204 



Mr. W. H. Grove on some anomalous cases 



something resembling the letter Z (see fig. 1), the extremities 

 immersed in a porcelain capsule containing the liquid to be ex- 

 perimented on, a graduated test-tube filled with the liquid being 

 inverted on the extremity of each. 



Kg. 1. 



From the Z form of the terminals the extremities projected 

 f ths of an inch into the test-tubes, so that no gas could possibly 

 escape. At first I tried distilled water, which had been boiled 

 immediately before the expei-imeut to deprive it of air; I 

 found, however, that from its want of conducting power, only an 

 infinitesimal decomposition was produced ; a few drops of sul- 

 phuric acid were added, and immediately a notable evolution of 

 gas took place, a spark being visible at the end of the wire, 

 which was worn beneath the surface of the glass whether this 

 were positive or negative, and none on that which was even with 

 the glass. This spark had a material influence on the relative 

 quantity of gas given ofi* by each terminal, the gas being always 

 less from the spark-giving terminal than from that which did 

 not yield a spark ; and when both were constructed so as to give 

 sparks, the quantities of gas were irregular, and bore no definite 

 relation to each other. Thus in one experiment the gas from 

 the negative was to that from the positive as 2*3 : 1 ; in another 

 experiment the gas from the positive was to that from the nega- 

 tive as 2*5 : 1 ; frequently the quantities from each were nearly 

 equal. It is obvious that when the wire was depressed below 

 the surface of the glass, a film of gas must intervene between 

 the wire and the Hquid, across which film the spark passes. 

 When the wire is even with the glass, the gas escapes more 

 readily, and there are fewer or no sparks. 



There is no doubt that as the bubble of gas forms on the point 



