ELECTRICITY. 



493 



points of contact. Mix now some red lead and sulphur 

 as intimately as possible, and by means of a bellows or 

 some similar contrivance, project them thus mixed 

 through the air. As they pass through the air, the red 

 lead by the friction becomes electrified vitreously, and 

 accordingly it will be attracted towards the resinous 

 spots. The sulphur electrifies itself resinously and will 

 accordingly be drawn towards the vitreous spots. Thus 

 the two powders will be entirely separated, and will ar- 

 range themselves in beautiful figures upon the plate. 

 They will gather around the vitreous spots in long and 

 beautiful ramifications, extending in every direction from 

 the point touched, and upon those electrified resinously 

 the powder will gather in a circle uniformly covered, 

 but not very distinctly defined. 



' These powders may be sifted over the electrified 

 body from a common sieve ; they may be tied up in linen 

 rags, and shaken out of them ; they may be projected by 

 means of a brush ; also by means of a pair of bellows. 

 But a more commodious method is as follows : Fix a 

 tube of wood, or glass, or metal, to the neck of a small 

 bottle of India rubber ; put the powders to be projected 

 into this bottle, and then tie a double piece of flannel 

 over the aperture of the tube. If this bottle, so prepar- 

 ed, be held in the hand, and be squeezed by alternately 

 Opening and shutting the hand, the powders will be pro- 

 jected in a fine diffused manner.' 



These experiments with the powders may be almost 

 endlessly varied. The following are some of the most 

 usual forms. 



(a) ' Take a pane of glass, clean and dry, hold it sus- 

 pended by one corner, or lay it flat upon a table, and 

 draw over the surface of it the knob of a Leyden phial, 

 moderately charged with positive electricity in its inside ; 

 then lift up the glass, if laid upon the table, and holding 

 it suspended, project upon it a mixed powder, consist- 

 ing of powdered dragon's blood and gum arabic in equal 

 parts. The two powders will be separated upon the 

 glass ; the red powder of dragon's blood falling on cer- 

 tain places, so as altogether to form an oblong, radiated 

 track, consisting of two colors intermixed in a thousand 



