.608	The colliery guardian.	a, mo,

___________________________________________________________

Mr. E. B. Wain, said he, also, appreciated the value
of the paper, which put in a scientific way what many
of them had dealt with in a rule-of-thumb manner in
the past. The use of iron or steel for a particular pur-
pose was, of course, of grave importance, and one looked
forward to the further development of the Shelton
Company’s enterprise in regard to Armco iron for the
production of yet another material for colliery use. He
would suggest that- for pit tubs, in particular, a new
material would be specially valuable. In the making of
tub bottoms, unless they had a very high grade of iron,
when they had to bend it in two directions, they often
met- with disaster. Steel was very much more easily
bent, but against that they had to set the rapid corro-
sion of steel pit tubs. For years past he had used only
a high quality of wrought iron for pit tub work, and it
had paid. At the same time, they would be glad to
have some new material that would give them a much
more durable tub. They all regretted that Mr. Simons
had not dealt with steel for wire ropes, for that was the
all-important use of steel at a colliery. Some of them
had been trying for a good many years to accumulate
data and analyses, in order to get something like a stan-
dard specification for high-class wire rope. He had a
long list of data himself, but he was sorry to say they
were so entirely contradictory to him., as a non-metal--
lurgist, that he did not know what to make of them. If
Mr. Simons could help them to obtain a standard speci-
fication for wire ropes of various stresses, it would be of
the utmost possible value. Mr. Hartley mentioned the
case , of a wire rope only lasting a short time after its
predecessor had been in use seven years. He wondered
whether, at the same time as they put on the new rope,
they changed the pulley. If it were the same pulley,
and the old rope had been working on that for seven,
years, and they put a new rope on the sharp edges, it
was not surprising that the new rope did not last. As
regards purchasing a particular quality of iron, he had
always been opposed to purchasing anything in the
nature of common iron for colliery use; there was always
the danger that it might be used for some purpose where
the better quality was required. Taking into account
the very little difference in the cost, it was far better to
have- a high quality for all purposes. Mr. Simons made
a very important point with regard to the annealing of
cage chains, and it needed careful thinking over. Anneal-
ing was often done in a casual sort of way, and if every
colliery would make a part of its plant a special anneal-
ing furnace, where this work could be done on proper
lines, it would be a huge advantage. It was true they
did not have many breakages at collieries, but that was
due to the fact that they used chains very much stronger
than they needed, rather than that they took the best
possible cate of the chains. The present circumstances
of the iron and steel trades were driving them to the
use of old-fashioned material in collieries. Some of
them were thinking that they would have to use wood
instead of iron for tubs, and wood in place of the present
steel roof supports.

Mr. A. M. Henshaw seconded the vote of thanks. It
was the first time, he said, that this subject had been
brought before them in such an interesting way. He
added his regrets that Mr. Simons had not dealt with
the subject of wire ropes. There was another subject ho
had omitted, and that was tool steel. That was a very ■
wide subject .indeed, and he hoped it would not be
asking too much that Mr. ’Simons should include with
the paper one or two paragraphs with regard to tool
steel. .	•

The vote of thanks was heartily accorded.

Mr. Simons, in reply, thanked the members for their
appreciative remarks, and said that if the paper would
serve any useful purpose, he would be amply repaid for
any trouble. He had felt some diffidence in putting
before them these figures, that steel was as good as iron,
lest he might be thought guilty of showing a little bias
on the subject, seeing that his firm were more interested
in steel than wrought iron, but he assured them he would
not stoop to do that. He wrote to Prof. Arnold pointing
out that he was astonished at the results, because the
general impression was that wrought iron would stand
fatigue better than steel. But Prof. Arnold assured him
that the results were in accordance with previous expert-
encerin other tests. He (Mr. Simons) still thought that
wrought iron was the most satisfactory for colliery work.
He agreed with Mr. Wain that nothing but the best
should be used at a colliery, and nothing but grade A.
Mr. Hartley asked if Armco iron would be suitable for
fireboxes. He could only say that they were making
one now, and they would be glad to let anyone know
the result. They were forced to do it, owing to the
high cost of copper and the inability to get it. Armco
was the purest material that could be obtained, and as
near copper as iron or steel could be. With regard to
tyres, the best ’ quality of steel was high grade acid
steel. It was reserved for tyres, but one need not
necessarily accept Rentoul’s test; the British Standard
tests were equal to any work that might be required.

___________________________

Partnerships Dissolved.—The London Gazette announces
the, , dissolution of the following partnerships : — F. M.
Knowles and W. Fisher, carrying on business as engineers
at London Works, Bridge-street, Sheffield, under the style of
Knowles and Fisher; G. H. Chappell, T. J. Chappell, and
A. W- Chappell, carrying on business as .scrap iron and metal
merchants, 1, Poplars-road, Leyton, as G. H. Chappell and
Sons; A. Graham, A. L. Dearlove, and E. A. Graham,
carrying on business as electiriaal engineers at St. Andrew’s
Works, Crofton Park, and Kilmorie Works, Forest Hill, as
Alfred Graham and Company.

