THE SUN. 67 



scribed, which is the most intense heat we can raise, and 

 in which platina melts like lead. 



(27.) On the benefits which the sun's light confers on 

 us it cannot be necessary to say much ; only one thing, 

 I think, may not be known to all who may read these 

 pages, viz., that it is not only by enabling us to see that 

 it is useful, but that it is quite as necessary as its heat 

 to the life and well-being both of plants and animals. 

 Animals, indeed, may live some time in complete dark- 

 ness ; but they grow unhealthy; lose strength and pine 

 away; while plants very quickly lose their green colour; 

 turn white or pale yellow; lose all their peculiar scent and 

 flavour; refuse to flower; and at last rot and die off. 

 What I have now to say about the light of the sun is of 

 quite a different nature. 



(28.) The sun's light, as we all know, is purely white. 

 If the sun sometimes looks yellow or red, it is because it is 

 seen through vapours, or smoke, or a London fog of smoke 

 and vapour mixed. It has been seen blue ;* but when 

 high up, in a clear sky, it is quite white. The whiteness 

 of snow, of a white cloud, of white paper, is the whiteness 

 of the sun's light which falls upon them. Whatever re- 

 flects the rays of the sun without choice or preference, appears 

 white. Whatever does not do so appears coloured ; and 

 if it does not reflect them at all black. Now I must 

 explain what I mean by saying " without choice or pre- 



* This has been denied by Arago. But I have a description of 

 the phenomenon by an eye-witness, accompanied with a coloured 

 drawing, which leaves no doubt on my mind of the reality of the fact. 

 It was after a hurricane at Barbadoes. 



