372 PROCEEDINGS OF THE AMERICAN ACADEMY. 



In the case of silver electrodes in pure water we might expect during 

 each unit of time : 



(1) At the anode, the formation of oxygen, or an oxide of silver, or 

 the solution of silver, the sum total making one equivalent. 



(2) The transfer of hydrogen ion (and later of silver ion if this is 

 formed) toward the kathode, and of either or both of the ions ++ and 

 OH - toward the anode. 



(3) At the kathode, evolution of hydrogen, and later precipitation 

 of metallic silver, the two together making up one equivalent. 



A case has recently come to my attention in which some of the 

 more minute phenomena which accompany electrolysis are evident and 

 in which lack of equivalence at the electrodes is especially evident. So 

 far only qualitative observations have been made, but the data secured 

 seem worthy of consideration. 



Figure 1. Electrolysis on microscopic slide between silver electrodes. 



If pure water be electrolysed between small silver electrodes at vol- 

 tages ranging from 1.40 to about 3.8 volts, and the space between and 

 about the electrodes be observed under the microscope with powers of 

 50 or so, the following series of minute phenomena are visible : — 



(1) A very short time after the circuit is closed a cloud of brownish 

 particles, very small and in violent Brownian movement, is formed in 

 the neighborhood of the anode. If silver foil is used as anode it can 

 be seen to dissolve rapidly and a dark film of silver oxide remains. 

 The particles first make their appearance at a slight distance from the 

 anode, and appear to be due to the formation of a silver compound 

 produced from the silver which has dissolved and one of the constitu- 

 ents of the water. 



(2) This cloud consists of approximately spherical particles of diam- 

 eter 0.3 to 1.0 mikron. It is readily soluble in very dilute acetic acid 

 and slightly soluble in water, forming an alkaline solution. The par- 

 ticles appear to be silver oxide. 



(3) If a cell of form similar to that shown in Figure 1 is used for the 

 electrolysis, the particles move along the floor of the cell toward the 

 kathode. During their migration toward the kathode they follow 

 the current lines, and Figure 2 shows drawings made about half a 

 minute apart, indicating the general appearance under a low magni- 

 fying power. The masses which move in this way are not the single 



