982

THE COLLIERY GUARDIAN

November 12, 1915.

CURRENT SCIENCE

Portable Electric Mine Lamps.

In a paper read before the West Virginia Coal Mining
Institute, Wheeling, West Virginia, Mr. H. H. Clark,
electrical engineer, United States Bureau of Mines, says
that for several years the Bureau of Mines has been
encouraging the development and adoption of portable
electric mine lamps as a measure of safety, and to this
end issued a set of specifications dealing with the safety
of the lamps, the amount of light, the distribution of
light, the time of burning on one charge of battery,
the characteristics of the lamp bulbs, the mechanical
construction of the equipment and its general reliability.
The specifications require that the lamps shall be pro-
vided with a device that will extinguish the bulbs as
soon as they are broken. The minimum amount of light
recommended by the Bureau was the amount of light
that is given by a good safety lamp. Almost every
electric lamp that the Bureau has investigated gives more
light than the Bureau’s specifications require. The time
of burning was set at 12 hours, in order to have a margin
of safety over the time that a lamp would actually be
used underground. The specifications put considerable
emphasis upon the distribution of light. Some of the
lamps submitted produced a narrow ray of light filled
with sharply contrasting areas of light and shadow. The
Bureau therefore asked that the angle of the ray be made
so large that light was thrown practically everywhere
that a man’s eye could turn, and further required that
the stream of light should be free from shadow and
sharply contrasting areas of bright and faint illumina-
tion. Another part of the equipment that had not been
developed satisfactorily was the bulb. The Bureau
has succeeded in securing the co-operation of some of
the bulb manufacturers to the extent of their agreeing
to make bulbs to the Bureau’s specifications. This will
result in bulbs of longer life and more uniform per-
formance than have been available heretofore. The
Bureau has also laid great stress on the need for making
all parts of the lamp construction substantial and
efficient, so as to prevent interruptions of service and
facilitate repairs.

A good mine lamp is more than the mere combina-
tion of a good battery and a good bulb. These parts
must be properly mounted, connected and protected,
and this involves the consideration of many details small
in themselves, but very important as a whole. The
battery casing must be strong and provided with a lock
and suitable arrangements for making electrical connec-
tion to the battery. The headpiece that surrounds the
bulb must be substantially constructed, must give a good
distribution of light, must be easily repaired and con-
veniently attached to and worn on the miner’s cap. The
headpiece and the battery must be connected by a
flexible electric conductor that will withstand the bend-
ing, slatting, and abrasion that mine service entails. It
may be said in passing that the design of this cord has
so far given more trouble than any other part of the
outfit. It is the part that gives out most frequently.

The first thing to be considered after selecting a lamp
is the appointment of a capable man to care for the
lamps. It is false economy to put an incapable man in
charge of a lamp house. Electric lamps will require
more lamp house space per lamp than oil lamps, and it
will be a good plan to lay out the lamp house carefully
and with reference to the needs of the individual mine.

Lighting of Factories and Workshops.

Numerous investigations have been carried out on
the subject of lighting, but, owing perhaps to the absence
of any statutory provisions in this country in regard
to lighting (analogous to those regarding heating and
ventilation), the question has never been attacked in a
really practical way. One of the few exceptions that
springs to mind is the test for safety lamps, which for
the first time, imposed a standard of lighting in mines.
The first report of the Departmental Committee on
lighting in factories and workshops, however, is, for the
reasons set forth, of more than ordinary interest.

There is nothing new, of course, in the assumption
that inadequate lighting is not only productive of acci-
dent, but is prejudicial to general health; in accordance
with common experience, these facts have been recog-
nised by modern factory owners in advance of legislation.
Now the Committee recommend that there should be
a statutory provision (a) requiring adequate and suitable
lighting in general lines in every part of a factory oi*
workshop; and (b) giving power to the Secretary of
State to make orders defining adequate and suitable
illumination for factories and workshops or for any parts
thereof, or for any processes carried on therein.

The next question that 'the Committee had to tackle
was the amount of illumination implied in the .terms
“ adequate and suitable.” The following epitomises
the recommendations under this head :—

Minimum.

Place.	illumination.*

ee __	.	Foot-candle.

Working areas of workrooms ........... 0‘25

Parts of foundries in which work is being
carried on or persons ordinarily pass . 0’4

Parts of factories and workshops over which
persons pass ........................... 0T

Open spaces in which persons are employed
during the day, and dangerous parts of the
regular road or way over a yard or other
approach.............................. 0’05

* Measured on a horizontal plane at floor or ground level.

These values are suggested without prejudice to the
special illumination required for the carrying out of the
work, which naturally varies greatly, according to the
nature of the operations.

Apart from the conclusions briefly set forth above, the
report and appendices contain information that will be
of use to all concerned in the question of lighting. The
foot-candle, it may be mentioned, is the illumination

AND TECHNOLOGY.

produced by a light source of one standard candle at a
point of a surface one foot from the source, and so placed
that the light rays from the source strike the surface at
right angles. Reflected light in the shape of “ surface
brightness ” may be also measured in this way.

