The Sun.
London, England, 1866-06-22 00:00:00

Mr. Gale's Non-Explosive Gunpowder.

The final Government trials to test to the utmost
the value of Mr. Gale's discovery were made on the
largest scale on Wednesday afternoon and evening
in one of the Martello towers on the beach half-way
between Hastings and Rye. Everything connected
with these experiments was entirely managed by
the members of the Ordnance Select Committee, and
workmen from Woolwich Arsenal were employed
t) mix the strongest Government powder with the
protecting composition, to barrel it, and to stack it
in the Martello tower. Mr. Gale's only share in the
proceedings was that he furnished the protecting
compound, that his directions as to its mixture were
implicitly followed, and when all was ready he was
invited to be present at these official tests, which,
like all such, were very properly of the most severe
and exacting kind. In the result they proved most
triumphantly that Mr. Gale is right when he asserts
that by means of his mixture the strongest powder
can easily be rendered not only non-explosive, but
even almost incombustible, and this without in the
slightest degree deteriorating from its destructive
power when the powder is separated as it can be at
once from his protecting compound. On Wednesday,
certainly, all efforts to blow up five tons of powder
when mixed according to Mr. Gale's directions not
only proved utterly fruitless, but the powder actually
twice went out, and it was after all found necessary
to set fire to the woodwork of the Alartello tower,
in which it was stored, in order to consume it at all,
and even then this was not entirely accomplished.
Nothing, therefore, could possibly have been more
complete than the success of the experiment, though
the value of the invention will perhaps be more fully
appreciated if we explain in a few words how simply
such au astounding result is brought about.
It is nearly 15 years since Mr. Gale began to
direct his attention as a chemist and electrician to
the discovery of a material which when mixed with
gunpowder should render the whole mass at once
fireproof, waterproof, and airtight, and at the same
time be easily separable, and when separated leave
the gunpowder totally uninjured. It is needless to
say how many and how combined were the compo-
sitions tried before one at last was found to fulfill all
these apparently irreconcilable conditions. This
composition is nothing more nor less than powdered
glass prepared in a peculiar manner. The com-
monest glass is heated to a bright whiteness and
then plunged into cold water, which utterly destroys
all the little fibre and elasticity glass can ever be
made to possess, and renders it so friable as to be
easily pressed to powder between the fingers. In
this state it is placed in a machine shaped like Et
cask, in which are many small iron shot, and the
machine being revolved rapidly a minute or a minute
and a half suffices to reduce the glass to a powder
so impalpable that even fine w'icat flour is coarse
in comparison with it. This is mixed with the
powder in the proportion of two parts to one, if it
is only meant to render it non-explosive, but still
leave it fiercely combustible ; in the proportion of
three parts of ground glass to one of common pow-
der, if it is meant to make it almost incombustible ;
and in the proportion of four parts to one of the
strongest gunpowder to make the latter absolutely
harmless. Four parts are, however, generally consi-
dered necessary only for the strongest Government
common powder. The method of mixing the two is
simply by an adaptation of Robinson's cask cleaning
machine, which gives to the cask it holds a rapid I
double motion, two minutes of which is sufficient
to blend the ground glass and the coarse grains
of powder perfectly. So complete is this mixture
that of 40 samples taken from as many casks after
two minutes mixing the relative proportions of the
two materials were found to be in all cases abso-
lutely exact. The 40 51b. samples when separated
were all found to contain precisely 11b. of gun-
powder and 41b. of powdered glass. The separa-
tion of the powder from the glass is made in a few
seconds by coarse copper sieves. The grain of the
best Government powder for cannon is nearly as
large as a coffee bean, and this coarseness, combined
with the fineness and weight of the powdered glass,
enables the two to be separated almost instantane-
ously, and a very simple piece of copper machinery
has been devised which will effect this process even
more quickly and on the largest scale. One of the
most important questions to be ascertained was
whether the minute portions of the powdered glass,
which more or less adhered to the grains of gun-
powder after sifting, in any way affected its explo-
sive qualities. For some time past, therefore, the
Ordnance Select Committee have made a most care-

