158 THE STORY-BOOK OF SCIENCE 



"Well, there is something still more hidden than 

 air, more invisible, more difficult to detect. It is 

 everywhere, absolutely everywhere, even in us; but 

 it keeps itself so quiet that until now you have never 

 heard of it. " 



Emile, Claire, and Jules exchanged glances full of 

 meaning, trying to guess what it could be that was 

 found everywhere and that they did not yet know of. 

 They were a hundred leagues from guessing what 

 their uncle meant. 



"You might seek in vain by yourselves all day, all 

 the year, perhaps all your life ; you would not find it. 

 The thing I am speaking of, you understand, is sin- 

 gularly well hidden ; scholars had to make very deli- 

 cate researches to learn anything about it. Let us 

 make use of the means they have taught us to bring 

 it to light. " 



Uncle Paul took from his desk a stick of sealing- 

 wax and rubbed it rapidly over his cloth sleeve ; then 

 he put it near a small piece of paper. The children 

 were all eyes. Behold, the paper flies up and sticks 

 to the sealing-wax. The experiment is repeated sev- 

 eral times. Each time the paper rises unaided, 

 starts off, and fastens on to the stick. 



' ' The piece of sealing-wax, which formerly did not 

 attract the paper, now does. The rubbing on the 

 cloth has, then, developed in it something that can- 

 not be seen, for the stick has not changed in appear- 

 ance; and this invisible thing is nevertheless very 

 real, since it can lift up the paper, draw it to the wax, 

 and hold it glued there. This thing is called elec- 

 tricity. You can easily produce it by rubbing on 



