ON THE CONSERVATION OF FORCE. 353 



therefore, of hydrogen for oxygen, like that of carbon for 

 oxygen, performs work in combustion, 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 separated, 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 



FIG. 48. 



g 



vessels filled with acidulated water, a and a 1 , 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 1 . 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 1 . 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 1 . 

 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 



