D. Alter on Physical Properties of Light in Metals. 55 
Arr. VI.—On certain Physical Properties of Light, produced by 
the combustion of different Metals, in the Electric Spark, re- 
fracted by a Prism; by Davin Aurer, M.D., Freeport, Penn. 
‘We are indebted to the celebrated M. Fraunhofer for the fact, 
that the Solar Spectrum is crossed by numerous fixed lines, and 
that the light of some of the stars differs from that of the sun, in 
the number and situation of these lines. 
In order to see some of these lines without the aid ofa teles- ° 
cope, I ground a prism of flint glass, with large refracting angle, 
74°), Viewing a fine slit made in sheet brass, when the source 
of light was the sky, nearly in the direction of the sun seen 
through this prism, I could count twelve or thirteen of F’raunho- 
fer’s dark lines. In viewing the blaze of a lamp, burning petro- 
leum, I could discover neither dark nor bright lines, although [ 
narrowed the light by passing it through the fine slit of sheet 
rass. I then tried the blaze of a tallow candle, when I could 
distinctly see an orange image of the blaze and one of faint yellow 
and one of green at the base of the blaze. ‘The base of the 
orange image appeared to be the reflection of the light without 
any dispersion. When the brass with the fine slit is held in a 
horizontal position and the refracted light seen through it, is 
rom the base of the blaze, bright bands, one of orange, one of 
yellow, one of green, one of blue, and one of violet, are seen. 
_ The flame of alcohol is the same, except that the orange band 
is wanting. A slip of white paper shows the same bands when 
illuminated by a tallow candle. The jet of a blowpipe shows 
the five images still more distinctly. 
_ The light from heated wire or charcoal shows no peculiarities. 
The electric spark from a Leyden Jar gave several bright images, 
which from optical illusion (perhaps from their brilliancy) appear- 
ed to extend beyond the sides of the spectrum, causing it to ap- 
pear serrated along the edges. — TH 
But the most interesting |—— =| 
effect of refraction, is from pe 
| 




the spark caused by breaking 
the galvanic circnit, or at the 
break of a powerful magneto- 
electric machine. The ma- }-— 
chine L used produced sparks |— 
nearly half an inch in length. au 
These sparks, viewed through | 
the prism, appear almost whol- a 
ly resolved into separate, col- (~— 
ored bands, as. illustrated in gaa oh Bi Myth 
the annexed figure, where Leg rr eer é 
is the red extremity of the spectrum, and V the violet. 






















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