The Sun.
London, England, 1868-08-20 00:00:00

INCREASED 7 UNNELLING FACILI7IES.

HAUPT'S IMPROVED ROCK DRILL AND NITRO-
GLYCERINE.
(From the Anglo-American Times.)

There is a good article in the last Westminster Review
on nitro-glycerine, which the writer believes, as an
explosive agent, to be destined to achieve great re-
sults. In conjunction with Haupt's improved rock
drill, we believe that the reviewer's anticipation
will be more than realised—a system of tunnelling,
boring, and blasting being introduced which will
give immense facilities in penetrating through the
bowels of the earth. An interesting experiment
has just been made at the Minera Lime quarries,
Wrexham, in North Wales, to test both the drill
and the explosive compound, and we will only say
here that the instrument and the compound were
alike successful. The rock drill is the invention of
the eminent American engineer General Herman
Haupt, of Philadelphia, lately and essentially modi-
fied and greatly improved. Messrs. Blanchard and
Mliean, 5, Rue Scribe, Paris, are the proprietors
of the European patents, and during the past year
have done much to adapt and perfect it for the pur-
poses required. The machine, as: used at Wrex-
ham, is 38 inches long, and in weight 140 lbs., re-
quiring one man only to work it. The parts brought
into operation are constructed of hardened steel,
and the machine is fixed in a simple frame, which
has four adjustable legs, weighing about 75 lbs.,
two men easily moving both machine and frame.
In motion it works as does the hand, viz., the stroke,
the revolution, and the feed all automatically made
by the machine, which adjusts itself to the differ-
ences in the hardness of rocks or varying speed of
penetration. It may be worked either by steam or
compressed air, which operates upon the piston iu
a small cylinder, giving the necessary impetus to the
drill to carry it through its automatical motions up
to 450 strokes per minute, the ordinary stroke
being 2001b5., which can be increased or lessened by
the turning of a screw. To work effectually two-
horse power of steam at 30 to 401bs. pressure is
required, which is obtained at small cost by a port-
able boiler. The smallest size machine will drill holes
up toll inches in diameter,but machines maybe made
to drill holes of any required dimensions, penetrating
from one to six or seven inches per minute according
to .the hardness of the stone. The machine used in
the Lime quarry was placed upon a flat surface,
occupying a space two feet square, a Winch drill
being passed through the cylinder. A flexible tube
attached to the locomotive gave the necessary
power, and the drill commenced hammering away
at full speed. In four minutes the tool had gone
to the depth of sixteen
,inches, the dust being ab-
sorbed and the drill kept cool by a jet of water
pouring into the hole. The tool was then changed
in two minutes and a half for one an inch and
three-eighths, and in three minutes the hole
had reached a further depth of fifteen inches, mak-
ing a good blasting hole in the hardest rock
of thirty-one inches in less than ten minutes,
including the time occupied in adjusting the ma-
chine and changing the drill. To have effected
this in the ordinary way two men would have
been engaged three hours. The machine was then
removed to other parts of the rock and other holes
bored with exactly the same result, which excited
the astonishment and satisfaction of those who
witnessed it. The machine as here tested was
horizontally placed, and in large tunnels three or
four may be kept working together one over the other
at different angles and wholly independent of each
other. The machine can be used on a columnar
stand weighing 100 lbs., and consisting of one or two
hollow iron columns with telescopic and screw adjust-
ments to suit any height of tunnel. The frame is placed
on a universal joint to drill at any angle, the direc-
tion being changeable in two minutes. The legs
are so framed as to stand on any surface, however
irregular, and shod with steel points. What adis so
much to the value of the machine is that it is pecu-
liarly adapted to submarine work. As it is equally
good in driving levels, sinking shafts, and open
quarry work; its introduction at the present time,
coupled with the use of dynamite, is very fortunate,
as it will encourage the prosecution of the three
huge projects now discussed—" the Sub-Channel
Railway from Dover to Calais"—another " from
Port Patrick to Donaghadee, connecting Great
Britain with Ireland"—and " and that under the
Firth of Forth between Linlithgow and Fife."
It may not be out of place here to condense from
the Westminster Review a few remarks about nitro-
glycerine : —lt hid its birth in the chemical
laboratory of an 'eminent French professor, M.
Pelouze, upwards of twenty years ago, It is
a mixture of four parts of oil of vitriol and
two parts of strong fuming nitric acid, the specific
gravity of which is as nearly as may be 1.52. When
this acid mixture has thoroughly cooled down, one
part of glycerine in the dehydrated state—that is
free from water—is poured into it and the whole well
stirred. Chemical action ensues, attended with
considerable increase of temperature, and with the
escape of ruddy, brown fumes. To prevent the
temperature becoming too great, the vessel is
externally cooled by being surrounded with ice.
When the chemical action ceases, it is found
that a yellowish oily-looking fluid comes to
the surface ; this is impure nitro-glycerine.
ro obtain it in the pure state, free from contami-
nating acid, the whole liquid mass is thoroughly
mixed with fifteen or twenty times its bulk of cold
water, and then permitted to settle. The nitro-
glycerine collects in the lower part of the vessel,
and is drawn off by means of a syphon, or separated
by the process of decantation. It is afterwards
washed so completely that not the slightest trace of
acid is found in the washings. When perfectly pure
it is a colourless fluid, decidedly heavier than gly-
cerine, perfectly inodorous, and possessed of a
sweetish, aromatic, and pungent taste. It is power-
fully poisonous, and even a small quantity placed
on the tongue produces violent headache ; and as
it acts similarly when absorbed through the pores, it
is advisable that gloves., be worn when working
with vessels containing it. When prepared in a
pure state it is a very stable compound at
ordinary temperatures. If, however, it be im-
pure, and contains any of the acid used in
preparing it, there is a proneness to decomposition,
and then explosive violence is almost certain to
occur. When pure it will safely hear exposure to
the temperature of boiling water. It is not in the
slightest degree volatile ; it is practically, if not
absolutely, insoluble in water, but in either alcohol,
and especially wood-spirit or methyl-alcohol, it is
freely dissolved. lts especial property is great ex-
plosive power, but it is not exploded with any
unusual degree of facility. It will not explode by
simple contact with fire or heat unless raised to about
360 deg. Fahr. If a flame be plunged into it the
liquid will simply burn so long as the match is applied,
and with an ordinary cotton wick it will burn like
common lamp oil. Gunpowder will explode with
a spark, and gun cotton at a temperature of 277
deg. Fahr. Some other agent than heat must be
employed, and that is concussion. When a quan-
tity of the liquid is spread over an anvil, on strik-
ing the,moisteued surface sharply with a hammer
there will be a detonation ; but only that part will
explode which is actually struck ; and there may
be many such explosions on the parts untouched by
the hammer. Experiments have been made with
glass bottles filled with the liquid ; they have been
dashed against hard rocks, thrown from great
heights, but no explosion has resulted, and