'ul series of experiments to resolve this doubt, and

the decision they have come to is that neither in
rapidity of ignition nor explosive force is the gun-
powder deteriorated. Not only is it not injured,
but its complete preservation from damp—almost as
important in the case of powder as its preservation
from fire—makes Mr. Gale's method of mixing far
preferable to the present mode of stowage. The
objections 'to the bulk which powder when thus
mixed would occupy in the Government stores
have also in a great measure disappeared upon
examination. About 25 per cent. of the kegs in
which gunpowder is now packed are left empty
that the grains may be free to roll, and so pre-
vent their " cakeing." This necessary precaution,
however, induces another evil, which is that the
Constant friction of the grains often reduces half
the contents of a keg to dust, and immense quan-
tities are thus 'yearly returned to the mills to be re-
corned before it can be used. Qt. course, against
.all.thtiise evils of fire, *Ater, friction; or deteriora-
tion, Mr. Gale's discovery is an absolute specific.
With the adoption of his plan all the necessities

! the mode of action of powder thus protected when
stored in a burning building. A strong body of
police were stationed at first to keep the spectators
at a safe distance from the tower ; but this precau-
tion, though wise, was soon found to be unnecessary,
and after a time every one came as near the build-
ing as he liked. In three of the barrels thus stowed
away were three powerful fusees, each connected
with a small quantity of pure gunpowder. These
were fired one at a time from a voltaic battery in
No. 38, Martello tower, ahout half a mile distant.
On the discharge of the first fusee no visible effect
whatever was produced outside the tower. When
the second fusee was fired, a small quantity of
smoke was seen to issue from the chimney at the
top of the tower roof, and no further effect beyond
this was produced by the firing of the third fusee.
After a short interval General Lefroy, with three
other gentlemen, entered the tower and found that
the heads of two of the barrels containing the fusees
had been blown out, and a small portion of the
contents had been scattered over the surrounding
barrels. The protected powder, however, had
ceased to burn and was nearly cold. The third
fusee had not taken effect at all.
It was then determined to set bre to the build-
ing. This was very easily done, as the floor of the
first story consisted of loose planks, placed at a
little distance from each other, so that they would
rapidly burn as the air could get between them. A
1
pile of dry firewood was placed on this floor at the
edge of the barrels of gunpowder, and on this
being fired dense volumes of smoke were seen to
issue from the door and windows of the tower.
It was soon evident, from the peculiar colour of
the vapour, that the gunpowder was being slowly
consumed ; and, although the quantity of smoke
was irregular and sometimes very dense, nothing in
the slightest degree approaching to an explosion
occurred. General Lefroy was soon so far satisfied
of the non-existence of danger that he allowed
several gentlemen to look in at the door of the
tower, to see how the gunpowder was burning.
Two barrels of protected gunpowder were then
placed on a pile of faggots which were lit. From
this a huge bonfire soon rose, and its flames were
fanned into an intense fierceness by the strong sea
breeze. These quickly penetrated the casks, which
broke up and let loose their contents in the midst of
the fire. Still there was not the slightest symptom
of explosion. On the contrary, the mass of pro-
tected powder rather deadened down the flames at
first, and it was only at its edges that the mixture
fizzed and spluttered like a bad portfire. During
this time the fire in the tower continued, and smoke,
but no flame, steadily issued from the openings.
Occasionally a sudden increase in the volumes of
smoke indicated that a barrel had burst and exposed
an unusual quantity of powder to the flames ; but
so confident had the gentlemen become who had
witnessed the experiments that Lthey continually
looked into the building and actually went inside
the door to see how the powder was burning. This
i they were enabled to do from the strong in-draught
of fresh air which entered at the bottom of the door-
way, while dense columns of smoke issued from the
top. So totally was the explosive character of the
gunpowder mastered, that after the fire had been
burning for nearly two Lours, a window which had
been closed on one side of the building was found
quite perfect, and the glass was broken from the out
side in order to admit more air to increase the fire.
Apparently, however, even this considerable accces-
sion of air produced no effect. The barrels kept
smouldering from one to another, emitting the most
dense volumes of suffocating smoke, but no snore.
In spite of the interior of the tower having been
fired, and the immense mass of burning embers which
the beams left, the conflagration, if such it may be
called, continued steadily to diminish as the barrels ,
burst, and the powder literally smothered out the
fire. Before nightfall the light in the tower had
quite dimmed down, and it was generally believed
that in a few hours more it would go out of itself,
leaving half the barrels untouched and their contents
in powder, when separated from the mixture, as
little injured as if they had never left the magazine.