The Sun.
London, England, 1865-04-15 00:00:00

Fire-Damp in Collieries.

A beautiful application of that mechanical power which
resides on the surface of bodies, and which is especially
developed in those having'a porous structure, known to us
as exomose and endosmoset has been made by Mr. G. F•
Ansell, of her Majesty's Mint. It is well known to most
of our readers that Professor Graham has been engaged for
many years m • examining all the phenomena connected
with the action of porous bodies, organic and inorganic,
upon gases and liquids. As the phenomena which Mr.
Graham groups under thegeneral term of osmose force may
not be familiar to all, a brief explanation may be desirable.
If salt and water be placed in a bladder, and this be placed

in a vessel containing pure water, the salt will pass out of
the bladder into the water. Recently an application of this
experiment has been made in Glasgow with much success.
In salting meat a large quantity of albuminous fluid flows
out of it with the diliquescing salt, and this, a valuable,
because nutritive, portion of the animal matter is lost. Now
this albuminous brine is placed in a bladder, and this again
in a vessel of water ; by virtue of osmose force all the salt
passes through the animal membrane, and pure albumen,
of considerable commercial value, is left behind. If in the
place of a membrane of this kind we employ a porous dia-
phragm of baked clay, plaster of Paris, or the like, the same
action takes place. By this means we may separate bodies
from each other which are mechanically mixed, and even

in many cases when chemically combined. Pursuing in-
quiries of this character, Mr. Ansell has been led to a dis-
covery which promises, above all others, to give us easy
methods by which we may determine the presence of car-
buretted hydrogen in our coal mines, and ho has inventeda
simple apparatus which promises to indicate the accumula,
tion of fire damp before it becomes dangerous, and either to
give the miner notice of it, or to convey that notice to the
surface by its connexion with some simple electro-telegra-
phic arrangement. Mr. Ansell has given two or three forms
to his apparatus. The first is that of a thin indiarubber
ball, which is filled with ordinary atmospheric air, and is
placed on a stand under a lever which slightly presses its
upper surface. This lever is connected with a spring,
which it liberates when from any cause the lever is raised,
and the liberation of the spring sets a bell in vibration,
This arrangement being placed in a vessel containing but
five per cent. of ordinary coal.gas exhibits the phenomenon
of endosmose with much rapidity. By the passing in of
the carburetted hydrogen the indiarubber ball swells, the

lever is of course raised, and the bell is rung. Experiments
made with the light carburetted hydrogen gas of the coal
mines show that the action is precisely the same in charac-
ter. This little apparatus, the cost of whick will be very
trifling, may be placed in any part of a colliery with the
certainty of its indicating the presence of fire-damp when
yet in small quantities, and c2nsequently before_there is any
real danger. If the "spring of this little instrument be so
arranged that it makes or breaks connexion with an elec-
trical battery, the signal of accumulating danger may beat
once conveyed by wires into the office, or any house on tho
surface of the colliery, and either by ringing a bell or
moving a magnetic needle, give the necessary warning to
tho owner or manager. Another form of arrangement as-
sumes the shape of a barometer. A glass tube is bent into
the form of a U, and upon one of the arms is fixed either a
porous earthenware cell or slice of graphite. The lower
portion of the U tube holds a few inches of mercury. The
moment a current of air, mixed with either heavy or light
carburetted hydrogen gas, even in small proportions,
passes over the
.graphite diaphragm or blows against
the porous cell the mercury is depressed in one arm
of the tube, and consequently raised in the other.' By
an arrangement precisely similar to that which is
adopted in the wheel barometer an index may be moved.
over a dial and made thus to indicate with accuracy the
appearance of dangerous gas in a colliery and register its
accumulation. It is not often that a more refined ap-
plication of a scientific discovery than this has been made,
while the arrangements, which have been patented by the
inventor (Mr. G. F. Ansell), are so simple that they may be
placed with confidence in the hands of any man to whom a
safety-lamp would be intrusted. As an unfailing indicator
of the presence of the collier's deadly enemy—fire-damp—
we cannot but regard this invention as one of the highest
value.