310 



ON THE CONSERVATION OF FORCE. 



If I hold a glass flask filled with water over the hydrogen 

 flame, the water, newly formed in combustion, condenses upon it. 



If a platinum wire be held in the almost non-luminous 

 flame, you see how intensely it is ignited ; in a plentiful current 

 of a mixture of the gases, hydrogen and oxygen, which have 

 been liberated in the above experiment, the almost infusible 

 platinum might even be melted. The hydrogen which has here 

 been liberated from the water by the electrical current has re- 

 gained the capacity of producing large quantities of heat by a 



FIG. 49. 



lit- 



fresh combination with oxygen ; its affinity for oxygen has re- 

 gained for it its capacity for work. 



We here become acquainted with a new source of work, the 

 electric current which decomposes water. This current is itself 

 produced by a galvanic battery, Fig. 49. Each of the four 

 vessels contains nitric acid, in which there is a hollow cylinder 

 of very compact carbon. In the middle of the carbon cylinder 

 is a cylindrical porous vessel of white clay, which contains 

 dilute sulphuric acid ; in this dips a zinc cylinder. Each zinc 

 cylinder is connected by a metal ring with the carbon cylinder 

 of the next vessel, the last zinc cylinder, n, is connected with 



