Electricity. 457 



electro-motive action of the strongest and weakest of the 

 electromotors upon the fluid, and are accelerated by the 

 immediate contact of two solid electromotors, when the 

 latter are good conductors. 



8. The chemical changes which take place in the fluid 

 are, it is true, in proportion to the neutralization of the 

 two electricities produced by the solid elements of the 

 chain. But these chemical changes, and the neutralization, 

 do not follow as cause and effect. 



9. In the system of chains which forms the pile of Volta, 

 the opposite electricities are completely neutralized by the 

 solid elements of each chain ; that is to say, by the pairs 

 of plates; and there is no electrical current from one pair 

 to the other. ' \L Institut . 150.) 



Electricity from deoxidation. It is well known, that 

 when the peroxide of manganese is brought in contact 

 with platinum, positive electricity passes into the platinum, 

 and the negative into the finger, or whatever body the pe- 

 roxide is touched with. De Larive has ascertained that 

 the developement of the electricity proceeds from chemical 

 action, as it is very weak with distilled water, but becomes 

 stronger with acids or alkaline solutions ; for wood being 

 substituted for the platinum, the same effects are produced 

 when the finger is dipped in an acid or alkaline solution, 

 and applied to it. {Ibid, 155.) 



Peroxide of Lead, according to Munck, when brought 

 in contact with other electromotors, as copper, zinc, car- 

 bon, and peroxide of manganese, developes negative elec- 

 tricity much more strongly than any other body hitherto 

 examined ; and forms an excellent conductor of elec- 

 tricity. Hence, it may be employed with great advantage 

 in the construction of dry piles, and even in common piles, 

 instead of copper. (Poggendorff's Ann. 1835-6.) 



Temperature of Vapour. It is generally supposed that 

 the vapour of water disengaged from a boiling saline solu- 

 tion, has exactly the same temperature as the upper layer 

 of this solution ; and that the vapour possesses only in this 

 case an elasticity equivalent to the pressure of the atnio- 



