Class-book of physiology : for the use of schools and families : comprising the structure and functions of the organs of man, illustrated by comparative reference to those of inferior animals . Fia 9 A W WiiRnr Pit fi/ T _#?- ?.?ar^hi. APPENDIX, THE AIR WE BREATHE. 1. The earth we inhabit, is surrounded by an atmosphere ofair, not less than 45 miles in height. Its pressure, or weight atthe level of the sea, is allowed to be 14 pounds to the square inchof the earths surface. Allowing the surface of a mans body ofmedium size to be fifteen square feet, or 2160 square inches, heBuffers
Class-book of physiology : for the use of schools and families : comprising the structure and functions of the organs of man, illustrated by comparative reference to those of inferior animals . Fia 9 A W WiiRnr Pit fi/ T _#?- ?.?ar^hi. APPENDIX, THE AIR WE BREATHE. 1. The earth we inhabit, is surrounded by an atmosphere ofair, not less than 45 miles in height. Its pressure, or weight atthe level of the sea, is allowed to be 14 pounds to the square inchof the earths surface. Allowing the surface of a mans body ofmedium size to be fifteen square feet, or 2160 square inches, heBuffers the enormous pressure of more than fifteen tons. Still,as the pressure from within and without is equal, it is unper-ceived except by its variations. The pressure is the greatest atthe level of the sea, and diminishes as we ascend high air floats around the earth in almost perpetual motion, andproduces gentle breezes, winds, gales, and tornadoes. 2. Atmospheric air, though apparently a simple element, is amixture of different gases. Its constituents, by weight, are—oxygen, parts, nitrogen, parts, and a portion of car-bonic acid, varying in amount from -p^o to t»6oo oxygen. 3. Oxygen is the only sustainer of an
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Keywords: ., bookcentury1800, bookdecade1860, booksubjectphysiologicalprocess