In a summary of replies from leading ophthalmo-
logists and ophthalmic surgeons, frequent reference is
made to the subject of miner’s nystagmus, which is now
generally believed to be due to defective lighting. Dr.
Stanley Percival, of Newcastle, however, still regards
it as being due to some inherent nervous instability
which shows itself in nystagmus after working in
strained positions, but he regards insufficient lighting
as a controlling and aggravating cause, as it entails
greater strain on the eyes. In one case he found a
chronic conjunctivitis which seemed to be due to electric
light; it ceased on using an oil lamp. Most of the
authorities recommend the use of shaded lights or pro-
tective glasses, and it is interesting to note that Dr.
H. S. Elworthy, of Ebbw Vale, urges that protection
for miners is needed from looking at naked lights when
going to and from work—a, recommendation made, we
believe, by one of the Belgian experts some years ago.
He lays stress generally on (1) character of light; (2)
reflecting surface on which light falls; and (3) lights
should be diffused rather than direct. All the
ophthalmologists agreed that electric lighting gave the
best results.

A Deep Borehole in Pennsylvania.

E. B. Wilson, in the Colliery Engineer, gives some
interesting information in regard to the Geary borehole
in Washington County, Pa., which reached a depth of
7,181ft., when the tools were lost. In South-Western
Pennsylvania, where the strata are conformable and
natural, three deep wells have now been bored within a
distance of 50 miles, and the temperature data may be
compared from them with some degree of satisfaction.
About 25 miles to the east of the Geary well, at West
Elizabeth, in Allegheny County, the Bedell well gave at
the depth of 5,000 ft. a rock temperature of 120-9 degs.
Fahr.; to the west of the Geary well, at Wheeling,
W.Va., there is another deep well, which at a depth of
4,500 ft. had a temperature of 110*3 Fahr. The follow-
ing temperatures were taken in the Geary well:—
5,150ft., 110degs.; 5,220ft., 120degs.; 5,800ft., 140
degs.; 6,095ft., 156 degs.; 6,270ft. (water), 156 degs.

The water, which was met at 6,270 ft., and rose
4,000 ft. in the hole, has created much interest, as it had
a specific gravity of 1-1085, and contained 9*696 per
cent, of solids. Dr. I. C. White, from the analysis,
judges it to be a case of fossil ocean water imprisoned
since mid-palaeozoic times. Mr. Wilson considers that
this occurrence greatly strengthens the theory of the
aqueo-magmatic segregation of minerals forming ores.
The United States Geological Survey and the Bureau of
Standards are co-operating on data obtained from this
well.

Selection of Coal.

Gerald B. Gould, in the course of an article in the
Engineering Magazine -on “ Waste in the Selection and
Purchase of Coal,” dealing mainly with power plant
requirements, suggests a tentative plan of commercial
classification of coals, as follows :—

Ash.	Sulphur. Volatile matter.

.js, ' .SB. ’ is. ’

A	Under 7%	...	I	Under 1*25% ... L Under 16%

B	7 % to 9%	...	2	1’2j% to 1*75% ... ML 16%	to 19%

C	9% to 11%	...	3	175% to 2-25% ...MH 16%	to 22%

D	Over 11%	...	4	Over 2’25% ... H 22%	to 26%

L = low, ML = medium low, MH — medium high,
H = high.

The above classification is for semi-bituminous coals, but
it is suggested that a similar classification can be devised
for bituminous coals. Of 291 coals examined, a great
proportion came under the classes B 1 ML and B 2 ML.

Sulphite Pitch as a Bind for Ore Briquettes.

Of all the organic binding media which have been
tried for briquetting friable ores, blastfurnace dust and
the like, the sulphite pitch, obtained as a by-product in
paper making, has alone given satisfactory results. This
pitch is prepared by boiling wood pulp with alkali, under
pressure, to extract resinous constituents, and concen-
trating the liquor until it assumes the solid form. The
product consists of 78 per cent, of organic substances,
12 per cent, of water, and 10 per cent, of mineral
matter, largely composed of salts of lime. It is pre-
ferably employed in the dry state, being crushed to
powder, and mixed, in the proportion of 3 to 6 per cent.,
with the ore or furnace dust to be briquetted, the mass
being treated with steam in a mixer, and moulded in a
press. Blastfurnace dust can be mixed hot with the
melted pitch, and pressed without further treatment.
The cost of manufacture depends to a large extent on
the material to be briquetted. For blocks, with a plant
turning out 300 tons per 24 hours, the cost is Is. per
ton; but ovoid briquettes can be made, with a 400-ton
plant, for about 7d. Light material requires a larger
proportion of pitch than heavy, blastfurnace dust taking
10 per cent., whereas concentrates and powdery ores
require only about 5 per cent. With sulphite pitch at
27s. per ton, briquettes of ordinary form can be made
for 3s. 5d. for light material, and 2s. 3d. for heavy, the
cost of ovoids being 3s. 2d. and Is. lOd. respectively.
The moisture content of the briquettes is low, only about
1 to 1| per cent. The pitch, which has a heating value
of 4,500 calories, is transformed by heat into coke,
amounting to 2 to 4 per cent, of the weight of mineral
matter in the briquettes. In the blastfurnace, these
briquettes become very porous, but, as their power of
withstanding atmospheric influence is low, they must be

made on the spot where they are to be used. This
method of briquetting is employed at the Deutscher
Kaiser, Hoesch, and Gutehoffnungfshutte works. The
cost of a plant for treating 400 tons per day amounts to
about £8,000.—Revue des Produits Chimiques.

