tiZo ) 
contribute to ihd]Phcenomenon, fince I have often obferv’d 
that Loaf Sugar, when (truck or broke in the dark, affords 
a Light, and I cannot tell but Salts as clofely united in 
their parts as the prementioned Sugar, may 'give a Light 
upon a violent reparation of them, till I have made fome 
Tryals, in relation (as near as I can ) to a true difcovery 
of "it : (Which 1 defign with the firft opportunity.) 
The firft will be to try whether the Medicine when broken 
in Vacuo will afford any Light, which I think 1 may ex- 
pert if it proceeds from the Mercury, fince if there be any 
fuch Quality in that body, it feems to be the mod proper 
Medium to difcover it in. Secondly,, what the Salts will 
do without Quick filver, both in the open Air and in Va- 
cuo 5 for there are fome Bodies that appear light in the 
dark in the open Air, which altogether lofe that finning 
Quality in Vacuo . As for inftance, I took a piece of 
Wood, (which 1 fuppofe had lain under ground a con- 
siderable time,) it was very mot ft, but not rotten, and 
appear’d very vividly of the Colour of Fire in the dark : 
Having included it under a Receiver on my Pump, l found 
as the Air was taken from it, fo did theFire-like Ap» 
pearance of it decay, till at lair in Vacuo it became per* 
ieftly void of Lights and as the Air was lec in again, fo 
by degrees it recover’d its priftine Appearance. This 
? repeated 1 feveral times with the like fuccefs. Now beg- 
ging pardon for this long digreffion, l proceed to the lat- 
ter part ©f the Experiment. After the Attrition of the 
exhaufted Globe was continu’d tor fome rime, the pre- 
men honed Cock was return’d, which gave liberty for the 
Air to infinuate into the Globe through the joynts of 
the Screw S;j the motion of the great Wueel and the 
application of the Hands continuing, ail the while And 
as the Air fill'd the Globe, fo the mode of Light conti- 
nu’d to- after;. till the. like quantity of Air had re enter’d 
as was taken from it , then, became a., great a difference 
af Light from what was proauc'dl when evacuated of 
