ANOMALOUS ELECTRO-CHEMICAL EFFECTS. 387 



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

 point of platinum the spark recombines a portion of it, and 

 the number of sparks, the size of the bubble preceding the 

 spark, and the quantity recombined, would vary indefinitely 

 in each different experiment, and even in the course of the 

 same experiment. 



I now give a selection of experiments from my note-book, 

 with the volumes and analyses of the gases evolved. The 

 decomposition was arrested in each case when the larger 

 volume of gas had reached to 0*3 c. i. The analyses were 

 made by an eudiometer, which I have formerly described,* 

 consisting of a loop of fine platinum wire sealed into a 

 graduated glass tube, and heated or ignited by the voltaic 

 battery : 



ist. The gas from the positive pole contracted to 0*4 of its 

 original volume ; the residue, mixed with half its volume of 

 oxygen, detonated, leaving a minute residue, apparently nitro- 

 gen. The gas from negative pole, 2*3 times the volume of 

 the positive, contracted to 0*15 of its volume ; the residue con- 

 tracted very slightly on the addition of hydrogen. 



2nd. Gas from positive, 2*5 volumes contracted to 07 of 

 its volume. 



From negative, i volume contracted to 0*4 ; the residues 

 mixed contracted again to 07 ; and this residue, mixed with 

 half its volume of oxygen, detonated, leaving only a very 

 minute bubble. 



3rd. Instead of two coated wires one coated wire was em- 

 ployed, and the opposite terminal consisted of a strip of 

 platinum foil, \ inch width and 4 inches length, exposing con- 

 sequently, reckoning both sides, 2 square inches of surface. 



This strip was attached to a platinum wire, which was 

 sealed into a glass tube, the extremity of the platinum foil 

 being \ an inch within the orifice of the tube, so that no gas 

 could escape. (See fig. 2.) 



With the coated point positive, the platinum plate nega- 

 tive, 0*3 c. i. of gas was collected from the point ; a minute 

 bubble only appeared in the tube containing the strip or plate ; 



* Phil Mag. Aug. ^841. Phil. Tram. 1847, p. i. 

 > CC2 



