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Article ON THE NATURE AND PROPERTIES OF AIR. ← Page 2 of 3 →
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On The Nature And Properties Of Air.
forty miles hig h ; but it is probable , the air may expand itself a great deal farther , there being properly no other limits to it , as we can conceive , but as it continually decreases in density , the farther remote it is from the earth , in a certain ratio , which , at last , as to our conception , must in a manner terminate . 6 . It is the means and matter of life itself . For , without air , no earthly creature could liveas the experiments made by the
air-, pump plainly demonstrate . —By putting dogs , cats , rats , mice , & c . into the exhausted receiver , and by with-drawing the air , you may see them expire in a minute . Thus air is the means of life . It is also the matter-of life ; because air is impregnated with a vivifying spirit , or vital principle , which it communicates to animals ; this is proper to feed , and , consequently , to be consumed by fire ; for no
creature can live , no , nor cannot burn , in a dust or burnt air , or such as has passed through the fire . 7 . It is necessary for vegetation , inasmuch as plants and trees breathe the air , on which their vegetative life depends , and by which it is preserved . 8 . It has an effect on bodies which tends to dissolve them ; ft is an universal menstruum ; it reduces crystal-glasses to powder in
time ; divers minerals , earths , stones , ore . which , perhaps , ever since the universal deluge , have laid under ground secure from corruption , yet , being exposed to the corrosive quality of the air , have soon mouldered away .
9 . It is the medium of all sound , as may be proved by the experiment of a bell in the receiver in the air-pump , which , before the air is exhausted , may be heard to a considerable distance ; but , when exhausted , can scarce be heard at the nearest distance . This shews that sounds are augmented or diminished , in proportion as the air is condensed orrarified . Lastly . It is the medium which diffuses liht ; forif there was
g , no atmosphere to refract the sun ' s rays ail around , no part of the , heavens would be bright , but that wherein the sun was : and should a spectator turn his back towards the sun , he would see all in darkness , and the least stars would shine and twinkle as they do in the clearest nig ht . The sun , before his setting , would shine as brisk as at noon ; but in a momentas soon as he was got below
, the horizon , the whole hemisphere would be involved in the blackest darkness . But , by means of the atmosphere it happens , that the sun , while he is above the horizon , illuminates with his rays the whole heavens , and thereby renders the stars invisible ; and after he is set , though we receive no direct light from him , } et we enjoy his reflected light for some time ; becauseas the
atmo-, sphere is higher than we are , it must be a long time before it is withdrawn from the sun . If a man was to run up to the top of a steeple , he might see the sun , after it was set to those at the bottom . The rays , which the atmosphere receives from the sun after he is withdrawn from our sight , are , by refraction , faintly
Note: This text has been automatically extracted via Optical Character Recognition (OCR) software.
On The Nature And Properties Of Air.
forty miles hig h ; but it is probable , the air may expand itself a great deal farther , there being properly no other limits to it , as we can conceive , but as it continually decreases in density , the farther remote it is from the earth , in a certain ratio , which , at last , as to our conception , must in a manner terminate . 6 . It is the means and matter of life itself . For , without air , no earthly creature could liveas the experiments made by the
air-, pump plainly demonstrate . —By putting dogs , cats , rats , mice , & c . into the exhausted receiver , and by with-drawing the air , you may see them expire in a minute . Thus air is the means of life . It is also the matter-of life ; because air is impregnated with a vivifying spirit , or vital principle , which it communicates to animals ; this is proper to feed , and , consequently , to be consumed by fire ; for no
creature can live , no , nor cannot burn , in a dust or burnt air , or such as has passed through the fire . 7 . It is necessary for vegetation , inasmuch as plants and trees breathe the air , on which their vegetative life depends , and by which it is preserved . 8 . It has an effect on bodies which tends to dissolve them ; ft is an universal menstruum ; it reduces crystal-glasses to powder in
time ; divers minerals , earths , stones , ore . which , perhaps , ever since the universal deluge , have laid under ground secure from corruption , yet , being exposed to the corrosive quality of the air , have soon mouldered away .
9 . It is the medium of all sound , as may be proved by the experiment of a bell in the receiver in the air-pump , which , before the air is exhausted , may be heard to a considerable distance ; but , when exhausted , can scarce be heard at the nearest distance . This shews that sounds are augmented or diminished , in proportion as the air is condensed orrarified . Lastly . It is the medium which diffuses liht ; forif there was
g , no atmosphere to refract the sun ' s rays ail around , no part of the , heavens would be bright , but that wherein the sun was : and should a spectator turn his back towards the sun , he would see all in darkness , and the least stars would shine and twinkle as they do in the clearest nig ht . The sun , before his setting , would shine as brisk as at noon ; but in a momentas soon as he was got below
, the horizon , the whole hemisphere would be involved in the blackest darkness . But , by means of the atmosphere it happens , that the sun , while he is above the horizon , illuminates with his rays the whole heavens , and thereby renders the stars invisible ; and after he is set , though we receive no direct light from him , } et we enjoy his reflected light for some time ; becauseas the
atmo-, sphere is higher than we are , it must be a long time before it is withdrawn from the sun . If a man was to run up to the top of a steeple , he might see the sun , after it was set to those at the bottom . The rays , which the atmosphere receives from the sun after he is withdrawn from our sight , are , by refraction , faintly