Dewey on Geology of Williamstown, &§c. 345 
gneiss to the east, and rises again in Hampshire County, 
“supporting the same rock of gneiss ;” but where it reappears 
the granite contains “ many imbedded minerals.” This section 
corresponds generally to the place and character of the mine- 
_rals in any section across Berkshire cou There are, 
however, some peculiarities which may be m tioned ata fu- 
ture day. The coloring corresponds to that on the geologi- 
cal map in Cleaveland’s Mineralogy. = 
C. DEWEY. 
Williams College, Jan. 27, 1819. 
P. S. [have a part of a rock crystal, which contains, ina hol- 
_low, a liquid and a little air, and some black or brown particles, 
which just sink in the liquid. It was found several years since 
at Diamond Hill in Cattskill. This hill is only a small emi- 
nence on the bank of the creek at that place, composed of 
was generously given me by Mr. Van Loon, who found it, is 
only a part of two crystals connected at their bases. Partly 
under one of the solid angles formed by the united pyramids, 
is the hollow, about § inch long, about # filled with the air, and 
about 1 inch wide. The principal curiosity about it is the 
liquid. It has never been known to freeze. It was exposed 
. Yesterday morning an hour to an atmosphere 4 and 5 de- 
grees below zero. It became less fluid, for the bubble of air 
moved with less ease and rapidity. Still the liquid was fluid. 
Its color, which is naturally white, had’a slight tinge of yellow. 
The Rey. Mr. Schaeffer of New-York supposes the black par-_ 
ticles are bitumen: Is it possible the liquid is naphtha? ‘This 
oil is sometimes colorless, and does not congeal at zero, and 
that which I distilled from the Seneca oil, does congeal at 
Some degrees below zero. It can hardly be salt water, unless 
it he very salt, and even then, it would have congealed at the 
temperature of the air yesterday. What way can be devised 
to ascertain its nature ? 
Jan. 30, 1819. 
