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one another, but have a repellent Force, which is 
reciprocally proportionable to‘ the DiAances of the 
Particles ; Agreeable to what Sir ffaac M^wfort fays 
in his Opticks, Quer. 31. “ The Part'cles, when they 
“ are fhaken oA from Bodies by Heat or Fcrmen- 
“ tation, fo loon as they are beyond the reach of 
“ tlie Attradion of the Body, receding from it, 
“ as alfo from one another, with great Strength, 
“ and keeping at diAance, fo as fometimes to take 
up above a million of times more fpace than they 
‘‘ did before in the form of a denfe Body,* which ' 
vaA Contradion and Expanfion Teems unintel- | 
“ ligible, by feigning the Particles of Air to be ^ 
“ fpringy and ramous, or rolled up like Hoops, or | 
by any other means than by a repulfive Power: 
Our Author made Tome Experiments upon a < 
Calves Lung’s, which help to confirm Dr. James 
Ke'th Affertion, viz, that the inner Surface of a t 
Man's Lungs is equal to about 150 *fquare Feet, ] 
which is about 10 times more than the Surface of 
the whole Body. Then by feveral Experiments and j 
curious Obfervations, found, that of the Air which 
is infpir'd by the Lungs in an Hour (viz. 4800a 
cubick Inches) about 3^3 Inches, or 100 Grains itr 
Weight are deftroy’d in that Time. 
He Ihews, that the reafon that Sulphureons Air 
is pernicious, is becaufe Sulphureous Air lofes its' 
ElaAicity fo faA, that the Lungs will fubfide in iti« 
and the Blood confequently Aagnate. He concludes, 
that when the Particles of fuch Air are united' 
into pretty large Molecula' in a fix'd State, they 
are too big to enter the Vefides of the Lungs. 
Since my making this Mr. Hales told w?, that the Inner Surface, 
if the Lungs Is double the Sluantlty here ex^refs'd, which wsts f*' fet down in. 
kls Book by ?rujlake. 
m 
