Chemistry and Physics. | ; 
the color of the eo oo if both eyes be open, the spots will both ap- 
pear of their natural ¢ 
rai we ought to expect. To fix the ideas, and avoid troublesome 
phrases, let I represent t the portion of the right retina on which the image 
of the spot falls, and I’ the Pil sip portion of the left retina. Let 
J’ represent the bon on of the retina of the left eye on which the i se 
falls, and J the corresponding portion of the right retina, Call 
E’ all those portions of the respective retinas except L+-I, and IN. 
Then the mind can make no distinction between the i impression conveyed 
by L, and that conveyed by L/, = so of the other portions. From the 
diclinaicl, of the glasses we hav 
On E red light, on E/ green ae result, an uncertain white. 
nI darkness, on I’ green light ; result, green 
On J red light, on # darkness ; result, red 
served t rat the greenness of the apparent image of the spot seen by the 
a) 
a double i image. It might then b gether that the red image wou 
preserve its color, since the nature of the light falling on the portions r 
J’, of the retinas is not changed; and that the other i image w would lose all 
coloration, since it is now produced by white light on the one retina and 
darkness on the other. But the real result will be singularly the con- 
verse of this. The first image will lose nearly every trace of red, appear- 
ing almost : perfectly black, while the second one will preserve its apparent 
greenness in all its brilliantty, an ae a Bae of green light (except 
what helps to form white,) can reach either eye! Vice versa, if the red 
glass be removed, the green mie will change to black, while the red 
one will preserve its apparent color. 
[No. 3 may be explained a the well known fact that when we rich at 
an object placed so near the eyes that a double image is seen, the ri 
image belongs to the left eye, and vice versa; also a black pigs on 
a red field soon assumes a green tint, and 2. v. 
bene _ 
Researches on the mutual relations of the Equivalents —With this 
tide 18 S. Sras has communicated the results of a ten years’ laborious 
investigation, devoted specially to the examination of Prout’s often dis- 
