Electrodes in Water free from Air 



145 



same direct current was started through the cell and galvano- 

 meter in one circuit, previously bringing the platinum plates 

 to a neutral condition. 



The first column in the subjoined Table gives the bridge- 

 reading, the second the electromotive force which this is equi- 

 valent to in absolute units (C. G. S.), the third the swing of 

 the needle with the direct current (charging), fourth the same 

 with the polarization current (discharge). 



Table I. — Polarization in Acidulated "Water free from Air 

 and kept in vacuo. 







Excursion of needle in 



Bridge- 



Electromotive 



degrees or fractions. 



reading. 



force. 



Direct current. 



Polarization 

 current. 







o 







275 



12110 



£ barely. 



1 



8' 



280 



18165 



*fulL 



i nearly. 



285 



24220 



§ nearly. 



i full. 



290 



30275 



1 



| nearly. 



300 



42385 



1 



* 



310 



54495 



H 



2 



320 



66605 



2 



§ nearly. 



330 



78715 



n 



f 



340 



90825 







350 



102935 



3" 



i 



400 



115045 



5 



1 



450 



224035 



7 



!| 



500 



284585 



10 



2} 



Since a Daniell's cell is about 100,000,000 units in electro- 

 motive force, the above Table shows that, with the galvano- 

 meter employed, the least electromotive force which, acting 

 for one minute under these circumstances on platinum plates 

 of 16*39 centims. surface, would leave a detectable polarization, 

 was about § ^0 of a Daniell's cell. 



The observations having been repeated several times with 

 the same results, the dilute acid was then removed, and tho- 

 roughly aerated by shaking it up with air under pressure, and 

 by bubbling air through it for some time. This aerated water 

 was then returned to the voltameter, all other arrangements 

 remaining the same, and the same observations repeated in this 

 case as in the last. The results are appended. 



