THE SMITHSONIAN INSTITUTION. 399 



in tlic formation of hydrochloric acid. On immersion in oxygen, the 

 hydrogen adhering to the phitinum plate is caused by the action of 

 the latter to combine with the oxygen, and thus the cause of the polari- 

 sation is removed. That oxygen does not destroy the positive po- 

 Itirity so quickly as chlorine, is owing merely to the slow action of 

 the oxygen. 



The fact mentioned under No. 4 is also favorable to the view, that 

 the cause of the polar condition of the electrodes exists in the 

 hydrogen and oxygen which adhere to them. The certainty of this 

 supposition is established by the fact stated in No. 5 ; at least this 

 appears to prove incontestably that the positive polarity of the nega- 

 tive electrode is due to hydrogen. 



A platinum wire which has not been used as a negative pole, and has 

 not been subjected in any way to the influence of a current, presented 

 all the voltaic properties of a positively galvanized wire, merely from 

 the fact of having been exposed a few seconds to hydrogen. 



Schonbein has, in fact, by these experiments, removed the vail 

 which has hitherto concealed the nature of galvanic polarization. 



Only two of the facts stated above, namely, those under 6 and 7, 

 appear to oppose the explanation he has given. 



While a phitinum plate, which has been used as a positive elec- 

 trode, is negatively polarized, the polarization cannot be produced by 

 exposure to oxygen ; this seems to show that the negative polarity of 

 the positive pole is not to be ascribed to oxygen. 



The circumstance that gold and silver wire do not become electio- 

 positive in hydrogen, while the same metals, if they have played the 

 part of negative electrodes but for a few seconds, become sensibly posi- 

 tively polarized, excites some doubt as to the correctness of the view 

 that the positive polarization of the negative electrodes is to be attrib- 

 uted to hydrogen. 



But before j^assing to a closer examination of this subject, we will 

 first consider the polarization of liquids which Schonbein also discusses 

 in the above mentioned memoirs. 



§40. Polarization of liquids. — If dilute hydrochloric or dilute sul- 

 phuric acid be placed in a U-shaped tube, and connected a few seconds 

 by platinum electrodes with the poles of a battery, the current of 

 which causes a sensible development of gas in the acidified liquid, 

 and if then the wires thus used be replaced by new ones, or such as 

 have not served as x)oles, and these wires be connected with the gal- 

 vanometer, the needle of this instrument will deviate, and in a direc- 

 tion which shows that the positive current of the liquid column in 

 which the negative pole was immersed passes in the direction of that 

 in which the positive electrode was, or, in other words^ the secondary 

 current is in the opposite direction to the current of the battery. 



Thus liquid columns indicate galvanic polarization. 



The cause and nature of this polarization are explained by the fol- 

 lowing experiments : 



1. Water, made conducting by a little sulphuric acid, being agi- 

 tated with hydrogen and placed in a tube closed below with a bladder, 

 and the tube put in a vessel which also contains some acidified water, 

 but free from hydrogen, and both liquids then connected with the 



