946

THE COLLIERY GUARDIAN.

May 10, 1918.

(the flash-point of carbon) is maintained. The water-
cooled arch, rear wall, and side walls are made of a
special form of firebrick, which slips in place over
the water tubes. After circulating through the
tubes, the water passes to the hotwell or heater at
approximately 190 degs. Fahr., entailing no appre-
ciable loss of heat.

Lignites and bituminous coal require no special
furnace. As the volatiles ignite between 600 degs.
and 700 degs. Fahr., from the radiant heat of the
walls, the flame is self-supporting, and every heat
unit in the fuel is liberated before coming into contact
with any cold surface.

Ash or Furnace Slag.—Anthracite, coke breeze and
lignite ash do not slag. Bituminous coal ash will
slag on the bottom of the furnace chamber, if not
blanketed with cooler air, properly admitted, and if
allowed to remain too long in the furnace. Most of
the ash from pulverised coal passes away through the
breeching to the cyclone, where the ash is separated
from the gases. That portion which settles to the
floor of the furnace should be removed from time to
time; the quantity is very small, and it is quite light.

Furnace Temperatures and Slag Formation. —
Temperatures between 1,800 degs. and 3,500 degs.
Fahr, can be maintained in the flame. Slag forms
more readily at high temperatures, necessitating
proper blanketing with cooler air, always remember-
ing the advisability of obtaining the maximum per-
centage of CO2. The author frequently obtains 16’5
to 17 per cent. CO2 under operating conditions.

Chequerwork in Metallurgical Furnaces. —
Experience seems to point to the necessity for vertical
baffle walls where the waste gases enter the regenera-
tive chambers. Turning the direction of the gases up
and down several times tends to discharge the dust
tangentially, allowing the major portion to settle in
the bottom of the passages, whence it is easily
removed, through proper cleaning doors at the sides,
without interfering with the operation of the furnace.
The gases then filter through chequerwork properly
spaced and installed. The narrow side of the brick
tile should be laid vertical and on rider walls, to
permit the use of longitudinal scrapers to remove the
ash which may have passed by the vertical baffle
walls. This arrangement will undoubtedly give the
regenerating chambers a life equal to the best record
ever attained, as the narrow edge of a vertical tile
presents very little surface for the flocculent ash to
rest and close the gas passages.

Furnace Life.—The life of furnaces in which pul-
verised fuel is used is equal .to that of hand-fired,
stoker, oil, or gas-fired furnaces. By absolute control
of the quantity of coal and air, the velocity of the
expanded gases can be reduced until erosion of
refractories becomes hardly discernible.

Economy of Pulverised, Coal.—In this connection,
all the benefits of pulverised coal should be taken into
account: labour saving, increased fuel efficiency,
ability for closer adjustment, absence of smoke, etc.

Method? of Firing.

The efficiency of hand firing depends upon the skill
and reliability of the fireman. With the best of
attention, a loss of 20 per zcent. heating value is
frequent, and it often reaches as high as 40 per cent.,
taking into consideration the analysis of the ash and
of the flue gas.

Stoker firing is relatively more efficient and more
regular than hand firing, but the feeding of moist coal
wastes part of the heat in the most undesirable place.
Losses also occur in breaking and removing the clinker,
in the discharge of unburned fuel, and in the flue gas.

Producer-gas firing: W. H. Blauvelt found that
131,280 cu. ft. of gas were produced from 1 ton of
coal, and contained 20,311,162 B.Th.U., or 155 B.Th.U.
per cubic foot, or 2,270 B.Th.U. per lb. of gas. The
composition of the coal from which this gas was made
was as follows:—Water, 1*26 per cent.; volatile
matter, 36'22 per cent.; fixed carbon, 57'98 per cent.;
sulphur, 0'7 per cent.; ash, 3'78 per cent. One ton
contains 1,159'6 lb. carbon and 724'4 lb. volatile
combustible, the energy of which is 31,302,200 B.Th.U.
Hence, in the process of gasification and purification,
there was a loss of 35'2 per cent, of the energy of
the coal. Producers are built to-day doing slightly
better than this.

Oil and natural-gas firing : Coal, properly pulverised
and burned, is on exactly the same basis as far as
thermal capacity is concerned, and the price of the
coal prepared and delivered into the furnace is directly
comparable, on the heat unit basis, with the cost of
fuel oil or gas delivered into the furnace, plus the
slight additional cost for ash removal.

Reduced Fuel Consumption.

Savings by the adoption of pulverised fuel in the
operation of various types of furnaces have been
attained as follow :—Heating and bushelling furnaces,
20 to 25 per cent. ; puddling furnaces, 30 to 50 per
cent. ; open-hearth furnaces, compared with gas
producers, 30 to 40 per cent. ; copper reverberatory,
smelting ore, 30 to 45 per cent. In other furnaces,
the consumption has been reduced to the following
figures:—Continuous billet heating, 160 lb. of coal
per ton of billets; de-sulphurising iron ore in rotary
kilns, 296 lb. of coal per ton of ore; drying and
nodulising iron ore in rotary kilns, o.n basis of 30 per
cent, free moisture and 11 per cent, combined moisture,
477 lb. of coal per gross ton of ore.

