The refraction of light, and the production of prismatic colours, surrounds us with most interesting phenomena. The laundress, whose active labours raise over the wash-tub a soapy froth, performs inadvertently one of the most delicate operations of chemistry--the chemistry of the imponderable agents--and the result of her manipulations manifests itself in the delicate colours that dance like a fairy light over the glassy films that follow the motion of her arms. The laughing child, throwing a bubble from the bowl of a tobacco pipe into the air, performs the same experiment, and produces a result such as that which filled the philosophic Newton with unbounded joy. The foam of the seashore, the plumage of birds, the various films that float upon the surface of waters, the delicate tints of flowers, and the rich hues of luscious fruits, all combine to remind us, that every ray of light comes like an angelic artist sent from heaven, bearing upon his palette the most celestial tints, with which to beautify the earth, and show the illimitable glory of God. CHAPTER XXIV. 502. _What is the difference between the refraction and the reflection of light?_ _Refraction_ is the deviation of rays of light from their course through the interference of a _different_ medium; _reflection_ is the return of rays of light which, having fallen upon a surface, are repelled by it. 503. _What is the radiation of light?_ The _radiation_ of light is its _emission in rays_ from the surface of a _luminous body_. 504. _Do all bodies radiate light?_ All bodies radiate light; but those that are not in themselves primary sources of light, are said to _reflect it_. 505. _Do black bodies reflect any light?_ Black bodies _absorb_ the light that falls upon them. But they reflect a _very small_ degree of light. 506. _Why is glass transparent?_ Because its atoms are so arranged that they allow the vibrations of light to continue through their substance. [Verse: "As in water face answereth to face, so the heart of man to man."--Proverbs xxvii.] 507. _Does glass obstruct the passage of any portion of light?_ Glass _reflects_ (sends back) a very small portion of light. This may be observed by holding a piece of paper, or a hand, a few inches from a window, when a faint reflection of it will be visible. Probably the small amount of light _reflected by transparent glass, which gives a passage to the greater part of the rays_, may serve to illustrate the small amount of light reflected from _black surfaces_, which _absorbs the greater portion of light_.