152 Prof. Ostwald on Chemical Action at a Distance. 



extremely slight tendency, if any at all, to form ions ; it is 

 far removed from the possibility of taking from the sodium 

 ions the necessary positive electricity. The entire action will 

 then be limited to the gathering of a few chlorine ions upon 

 the surface of the gold, and of a corresponding slight excess 

 of sodium ions upon the platinum. But if now chlorine 

 molecules be present, they find here opportunity to go over 

 into negatively charged ions ; the corresponding quantity of 

 positive electricity, which must be produced at the same time, 

 passes through the platinum to the gold, and the latter is put 

 in position to send out, or one may say is directly forced to 

 send out, a corresponding number of positively charged atoms, 

 or ions. 



I wish to emphasize here that, without in any way altering 

 the final result, the explanation may be also given somewhat 

 differently. Instead of recognizing the direct cause of the 

 action in the tendency of chlorine to form negative ions, the 

 active role may be ascribed to the gold, and to it be referred 

 a positive tendency, though slight yet at hand, to the forma- 

 tion of ions. Chlorine would then play the more passive role 

 by opposing to its transfer into negative ions a very small 

 resistance, which is overcome by the positive tendency of the 

 gold. At present it may not be entirely easy to decide 

 finally between these views ; yet, without a closer discussion 

 of the question, for which, however, some material already is 

 at hand, I believe that the preference is due to the first. 



This presentation brings out under all circumstances the 

 fact that the great significance which the positive ion of the 

 electrolyte has in cases of metals of the character of zinc, com- 

 pletely disappears in this case of the nobler metals. In fact, 

 under the given conditions, gold dissolves as well when sodium- 

 chloride solution, as when hydrochloric acid, both saturated 

 with chlorine, is present at the platinum, which proves that 

 the positive ion present, which suffers no change at all by the 

 action, is not concerned, but instead only the substance which 

 is able to furnish negative ions. Weaker oxidizing agents, 

 that is such with less tendency towards the formation of 

 negative ions, as for example bromine, are ineffective, as I 

 have convinced myself by making the experiment. 



It is perhaps fitting, at this place, to say a few words in 

 regard to the expressions " Tendency " and " Inclination," of 

 which use has here been made. Expressions of this kind are 

 properly looked upon in exact science as suspicious, so long 

 as they are not accompanied by satisfying explanation in the 

 form of a controllable definition. On the other hand, there 

 manifests itself everywhere the need of expressions of this 



