12 
Mr. Davy’s Lecture on some 
portion of nitrogene gas remaining in contact with the water, 
seemed adequate to the effect. 
I repeated the experiment under more conclusive circum- 
stances. I arranged the apparatus as before ; I exhausted 
the receiver, and filled it with hydrogene gas from a conve- 
nient airholder ; I made a second exhaustion, and again intro- 
duced hydrogene that had been carefully prepared. The 
process was conducted for 24 hours, and at the end of this 
time neither of the portions of the water altered in the slightest 
degree the tint of litmus. 
It seems evident then that water, chemically pure, is de- 
composed by electricity into gaseous matter alone, into oxygene 
and hydrogene. 
The cause of its decomposition, and of the other decompo- 
sitions which have been mentioned, will be hereafter discussed. 
III. On the Agencies of Electricity in the Decomposition of 
various Compounds. 
The experiments that have been detailed on the production 
of alkali from glass, and on the decomposition of various 
saline compounds contained in animal and vegetable sub- 
stances, offered some curious objects of enquiry. 
It ,was evident, that in all changes in which acid and alkaline 
matter had been present, the acid matter collected in the water 
round the positively electrified metallic surface ; and the al- 
kaline matter round the negatively electrified metallic surface ; 
and this principle of action appeared immediately related to 
one of the first phenomena observed in the Voltaic pile, the 
