( ^2^4 ) 
of fubftance that is^ which, though hitherto overfeen 5 and 
being a Fluid far more fubtile tbao vifible Liquorsjand able to 
pierce iato the CompaS: aad Solid bodies of Metals, can yet 
^ddjr^^ that has do dcfpicable weight upon 
the BajlaQcej aodisableforacoofiderable time to continue, 
fixtio the Fire^ 
This part is followed by fotne Additional Experiment/ about 
Arrejiing ^Lud Weighing of Igneom CorpufcUs y which fmce they 
ihtWj that what is afK>rded by Fire may in a corporeal way in- 
vadfj adhere, aod add Weight to even fixt and ponderous 
Bodiesjdo thereby open a large field to the Speculative to ap- 
ply this difcGvery to divers Fhcenomena of Nature and Chy- 
After this he proceeds to another Dlfcove ry^ which is of the 
Permofijkefs of G/afi to Ponderable Parts of Flame^ And here^ 
that he xBighc not only obviate fome fcruples that may be en- 
tenaio'dby fufpitious Wits upon that Circutnftance of the 
prccediag Additional Experiments 5 v\z, thai the GUffes em^ 
phjed about them were mt expofed to the aUton of meer Flame j 
^^tmreheldupon Charcoals h which may feem to contain but a 
grofie : kind of Fire 5 but alfo that by diverfifying the Way of 
tryal , he might render fuch Experiments both more fit to af- 
ford Corollaries^ /i^J moreferviceable tqhis other purpofesj 
He attempted to make it fucceed with a Body fo thio and dif- 
engaged from grofs matter 5 as meer Flame is allow'd to be^ 
knowing, that by going cautioufly with it to work , one might 
/ handle a Retort without breaking it^ io fpite of a violent agi- 
tation of kindled matter. 
Meantime, by the Experiments here recited concerning 
this argument^ the Author pretends not to make out the Poro* 
jity of Glafs any furthers than is expreft in the Title of this 
Difcoursj namelyj io reference to fome of the Ponderable 
Parts of Flame, For he thinks not Glafs to be eafily penetra- 
ble either by Chymical Liquors^^jr by Quickfil ver,<?r at leaft by 
our Air, Again^haviog compared the increafe,he obferv'd ro be « 
made in the Weight of the Bodies expo fed by him to the naked 
Fife , and thole of tha fame or the like kind^ included by hira 
.io Glafles, orfomuch as io Crucibles , he efteems it worth 
eoofideiiogj Whether this difference io acquired Weight may , 
' Dol:" 
