Part 89 (1/2)
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.