PROCEEDINGS OF THE POLYTECHNIC ASSOCIATION. 873 



sium acts in this respect like the sun. Bhie predominates in this 

 flame, which is really whiter than sunlight. Sodium l)urns with 

 a yellow (monochromatic) flame, aud all colois are altered under 

 this light, with the exception of hlue-violct, which is compliment- 

 ary to the j-ellow. This flame ma}' l)e obtained by burning chlo- 

 ride of sodium (common salt) supported by platinum, in the flame 

 of a Bunsen lamp, or by burning alcohol saturated with salt. He 

 made a spectrum, by applying pigments to white paper, and found 

 the monochromatic flames produced the following changes of color. 

 Eed ochre — sesquioxide of iron— became black. Orange iodide 

 of mercury and yellow chromate of lead, both appeared white ; 

 while manganate of bai-yta and aniline blue were both black. The 

 flame of magnesium instantly restored the normal colors, even 

 while the sodium flame was burning in the neighborhood. Minute 

 quantities of sodium, existing in all ordinary flames, are derived 

 from mineral matters in the wicks of, Inmps and candles, and the 

 ashes of fuel. Traces of it have been detected in atmospheric air 

 by Bunsen. The efie'ct of a small quantity of this metal in com- 

 mon flames is to alter in degree the color of objects; darkenino- 

 some and enlivening others, and creating confusion between green 

 and blue. The phenomena of the soda flamc^ explain physiologi- 

 cal efiects heretofore unaccounted for. In the flame of alcohol 

 and salt the hands and face appear a livid gi-ecn, while the lips 

 change to a violet-blue. The livid tint seen in burning punch or 

 pudding is due to the alcohol, more or less saline, which is 

 employed in these mixtures. Workmen at furnaces and forges 

 are familiar with these peculiar tints appearing upon the features 

 illuminated by their fires, which arise from the soda contained in 

 the dross and ashes of combustible matters. The question arises 

 why the natural flesh color is changed to a bluish or livid green? 

 The colors which best resist the extinctive efiect of the soda flame 

 come from blue ] the latter is the color of the human blood, as 

 seen in the large veins through the skin of the hand ; the other 

 colors of the flesh having disappeared, the predominant yellow of 

 the sodium mingles with the blue, and makes a green, which 

 varies in shade from yellowish to bluish, according to the inten- 

 sity of the blue, and producing a most sinister aspect on the 

 human countenance. M. Nickles further states that one cannot 

 work for any length of time in this yellow light without finding 

 the retina of the eye seriously aflected. 



