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Scientific American Supplement, No. 520, December 19, 1885 online

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each working eight hours - they would now find one man walking around the
boiler house, simply watching the water gauges, etc. Not a particle of
smoke would be seen. In the iron mills the puddlers have whitewashed the
coal bunkers belonging to their furnaces. I need not here say how much
pleasure it will afford me to arrange that any fellow members of the
Institute who may visit the republic are afforded an opportunity to see
for themselves this latest and most interesting development of the fuel
question. Good Mother Earth supplies us with all the fuel we can use and
more, and only asks us to lead it under our boilers and into our heating
and puddling furnaces, and apply the match. During the winter several
explosions have occurred in Pittsburg, owing to the escape of gas from
pipes improperly laid. The frost having penetrated the earth for several
feet and prevented escape upward, the freed gas found its way into the
cellars of houses, and, as it is odorless, its presence was not detected.
This resulted in several alarming explosions; but the danger is to be
remedied before next year. Lower pressure will be carried in the pipes
through the city, and escape pipes leading to the surface will be placed
along the surface at frequent intervals. In the case of manufacturing
establishments, the gas is led into the mills overhead, and, all the
pipes being in the open air, no danger of explosion is incurred.

The following extract from the report of a committee, made to the
American Society of Mechanical Engineers at a recent meeting, gives an
idea of the value of the new fuel: "Natural gas, next to hydrogen, is the
most powerful of the gaseous fuels, and, if properly applied, one of the
most economical, as very nearly its theoretical heating power can be
utilized in evaporating water. Being so free from all deleterious
elements, notably sulphur, it makes better iron, steel, and glass than
coal fuel. It makes steam more regularly, as there is no opening of
doors, and no blank spaces are left on the grate bars to let cold air in,
and, when properly arranged, regulates the steam pressure, leaving the
man in charge nothing to do but to look after the water, and even that
could be accomplished if one cared to trust to such a volatile
water-tender. Boilers will last longer, and there will be fewer
explosions from unequal expansion and contraction, due from cold draughts
of air being let in on hot plates.

"An experiment was made to ascertain the value of gas as a fuel in
comparison with coal in generating steam, using a retort or boiler of 42
inches diameter, 10 feet long, with 4 inch tubes. It was first fired with
selected Youghiogheny coal, broken to about 4 inch cubes, and the furnace
was charged in a manner to obtain the best results possible with the
stack that was attached to the boiler. Nine pounds of water evaporated to
the pound of coal consumed was the best result obtained. The water was
measured by two meters, one in the suction and the other in the
discharge. The water was fed into a heater at a temperature of from 60°
to 62°; the heater was placed in the flue leading from the boiler to the
stack in both gas and coal experiments. In making the calculations, the
standard 76 lb. bushel of the Pittsburg district was used. Six hundred
and eighty-four pounds of water were evaporated per bushel, which was
60.9 per cent. of the theoretical value of the coal. Where gas was burned
under the same boiler, but with a different furnace, and taking 1 lb. of
gas to be 2.35 cubic feet, the water evaporated was found to be 20.31
lb., or 83.4 per cent. of the theoretical heat units were utilized. The
steam was under the atmospheric pressure, there being a large enough
opening to prevent any back pressure, the combustion of both gas and coal
was not hurried. It was found that the lower row of tubes could be
plugged and the same amount of water could be evaporated with the coal;
but with gas, by closing all the tubes - on the end next the stack - except
enough to get rid of the products of combustion, when the pressure on the
walls of the furnace was three ounces, and the fire forced to its best,
it was found that very nearly the same results could be obtained. Hence
it was concluded that the most of the work was done on the shell of the
boiler."

In no other way can I give the members of the Iron and Steel Institute so
much information in regard to this new fuel as by including in this paper
a very able communication from the chief chemist at our Edgar Thomson
Steel Works, Mr. S.A. Ford, who is to-day the highest authority upon the
subject:

"So much has been claimed for natural gas as regards the superiority of
its heating properties as compared with coal, that some analyses of this
gas, together with calculations showing the comparison between its
heating power and that of coal, may be of interest. These calculations
are, of course, theoretical in both cases, and it must not be imagined
that the total amount of heat, either in a ton of coal or 1,000 cubic
feet of natural gas, can ever be fully utilized. In making these
calculations I employed as a basis what in my estimation was a gas of an
average chemical composition, as I have found that gas from the same well
varies continually in its composition. Thus, samples of gas from the same
well, but taken on different days, vary in nitrogen from 23 per cent. to
_nil_, carbonic acid from 2 per cent. to _nil_, oxygen from 4 per cent,
to 0.4 per cent., and so with all the component gases. Before giving the
theoretical heating power of 1,000 cubic feet of this gas I will note a
few analyses. The first four are of gas from the same well; samples
taken on the same day that they were analyzed. The two last are from two
different wells in the East Liberty district:

ANALYSES OF NATURAL GAS.

