A Guide To The Scientific Knowledge Of Things Familiar - novelonlinefull.com
You’re read light novel A Guide To The Scientific Knowledge Of Things Familiar Part 54 online at NovelOnlineFull.com. Please use the follow button to get notification about the latest chapter next time when you visit NovelOnlineFull.com. Use F11 button to read novel in full-screen(PC only). Drop by anytime you want to read free – fast – latest novel. It’s great if you could leave a comment, share your opinion about the new chapters, new novel with others on the internet. We’ll do our best to bring you the finest, latest novel everyday. Enjoy
Q. _How does the COMBINATION of OXYGEN with the BLOOD produce animal HEAT?_
A. The princ.i.p.al element of the blood is _carbon_, which (combining with the oxygen of the air inhaled) produces _carbonic acid gas_, (in the same way as burning fuel.) (_see pp._ 33, 36).
Q. _What becomes of the NITROGEN of the air, after the oxygen enters the blood?_
A. The nitrogen is _exhaled_, and taken up by the leaves of trees and other vegetables. (_see p._ 35).
Q. _Why does the vitiated air (after the oxygen has been absorbed) COME OUT of the MOUTH, and not sink into the stomach?_
A. The vitiated air (being _heated by the heat of the body_) _ascends naturally_, and pa.s.ses by the _heavier fresh air_ (which we inhale) without obstruction or injury.
Q. _If (both in combustion and in respiration) the OXYGEN of the air is CONSUMED, and the NITROGEN REJECTED--Why are not the PROPORTIONS of the AIR DESTROYED?_
A. Because the _upper surface of vegetable leaves_ (during the day) _gives out oxygen_ and _absorbs nitrogen_, and thus the proper balance is perpetually restored.
Q. _Show how G.o.d has made ANIMAL and VEGETABLE life DEPENDENT on each other?_
A. _Animals_ require _oxygen_ to keep them alive, and _draw it from the air_ by inspiration; the upper surface of _leaves_ (all day long) _gives out oxygen_, and thus supplies the air with the _very gas_ required by man and other animals.
Q. _Do not animals EXHALE the VERY GAS needed by VEGETABLES?_
A. Yes; animals reject the _nitrogen of the air_ (as not suited to the use of animal life), but _vegetables absorb it_, as it is the food they live on; and thus the vegetable world restores the equilibrium of the air, disturbed by man and other animals.
Q. _Is AIR a good CONDUCTOR?_
A. No; air is a very _bad conductor_.
Q. _How is AIR HEATED?_
A. By "convective currents."
Q. _What are meant by "CONVECTIVE CURRENTS?"_
A. When a portion of air is heated, _it rises upward in a current_, carrying the heat with it: other _colder air succeeds_, and (being _heated_ in a similar way) _ascends also_; and these are called convective currents.
("Convective currents;" so called from the Latin words, c.u.m-vectus (_carried with_) because the _heat_ is "carried with" the current.)
Q. _Is AIR HEATED by the RAYS of the SUN?_
A. No; air is _not heated_ (in any sensible degree) _by the action of the sun's rays_ pa.s.sing through it.
Q. _Why then is the AIR HOTTER on a SUNNY DAY, than on a CLOUDY one?_
A. On a fine day, the sun _heats the surface of the earth_, and the air (resting on the earth) _is heated by contact_; as soon as it is heated _it ascends_, and _other_ air succeeding is _heated in a similar way_, till all is heated by convection.
Q. _If AIR be a BAD CONDUCTOR, why does hot IRON get COLD, by being EXPOSED to the AIR?_
A. A piece of hot iron exposed to the air, is made cold--1st--By "convection;" and
2ndly--By "radiation."
Q. _How is hot iron (exposed to the air) made cold by CONVECTION?_
A. The air around the iron (being intensely heated by contact) rapidly ascends, _carrying some of its heat with it_: other air succeeds, _absorbs more heat_, ascends, and gives place to that which is _colder_; till the hot iron _is cooled completely down_.
Q. _How is hot iron cooled by RADIATION?_
A. While the heat of the iron is being carried off by "convection," it is _throwing off heat_ (on all sides) _by radiation_.
Q. _What is meant by RADIATION?_
A. Heat emitted (in all directions) from any surface, by _innumerable rays_.
Q. _Why is BROTH COOLED by being left exposed to the AIR?_
A. Hot broth throws off _some_ heat by _radiation_; but it is _mainly_ cooled down _by convection_.
Q. _How is hot BROTH cooled down by CONVECTION?_
A. The air _resting on the hot broth_ (being heated) _ascends_; _colder_ air succeeding _absorbs more heat_, and _ascends also_; and this process is repeated, till the broth is _made cool_.
Q. _Why is hot TEA and BROTH COOLED faster, for being STIRRED about?_
A. 1st--The agitation a.s.sists the liquor in _bringing its hottest particles to the surface_:
2ndly--The action of stirring _agitates the air_, and brings it _quicker_ to the broth or tea: and
3rdly--As the hottest particles are more rapidly brought into contact with the air, therefore _convection is more rapid_.