even after being heated to 120 degrees Fahren-
heit. When it is desired to employ this substance

as a blasting agent, bore-holes are made in the
usual way, which are filled up to a sufficient height

with the liquid, and then rock powder, or sand, or
water is introduced above the nitro-glycerine as the
tamping material. Hard stamping or stemming
is very objectionable just mentioned,, water

will suffice; for as the nitro-glycerine is fully one
and a half times the weight of water and insoluble
in it, the latter will rise to the surface, even
though the drill-hole contain water when the
nitro-glycerine is poured into it, so it may be
used in wet rocks or water-bearing strata with
impunity. When the liquid is in the drill-
hole, the fuse-tipped with a tightly fitting per-
cussion-cap, is introduced into it either before
or after the tamping is done, but the cap must be
actually in the blasting liquid. When the explo-
sion is effected there is no residue nor smoke, and
being much quicker than gunpowder the operation
is. performed with greater than ordinary rapidity.
It is the most powerful explosive known, one pound
of nitro-glycerine doing as much mechanical work
as ten pounds of gunpowder, and some affirm even
thirteen. Weight for weight it costs seven times
as much as gunpowder, but the economy of its use
is seen in the effect produced by the explo-
sion. So great is this in comparison with
gunpowder that few bore-holes are required,
and a swing results of from thirty to forty
per cent. in mines, and 50 to 60 in quarries.
Although the Reviewer alludes pointedly to its use in
Sweden, a late order of that Government prohibits
its use in that country, from which we must con-
clude that experienze proves it to be a more unsafe
compound than he represents. It may, however,
result from ignorance, and the fright caused by the
destructive nature of the explosions at Newcastle-
on-Tyne, and he commences his article by showing
the absolute necessity for safety to obtain the
liquid in a pure state, when he affirms it to be far
lea dangerous than gunpowder.