a Daguerreotype Experiment. 
the other resembles in color, the flame produced by the combustion 
of an alcoholic solution of chloride of sodium, more nearly than any 
thing else with which we can compare it. ‘The charcoal points were 
shifted, each to the opposite pole of the battery, without producing any 
change in the color of the light given off by the poles respectively. 
Other pieces of charcoal were substituted, in the place of those with 
which this phenomenon was first observed, but the difference in-the 
color of the two images was always present, and did not seem to be 
connected in any manner with the particular charcoal points employed, 
but the yellow image was uniformly given by one pole, and the purple 
image by the other pole of the battery. We are under the impress 
sion, that the yellow colored image was produced from the charcoal 
point, in connection with the positive pole of the battery, and that the 
strontia colored image came from the negative pole of the» battery, 
though of this no note was made at the time. No attempt was made 
to ascertain by direct experiments, whether these images possessed 
a different degree of power or not, in producing an impression upon 
an iodized plate. The difference in their color was presumptive evi+ 
dence that one image, (that from the negative pole,) possessed more 
of the chemical rays than the other. But evidence is (we are of 
opinion) afforded indirectly that such is the fact. The light from 
both charcoal points made a slight impression on the iodized plate, 
before they were brought so close together: as to unite in forming 4 
general blur: these two small spots or impressions are opposite, 
or at each extremity of one diameter of the blur,:and without its cir 
cumference; one of them is more distinct than the other. Within 
the edge of the blur, and nearly in the same diameter with the two 
spots above named, there are also two imp , darker and more 
_ strongly marked, than is the general impression sale by the light from 
the points. One of these spots is doubtless made by the light from one 
point, while the other is due to the light from the other point, and one 
_ of them far exceeds the other in distinctness. Now the more strongly 
marked spot without the blur, and the more strongly marked one with 
in it, are close to each ‘other on the same edge of the blur, and are 
doubtless produced by the light from one and the same. charcoal: point. 
oe mh r spots, viz. that without, and that within the blur, 
. ta distinct son cepe ambien “stare ne 
