Lesson xxi.] ELECTRICITY. 127 



piece of flannel, rub briskly that side of the under 

 plate which is covered with sealing-wax, place it on 

 a table with the excited side upward ; set the upper 

 plate exactly on the lower, touch the upper plate 

 with the finger, then raise the upper plate by the 

 handle, and it will give a spark of Electric Fire to 

 any conducting substance. By repeating the ope- 

 ration, another spark may be obtained, and s on. 

 If the upper plate be not touched with the ringer, 

 or some conducting substance, no spark can be 

 obtained. If the sparks be given to the ball of,a 

 coated* phial, it will become charged, and the 

 Electric Shock may be given. 



Having said thus much concerning an Electrical 

 Machine, I will proceed to describe a few more 



experiments. If one body, as suppose a piece 



of metal, be kept for some time in an electrified 

 state, by means of the machine, and an unelectri- 

 fied light body, as suppose the down of a feather, 

 be brought near the metal, the feather will be at- 

 tracted to it, and thence electrified: on which ijt 

 will be immediately repelled from it, and will not 

 return to it again, till after it has touched some un- 



* Bottles may be easily coated in the following manner : 

 Take bismuth two parts, lead and tin of each one part, melt 

 them together and carefnlly skim off the dross ; remove the 

 mixture from the fire, and, before, it grows cold add ten parts 

 of hot mercury ; stir the whole together, and the amalgam 

 when cold, is fit for use. Let the bottle, to be coated, be quit* 

 new and clean ; put into it a sufficient quantity of the amal- 

 gam, incline the bottle, and gently turn it round that the 

 composition may adhere to every part, ponr out the super- 

 fluous amalgam, and the bottle will be beautifully coated. 



G 4 electrified 



