108 On the Franklin'wn Theory 



TABLE OF EXCITATION. 



T.li-cty'icnl 'Substances. Rubber. ^iwliiy. 



Back of a cat Every substance - - pos. 



Glass — smooth Ditto _ _ - - pos» 



rough Silk, sulphur, or metals - pes. 

 ditto Woollens, paper, wax, hand neg. 



Tourmalin - Amber or air blown upon it pos- 



Ditto - Hand . _ - - neg. 



Harcskin - Metals, silk, leather, hand - pos. 



Ditto - Fine furs - - - - ncg. 



iiilk — black - Sealing-wax _ - - pos. 



Skins, metals, hand - - neg. 



white - Black silk or cloth, metals - pos. 



Paper, skins, hand - - neg. 



Sealing-wax IMetals _ - - - pos. 



Skins, hand, woollens - - neg. 



Baked wood Silk _ _ _ - pes. 



Flaimel _ _ _ - neg. 



The sixth proposition comprises another material source 

 of electrical knowledcre. It states, in the drst place, that 

 an excited electric is capable of conn-nunicating, by contact 

 or by such proximity as shall permit the free passage of the 

 electric fluid through the air, an electricity producing upon 

 other bodies precisely the same effects as such excited elec- 

 tric. From this principle is derived the utility of what is 

 called the prime conductor of an electrical machine. This 

 conductor receives, and retains by its insulation, the electric 

 •fluid from the excited cylinder, which by this means wc 

 have the advantage of obtaining in a more powerful and 

 concentratcfl state, since by its facility of transmission over 

 ♦he whole surface of such conductor the quantity collected 

 from its yarious points, on presenting to it another con- 

 ducting substance, passes off in a single spark, not in mi- 

 nute portions as it was received. This proposition states 

 in the second place, that an excited electric, w hose position 

 is such with respect to another body that no spark or other 

 passage of the fluid can take place, will induce upon that 

 body an opposite state of electricity. If an excited t^ibe be 

 brought near any substance communicating with the ground 

 (but prepared for insulation), this substance when insulated 

 will be found to indicate the negaiive state of electricity : 

 jf^ on the contrary, an excited stick of sealing-wax be pre- 

 eented, the positive st.'.te will be induced. This circum- 

 stance appears to be owing to the repulsive qr.a^.ities imputed 

 to the electric fluid, so often ;:''iiced in the course of our 

 inquiry : the fluid in the excited tube is supposed to repel 



♦I quantity 