CURRENT SCIENCE AND TECHNOLOGY.

Miners’ Carbide Lamps.

James W. Paul is the author of a “ Miners’ Circular
on the above subject, issued by the United States
Bureau of Mines.

Within recent years there has come into use in metal
mines and , in many coal mines in the United States a
type of open flame cap lamp for burning acetylene gas,
the gas' being made within the lamp by the use of
calcium carbide and water. In some non-gaseous coal
mines this type of lamp has almost, entirely taken the
place of the miners’ open flame oil lamp, and in many
metal mines it has replaced candles. The number of
acetylene lamps in daily use in the mines of the, United
States is estimated at fully 300,000; 60 per cent, of the
lamps used in non-gaseous coal mines, and 15 to 20 per
cent, of those in metal mines being acetylene, lamps.

It is considered that the introduction of carbide
lamps in metal mines and in non-gaseous coal mines
that are well ventilated, should materially reduce the
number of accidents resulting from poor light.

The types of carbide cap lamps now in use give much
more light than the miner’s oil burning lamp. When
fitted with a reflector, carbide lamps, with a flame 1 to
l|in. long, give a candle-power head-on of 4-2 to 6-2,
and at right angles to the flame of 0-87 to 1-45. With-
out a reflector, the head-on candle-power of the lamps
averages 1-9 to 2-15, and at right angles 1’9. The
miners’ and drivers’ oil burning lamps, when the flame
is adjusted so as to give the most light, have average
candle-powers of 1-4 to 1-9.

Some of the advantages that may be justly claimed
for carbide lamps are as follow :—As compared with
an ordinary miner’s oil lamp or a candle, a carbide
lamp gives much more light. A carbide lamp is clean,
and the flame produces little smoke. The gases of com-
bustion are principally carbon dioxide and steam (water
vapour), and the acetylene is not injurious to health.
The flame will not drop sparks and thus ignite explosives
or anything that will burn, as sparks from an oil lamp
may do; however, the flame of acetyplene will set fire
to anything inflammable more quickly than will the
flame of an oil or candle. With the better light the
working place can be more easily examined and
dangerous roof conditions can be more readily detected.
The general efficiency of the men is increased, because
they are able to do more work with a better light. The
cost of upkeep of carbide lamps is: less than that of oil
lamps or candles.

Some of the disadvantages in the use of carbide lamps
are as follow :—The flame, compared with that of an oil
burning lamp, is more easily put out by a sudden jar or
shock to the mine air, such as is frequently produced by
blasting; however, the lamp may be quickly relighted
if it is provided with some form of cerium igniter. When
the flame is put out before the supply of carbide and
water is used, the acetylene produced has a bad smell.
As a carbide lamp will burn in air containing less oxygen
and more carbon dioxide or black damp than will an oil
lamp or candle, a miner using a carbide lamp may, with-
out realising it, work in air that is bad for his health or
even dangerous to his life. The use of carbide lamps
tends to lessen attention to the ventilation of the mine,
especially as regards the presence of carbon dioxide or
blackdamp. Careless or improper handling of carbide,
such as permitting a quantity of it to come in contact
with a pool of water in a mine, may cause an explosion
or burn the men. Carrying carbide in the mine in a
glass jar resulted seriously to a miner who accidentally
dropped the jar in a wet place and ignited the gas. Cap
lamps which have the gas generator attached to the belt
of the miner are liable to leak at the generator or its
tube connection; and the escaping acetylene gas may
take fire and fatally burn the miner. Owing to the ease
with which the flame may be put out by sudden jars or
by shock to the air, the carbide lamp is not well adapted
for use by drivers, trip riders, or motormen.

At mines where carbide lamps are used there should
be rules to govern the storage, handling, and use of
carbide. The following suggestions are offered as a basis
for such rules :—■

(1)	Never store carbide in a mine.

(2)	Limit the quantity of carbide each man may take
into or have in the mine.

(3)	Always carry carbide into the mine in a metallic,
air-tight box or can having a screw or other close-fitting
top. Do not use glass jars or copper vessels for carrying
carbide.

(4)	Never leave unused carbide on the floor or in the
gob of a mine, or among greasy waste or other materials
that will burn.

(5)	Never throw the refuse (slaked lime) in the work-
ings or abandoned parts of a mine, but put it in a dry,
metallic can having a lid with a vent, and take it out
of the mine.

(6)	Never use carbide in a lamp made of copper; the
lamp may explode.

Pitch as a Gas-Ma,king Material.

