230 



ORIGIN OF THE NITRATES. 



without there being either any voltaic current properly so called, 

 as with a closed battery, or elevation of temperature, as with 

 the spark, or sudden and incessant variations of tension, as with 

 the silent discharge developed under influence of the Holtz or 

 Kuhmkorff machines ? The following experiments were made 

 in order to solve these questions. 



Fifth Section. Action of Electricity at very Low Tension. 

 1. These fresh trials were made with a battery, without closing 



Fig. 37. Apparatus open. 



Fig. 38. Apparatus arranged 

 for the experiment. 



the circuit, and under such conditions that the entire experi- 

 ment resolved itself into the establishment of a constant 

 difference of potential between the two armatures. This 

 difference was measured by the electro-motive force of five 

 Leclanche cells (a force equivalent to about seven Daniell cells) 

 in the greater number of the experiments about to be described. 

 Each experiment lasted from eight to nine consecutive months. 

 2. Metallic armatures had to be given up on account of the 

 special reactions they bring about, and it was necessary to 



