( I 2 *5 ) 
attraCs or repels ir. If it attraC:?, 'tis certainly of 
that kind of Electricity which I call vitreous-, if on 
the contrary it repels, ’tis of the fame kind of Electri- 
city with the Silk, that is, of the reft nous. 1 have 
likewife obferved that communicated EleCtricity re- 
tains the fame Properties : For if a Ball of Ivory, or 
Wood, be fet on a Glafs Stand, and this Ball be ren- 
der’d eleCtrick by tlae Tube, it will repel all fuch Sub- 
ftances as the Tube repels ; but if it be rendered 
electrick by applying a Cylinder of Gum-Lac near 
ir, it will produce quite contrary EffeCts, viz-, pre- 
citely the fame as Gum-Lac would produce. In or- 
der to fucceed in thefe Experiments, ’tis requifire 
that the two Bodies, which are put near one another, 
to find out the Nature of their EleCfricity, be ren- 
dered as- eleCtrical as poflible ; for if one of them 
was not at all, or but weakly eleCrical, it would be 
attraded by the other, though it be of that Sort, 
that fhould naturally be repelled by it. But the 
Experiment' will always fucceed perfeCly well, if 
both the Bodies are fufficiently eleCtrical. 
I havefeveral other Methods to difeover the Ma- 
ture of the EleCricity any Body is of; but my 
Letter is already long enough, and my Defign was 
only to give your Grace a very fuccinC: ExtraC of 
the Experiments I have made this laft Year. I be- 
feech your Grace to communicate it to the Royal 
Society , and in particular to Mr. Gray , who works 
on this SubjeC with fo much Application and Succefs, 
and to whom I acknowledge my feif indebted for 
the Difcoveries I have made, as well as for thofe I may 
poflibly make hereafter; fince 'tis from his Writings 
. that 