- - - - - - - - - - + - - - - + - - - - + - - - - + - - - - + - - - - + - - - - +
| 1 | 2 | 3 | 4 | 5 | 6 |
- - - - - - - - - - + - - - - + - - - - + - - - - + - - - - + - - - - + - - - - +
When tested.........|10-28-84|10-29-84|11-24-84|12-4-84 |10-18-84|10-25-84|
| per ct.| per ct.| per ct.| per ct.| per ct.| per ct.|
Carbonic acid ......| 0.8 | 0.6 | Nil. | 0.4 | Nil. | 0.30|
Carbonic oxide......| 1.0 | 0.8 | .58 | 0.4 | 1.0 | 0.30|
Oxygen... ... ......| 1.1 | 0.8 | .78 | 0.8 | 2.10| 1.20|
Olefiant gas .......| 0.7 | 0.8 | 0.98| 0.6 | 0.80| 0.6 |
Ethylic hydride ....| 3.6 | 5.5 | 7.92| 12.30 | 5.20| 4.8 |
Marsh gas ..........| 72.18| 65.25| 60.70| 49.58 | 57.85| 75.16|
Hydrogen ...........| 20.02| 26.16| 29.03| 35.92 | 9.64| 14.45|
Nitrogen ...........| Nil. | Nil. | Nil. | Nil. | 23.41| 2.89|
Heat units .........|728,746 |698,852 |627,170 |745,813 |592,380 |745,591 |
- - - - - - - - - - + - - - - + - - - - + - - - - + - - - - + - - - - + - - - - +

"We will now show how the natural gas compares with coal, weight for
weight, or, in other words, how many cubic feet of natural gas contain as
many heat units as a given weight of coal, say a ton. In order to
accomplish this end we will be obliged, as I have said before, to assume
as a basis for our calculations what I consider a gas of an average
chemical composition, viz.:

Per cent.
Carbonic acid............................ 0.60
Carbonic oxide........................... 0.60
Oxygen................................... 0.80
Olefiant gas............................. 1.00
Ethylic hydride.......................... 5.00
Marsh gas............................... 67.00
Hydrogen................................ 22.00
Nitrogen................................. 3.00

"Now, by the specific gravity of these gases we find that 100 liters of
this gas will weigh 64.8585 grammes, thus:

Weight,
Liters. grammes.

Marsh gas................. 67.0 48.0256
Olefiant gas.............. 1.0 1.2534
Ethylic hydride........... 5.0 6.7200
Hydrogen.................. 22.0 1.9712
Nitrogen.................. 3.0 3.7632
Carbonic acid............. 0.6 1.2257
Carbonic oxide............ 0.6 0.7526
Oxygen.................... 0.8 1.1468
- - - -
Total................................... 64.8585

"Then, if we take the heat units of these gases, we will find:


Heat units
Grammes. contained.

Marsh gas................ 48.0256 627,358
Olefiant gas............. 1.2534 14,910
Ethylic hydride.......... 6.7200 77,679
Hydrogen................. 1.9712 67,929
Carbonic oxide........... 0.7526 1,808
Nitrogen................. 3.7630 - - -
Carbonic acid............ 1.2257 - - -
Oxygen................... 1.1468 - - -
- - - - - - - -
Totals 64.8585 789,694

