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 89 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
A. Because they _absorb none of the rays of light_, but reflect them _all_.
Q. _Why are COALS BLACK?_
A. Because they _absorb all the rays of the sun_ which impinge upon them, and stifle their reflection.
Q. _Why is SNOW WHITE?_
A. Snow consists of a vast number of crystals (or small prisms), which separate the rays into their elemental colours; but as these crystals are very numerous, the colours _unite again_ before they meet the eye, and _appear white_.
N. B. The combination of _all_ colours makes WHITE.
Q. _Why is SUGAR WHITE?_
A. Sugar consists of a vast number of small crystals, which separate the rays into their elemental colours; but as these crystals are very numerous, the colours _unite again_ before they meet the eye, and appear _white_.
Q. _Why is SALT WHITE?_
A. Salt consists of a vast number of small crystals, which reflect the various rays of light from different points of the salt; and as these colours _unite_ before they meet the eye, the salt appears to be _white_.
N. B. The combination of _all_ colours makes WHITE.
Q. _Why are the LEAVES of plants GREEN?_
A. Because the _carbon_ of the leaves is a _bluish olive_, and the _sap_ and _tissue of the cells_, YELLOW; when, therefore, the _yellow sap_ flows into the _blue carbon_, it produces a _green leaf_.
Q. _Why are leaves a LIGHT green in SPRING?_
A. Because the young leaves of spring have _more sap_ than _carbon_; and, therefore, the _yellow_ of the green prevails.
Q. _Why are leaves a YELLOWISH BROWN in AUTUMN?_
A. Because the _carbon_ of the leaves is _dying away_, and the yellow tinge of the _tissue_ and _falling sap_ prevails over the blue.
Q. _Why are plants a PALE YELLOW when kept in the DARK?_
A. Solar light is essential for the production of _carbon_; and as plants kept in the dark _lose their carbon_, they lose the _blue colour_ which should convert their yellow sap to _green_.
Q. _Why are POTATOES YELLOW?_
A. Potatoes are grown _underground_, and, therefore, contain very little _carbon_ (or blue colour); hence the _yellow sap_ of the potato is not converted to green by carbon.
Q. _Why are potatoes (which grow EXPOSED to the air and light) GREEN?_
A. Because the sun-light _increases their carbon_; which (mingling with the yellow sap) turns the potato _green_.
Q. _Why is it DANGEROUS to SLEEP in a room which contains LIVING PLANTS?_
A. Because they _exhale carbon in the dark_ in the form of CARBONIC ACID GAS, which is destructive to animal life.
Q. _Why are SOME things (like gla.s.s) TRANSPARENT?_
A. In transparent bodies (like gla.s.s) all the rays of light _emerge on the opposite side_.
Q. _Why are SOME things SHINING and splendid?_
A. Those objects which _reflect the most rays_ are the most _splendid_; and those which _absorb_ them most, are _dull_.
Q. _Why are DESERTS so DAZZLING in summer time?_
A. Because each separate grain of sand _reflects the rays of the sun_ like a mirror.
Q. _If you move a stick (burnt at one end) ROUND pretty briskly, it seems to make a CIRCLE OF FIRE,--WHY is this?_
A. Because the eye _retains the image_ of any bright object, _after the object itself is withdrawn_; and as the spark of the stick returns _before the image has faded_ from the eye, therefore, it seems to form a _complete circle_.
Q. _If separate figures (as a man and a horse) be drawn on separate sides of a card, and the card TWISTED quickly, the man seems to be seated on the horse,--WHY is this?_
A. Because the image of the horse _remains upon the eye_ till the _man_ appears.
The Thaumatrope is constructed on this principle.
Q. _Why do the STARS TWINKLE?_
A. Fixed stars are _so far off_, that their rays of light do not strike upon the eye _in a continuous flow_, but at _intervals_: when their rays _reach the eye_, the star becomes _visible_, and then is obscured _till the next batch of rays arrive_; and this _perpetually_ occurring, makes a kind of _twinkling_.
Q. _If we look at a RED-hot FIRE for a few minutes, WHY does every thing seem TINGED with a BLUISH GREEN colour?_
A. Because bluish green is the "ACCIDENTAL COLOUR" of red: and if we fix our eye upon _any colour whatsoever_, when we turn aside, we see every object tinged with _its accidental colour_.
