( U79 ) 
duc’d in the Mercurial Experiments, ( but not as to Co- 
lour ) for in thofe Experiments it was always pale: And 
there being fuch a teeming Congruity of Appearances 
in all the Circumftances of them, with thofe made on 
the Attrition of Glafs without it, that one might with 
fome probability conclude, that the Light produc'd pro- 
ceeds from a Quality in the Glafs, upon fuch a Fri&ion 
or Motion given it 5 and not from the Mercury, any 
other ways than as a proper Body, which falling or rub- 
bing on the Glafs, produces the Light. And that which 
would feem farther to Corroborate fuch a Conclufion is. 
That fome time ago I took a Mercurial Barometer, and 
rubb’d the upper or Deferted part of the T ube between 
my Fingers, and a Light enfu’d, without the motion of 
the Quickfiiver. Yet for all this the Conclufion is doubt- 
ful, and there may be fuch a Quality as Light in Mercury, 
as well as in Glafs or any other body, fince an Experiment 
lately made on purpofe feems to contend for it, and is as 
follows. I took a fmall quantity of Quickfilver, and put it 
into a Galleypot, wherein Varnifb often had been ufed, 
and by that means it had got a pretty thick Lining of it i 
the Weather was at that time moift ( which I purpofe- 
Iy mention, becaufe tl ' humidity in the Air, would fome- 
times render the Expe; ment unfuccefsful even in Glafs, or 
at lead mightily impair the appearance of ir, ) which 
had an influence on the Varnifli,as fomething to foften if- 
However, the fuccefs of the Experiment was, That when 
the Galleypot with its contain’d Mercury came to be in 
Vacuo, upon fhaking the Pump a Light did appear, and 
this without the Concurrence of Glafs, or the favour of a 
more proper Seafon to affift it. Moreover, I am inform’d 
by feveral Perfons. of credit, that the Medicine call’d Mer- 
curius Dutch, when broken in the dark, gives notable 
FlaQies of Light 5 but the Mercury in the Medicine being 
pointed with Salts, each little Globule of it is enveloped 
with the fame, that I cannot be alfur’d the Salts do nor 
148 2 con- 
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