AND ON THE COLOURS EXHIBITED BY CERTAIN FLAMES. 457 



rated from each other, by a very obscure, but not wholly black 

 space, almost equal in breadth to the red. This red, however, 

 consists entirely of the more refrangible portion, and is extin- 

 guished by a standard glass, which transmits only the extreme 

 red rays. The yellow image is remarkable. Narrow as it is, 

 it is evidently bifid, being divided by a black line into two 

 images, of tints very visibly dhTerent. The most refracted is 

 a pure pale yellow, without any ruddy or green tinge. The 

 least is a decided orange, equally contrasted with the yellow 

 on the one side, and the red on the other. What is yet more 

 remarkable is, that when this bifid image was viewed through 

 the bright-red glass, described in Art. 3., it was rendered 

 single, the yellow being entirely absorbed, while the orange 

 was very little affected. At the point of the flame, the yellow 

 image (which seems strictly homogeneous, and is quite sharp- 

 ly defined on both sides), terminates the spectrum ; but in the 

 lower part a faint green image is visible, and some traces of 

 the blue and violet, becoming stronger as we approach the 

 bottom. (See Fig. 13.) 



Muriate of lime dissolved in spirits gives no such orange 

 image. The type of this flame is as in Fig. 14. Neither does 

 muriate of baryta or corrosive sublimate, the type of whose 

 flames, which are very similar, is represented in Fig. 15. 



The solution of muriate of copper in alcohol is of an emer- 

 ald-green colour ; that of the nitrate is blue. The colours of 

 their respective flames are the reverse; the former giving a 

 blue, and the latter a fine green flame, the types of which are 

 given in Figures 16. and 17. 



Boracic acid has often been remarked for its efficacy in com- 

 municating a green tinge to the flame of alcohol. Examined 

 with the prism, the spectrum of this flame is seen divided into 

 six, a feeble red, a bright yellow, two greens of the same tint, 



one 



