3 88 EXPERIMENTAL INVESTIGATIONS. 



the gas contracted in the eudiometer to 07 of its volume ; the 

 residue, mixed with half its volume of oxygen, detonated, 

 leaving a very small residuum. 



4th. In the converse experiment, i.e. coated wire negative, 

 plate positive, o - 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 



Fig. 2. 



improve its conducting power, without paying any particular 

 attention 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 pla- 

 tinum foil the negative ; O'3 c. i. was collected from the coated 

 wire, and not a trace of gas was perceptible in the tube con- 

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

 in the eudiometer, and the residue, mixed with one-half its 

 volume of oxygen, contracted to 0*3 of its original volume ; 

 the residue of this second contraction appeared to be nitrogen, 

 and its greater quantity in this than in the previous experi- 

 ment 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. 



