dnalyfis of the Ah. 2 5 9 



From thefe violent and fatal effe&s of very 

 noxious vapours on the refpiration and life 

 of animals, we may fee how the refpiration 

 is proportionately incommoded, when the air 

 is loaded with lefTer degrees of vapours, which 

 vapours do, in fome meafure, clog and lower 

 the air's elaflicity ; which ic bed regains by 

 having thefe vapours difpelled by the venti- 

 lating motion of the free open air, which 

 is rendered wholefome by the agitation of 

 winds : Thus, what we call a clofe warm 

 air, fuch as has been long confined in a room, 

 without having the vapours in it carried off 

 by communicating with the open air, is ape 

 to give us more or lefs uneafinefs, in pro- 

 portion to the quantity of vapours which 

 are floating in it. For which rcafon the 

 German ftoves, which heat the air in a room 

 without a free admittance of frefh air to 

 carry off the vapours thac are raifed, as alfo 

 the modern invention to convey heated air 

 into rooms through hot flues, feem not fo 

 well contrived, to favour a free refpiration, 

 as our common method of fires in open 

 chimneys, which fires are continually car- 

 rying a large ftream of heated air out of the 

 rooms up the chimney, which ftream mufl 

 neceflarily be fupplied with equal quantities 



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