THE GERMAN AND AUSTRIAN COAL
AND IRON TRADES.

We give below further extracts from German
periodicals that have reached us, showing the course of
the coal and iron trades in Germany and Austria :—

The Siegerland Iron Ore and Iron Market.

Although the negotiations between the bar mills in the
various districts resulted in an extension of the price
agreement up to the end of March next, there does not
seem any prospect of an improvement in the existing
slack demand. Endeavours are being made to establish
the relations between the works on a firmer footing than
heretofore, in order to prevent prices falling; but there
are still many difficulties in the way of a solution. In
view of the uncertainty in this respect, buyers are only
placing orders for their immediate requirements, or for
delivery at early dates, which suits the makers, owing
to their labour difficulties. Supplies of raw materials
and wholly or partially finished products are generally
available in larger quantity than hitherto.

Iron Ore.—Owing to the increased number of men at
work in the mines, supplies from the spathic and brown
ironstone mines in this district and ores from Hesse-
Nassau and Hesse are more plentiful, though hindered
by a scarcity of railway wagons. Prices of Siegerland
ore remain at 156 mk. (per 10 tons) for raw, and 245 mk.
for roasted spathic ore, brown ironstone being 165mk.;
all basis prices ex- pit. The question of sales for the
first quarter of 1916 has not yet been mooted, but it is
believed that there will be no change in rates.
Dillenburg red ironstone is being dealt in, for next year,
at about 20 mk. per ton, ex pit, for 50 per cent. ore.
Brown ironstone from Hesse for next year remains at
about the old price. Only small parcels of German
manganese ore are available for smelting. Purchases
of Lothringen and Luxemburg ores for forward delivery
are only going through slowly, the production of the
corresponding grades of pig iron being small for the
time being, and iron masters uncertain of what the
demand next year may be.

Pig Iron.—The daily output of the furnaces in this
district during September amounted to 2,170 tons. So
far as is known, the consumers of the various grades of
pig have covered their requirements up to the end of
the year at the old prices, and it is believed that these
will also remain in force for next quarter, having reached
a level which is profitable in spite of the increased cost
of production. The grades high in manganese may,
however, advance, the demand being very active, whilst
that for foundry pig has somewhat receded.

Scrap.—The depressed condition of this market can
best be gauged by the result of the last sales by the
Railway Administration, the prices obtained for core
scrap from mild steel and welding iron being only 10 mk.
per ton (against 15 mk. early in the year), whilst
turnings and borings fetched only 8 mk., and plate scrap
up to about 15 mk. per ton. The supply being far in
excess of the demand, there is little prospect of any
increase in prices for some time to come.

Semi-manufactured Products.—There is little change
in this market, such of the output as is not consumed in
the steelworks themselves finding a ready outlet in the
mills and forges at practically unaltered prices. Foreign
business is unimportant.

Plate.—The chief consumption is still for war pur-
poses, but the neutral demand, especially for heavy
plate, continues good, and all the works are kept busy.
The difficulties in the way of production persist, so that
present prices are well earned. Fine plate is in
improved request, at higher prices, and contracts have
been placed for delivery next year. The fine plate mills
are not inclined to sell for late delivery at the present
basis price of 185-190 mk. per ton, ex works, and this
also applies to medium plate, which is quoted at 170-
180 mk., both being higher for export. Heavy plate
remains unchanged at 150 mk. net, ex Siegen; boiler
plate costing 15 mk. more. Tin-plate makers, who are
chiefly producing goods for military purposes, are well
occupied at good prices.

Bars.—Whilst the production in this district is not
very large, it cannot escape from the influence of the
Rhenish-Westphalian and other important industries,
and has to some extent to follow their prices. In spite
of the price agreement, rumours are heard of under-
selling, probably by dealers. The present basis rate, up
to the end of the year, is 140 mk., ex Oberhausen, net,
with an extra 15 mk. for open-hearth quality. The
Union is said to contemplate stricter regulations on
prices and output, so that the trouble in this respect is
expected to be soon over. The price of welding iron
bars is unchanged, as is also the volume of business.
The building trade being stagnant, there is no enquiry
for the products used in that industry, and the only
demand for girders is from constructional engineers and
wagon builders, the former of whom have as much work
as they can cope with in view of their restricted
capacity. The scarcity of railway wagons, however, is
impeding delivery all round.

German Steel Union.

It was reported at the last meeting that little change
had taken place in business in semi-manufactured pro-
ducts, either for home market or export. In railway
superstructural material, the requirements of the State
railways for the Stettin districts in the coming year
will be lower than before, but those of the Saxon State
Railways are higher. Large orders have been received
from neutral markets. Tram rails have been quiet,
but the demand for pit rails is up to the average. The