206 Mr. W. R. Grove on some anomalous cases 



With the coated point positive, the platinum plate negative, 

 0'3 c. i. of gas was collected from the point ; a minute bubble 

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

 contracted in the eudiometer to 0*7 of its volume; the residue, 

 mixed with half its volume of oxygen, detonated, leaving a very 

 small residuum. 



4th. The converse experiment, i. e. coated wire negative, plate 

 positive, 0'3 c. i. of gas was collected from the negative coated 

 wire, and, as in the former case, only a minute bubble appeared 

 in the tube containing the plate, and far too minute for analysis ; 

 the gas from the negative point contracted to half its volume in 

 the eudiometer ; the residue was hydrogen as before. 



5th. In the above experiments I had used from 2 to 3 oz. of 

 distilled water, with a few drops of sulphuric acid added to im- 

 prove its conducting power, without paying any particular atten- 

 tion to the exact quantity of acid which was mixed. 



I now determined to try different degrees of dilution of the 

 acid, and to note more accurately its proportion to the water. I 

 first took the extreme case of dilution, using 3 oz. of distilled 

 water, and merely touching it by a narrow glass rod which had 

 been dipped into sulphuric acid. 



The coated wire was the positive pole, the plate of platinum 

 foil the negative ; 0*3 c. i. was collected from the coated wire, 

 and not a trace of gas was perceptible in the tube containing the 

 plate. The gas contracted to one-half its volume in the eudio- 

 meter, and the residue, mixed with one-half its volume of oxy- 

 gen, contracted to 0*3 of its original volume ; the residue of this 

 second contraction appeared to be nitrogen, and its greater quan- 

 tity in this than in the previous experiment was doubtless due 

 to the greater time which, from the inferior conducting power of 

 the solution, was necessary for the decomposition, more air having 

 thus entered into solution. In this experiment the liquid was 

 exposed for twenty-four hours, during ten of which the discharges 

 were kept up, while in the previous experiment less than an hour 

 was sufficient, and the water had not cooled from its preliminary 

 boiling before the experiment was completed. 



6th. I next tried a strong solution of sulphuric acid, spec, 

 grav. 1'23; the gas from the coated point, which was positive, 

 contracted to 0*2 of its volume ; the residue was hydrogen. 



7th. I used a still stronger solution, spec. grav. 1*45, both 

 points being coated ; the volume from the negative pole was to 

 that from the positive as 4*5 to 3*25 ; the gas from the negative 

 pole contracted in the eudiometer to only 0*95 of its volume ; 

 the residue was pure oxygen ; the gas from the positive pole 

 contracted to 0*5; the residue was hydrogen. Here, to my 

 surprise, there was, after the first contraction, a residuum of 

 oxygen in the ratio of more than 2 volumes to 1 of the residuum 



