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D. Alter on the Light of the Electric Spark. 213 
tification. 
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Arr. XXI.—On certain Physical Properties of the Light of the 
Electric Spark, within certain Gases as seen through a 
Prism ; by D. Aurer, M.D., of Freeport, Pa. 
In a former communication, I noticed the peculiar character of 
the light produced by interrupting the galvanic circuit, between 
different kinds of metal. I also mentioned that several bright 
Spectrum. In the other gases it is feeble, except in the bands 
before mentioned. The quantity of light in the red band of the 
Spark, in hydrogen, is quite remarkable, being so great, that the 
s e aran 
Ceive the cause of the difference in color, in the flashes of light- 
hing—for when the electricity has a watery conductor, in much 
of its course, it will emit red light, but when it passes through 
4ir, the light will be white; as in the spark through that medium, 
