced tendency to form complexes, such as 

 calcium salts for example, but in these cases reaction between the com- 

 plex and the solvent medium takes place very rapidly. The behavior of 

 these complexes in water does not differ greatly from that of calcium 

 chloride in propyl alcohol, whose ionization is greatly increased on the 

 addition of water. On the other hand, it is to be borne in mind that in 

 non-aqueous solutions those salts which exhibit only a slight tendency to 

 form complexes with water are highly ionized in all cases. This is 

 particularly true, for example, of potassium salts. It appears probable 

 that such salts do not form complexes similar to the metal-ammonia 

 salts. It is probable, however, as we have seen, that all ions are hydrated. 

 It appears likely that the solvent molecules may be associated with the 

 ions in several ways. Certain of the solvent molecules may be combined 

 in a more or less definite manner, as in the metal-ammonia complexes, 

 while other molecules may be associated with the ions due to the opera- 

 tion of purely electrical forces. 



7. Positive Ions of Organic Bases. With the exception of ions of 

 salts of organic bases and a few salts of the type of the ammonium salts, 

 the positive ions consist essentially of metallic elements. This tendency 

 of the metallic elements to form electropositive ions is in harmony with 

 prevailing conceptions regarding atomic structure. The organic bases 

 are derived from the less electropositive elements on the introduction of 

 organic radicals, such as alkyl and aryl radicals, into combination with 

 the nuclear element. The number of carbon radicals introduced depends 

 upon the valence of the element in question, and upon its position in the 

 periodic system. For elements up to the fifth group, the organic bases 

 have the constitution: R n _-jM n X, where n is the maximum valence of the 

 element with respect to negative elements. For elements of the fifth to 

 the seventh groups, inclusive, the bases have the constitution: R^, ^M n X, 



where n is the valence of the element toward hydrogen. Thus, we have 

 the organic bases: CH 3 HgOH, (CH 3 ) 2 T10H, (CH 3 ) 3 SnOH, (CH 3 ) 4 NOH, 

 (CH 3 ) 3 SOH and (C 6 H 5 ) 2 IOH. The strength of the organic bases de- 

 pends upon their constitution. As hydrogen is substituted by organic 

 groups, particularly alkyl groups, the strength of the base in general 

 increases, although a marked increase does not take place until the sub- 

 stitution of the last hydrogen atom occurs, in which case the resulting 

 base exhibits a maximum strength. Thus, monomethyl-, dimethyl- and 

 trimethylammonium hydroxides are comparatively weak bases, while 



