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2(58 Analyfis of the Air. 



weight of a C) Under of Mercury, whofe bafe 

 is commenfurate to the area of the 'Dia- 

 phragm, and its height 2 inches, whereby the 

 'Diaphragm muft at that time fuftain a 

 weight equal to many pounds. Neither are 

 its counter- acting mufclcs, thofe of xhz Abdo- 

 men, able to exert a greater force. 



For notwithftanding a man, by ftrongly 

 compreiilng a quantity of air included in his 

 mouth, may raife a column of Mercury in 

 an inverted fyphon, to 5 or 7 inches height, 

 yet he cannot with his utmoft {trainings 

 raife it above 2 inches, by the contracting 

 force of the mufcles of the Abdomen, 

 whence we fee that our loudeft vociferations 

 are made with a force of air no greater than 

 this. So that any fmall impediment in 

 breathing will haften the fuffocation, which 

 confifts chiefly in the falling flat of the 

 lungs, occafioned by the groflhefs of the 

 particles of a thick noxious air, they being 

 in that floating ftate moft eafily attracted by 

 each other : As we find in the foregoing 

 experiments that fulphur and the elaftick 

 repelling particles of air do: And confe- 

 quently unelaftick, fulphureous, faline and 



other floating particles will moft eafiiy 



coalefce, 



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