76 
MESSRS. W. DE LA RUE AND H W. MULLER ON THE 
cells there was not the slightest indication of any alteration of volume of the contained 
gas, so that there was neither condensation about the discs which would have caused a 
Fig. 74 . 
contraction, nor repulsion from the discs which would have caused an expansion of 
volume. The fluid in the stem, whose internal diameter is 0T85 inch, was observed 
with a lens, but not the slightest motion of it took place. The same result was 
noticed even when water was substituted for sulphuric acid. So far, then, as this 
apparatus, in which the area of the gauge is vioth of that of each disc, would indicate 
it, the result is entirely negative. 
The discharge between two discs 1*5 inch in diameter. 
The following series of experiments were made by placing the micrometer-discharger 
under a bell-jar, and in the first instance adjusting the discs to the striking distance 
at atmospheric pressure for the battery of 11,000 cells. Afterwards a less number of 
cells was connected with the discs and the bell-jar gradually exhausted until the 
discharge occurred ; the height of the gauge was then read off. Then a less and 
lesser number of cells was connected with the discs and the operation was repeated. 
Fig. 75 shows the arrangement of the micrometer discharger under the bell-jar. The 
