60 Mr H. H. Blackadder o?i the Coinhustmn of 



likewise steam, is generated, and discharged into the interior of 

 the flame. After the diluted alcohol in the reservoir has been 

 consumed, the quantity of water remaining in the wick is not 

 equal to that contained in the original fluid, as may readily be 

 determined, by ascertaining the specific gravity of the alcoholic 

 fluid that is employed. It thus appears, that, in the interior 

 of the yellow flame of diluted alcohol, there is present a certain 

 admixture of steam, which does not exist in the blue coloured 

 flame of the same fluid ; and when steam is generated, much 

 heat is necessarily consumed ; but it does not follow that the 

 presence of steam is the cause of the yellow colour. Alcohol of 

 the strength formerly mentioned, and that which is considerably 

 stronger, may be burned, so as to give out yellow light ; and 

 alcohol that cannot be made, in one way or another, to extricate 

 yellow light during its combustion, has not been procured for 

 experiment. 



It would appear that, though some attention has been paid to 

 the noting of such substances as give out particular kinds of co- 

 loured light, when subjected to a high temperature, or when dis- 

 solved in the fluid which supports combustion, but little atten- 

 tion has hitherto been paid to the coloured light of a flame, with 

 the view of ascertaining the mode of its production. That this 

 and the other substance gives a yellow or green flame, and that 

 the quantity of yellow light may be increased by particular 

 means, has been ascertained ; but on what the extrication of yel- 

 low light depends, or what particular process goes forward du- 

 ring its production, remains to be investigated. The following 

 short extracts from a pubhcation of modern date, and by a gen- 

 tleman distinguished in the ranks of science, will be found in-' 

 teresting : — " After numerous experiments, attended with much 

 trouble and disappointment, I found that almost all bodies in 

 which the combustion was imperfect, such as paper, Hnen, cot- 

 ton, &c. gave a light in which the homogeneous yellow rays pre- 

 dominated ; that the quantity of yellow light increased with the 

 humidity of these bodies ; and that a great proportion of the 

 same light was generated, when various flames were urged me-' 

 chanically by a blowpipe or a pair of bellows. As the yellow 

 rays seemed to be the product of imperfect combustion, I con- 

 ceived that alcohol, diluted with water, would produce them in 

 greater abundance than when it was in a state of piuity ; and, 



