ON THE CONSERVATION OF FORCE. 



309 



which appears in the form of heat. In the water which 

 has been formed during combustion, the force of affinity 

 is exerted between the elements as before, but its capacity 

 for work is lost. Hence the two elements must be again sepa- 

 rated, their atoms torn apart, if new effects are to be produced 

 from them. 



This we can do by the aid of currents of electricity. In the 

 apparatus depicted in Fig. 48, we have two glass vessels filled 

 with acidulated water, a and a which are separated in the 

 middle by a porous plate moistened with water. In both sides 

 are fitted platinum wires, k, which are attached to platinum 



plates, i and i ,. As soon as a galvanic current is transmitted 

 through the water by the platinum wires, k, you see bubbles of 

 gas ascend from the plates i and i j. These bubbles are the two 

 elements of water, hydrogen on the one hand, and oxygen on 

 the other. The gases emerge through the tubes g and g ,. If 

 we wait until the upper part of the vessels and the tubes have 

 been filled with it, we can inflame hydrogen at one side; it 

 burns with a blue flame. If I bring a glimmering spill near 

 the mouth of the other tube, it bursts into flame, just as happens 

 with oxygen gas, in which the processes of combustion are far 

 more intense than in atmospheric air, where the oxygen mixed 

 with nitrogen is only one-fifth of the whole volume. 



