ELECTRICITY. 479 



serve special mention. These are however few. Near- 

 ly all the phenomena which have attracted attention, are 

 those which result from disturbances, produced by nature 

 or art, in the equilibrium which electricity ordinarily 

 assumes. Sometimes this equilibrium is disturbed, i. e. 

 an unusual quantity of electricity is collected, or a body 

 is deprived of its natural share by the electrical machine, 

 and sometimes this effect is produced by the great pro- 

 cesses of nature. We are thus presented with the various 

 phenomena of the laboratory, or the dreadful explosions, 

 which take place in clouds and storms. We proceed, 

 therefore, to describe the modes by which electricity is 

 accumulated. 



II. MEANS OF ACCUMULATING THE ELECTRICAL POWER. 



1. By condensation of moisture. If water is poured 

 upon burning coals, a great quantity of vapor is produc- 

 ed, which, rising into the cold air, is immediately con- 

 densed, forming a white cloud, which ascends from the 

 blackened coals. If now a wire is exposed to this vapor, 

 which wire is connected with a delicate electrometer, 

 i. e. an instrument hereafter to be described, by which 

 minute quantities of electricity are made sensible, it 

 will be found (hat electricity is accumulated in the va- 

 por. This method is never employed however for prac- 

 tical purposes. It is interesting chiefly from its being 

 the mode by which the fluid is generally accumulated in 

 nature. The clouds are masses of condensed vapor. 

 When they are suddenly formed, they become rapidly 

 charged with the fluid, which darts to other clouds and 

 to the ground, and constitutes the lightning.* 



It is a common though very absurd notion, that the 

 lightning is caused by sulphurous vapors which collect 

 in the air, and by some unaccountable means, take fire 

 and explode. There is no way by which such vapor? 

 can be formed ; if they were formed they would bo 

 diffused and mixed with the atmosphere, and rendered 

 no longer inflammable ; and even if we suppose them 



* See Scientific Tract on the Weather. 



