COMMON THINGS. WATER. 



Fig. 3. 



bodies ; the positive pole for some, and the negative for others. 

 Now it happens that of all natural bodies that for which the 

 positive pole has the strongest attraction is oxygen, and one of 

 those for which the negative pole has a strong relative attraction 

 is hydrogen. If, therefore, under certain conditions the two poles 

 be brought to act on water, it may be ex- 

 pected that its decomposition will ensue, the 

 oxygen being disengaged at the positive, 

 and the hydrogen at the negative pole, and 

 this in fact does take place. 



44. Various forms of apparatus have been 

 contrived for the exhibition of this experi- 

 ment. The most simple and instructive is 

 represented in fig. 3. 



Two small holes are pierced near the 

 bottom of a wine-glass, through which the 

 ends of two wires, G and H, being inserted, 

 so as to rise to the height of an inch or 

 two near each other in the glass, they are 

 cemented in the holes by mastic. These 

 wires are put in connection, one with the 

 positive or -}- pole, and the other with the 

 negative or pole of a voltaic battery. 

 Water, slightly acidulated to give it more 

 conducting power for electricity, is then 

 poured into the glass, and two graduated glass tubes, A B and c D, 

 each about half an inch in their interior diameter, being first filled 

 with acidulated water, and being stopped at the open ends by the 

 hand, are inverted and immersed in the glass, one over each of the 

 wires. The water will then be supported in the tubes by the 

 atmospheric pressure. 



The electric current will now immediately begin to flow from 

 the extremity of one wire through the water to the extremity of 

 the other, and by its attraction the water will be decomposed, the 

 oxygen constituent being attracted to the extremity of the positive, 

 and the hydrogen to that of the negative wire. These gases will 

 be therefore disengaged at the points of the wires as if they 

 issued from them, as they would from small apertures in vessels 

 containing them. They will be seen rising rapidly in small 

 bubbles in each of the tubes, in the upper parts of which they 

 will collect, displacing the water and pressing it downwards. 

 After a short time, the tube containing the negative wire will be 

 filled with gas, the water being totally expelled from it from the 

 top to the level of the water in the glass, and at the same time 

 the tube over the positive wire will be half filled. 

 110 



