The Wallace miner. [volume] (Wallace, Idaho) 1907-current, 1917-08-02

fuSe Is subjected to severe handling
merely argues for the excellence OF
! its manufacture. If all articles il
common use were as honestly made
, as explosive materials the world might
: draw moral inspiration from com.
!, merce. Although "the function of al
} explosive is to explode" as was Ia
conically stated by Lieutenant Walker
J of the United States navy the extreme
care taken by the manufacturers tC
afford an ample margin of safety
against the vicisstudes of handling
such delicately balanced agents oil
destruction, permits rougher usage
than intelligent caution might COM
mend. Mr. Higgins points out that
the practice Of inserting the cap in
the wrong end of the cartridge, and
doubling back the fuse, is the fertile
cause of misfires. and misfires are re-
Isponsible for one-fourth of the fatal
titles overtaking those engaged in min
ing within the state of California
which state does not stand alone in
this respect. Fuse not infrequently
does spit fire through the walls; sell
dom will a coil cut into 3-foot lengths
of this defect That should be sutfi-
cient warrant for taking pains to
avoid any chance. of accident arising
from this source. The advice of man
| ,,fo of1 to 10 hnl ha ho
fuse may not come into contact with
the powder. The fuse should be dry,
as our correspondents insist it
should be cut with a sharp clean
cutter often combined with crimper,
because the fuse becomes pinched,
shutting off the powder train and
causing side spit near the end that
may fail to explode the cap; the cut
should be square across the fuse; the
cap should be placed upon the fuse,
preferably holding the latter upward
and drawing the inverted cap down
explain the difference in efficiency be-
tween threading a needle and needing
the thread, so is there a difference,
tending to security and efficiency, be-
tween fusing a cap and Gaping a
fuse. The double crimp is preferable;
| it insures holding the fuse in firm
contact with the illuminate in the cap.
The man who bites the cap upon the
10 lit Sn
as he frequently does
| We venture to say that any mine
breaking as much as 100 tons per diem
of ore and rock will find it economi-
[cal to employ man to make prim-
ers, and distribute all explosives to
| the miners. In no other way can the
proper making and use of primers be
insured. The powder monkey, as this
employee is generally called, can be
trained to observe all the proprieties
in making reliable primers, and in
tracing the inefficient use of blasting
materials if he be given responsible
ity as powder foreman. 1t then be-
comes possible also to make primers
lof powder containing a larger pro-
portion of nitro glycerine, which in
sures higher order of defamation,
developing increased useful effort in
the lower grade powder used in regu-
lar blasting. Primers of 60 per cent
dynamite, three inches long, with -6X
caps. will be found to effect a saving
in powder per unit of rock broken.
The wooden borer with a shoulder to
limit the depth of hole for the cap,
not only protects against premature
ignition of the charge by side splitting
from the fuse, but 1t prevents an air
4 space being left beneath the cap. In
significant as it may appear, the tiny
air cell left under cap when point
ed object is used to make the hole
reduces the initial force Of the explo-
sion by reason of the compression OF
that air before it can transmit the de-
tonating wave. 1t reduces the veloc-
ity and the order of defamation, which
means loss of power, waste of powder
less ore produced per pound Of dyna-
mite.
| Tamping opens another interesting
question, where room for argument
may exist. The suddenness of de-
donation of high explosive develops
almost instantaneously an enormous
expansive effort. On account of its
suddenness the maximum resistance
of the air due to its inertia is sup
posed to be realized. With unabsorb-
ed nitro -glycerine this result Is APP
: proximately obtained. especially when
the superficial area of the explosive
exposed to the air Is considerable. Thu
lease Is different with practical blast
ling powders; their velocity of deton-
alton is highly modified by the alb
sorbent. Moreover the projection OF
a slender column of air into the sur
rounding atmosphere introduces a new
physical condition; the power re-
auired to impel jet is different from
that required to overcome the inertia
of the air surrounding sand blast II
bulldozing. Plastic tamping is frs
compressed and frightened In the hole
Ithen the friction developed between
the tamping and the wall, under tht
lenormous suddenly applied pressure
ldue to the defamation, makes tht
Istemming almost as resistant as thu