Birmingham state herald., 1896-11-08
doors-Mayberry 6 Watson.
CAUSES OF COLOR.

SAOoEo OF SO1Oh.
 Knowledge.
 The beauty of the objects of nature around us depends so much on the varie- ties of color which they exhibit that it becomes an interesting question what is the cause of these differences. We have only to think of the blue sky, the green foliage and the various Splendors of flowers and fruits to realize to how great degree the pleasure we experience in viewing a country scene Is due to the many hued surfaces of natural objects. The pleasurable feelings aroused by the sight of the deep blue of the sea contrast ing with the bright red color of the sand stone cliffs, or the effect of the sunshine when 1t lights up the splendid purple of the heather on the slopes of the hills, can be forgotten by none who have ex- perienced them; and the striking effect of eastern scenes is owing largely to the brillance of the tints which meet the eye. It is needless to enlarge on the part played by color in this world of ours; the difference between a world of color and one in which surrounding objects were only distinguished by different shades of gray may be realized by all
 When we come to inquire how the red color of a rose is produced, and why 1t differs in appearance from blue flower, we must consider what happens to the light which falls upon the petals of the rose. We see the flower because the light from the sun is reflected from it, but something has happened to the light be- fore it reaches our eyes: the light we re- ceive differs from that which fell upon the flower. The rays from the sun pene- trate to certain extent into the sub stance of the flower and most of them are reflected from particles beneath the surface. Now the cells making up the petals of rose contain fluid which has the power of absorbing certain of the rays of light, and the light entering the eye after penetrating short distance below the surface of the petals and coming back has passed through this fluid, and in its course some of the rays of the sunlight have been abstracted from 1t. Thus the light reaching us is lacking in certain of the constituents of white light-that is. it is colored. White light may be con- sidered as made up of the three funda- mental colors, red, green and violet, blended together. The light which has passed through certain extent Of the substance of the rose petals has been de- prived of its green and violet portions, and thus the red rays alone reach our eyes. All substances which possess color exer- else this power of sitting the rays of light Light falling on the leaves of the rose hlsh passes through their superficial lay ers and is reflected from below the sur face; thus it has to traverse certain par ticles which take from it the red and violet rays and allow the green to pass The green rays which escape absorption are the only ones which reach our eyes,
  When white light passes through prism it is found that in the band of color or spectrum produced. the blue and violet rays are the most bent out of their origin al course; they are the most refrangible. The red rays are the least bent. It is found also that the vibrations of the ether filling space which produce waves of light are quickest in violet light and siowest in red light. Some substances absorb the quick vibrations more rapidly, pd reddish in color Others absorb the slower vibrations, allowing the others to pass through, and there fore have green or blue color.
 When a substance is heated its parti- ces are thrown into state of rapid mo- tion, and soon set up motion in the ether which, when the vibrations are of a certain rapidity, produces light. If ball of iron is heated 1t first of all gives out radiation consisting of dark rays which have the effect of producing heat As it's particles become hotter and hotter. and thus vibrate more rapidly. the radi- ation begins to affect our eyes and the ball glows with a dull red heat AS vii brations of greater and greater rapidity take place owing to the further heating. the ball appears bright yellow, and finally white, when vibrations of all the differ ent rapidities which affect our eyes are given out. In this case it is the mo- tion of the particles or molecules Of the heated body which is imparted to the ether and so produces the effect we call light Now those molecules which are able to execute certain vibrations and give them to the ether absorb these same vibrations from the ether-that is, absorb certain rays of light This effect is best seen in the case of gases, and the phe- nomenon is analogous to that which oc- CUTS with sound. A tuning fork or stretched wire which can give certain note when 1t is struck, is able to take up and absorb the note from the vibrat- ing air around it when that note Is sounded in it's neighborhood.
 It may be noticed that the light from the electric arc when seen near at hand has a distinctly bluish color; but this same light when viewed from distance appears yellowish as certain of its rays have been absorbed by the water vapor in the air on it's passage to the eye. For a similar reason tho sun Is now considered to be blue star; his light. which would rays especially, if 1t could be seen from beyond our atmosphere. appears yellow ash after 1t has passed through that at- mosphere and has lost some of it's re- frangible constituent rays. The effect of absorption in producing color is seen from the fact that powdered bodies gen. orally appear white. This Is accounted sists of particles arranged at all angles so that the light falling upon 1t meets various surfaces and is mostly reflected before it has passed below the surface Thus the white light reaching it. is not deprived of some of its constituents by penetrated the substance and was then reflected. In this way powdered red glass appears white. The light is reflected from the surface of numerous small bub- bles and does not pass much through the liquid itself. Thus also a cloud is very