298 
ON VOLTA-ELECTRIO INVERSION. 
In the battery now described there is contact neither of 
dissimilar metals nor of dissimilar liquids ; but, unlike Dr. 
Fleming’s battery, the battery now described employs but one 
liquid, the temperatures in alternate cells being different, and 
resulting chemical actions being different, and the differences of 
potential being also different. 
10. The author has not yet satisfied himself what the exact 
state of things is chemically at the moment when the point of 
inversion is reached ; whether there is no chemical action, or 
whether both electrodes are being dissolved at rates which are 
electro-chemically equal. The key to the whole reaction would 
appear to be in an observation made by Warburg^ on the 
electrolysis of concentrated sulphuric acid. Electrolysed below 
80° C., he found it to yield 0 and H gases only. Between 80° 
and 90° C., he obtained 0 at the anode, and at the kathode 
H and S. Above 90°, he found S alone to be evolved at the 
kathode. 
11. In conclusion, the author would note that these observa- 
tions have an important bearing on the theory of the voltaic cell 
as to whether the origin of the electromotive force be contact or 
chemical action. In the battery described in § 8, the copper is 
attacked more than the iron in the hot cells, the iron more than 
the copper in the cold cells. 
I Pogg. Ann. cxxxv., 114. 