Some experiments have been carried out at Oldham
by Mr. T. Duxbury. In the first tests, coal and ordinary
pitch mixtures were used, the coal being Hemsworth
washed nuts; 5 per cent., or lewt., of pitch per ton of
coal carbonised gave an increased yield of 310 cu. ft. of
gas per ton of coal, 75 lb. of coke, and 34 gals. of
tar. This is equivalent to 6,200 cu. ft. of gas,
1,500 lb. of coke, and 70 gals, of tar per ton
of pitch. The calorific value of the gas was
increased from 581 British thermal units to 594, and the
candle-power from 16’20 to 16’73. The coke .was
improved, the heats being higher after using pitch each
test. Similar comparative results were obtained by
carbonising 10 per cent, of pitch. The tar analysis was

not completed,.bub the specific gravity-is slightly higher,
also the-tar contains more naphthalene..

Using coal and hard pitch mixtures an ■ addition of
5 per'cent, of pitch gave an increased yield of 676 cu. ft.
of gas per. ton of coal, 60 lb.- of coke, and 4 gals, of tar.
The .calorific value of the gas was increased from 531
British thermal units to 552, and the candle-power from
14-96 to 15-23.

An examination was. made of tar from coal treated
with 10 per-cent, of hard-pitch and .from untreated
coa. ;2-,000 c.c. of tar ,were taken and distilled up to
300 degs. Cent. The following were the results :■—

Untreated. Treated.

Gas made, corrected to 540 B.T.U.

(cub ft.)........................................ ... 13,880 ... 15,020

Tar made (gallons).................	Ill ... 17.......

Water content in tar (per cent.) ...	4'3	...	3’6

Naphthalene, &c.> per cent, (by

volume) ........................	13'25	...	17 5

Toluol per ton of tar (gallons)*.....	2'460	...	2*040

Toluol per ton of coal (gallons)*....	0'141	...	0'173

Pitch by weight (per cent.).........	69'62f	...	71'801

* Corrected for paraffins and to 5 per cent, wa^er content. .
f Hard and dull. J Softer and brighter.

Mr. H. Kendrick, Stretford, endorsed the view that
the best way of restricting accumulations of pitch and o-f
preventing the further, lowering of the price was its use
admixed with coal for gas making; and Mr. Glover, St.
Helens, said this suggestion of the carbonisation of a
suitable percentage of pitch in gasworks was a way by
which the tar maker could control to some extent the
value he should ultimately receive for his tar, inasmuch
as it would help to remove to the extent of his own
production the incubus of an increasing stock of pitch
and a drop in the price -of tar, which would surely come
about if pitch could not be removed into a new market
for the time being. A comparison of prices, between
coal 'at the present day and pitch at the price at which
it had descended, made this proposition quite a
practicable one.

An Automatic Slate Gate.

A breaker foreman at Westmoreland Colliery, Lacka-
wanna Division, has perfected an automatic slate gate
for jigs that has proven its worth in several of the
collieries of the Wyoming region the past year. A
description appears in the Lehigh Employes Magazine.

The accompanying drawing shows the gate E closed,
and the rod and weight D, by which a balance is effected.
When a certain depth of rock, at E, is formed sufficient

# ow

to overcome the counterweight D, the gate opens, and a
certain amount of refuse passes off, after which the
decreased pressure on the gate permits the counter-
weight to move downward, and the gate is closed.

Storage of Coal and Spontaneous Combustion.

In a recent number of the Journal of the American-
Society of Naval Engineers an article was published on
“Land Storage of Bituminous Coal and the Factor of
Spontaneous Combustion.”

The author says that ia plant designed to store coal
in such a manner that rapid discharge and loading of
vessels can be effected, and with a capacity of nearly
16,000 tons, can only be utilised for the storage of
approximately 11,000 tons. If this condition applies to
other naval storage plants a large amount of Government
funds have been expended unnecessarily, as well as
valuable property utilised for an unnecessary purpose,
and, furthermore, an even more vital item presents itself
in view of the fact that these plants, being built for a
certain capacity, would probably be called upon in time
of war to work to this capacity. It is easy to see that
conditions might very probably arise that when this
coal was very urgently needed, it would either be too
hot to place in the vessels’ bunkers with safety, or that
the prolonged and continual process of heating had so
exhausted its calorific qualities as to render it not good
steaming coal. . If not this, even the fact that the plant
was not worked to capacity might seriously affect the
situation by the absence of the amount of coal, the
difference between what could be carried with reasonable
safety-and-the plant’s designed capacity.

It is.believed that an open shed with just enough
superstructure to support the overhead mechanical
devices for rapidity of handling of coal is far superior
and safer than the closed type. It is possible that a
light roof that can be easily opened and shut might be
an advantage. It is especially so at the Key.West
station, where they are so dependent upon rain for their
water supply.