CH. XXIX. EXPERIMENTS IN ELECTRICITY. 255 



You must also know^ that when any substance is full of 

 electricity, if you bring your finger or a piece of metal near 

 to it, a spark will pass between the electrified substance and 

 your finger or the metal. 



You will now, I think, be able to follow Franklin's 

 experiments. He put a person, whom we will call A, upon 

 a glass stool, and made him rub the metal cylinder of an 

 electrical machine with one hand and place his other hand 

 upon it to receive the electricity. Now, he said, if elec- 

 tricity is created by the rubbing, this person must be filled 

 with it, for he will be constantly taking it from the machine, 

 and it cannot pass away, because of the glass legs under the 

 stool. But he found that a had no more electricity in 

 him after rubbing the cylinder than he had before, neither 

 could any sparks be drawn out of him. He then took 

 two people, A and b, and placing each of them on a glass 

 stool, made a rub the cylinder, and b touch it, so as to receive 

 the electricity. Now notice carefully what happened, b was 

 soon so full of electricity that when Franklin touched him, 

 sparks came out at all points ; but what was still more curious, 

 when Franklin went to a and touched him, sparks came out 

 between them just as they had done between him and b. 



This he explained as follows : ' a, b, and myself,' he said, 

 ' have all our natural quantity of electricity. Now when a 

 rubbed the tube, he gave up some of his electricity to it, and 

 this B took, so that a had lost half his electricity and b had 

 more than his share. I then touched b, and his extra 

 charge of electricity passed into me and ran away into the 

 earth. I now went to a, and I had more electricity in me 

 than he had, because he had lost half his natural quantity, 

 and so part of my electricity passed into him, producinff 

 the sparks as before.' 



