178 7 Intelligence and Miscellanies. 
5. Notice of the Plumbago of Ticonderoga: by PRoressor 
Hau. 
Middlebury College, August 27, 1822. 
TO PROFESSOR SILLIMAN. 
I do not remember to have seen in the “ American Jour- 
ual of Science,” any account of the Plumbago, Graphite, or 
Black Lead, found on Cobble Hill in the town of Ticonde- 
roga. That which occurs in the vicinity of Roger’s Rock 
has been frequently described. 1 visited the locality on 
Cobble Hill, last week. It is about three miles N. W. from 
the Upper Falls. The Plumbago is found in numerous 
places, on the south side of the hill, in deep veins, from 
one to eight inches in thickness. The veins are, generally, 
perpendicular to the horizon, and nearly parallel with each 
other. The gangue is graphic granite. 
itatfthe hill the ni h 
? Near the th : Pp g is ji ii it Jit 
all parts of the gangue, occurring, sometimes insmall nodules, 
but oftener, inthin lami hibiting a brilliant metallic lustre. 
Some of the plates are very large. I measured one which 
“at the most elevated locality, is found a greenish stone, ex- 
tremely hard, which jn its external appearance, resembles 
Green Hornblende, but it is too hard for that mineral. I 
am ata loss what it is. 
The graphite, in veins, is uncommonly pure. It occurs, 
here and there, in irregular, hexahedral prisms. I saw very 
little that was granular. Most of it is foliated. In a few 
instances, it appears to be fibrous; but, on examining it more 
closely, you perceive that the fibres, which are often long, 
running across the whole vein, are composed of narrow, thin 
lamine.. It is removed from its gangue by means of chisels, 
pick axes, and iron bars, and conveyed to the Falls, where 
it is pulverized and purified. It has been prepared for the 
market, chiefly hy Guy C. Baldwin Esq. who informed me, 
that about three tons are disposed of annually. The average 
price, at which it is sold, is sixteen dollars a hundred. 
