Mr. keir on the 
534 
ragged and irregular; but feveral of them fhew a ten- 
dency to an hexagonal form, the regularity of which 
may have been dilturbed by the motion of the melted 
glafs acting upon and bending thefe very thin cryltals, 
while they were hot and flexible, at the time when the 
pot was pulled out of the furnace. 
The fpecimens marked N° 3. are pieces of a glafs- 
houfe pot, down the outer fides of which fome melted 
glafs had run, and adhered long enough for the forma- 
tion of various kinds of cryltals. The inner Tides alfo of 
thefe pieces are covered with glafs varioufly cryltallized. 
Some of thefe cryltals feem to be femi-columns, of 
which the flat fides, or interior furfaces, are expofed to 
view, and are reprefented by fig. 9. Other cryltals, 
reprefented by lig. 10. feem to confilt of feveral lem i- 
columnar ones, uniting together in the fame plane round 
a common center, like broad, flat fpokes of a wheel. 
Many of thefe fpokes feem to become narrower as they 
approach the center of the wheel, and, therefore, refera- 
ble more the fegments of frufia of cones cut along their 
axis, than of cylinders. But, perhaps, this appearance 
proceeds only from the femi-columns being fo difpofed 
near the center of the wheel, that the edge of one is laid 
over the edge of the contiguous femi-column, like the 
fpokes of a fan. 
In the fpecimen of glafs, marked N° 4. which had run 
through a crack in a pot, and had remained adhering to 
the l^ars of the grate of a furnace, fufficiently long for a 
cryftaliization to take place; fome of the cryltals appear 
oblong 
