GALVANISM. ISQ 



finished. The sides of the pile may be supported with rods 

 of glass, or varnished wood, fixed in the board on which it is 

 built. Having wet both hands, touch the lower part of the 

 pile with one hand, and the upper part with the other, 

 constant little shocks of electricity will be felt until one 

 hand be removed. If the hand be brought back a similar 

 repetition of shocks will be experienced. Hold a silver 

 spoon in one hand, and touch with it the battery in the lower 

 part, then touch the upper part with the tongue ; the bitter 

 taste is extreme. If the end of the spoon be put under the 

 eyebrow, close to the ball of the eye, a sensation will be felt 

 like the burning of red-hot iron, but which ceases the instant 

 the spoon is removed. The plates will soon become oxy- 

 dated, and require cleaning in order to make them act. 



Questions. — 1. What is galvanism ? 2. Give an account of the 

 origin of this branch of philosophy. 3. How may a person be n)acle 

 sensible of this kind of electric action ? 4. What was the discovery 

 of Volta ? 5. What are perfect conductors of galvanic fluid .'' — im- 

 perfect .'' 6. What is necessary in order to render the galvanic or vol- 

 taic power sensible .'' 7. When is the combination said to be of the 

 first order ? — second order ? 8. How may a pile or battery of the first 

 order be formed .'' 0. What is a cheap and easy method of forming 

 a voltaic pile ? 10. What experiments may be formed with such a 

 pile ? 11. Why do the plates require cleaning ? (See Voltaic pile, 

 fig. 47.) 



LESSON 71. 



Galvanism (continued.) 



Lab'oratory, a room fitted up with apparatus for the performance 



of chemical operations. 

 Deflagrate, to burn rapidly: nitre thrown on hot coals defla- 

 grates. When accompanied with a loud noise it is termed d^t- 

 o-na'tion. 

 The most convenient kind of galvanic battery consists of 

 a trough made of baked wood, three inches broad, and about 

 as deep ; in the sides of the trough are grooves opposite to 

 each other ; into each pair of grooves is fixed; by cement, a 

 plate of zinc and silver soldered together, and in the order 

 of silver and zinc ; the cement must be filled in so as to pre- 

 vent any communication between the difierent cells. The 

 cells are to be filled with water and nitrous acid^ and then 



