204 Our Surroundings 



magnetism, for the magnet will not attract paper. It remained 

 for William Gilbert, physician to her majesty Queen Elizabeth 

 of England, to show that other objects possess the same power 

 of attraction. He it was who coined the word electricity from 

 the Greek word elektron, meaning amber. 



Substances that attract other substances as amber does are 

 said to be electrically charged. Glass stroked with silk, and seal- 

 ing wax rubbed with woolen cloth have been used for centuries, 

 and still are used, to illustrate this phenomenon of static elec- 

 tricity in electrically charged substances. Many other materials 

 will become electrically charged under favorable conditions. 



Experiments to Illustrate Static Electricity. Rub a stick 

 of sealing Wax with fur or with a dry, warm, woolen cloth. Then 

 bring the wax near small feathers. Notice what happens to the 

 feathers and give the reason. 



Rub a perfectly dry and warm tumbler with a silk handker- 

 chief, also dry and warm. Tear up scraps of paper and hold the 

 tumbler over them. Notice what happens to the scraps of paper 

 and give the reason. 



Cut up, or file, two or three corks into small bits. Put the 

 bits on the middle of a sheet of paper on each end of which 

 are small wooden blocks of equal height. Place a warm pane 

 of glass across the wooden blocks over the cork bits. Rub the 

 upper part of the glass with a warm, dry silk handkerchief. 

 Notice what happens to the bits of cork and give the reason. 



Rub a warm, dry piece of flannel forcibly over a warm, dry 

 fountain pen. Then hold the pen over scraps of paper or over 

 small feathers. Notice what happens and give the reason. 



Kinds of Electrification. There are two kinds of electrifi- 

 cation, named by Benjamin Franklin in the 18th century, posi- 

 tive and negative. The experiment of rubbing glass with silk 

 developed on the glass a charge of positive electricity, and on 

 the silk a negative charge. The experiment with the sealing wax 

 and the fur developed a negative charge on the sealing wax and 

 a positive charge on the fur. The electrical charges developed 

 on these objects by friction sustain a relation to each other 

 quite similar to that of the poles of magnets, in which unlike 



