Prof. Ostwald on Chemical Action at a Distance* 14? 



action. Similarly silver can be dissolved in a solution of 

 sodium acetate. 



In the same way gold may be dissolved in a solution of 

 common salt, when the platinum is brought in contact with 

 chlorine (with a salt-solution saturated with chlorine). After 

 but two or three minutes, in the solution which surrounds the 

 gold, the characteristic reactions of this metal with ferrous 

 sulphate or stannous chloride may be obtained. 



I have for the most part carried out the experiments briefly 

 described here by bringing into a small beaker an open short 

 tube of about 2 centim. diameter, closed below with parch- 

 ment-paper, and then filling both with the indifferent liquid, 

 taking care at the same time to have the level in the tube 

 always above that in the beaker. In the tube was placed the 

 metal to be dissolved, the platinum wire connected therewith 

 went to the bottom of the beaker. The solvents added were 

 so chosen that they were heavier than the indifferent liquid; 

 when a few drops thereof were brought with a pipette upon 

 the bottom of the outer vessel they remained lying there 

 without approaching the parchment-paper partition, which 

 remained in the upper part of the liquid. After the close of 

 the experiment the contents of the glass could then be easily 

 investigated. 



These phenomena, which were in part already known, I 

 have termed chemical action at a distance ; because the ap- 

 pearance in every case is as if the specific solvent of the 

 the metals, when applied at the platinum, exercises its action 

 at a distance upon the metal in question. As concerns the 

 explanation, therefore, there can plainly be no doubt that the 

 electrolytic relations play here the decisive role. In fact the 

 simplest means of deciding whether solution ensues or not is 

 to switch a moderately sensitive galvanometer into the circuit 

 between the metal and the platinum. While compounds 

 which exert no action give a current of only short duration, 

 which falls at once to a very slight amount, addition of the 

 acting substance (acid or oxidizing agent) to the platinum 

 causes at once a strong deflexion of th.e> needle. No deflexion, 

 on the contrary, is observed when the acting substance is 

 brought into contact with the metal to be dissolved. 



As before mentioned, certain phenomena of this kind are 

 already known. Thomsen, thirty years ago*, described a 

 galvanic element which consists of copper in dilute sul- 

 phuric acid and carbon in a chromate mixture ; on closing 

 the connexion by means of a conductor between the copper 

 and the carbon, the metal, which alone is not soluble in sul- 

 * Poggendorffs Annalen, cxi. p. 19:2 (1860). 

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