284 Amlyfts of the Air. 
fulphur in its Analyfis is found to contain 
an inflammable oil, an acid Salt, a very fixt 
earth, and a little metal. 
Now fulphur and air are fuppofed to be 
acted by that ethereal medium, “ by which 
(the great Sir Ifaac Newton fuppofes) 
light is refraCled and reflected, and by 
whofe vibrations light communicates heat 
to bodies, and is put into fits of eafic 
reflection, and eafie tranfmillion : And 
do not the vibrations of this medium 
in hot bodies contribute to the intenfe- 
nefs and duration of their heat? And do 
not hot bodies communicate their heat 
to contiguous cold ones, by the vibra- 
tions of this medium, propagated from 
them into cold ones? And is not this 
medium exceedingly more rare and fub- 
tie than the air , and exceedingly more 
elaftick and aCUvc ? And does it not rea- 
dily pervade all bodies, Optick qti, 18. 
The elaftick force of this medium, in 
proportion to its denfity, muft be above 
490,000,000,000 times greater than the 
elaftick force of the air is, in propor- 
tion to its denfity, ibid, qu, 21.” A force 
fufficient to give an intcnfe degree of heat, 
3 cfpecially 
