85 
Virginia, and westward through Michigan, Illinois, Iowa and 
Missouri. 
Dr. L. FEUCHTWANGER exhibited an interesting specimen 
of Wolfram from Trumbull, Conn. It consists for the most part 
Scheelite, Tungstate of Lime, but at places this mineral has 
been replaced by the Wolfram, Iron and Manganese taking 
the place of the Lime, but the crystaline form of the 
Scheelite has been retained so that we have a remarkable 
example of pseudomorphism where large crystals appear 
having the form of Scheelite, but composition of Wolfram. 
This is stated by Dana to take place by the action of a 
solution of Bicarbonate of Iron and Manganese, or perhaps 
mainly through Sulphate of Iron arising from the decom- 
position of Pyrites. He also exhibited a finely crystalized 
specimen of Pyrargyrite, a Sulphuret of Antimony and 
Silver, containing from 58 to 60 per cent. of the latter metal, 
from Germany. 
Dr. NEWBERRY presented a Preliminary Geological Map of 
Ohio, constructed by himself and exhibiting the progress of the 
survey, now being carried on, of that state under his superin- 
tendance. A more complete, and larger map will be 
‘hereafter published as the survey progresses in its work. 
The following paper was read : 
On the Colors of Metals. 
By Pror. C. A. SHELY. 
Of all the metals two only, Gold and Copper are distinctly 
colored. When nicely polished the surfaces of all metals 
become nearly perfect mirrors, reflecting almost all the light, 
whatever be its tint, which falls upon them and the chemically 
clean mat surfaces of all metals except gold and copper 
appear white to the eye. Yet the white hight from such 
surfaces is invariably contaminated with a small amount of 
colored light, and this colored light is without doubt the 
result of a normal and ordinary decomposition of the incident 
