Opticks 1717 - Up

and cons;cstcd into F~mc xnd V:ipour : Which
T/'apour , by the violence Q( that a?-Sian, bc-
Coming fo hot as to Ihinc, q3pcars in the fOlTl3
of &hme.
sf. II. .Do not great Bodies ionferve their
heat the longeit, their part3 ll~iltil~~ Olle anothcs,
and may not great deidk and f&d. Bodies,
when heated beyond a certain degree, e-
mit Light fo copiously, as by thcEmiklion and
l&e-a&on of its Light, and the Keflexlons and
efraf3ions of its Rnj~ within its Ports to grow
itill hotter, Iill it co&s to a &xtain peri0d.d
heat, hch as is that of the Sun? And L1i-e not
the SLl2.1 a1:d fiu'd Stars gmr E?ITllS vel~elnently
hot, IA7llOf‘C llC3t is COilieWCd bV t-he @T~ltlldb
of the Bodies, and the mutual Action and Ken&ion
between them, and the Light which they
emit, and mhofe parts are kept ii-on1 fuining a-
t37q7, not only by their f-kityY but alfo by the
wit weight and dcnfity of the Atmofphercs incumbent
upon them ) and very itrongly comreffing
them, and condeniing the Vapours and
E ‘shalations which arife from tficni ? For if
Water be made warm in ,any pellucid V&e1
ennptied of Air, that WateF in the Vaczt~z will
bubble and boil as vehemently as it would in
the opeu Air in a VeiGI fet upon the Fire till
it conceives a much greater heat. l?os #the
weight of the incumbent Atmofphere keeps
doxvn the Yapours, and hinders the Water from
boiling, until it-grow much hotter thau is requiiite
to made x-r boil in VaCzbo. Alfo a mixture
of Tin and Lead being put upon a red hot
km ia mcm emits a Fume and Flame, but the
fame