160 THE POPULAR SCIENCE MONTHLY. 



Place an egg, J, Fig. 11, on its side upon a dry wineglass ; bring 

 your excited glass tube, 6r, within an inch or so of the end of the egg. 

 What is the condition of the egg ? Its electricity is decomposed ; 

 the negative covering the end a adjacent to the tube, the positive 

 covering the other end b. Remove the glass tube : what occurs ? 

 The two electricities flow together and neutrality is restored. Prove 

 this neutrality. Neither a carrier touching the egg, nor the egg it- 

 self, has any power to affect your electroscope, or to attract a lath 

 balanced in the manner already described. 



Again, bring the excited tube near the egg. Touch its distant 

 part b with your carrier. The carrier now attracts the straw or the 

 balanced lath. It also causes the leaves of your electroscope to di- 

 verge. What is the quality of the electricity ? It repels and is re- 

 pelled by rubbed glass ; the electricity at b is, therefore, positive. 

 Discharge the carrier by touching it, and bring it into contact with 

 the end a of the egg nearest to the glass tube. The electricity you 

 take away repels and is repelled by gutta-percha. It is, therefore, 

 negative. Test the quality, also, by the electroscope. 



While the tube G is near the egg touch the end b with your fin- 

 ger; now try to charge the carrier by touching b: you cannot do so 

 the positive electricity has disappeared. Has the negative disap- 

 peared also. No. Remove the glass tube, and once more touch the 

 egg at b with the carrier. It is charged, not with positive, but with 

 negative electricity. Clearly understand this experiment. The neu- 

 tral electricity of the egg is first decomposed into negative and posi- 

 tive ; the former attracted, the latter repelled by the excited glass. 

 The repelled electricity is free to escape, and it has escaped on your 



Fig. 12. 



touching the egg with your finger. But the attracted electricity can- 

 not escape as long as the influencing tube is held near. On removing 

 the tube which holds the negative fluid in bondage, that fluid imme- 

 diately diffuses itself over the whole egg. An apple, or a turnip, will 

 answer for these experiments at least as well as an egg. 