"64.8585 grammes are almost exactly 1,000 grains, and 1 cubic foot of
this gas will weigh 267.9 grains; then the 100 liters, or 64.8585
grammes, or 1,000 grains, are 3,761 cubic feet; 3,761 cubic feet of this
gas contains 789,694 heat units, and 1,000 cubic feet will contain
210,069,604 heat units. Now, 1,000 cubic feet of this gas will weigh
265,887 grains, or in round numbers 38 lb. avoirdupois. We find that
64.8585 grammes, or 1,000 grains, of carbon contain 523,046 heat units,
and 265,887 grains, or 38 lb., of carbon contain 139,398,896 heat units.
Then 57.25 lb. of carbon contain the same number of heat units as 1,000
cubic feet of the natural gas, viz., 210,069,604. Now, if we say that
coke contains in round numbers 90 per cent. carbon, then we will have
62.97 lb. of coke, equal in heat units to 1,000 cubic feet of natural
gas. Then, if a ton of coke, or 2,000 lb., cost 10s., 62.97 lb. will cost
4d., or 1,000 cubic feet of gas is worth 4d. for its heating power. We
will now compare the heating power of this gas with bituminous coal,
taking as a basis a coal slightly above the general average of the
Pittsburg coal, viz.:

Per cent.
Carbon................................... 82.75
Hydrogen................................. 5.31
Nitrogen................................. 1.04
Oxygen................................... 4.64
Ash...................................... 5.31
Sulphur.................................. 0.95

"We find that 38 lb. of this coal contains 146,903,820 heat units. The
64.4 lb. of this coal contains 210,069,640 heat units, or 54.4 lb. of
coal is equal in its heating power to 1,000 cubic feet of natural gas. If
our coal cost us 5s. per ton of 2,000 lb., then 54.4 lb. costs 1.632d.,
and 1,000 cubic feet of gas is worth for its heat units 1.632d. As the
price of coal increases or decreases, the value of the gas will naturally
vary in like proportions. Thus, with the price of coal at 10s. per ton
the gas will be worth 3.264d. per 1,000 cubic feet. If 54.4 lb. of coal
is equal to 1,000 cubic feet of gas, then one ton, or 2,000 lb., is equal
to 36,764 cubic feet, or 2,240 lb. of coal is equal to 40,768 cubic feet
of natural gas. If we compare this gas with anthracite coal, we find that
1,000 cubic feet of gas is equal to 58.4 lb. of this coal, and 2,000 lb.
of coal is equal to 34,246 cubic feet of natural gas. Then, if this coal
cost 26s. per ton, 1,000 cubic feet of natural gas is worth 9½d. for its
heating power. In collecting samples of this gas I have noticed some very
interesting deposits from the wells. Thus, in one well the pipe was
nearly filled up with a soft grayish-white material, which proved on
testing to be chloride of calcium. In another well, soon after the gas
vein had been struck, crystals of carbonate of ammonia were thrown out,
and upon testing the gas I found a considerable amount of that alkali,
and with this well no chloride of calcium was observed until about two
months after the gas had been struck. In these calculations of the
heating power of gas and coal no account is of course taken of the loss
of heat by radiation, etc. My object has been to compare these two fuels
merely as regards their actual value in heat units."

Bearing in mind that it is never wise to prophesy unless you know, I
hesitate to speak of the future; but considering the experience we have
had in regard to the productiveness of the oil territory, which is now
yielding 70,000 barrels of petroleum per day, and which has continued to
increase year after year for twenty years, I see no reason to doubt the
opinion of experts that the territory which has already been proved to
yield gas will suffice for at least the present generation in and about
Pittsburg.

* * * * *




A GAS-ENGINE WATER-SUPPLY ALARM.


[Illustration]

A very useful contrivance for the purpose of reporting automatically the
failure of the water supply to a gas-engine has been arranged by
Professor Ph. Carl, of Munich. What led to the adoption of the device was
that, during last winter, the water supply in the neighborhood of the
Professor's laboratory was several times cut off without previous notice;
the result being the failure of the water needed for cooling the cylinder
of his Otto gas-engine. On inquiring into the matter, he discovered that
the same thing frequently occurred in other places where gas-engines were
in use; and this caused him to design a contrivance to put an alarm-bell
into action at the instant when the water ceased to flow, and so enable
any overheating of the engine, and injuries thereby resulting, to be
prevented in time. The arrangement (represented half size in the
accompanying engraving) is screwed down directly to the water outflow
pipe, R. Before the aperture of the pipe is a lever, with a disk on one
arm, on to which the issuing water impinges, thereby keeping the lever in
the position indicated by the dotted lines. The effect of this is to
break the platinum contact at C, and so interrupt the circuit of an
alarm-bell placed in any suitable position. Suppose the water ceases to
flow; the spring, F, comes into play, contact is made at C, and the bell
continues to ring till some one comes to stop it. It is almost needless
to remark that the disk, D, and the pin, E, are composed of insulating
material, such as vulcanite. - _Jour. Gas Lighting._

* * * * *




SOLDERING AND REPAIRING PLATINUM VESSELS IN THE LABORATORY.

