fcended fome quicker than others, according to their Different 
Magnimdes. That the Defeending Globules of Light (as by 
a ftrift Obfervation I have fince made) did not Aide down 
the fides of the Glaflles, but were carried round by their own 
weight, as if they were turn'd on an Axk: Which is very 
well worth notice. That the Defcending Globules had a 
Double Motion, the one Perpendicular, the other as a Rota- 
tion on an Axk. And in that motion the Adhering parts of 
Quickfilver were continually tearing from the fides of the 
Glaffes, producing an Apt form, which in fuch a mzdium^ 
from fuch a Body, exhibits Light. That the fmaller Glo- 
bules, whofe weight were not fufHcient to caufe their De- 
fcent, remained opake, there being (in this as well as all other 
Mercurial Experiments ) no Light to be obtained withouc 
Motion. That the fame Motion given to the like Globules 
ot Quickfilver in common Air, produce not the fame EfFedt, 
as I have lately try'd, by forcing Mercury through Leather, 
by Condenfing Air ftrongly on the furface of it. From all 
which it feems to appear very Plain, thatt there is Required 
the Concurrence of a Proper Figure, Medium^ and Motion^ 
to Produce the Mercurial Phofphore^ 
Experiment IIL 
Shemng that it requires not fo thin a Medium, as is made by the 
Weight of the Mercury in the Torricillian Experiment^ t§ 
produce the Mercurial Phqfphore. 
'Tr*0 try whether fo thin a Medium as a Vacuum^ or the 
Jl Neareft Approach to it, was Abfolutely neceflary m 
the Produftion of fuch a Light as is Difcoverable in the 
Barometer, by putting the Meu ury in motion, I made ufe 
of the Gage belonging to my air Pump, as (I thought J the 
moft Proper Inftrument for that Purpofe. f Which Gug;s 
being fo well known to this Soc-iety, I need not here trou!;ie 
you with a Defcription of it. ^ Upon the Plare ot tha 
Pump I placd a fmall Receiver, the Air from which being 
