Fig. 10. NEWTON'S EXPERIMENT SHOWING THE RECOH POSITION or LIGHT. 



COMMON THINGS. 



COLOUR. 



CHAPTEE I. 



1. Colours depend upon reflected lights. 2. Bodies luminous and non- 

 luminous. 3. Luminaries. 4. Non-luminous bodies. 5. Trans- 

 parency and opacity. 6. Transparency never perfect. 7. Opacity 

 never perfect. 8. Bodies rendered visible by reflected light. 9. 

 Irregular reflection. 10. Reflecting powers vary. 11. The blackest 

 body reflects some light 12. Irregular reflection necessary to vision. 

 13. Use of the atmosphere in diffusing light. 



1. THE colours of objects, natural and artificial, depend on the 

 light which they have the peculiar property of reflecting. A red 

 object is one which is capable of reflecting red light exclusively, 

 or at least in a much larger proportion than the lights of other 

 colours. A green object is one which has the property of re- 

 flecting a predominance of green light, and so on. 



These effects, familiar as they are to every one from the moment 

 the senses are excited by external objects, are> nevertheless, 

 very imperfectly understood, and often altogether misunderstood. 

 Indeed, it was not until the time of Newton that the true physical 

 cause of the colours of visible objects was fully explained. 



The phenomena depend on certain properties of light, which 



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