By J.W. PRATT, F.C.S.


It frequently happens in the laboratory that platinum vessels, after
long-continued use, begin to show signs of wear, and become perforated
with minute pinholes. When they have reached this stage, they are usually
accounted of no further utility, and are disposed of as scrap; not that
it is impossible to repair them - for with fine gold wire and an
oxyhydrogen jet this is easily feasible - but that the proper appliances
and skill are not in possession of all. Irrespective of the manipulation
of the hydrogen jet, it is rather difficult without long practice to hold
the end of the fine wire precisely over the aperture and to keep it in
position. It occurred to me that, if the gold in a finely divided
condition could be placed in very intimate contact with the platinum,
judging from the fusibility of gold-platinum alloys, union could be
effected at a lower temperature over the ordinary gas blowpipe. I tried
the experiment, and found the supposition correct. The substance I used
was auric chloride, AuCl_{3}, which, as is well known, splits up on
heating, first into aurous chloride, and at a higher temperature gives
off all its chlorine and leaves metallic gold. Operating on a perforated
platinum basin, in the first instance, I placed a few milligrammes of the
aurous chloride from a 15 grain tube precisely over the perforation, and
then gently heated to about 200° C. till the salt melted and ran through
the holes. A little further heating caused the reduced gold to solidify
on each side of the basin. The blowpipe was now brought to bear on the
bottom of the dish, right over the particular spots it was wished to
solder, and in a few moments, at a yellow-red heat (in daylight), the
gold was seen to "run." On the vessel being immediately withdrawn, a very
neat soldering was evident. The operation was repeated several times,
till in a few minutes the dish had been rendered quite tight and
serviceable.

Using the gold salt in this way, the principal difficulty experienced in
holding gold wire unflinchingly in the exact position vanishes, while
only a comparatively low temperature and small amount of gold is
necessary. Care must be taken to withdraw the platinum from the flame
just at the moment the gold is seen to run, for if the heat be continued
longer, the gold alloys with a larger surface of platinum, spreads, and
leaves the aperture empty. As in the case of all gold-soldered vessels,
the article cannot afterward be safely exposed to a temperature higher
than that at which the soldering was effected, and on this account it is
advisable to use as small an amount of auric chloride as possible. When
the perforations are of comparatively large size, the repairing is not so
easy, owing to the auric chloride, on fusing, refusing to fill them. I
find, however, that if some spongy platinum be mixed with a few
milligrammes of the gold salt, pressed into the perforation, and heat
applied as directed, a very good soldering can be effected. It is well to
hammer the surface of the platinum while hot, so as to secure perfect
union and welding of the two surfaces. This may be done in a few minutes
in such a manner as to render the repair indistinguishable. Strips of
platinum may be joined together in much the same way as already
described - a few crystals of auric chloride placed on each clean surface
and gently heated till nearly black, then bound together and further
heated for a few moments in the blowpipe flame. Rings and tubes can also
be formed on a mandrel, and soldered in the same fashion, and the chemist
thus enabled to build up small pieces of apparatus from sheet platinum in
the laboratory. - _Chem. News._

* * * * *




THE HELICOIDAL OR WIRE STONE SAW.


The sides of solid bodies, whatever be the degree of hardness, and
however fine the texture, possess surfaces formed of a succession of
projections and depressions. When two bodies are in contact, these
projections and indentations fit into one another, and the adherence that
results is proportional to the degree of roughness of the surfaces. If,
by a more or less energetic mechanical action, we move one of the bodies
with respect to the other, we shall produce, according as the action
overcomes cohesion, more or less disintegration of the bodies. The
resulting wear in each of them will evidently be inversely proportional
to its hardness and the nature of its surface; and it will vary, besides,
with the pressure exerted between the surfaces and the velocity of the
mechanical action. We may say, then, that the wear resulting from rubbing
two bodies against each other is a function of their degree of hardness,
of the extent and state of their surface, of the pressure, of the
velocity, and of the time.

[Illustration: FIGS. 1, 2 and 3. - APPARATUS FOR SAWING STONE.]

According as these factors are varied in a sense favorable or unfavorable
to their proper action, we obtain variations in the final erosion. Thus,
in rubbing together two bodies of different hardness and nature of
surface, we obtain a wear inversely proportional to the hardness and
state of polish of their surfaces. Through the interposition of a
pulverized hard body we can still further accelerate such wear, as a
consequence of the rapid renewal of the disintegrating element.

