Hf. Morton on the color of Fluorescent solutions. 855 
Now, copper and silver belong to a class distinct from the 
| _ baser metals in that, by reason of their smaller affinity for oxy- 
! gen, they are more readily reduced to the metallic state, the 
condition of greatest permanence in presence of the usual rea- 
gents to which they are exposed. If the arresting cause of 
these metals was, as we have supposed, their reduction by pro- 
_ toxide of iron, it is a cause which would have been powerless 
as regards the salts of the baser metals, and we may suppose 
__ these to have continued in solution till they reached some re- 
gion where they were arrested by the presence of organic mat- 
ter, or of sulphureted hydrogen, ete. 
Arr. XLVIL— Observations on the color of Fluorescent solu- 
tions—No. IL; by Henry Morton, Ph.D., President of the 
Stevens Institute of Technology. 
SINCE the publication of my article on the above subject, in 
the August number of this Journal, I have discovered a curi- 
ous action which, while it in no respect affects my general con- 
clusions, nor the main observations on which they were founded, 
Ws out one of the corroborative experiments by which I 
thought that they might be established when a spectroscope 
Was not at hand. 
Obtaining some very anomalous results of late, I was led to 
mistrust the action of the Geissler tubes in which the solutions 
been examined. 
Late experiments have, however, proved that this was not so. 
Any liquid, however devoid of fluorescent properties, gives all 
- “Re of fluorescing in these tubes, and on a little 
Tn passing from the glass to air, most of the light will suffer 
tal reflection at the oer surface of the glass, but if water or 
