110 Dr. J. Reade o?i the Nature of Light and 'Shado'w. 



one orange, produced by the light of the window, rarefied by 

 that of the candle; and the other blue, rarefied by that of the 

 sun. On bringing these shadows on a straight line with the 

 window, they overlapped, and produced one shadow of a per- 

 fect green colour. The orange shadow could be changed to a 

 yellow by bringing the shadow near to the blaze of the candle ; 

 or it may be made a brown at a still greater distance : in like 

 manner, the blue shadow could be changed to a perfect violet 

 by removing the paper to a certain distance from the blaze, 

 and likewise to indigo. Thus we have all the colours of the 

 rainbow or spectrum, except red and purple : indeed, we have 

 an extra colour, never to be found in the prism — brown. 



Experiment 3. — About one o'clock I perceived a large spot 

 of light reflected by the sun on the side-wall of my study, and 

 it occurred to me that the colours might be different. Anxious 

 to produce a red from a black shadow, having held the quire 

 of white paper opposite this reflected fight, and holding the 

 coil of paper over it, I perceived two shadows, the one yellow, 

 the other purple ; and on holding a lighted candle near the 

 purple, it changed to a lake, or perfect red. For the purpose 

 of changing this red to a black, I stood between the paper and 

 the side-window, so as to intercept the light coming from the 

 clouds, and only to admit the reflected sunshine to the paper; 

 when the purple immediately changed to a black, the candle 

 being previously removed. Thus without any refraction have 

 we changed a black shadow into all the variety of colours in 

 the spectrum ; for the most devoted admirers of the Newtonian 

 doctrines cannot argue that the atmosphere between the candle 

 and the paper was a refracting medium, or that it stopped 

 some and transmitted others of the solar rays ; all astronomers 

 admitting that the rays coming from the sun are nearly paral- 

 lel on account of the great distance. I forgot to remark, that 

 on bringing the candle to act on the purple shadow, a blue 

 shadow was formed as in the other experiments ; and, conse- 

 quently, there were three shadows on the paper, — blue, lake, 

 and yellow; the blue rarefied by the candle, the lake produced 

 by the sunshine, and the other formed by the light of the win- 

 dow ; for it is well known that every different light forms a 

 separate shadow. As to the idea that black proceeds from the 

 absorption of the seven rays of compound light, it is completely 

 upset by these experiments ; for we cannot suppose that the 

 quire of white paper was at one moment an absorbing sub- 

 stance, and at the next a reflecting one ; therefore we must 

 admit, contrary to the opinions of Boyle and Newton, that 

 black is as much a reflected and independent colour as blue, 

 red, or any other colour of the seven. I shall not take up the 



reader's 



