THE REASON WHY. 133 



The Lord also thundered in the heavens, and the Highest gave his voice ; hail- 

 stones and coals of fire. 



or upon the tendency of vitreous electricity to seek out and combine 

 with resinous electricity (assuming that there are two fluids), 



572. Sow does the equilibrium of electricity become 

 disturbed ? 



By changes in the condition of matter. As electricity resides in 

 all substances, and is, perhaps, an essential ingredient in their 

 condition, so every change in the state of matter whether from 

 heat to cold, or from cold to heat ; from a state of rest to that of 

 motion ; from the solid to the liquid, or the aeriform condition, or 

 vice versa ; or whether substances combine chemically and produce 

 new compounds in every change the electrical equilibrium is 

 disturbed ; and, in proportion to the degree of disturbance, is the 

 force exerted by electricity to resume its balance in the scale of 

 nature. 



573. How does electricity seek to regain equilibrium ? 



By passing through substances that are favourable to its diffu- 

 sion ; therefore they are called conducting or non-conducting bodies, 

 according as they favour or oppose the transmission of the electrical 

 current. 



574. What substances are conductors of electricity ? 

 Metals, charcoal, animal fluids, water, vegetable bodies, animal 



bodies, flame, smoke, vapour, &c. 



575. What substances are non-conductors ? 



Rust, oils, phosphorous, lime, chalk, caoutchouc, gutta percha, 

 camphor, marble, porcelain, dry gases and air, feathers, hair, wool, 

 silk, glass, transparent stones, vitrefactions, wax, amber, &c. These 

 bodies are also called insulators. Some of these substances, as 

 chalk, feathers, hair, wool, silk, &c., though non-conductors when 

 dry, become conductors when wetted. 



Insulating preventing from escaping. 



576. Why are amber and wax classed among the non^ 

 conductors, token they have been pointed out as electrics, and 

 used to illustrate electrical force ? 



It is because they are non-conductors that they have displayed, 

 under excitement, the attractive force shown in respect to the 



