( *6 A ) 
Electricity, and the other reftnous Electricity. The 
firfl is that of Glafs, Rock-Cryltal, Precious Stones, 
Hair of Animals, Wool, and many .other Bodies: 
The fecond is that of Amber, Copal, Gum-Lack, 
Silk, Thread, Paper, and a vaft Number of other 
Subftances. The Charaderiftick of thefe two Elec- 
tricities is, that a Body of the vitreous Electricity, 
for Example, repels all fuch as are of the fame E- 
leCtricity ; and on the contrary, attracts all thofe 
of the reftnous Electricity \ fo that the Tube, 
made eledrical, will repel Glafs, Cryftal, Hair of 
Animals, &c. when render’d eleCtrick and will at- 
trad Silk, Thread, Paper, &c. though render’d 
eledrical likewife. Amber on the contrary will at- 
trad eleCtrick Glafs, and other Subftances of 
the fame Clafs, and will repel Gum-Lac, Copal, 
Silk, Thread, &c. Two Silk Ribbons rendered' 
electrical, will repel each other ■, two Woollen 
Threads will do the like ; but a Woollen Thread 
and a Silk Thread will mutually attrad one another. 
This Principle very naturally explains, why the Ends 
of Threads, of Silk, or Wool, recede from one ano- 
ther in Form of a Pencil or Broom, when they have 
acquired an eledrick Quality. From this Principle one 
may with the fame Eafe deduce the Explanation of a 
great Number of other Phenomena. And ’cis pro-' 
bable, that this Truth will lead us to the further 
Difcovery of many other things. 
In order to know immediately, to which of the 
two Gaffes of Electricity belongs any Body what* 
foever, one need only render Eledrical a Silk Thread, 
which is known to be of the reftnous Electricity, , 
and fee whether that Body, render’d electrical, ,, 
attracts 
