surrounding Media on Voltaic Ignition. 



115 



platinum wire, one-eightieth of an inch diameter and 3*7 inches 

 long when uncoiled. Tube A was filled with oxygen, tube B 

 with hydrogen, and the tubes thus prepared were immersed in 

 two separate vessels, in all respects similar to each other, and 

 containing each 3 oz. of water. A thermometer was placed in 

 the water in each vessel ; the copper wires were connected, so 

 as to form a continued circuit, with a nitric acid battery of eight 

 cells, each plate exposing eight square inches of surface. Upon 

 the circuit being completed the wire in the tube containing 

 oxygen rose to a white heat, while that in the hydrogen was 

 not visibly ignited ; the temperature of the water, which at 

 the commencement of the experiment was 60° F. in each 

 vessel, rose in five minutes in the water surrounding the tube 

 of hydrogen from 60° to 70°, and in that containing oxygen 

 from 60'' to 81°*. 



Before I enter into a further detail of experiments, I would 

 remark upon the extraordinary character of this result. The 

 same current or quantity of electricity passes through two 

 similar portions of wire immersed in the same quantity of 



Fig. 1. 



* After the publication of the Bakerian Lecture, my experiment on the 

 peculiar effect of hydrogen on the ignited wire was noticed in a paper by 

 M. Matteucci, which though I had it in my hand shortly after its publi- 

 cation, I regret to say I did not read with the attention it deserved. I have 

 read it since the experiments in this paper were commenced, and I see that 

 I am now executing a task assigned to me by my friend. M. Matteucci, 

 for a different object, makes a somewhat similar experiment to the one 

 given above, which however differs from mine in the material point, that 

 he operated first on one gas and then on the other, and thus did not com- 

 pare the effects produced by the same quantity of electricity. I cannot 

 quite agree in the conclusions deduced by him from this and the other 

 experiments he cites, but I will not here contest them, as it would lead me 

 away from the main point of this paper. 



1 2 



