Chemical Theory of Electricity and Magnetism. 69 



sion even in passing through eggs and through water, as mentioned 

 above. 



VIII. The shock from the coated jar, and of electric condensation. . 



1. When a glass jar is coated on both sides, and either vitreous or 

 resinous electricity is thrown upon the coating on one side, and there 

 is a communication to the earth from the other side, the same thing 

 happens as in the plate of air between the finger and prime conductor 

 above described; that is, the accumulated electricity, if it be of the 

 vitreous kind, on one coating of the glass jar will attract the resinous 

 part of the electricity, which surrounds or penetrates the coating on 

 the other side of the jar, and also repel the vitreous part of it; but 

 this occurs on a much more extensive surface than in the instance of 

 the plate of air between the finger and prime conductor. 



The difference between electric sparks and shocks consists in 

 this circumstance, that in the former the insulating medium, whe- 

 ther of air, or of thin glass, is ruptured in one part, and thus a com- 

 munication is made between the vitreous and resinous ethers, and 

 they unite immediately, like globules of quicksilver, when pressed 

 forcibly together: but in the electric shock a communication is made 

 by some conducting body applied to the other extremities of the 

 vitreous, and of the resinous atmospheres, through which they pass 

 and unite, whether both sides of the coated jar are insulated, or only 

 one side of it. 



And in this line, as they reciprocally meet, they appear to explode 

 and give out light and heat, and a new combination of the two ethers 

 is produced, as a residuum after the explosion, which probably occu- 

 pies much less space than either the vitreous or resinous ethers did 

 separately before. At the same time there may be another unrestrain- 

 able ethereal fluid yet unobserved, given out from this explosion, 

 which rends oak trees, bursts stone-walls, lights inflammable substances, 

 and fuses metals, or dissipates them in a calciform smoak, along with 

 which great light and much heat are emitted, or these effects are pro- 

 duced by the heat and light only thus set at liberty by their synchro- 

 nous and sudden evolution. 



