Massachusetts spy and Worcester advertiser. [volume] ([Worcester, Mass.]) 1823-1825, 1823-09-17

4 ne1v Fluid, 9th. remarkable Physical
Properties, discovered in the ccpities of
Minerals.
A NEW fluid, of very singular ma
ture, has recently been discovered by
DR.. Brewster in the Cavities of Mine
rails. 1t possesses the remarkable pro-
perry of expanding about thirty times
more than water; and, by the heat of
the hand, or between 75o and $50, it
always expands so as 10 fill the cavity
which contains it. The vacuity which
is thus filled up, is of course perfect
vacuum ; and at temperature below
that now mentioned, the new fluid con-
tracts, and the yacuity re-appears, fire.
quently with rapid efervescence.
These phenomena take place instanta-
neously, in several hundred cavities, at
the same time. The new fluid is also
remarkable for its extreme volubility;
adhering very slightly to the sides of the
cavities; and is likewise distinguished
byits optical PROPERTIES. 1t exists, how
ever, in quantities too small to be sus-
ceptible of chemical analysis. This
new fluid is almost always accompanied
with another fluid like water, with which
it refuses to mix, and which does not
perceptibly expand at the above men
toned temperature. In a specimen of
CymophGne, or Ckrysobeyrt, DR.. Brew
ster has discovered a stratum of these
cavities, in which he has reckoned, in the
space of 7th of an inch square, hirtu
thousand cavities, each containing this
new fluid, portion of the fluid like
water, and vacuity besides. All these
vscuities simultaneously disappear at
temperature of $50. If such a fluid
could be obtained in quantities, its utility
in the construction of thermometers and
levels would be iacalculable. There
are many cavities in chrystals, such as
those opened by Sir Humphrey Davy,
which contain only water. and which, of
course, never exhibit any of the proper
ties above described.
Method Of forming Three Haloes ortif-
cla'ty round the San, or any luminous
object.
The following experiment, which il
illustrates in pleasing manner the actual
formation of haloes, has been given by
Or. Brewster.-Take saturated solu-
ton OF alum, and having spread a few
drops of it over plate of glass, it will
rapidly chrystalize in small flat octohe-
drons, scarcely visible to the eve.
When this plate is held between the OBJ
server and the sun, or candle, with the
eye very close to the smooth side of the
glass plate, there will be seen three
beautiful haloes of light, at different
distances from the luminous body. The
innermost halo, which is the whitest, is
formed by the images refracted by a
pair OF faces of the octohedral crystals,
not much inclined to each other; the
second halo, which is more coloured,
with the blue rays outward. is formed
by pair of faces more inclined; and
the third halo, which is very large and
highly coloured, is formed by a still
more inclined pair of faces.
Each separate crystal forms three
images of the luminous body, placed at
points 1909 distant from each other, in
all the three haloes; and as the nu-
merous small crystals have their refract-
ing faces turned in every possible drec-
ton, the whole circumference of the
haioes will be completely filled up.
The same effects may be obtained
with other crystals; and when thew
have the property Of double refraction,
each halo will be either doubled. when
the double refraction is considerable. or
rendered broader, and otherwise modi-
ned in point of colour, when the double
refraction is small. The effects may be
c'urIously varied, by crystalizing upon
the same plate of glass, crystals of a
decided colour, by which means we
should have white and coloured haloes.
Edin. Phil. Jour.
A paper on the compressibilitv of
Water, Air, and other fluids, and on the
Capitalization of Liquids, and the lioue-
faction of Aeriforml Fluids, by simple
pressure, was prepared by Mr.. Perkins.
LOT the purpose of submitting it to the
Royal Society at their last meeting hut
il was accidnntolIx, .,>:..i1