The gradual wear effected over the entire surface of a body brings about
a polish, while that effected along a line or at some one point
determines a cleavage or an aperture.

The process usually employed in quarries or stone-yards for sawing
consists in slowly moving a stone-saw backward and forward, either by
hand or machinery, and with scarcely any pressure. Mr. P. Gray has,
however, devised a new process, which is based upon the theoretical
considerations given above. His _helicoidal saw_ is, in reality, an
endless cable formed by twisting together three steel wires in such a way
as to give the spirals quite an elongated pitch.

The apparatus in its form for cutting blocks of stone into large slabs
(Figs. 1, 2, and 3) consists of two frames, A A, five feet apart, each
formed of two iron columns, 7½ feet in height and one foot apart, fixed
to cast iron bases resting upon masonry. At the upper part, a frame, B B,
formed of double T-irons cross-braced here and there, supports a
transmission composed of gearwheels, R R, and a pitch-chain, G G. Along
the columns of the frame, which serve as guides, move two kinds of
pulley-carriers, C C. The pulleys, D D, are channeled, and receive the
cable, a a, which serves as a helicoidal saw. The direction of the saw's
motion is indicated by the arrow. The carriages, C C, are traversed by
screws, V V, which are fixed between the columns. The extremity, v, of
the axle of the pulley to the right is threaded, and actuates a
helicoidal wheel, E, which transmits motion to the wheel, R, through the
intermedium of the vertical shaft, F. This transmission, completed by the
wheels, R R, and the pitch-chains, G G, is designed to move the saw
vertically, through the simultaneous shifting of the carriages, C C. A
tension weight, P, through the intermedium of pulleys, D_{1} D_{1},
permits of keeping the saw taut. A reservoir, H, at the upper part of the
frame, B B, contains the water and sand necessary for sawing. The feeding
is effected by means of a rubber tube, I, terminating in a flattened
rose, J, which is situated over the aperture made by the saw. A small
pump, L. over the reservoir takes water from K, and raises it to H. The
sand is put in by hand.

Above the basin, K, a system of rails and ties supports the carriage, Q,
upon which is placed the block of stone to be sawn. When one operation
has been finished, and it is desired to begin another, it is necessary to
raise the pulley-carriers and the saw. In order to do this quickly, there
is provided a special transmission, M, which is actuated by hand, through
a winch.

The work done by this saw is effected more rapidly than by the ordinary
processes, and certain very hard rocks, usually regarded as almost
intractable, can be sawed at the rate of from one to one and a half
inches per hour.

[Illustration: FIG. 4. - APPARATUS FOR SAWING STONE INTO SLABS.]

For sawing marble into slabs of all thicknesses, the arrangement
described above may be replaced by a system consisting of two drums
having several channels to receive as many saws, or two corresponding
series of channeled pulleys, b b (Fig. 4), independent of each other, but
keyed to the same axles, i i. When the pulleys have been properly spaced
by means of keys, the whole affair is rendered solid by a bolt, g. The
extremity of the axles forms a nut into which pass vertical screws, c c.
These latter are connected above with cone-wheels, l l, which, gearing
with bevel wheels keyed to the shafts, e, secure a complete
interdependence of the whole. The ascending motion, which is controlled
by the endless screws, f, and the helicoidal wheels, m, is in this way
effected with great regularity. Uprights, a a, of double T-iron, fixed to
joists, k k, and connected and braced by pieces, d d, form a strong
frame.

[Illustration: FIG. 5. - APPLICATION OF GAY'S STONE SAW IN A MARBLE
QUARRY.]

The power necessary to run this kind of saw is less than _n_ × ¼ H.P.,
on account of the number of passive parts. The most interesting
application of the helicoidal saw is in the exploitation of quarries.
Fig. 5 represents a Belgian marble quarry which is being worked by Mr.
Gay's method.

_Tubular Perforators_. - Mr. Gay has rendered his saw completer by the
invention of a tubular perforator for drilling the preliminary well. It
is based upon the same principle as the Leschot rotary drill, but differs
from that in its extremity being simply of tempered steel instead of
being set with black diamonds. A special product, called metallic


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Online LibraryVariousScientific American Supplement, No. 520, December 19, 1885 → online text (page 3 of 9)