NATURAL PHILOSOPHY. 137 



have been observed in the space between D and E in the spectrum 

 given by the burning of nitrate of strontia in the flame of alcohol. 



ON THE SENSATION OF LIGHT. 



Mu. JONES, in a recent paper before the Royal Institution, remarks, 

 that the sensation which we experience in consequence of an impres- 

 sion upon the eye is called light, and the external agent which com- 

 monly causes the impression is also designated by the same name. 

 But the sensation and the external agent which, by iis impression on 

 our optic nerve, excites in us the sensation, are totally cliiYerent things. 

 Some years ago a remarkable medico-legal case occurred in Germany, 

 in which the sensation of light excited by a blow upon the eye was 

 confounded with the agent light. In this case a worthy clergyman was 

 ; suited one dark night by two men, one of whom struck him on the 

 right eye with a stone. By the light which streamed from his eye in 

 consequence of the blow, the clergyman alleged that he was able to 

 see and recognize the man who committed the outrage. The question 

 whether this were possible having been raised, it was referred to the 

 official district physician, who thought that there was some proba- 

 bility in the clergyman's allegation, though he did not fully admit 

 it. Professor Miiller, of Berlin, in commenting on this curious case, 

 very justly observed, that, if the physician had pressed upon his own 

 eye in the dark, and tried to read by the light thereby emitted, he 

 would probably have come to a more decided conclusion. Athenccum, 

 June. 



THEORY OF COMPLEMENTARY COLOKS. 



M. MAUMENE, in a letter to the French Academy, describes an 

 experiment, which is interesting as regards the demonstration of the 

 theory of complementary colors. It is well known that the combina- 

 tion of the complementary colors produces white ; and this is usually 

 shown in lectures by employing two glasses, one of a red and the 

 other of a green color, the tints of which, although of considerable 

 intensity, entirely disappear during the simultaneous interposition 

 of the glasses betw r een the eye and the source of light. M. Mau- 

 menc several years since arrived at the same result by using colored 

 liquids, and especially by mixing a solution of cobalt with one of nick- 

 el, both perfectly pure, and so diluted that their color is nearly of 

 equal intensity. The rose-red color of the cobalt is completely de- 

 stroyed by the green of the nickel, even in concentrated solutions, and 

 the mixed liquid remains colorless. Journal de Chimie, March. 



THE TJNDULATORY AND CORPUSCULAR THEORIES OF LIGHT. 



ARAGO has given to the French Academy an account of the entire 

 success of an experiment, suggested by himself in 1839, for settling 

 beyond the slightest doubt the long dispute between the corpuscular 

 and undulatory theories of light. Hitherto it has been found impossi- 



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