open Air you put your hand or any thing elfe a littic 
over it, to hinder its Communication with the Sky, it 
gives no Light: And Ido alTureyou, I have try*d^^ll or 
moft of the other Precious Stones, but could find' no'fuch 
in any of them ^ and I muft further add, that 
all the Experiments here related were made at the latter 
end of May and beginning of and thereforel can*t 
pretend to account for' the Fk^namena that may attend 
Experiments made while the Sun is on the other fide ot 
the Equator. 
There are fome other Bodies that afford Light, and [per- 
haps many more remain yet undifeover’d, but I’m well 
allur’d, that all or moft of the Bodies which haA C an 
£le<ftricity yield Light 5 for in my Opinion, ’fis the Light 
that is in ’em, which is the caufe of their being Eledtral; 
yet this Eledtriciry never (hows it feU wkhout fridtion ^ 
if ycu rub any Body that has an Ele(ftricity, and apply it 
near to Tome light Bodies, as particularly very thin Sli- 
ces of Cork, ’twill put them into a great Agitation, and. 
makqthera feetn to the Eye as hanging at the Body by a 
fine Hair. 
I forbear fpeaking of Jet, which Teems to me to be a 
black Amber, having moft of the Properties of Amber, 
but not fo perfedf and pure. 
I muft not forget'to fpeak of another Subftance fo fre* 
qnently made ufe of by almoft all forts of People, not 
hitherto by any, I as know, taken notice of to be endu’d 
with a luminous Quality, wdiich is alfo another Natural 
Pkofphorfis^oT No&iluca^SLnd that is Gum L^r,and alfo Red 
Sealing-Wax, which is made with Gum Lac 3.nd Cinabar^ 
the way impeding, but rather promoting itsLu** 
minous Quality, for I caus’d long taper Rolls to be made 
up of Lae alone, and of pure Red Sealing-Wax, both be* 
ing well polifh’d :■ The Sealing-Wax upon fridfion, feems 
tome to emit its Crackling and Light fooner than the 
which. 