The above figures , are from actual operations over
extended periods, and confirm the contention that
coal burned in true pulverised form is the only method
by which every heat unit in the fuel will develop its
full value.

The Minister of Munitions states that power-driven
machine tools come under Regulation 30a of the Defence
of the Realm Regulations, and intending purchasers must
make application for permission to purchase the machines.

By an Order made by the Minister of Munitions every
person must furnish to the Controller, Department of
Engineering, Ministry of Munitions, such returns as to
boilers in his possession or under his control as shall
be notified to him by the Controller.

CURRENT SCIENCE

Fais and Fatty Acids from Petroleum.

Messrs. R. J. Moore and Gustav Egloff (Metal-
lurgical and Chemical Engineering), in considering
the conversion of petroleum hydrocarbons to fats and
fatty acids, point out that work has already been
done on this subject by four different methods: —
Through halogenation of aliphatic hydrocarbons; by
way of Grignard’s reaction; by way of naphthenes;
and through direct oxidation of paraffins or olefins.
By the halogenation methods, the Badische Anilm and
Soda Fabrik produce halogen derivatives of the
paraffin series by mixing the oil and the halogen in
the dark, vaporising and subjecting the mixture to
the action of the silent electric discharge. Halogena-
tion takes place immediately. Pfeifer and Szarvasy
also use the silent discharge to effect the reaction,
while Ellis uses ultraviolet light for the halogenation
of various hydrocarbons.

The writers, in a series of preliminary experiments,
passed vaporised kerosene and chlorine, after heating,
into an electrical silent discharge field of high
potential, adding carbon dioxide at the same time.
The experiments, though preliminary in nature,
showed an increased specific gravity in the oil, and
a tendency to emulsify with sodium hydroxide solu-
'tion. Indications are that a certain amount of fatty
acids are formed under these conditions. Further
work along these lines is in progress.

By Grignard’s reaction, Zelinski chlorinated
petroleum, dissolved it in anhydrous ether and treated
this mixture with metallic magnesium and the
catalyst. Subsequently, when cold, a current of
carbon dioxide was passed through, and the fatty
acids were liberated from the magnesium compounds
by dilute acid. Zelenski claims for this method a
yield of 60 per cent, of the theoretical. He succeeded
in synthesising acids containing up to ten carbon
atoms in the molecule, and whilst it is true that acids
with more than ten carbon atoms show an essentially
different action chemically from that of the lower
fatty acids, still, if the lower acids may be so readily
prepared, the synthesis of the higher acids is merely a
matter of degree, which further research should make
possible. Moreover, hydrogenation of unsaturation
of unsaturated acids and bromine substitution is being
rapidly improved, and the transformation to higher
or lower acids is becoming more and more a commercial
practice.

Naphthenes, which form the bulk of the Russian
and Galician oils, yield naphthenic acids, which in
turn readily furnish glycerides, but the resulting fats
show characteristic differences in properties from
natural fats, being heavier than water (specific gravity
1'008 at 15 degs. Cent.), and tending to form plastic
masses.

- Probably the most direct method of synthesising the
fats, and the method which, at the same time, seems
to be of commerical significance, is the oxidation of
paraffins and olefines to acids. This may be accom-
plished by air or other oxidising agents and by way
of alcohols or aldehydes. In two recent patents,
paraffin wax, in a molten condition, is treated with
a blast of air or oxygen for a prolonged period, at a
temperature of 100 degs. Cent, to 120 degs. Cent.
The colour changes to light red, light yellow, and
finally to a deep yellow. At this stage about 70 per
cent, of the wax has been converted into fatty acids,
and a small quantity of alcohols, formaldehyde, and the
like. The different products are separated by distil-
lation, and the unchanged wax re-treated. Mercuric
oxide or wax that has already been treated may be
used as catalysts. By this process it seems possible
to convert some 80 to 90 per cent, of paraffin wax
into fatty acids. Gray blows air through the oil, at
the same time subjecting to the actinic rays of ultra-
violet light. With the assistance of heat (90-175 degs.
Cent.), pressure and catalysts, such as finely divided
metals, he converts part of the oil into fatty acids.

Since the paraffin oils in question are saturated
compounds and decidedly stable, it would seem
advisable to use as a starting material olefines which
are unsaturated in structure and much more readily
oxidised to acids. Olefines are not found to any con-
siderable extent in natural petroleums, but are readily
obtained from these latter in many ways, e.g., by
cracking. Greenstreet passes mineral oils mixed with
steam through long coils of pipe heated to a cherry
red, thus cracking to olefines, which are then oxidised
and the products separated by fractional distillation.
Oxidation may be effected by treatment with sulphuric
acid to convert to the corresponding sulphuric ethers
and then converted by water to alcohols. Or the
olefines may be oxidised directly to aldehydes and
acids by permanganate or chromic acid solution.

It seems feasible, therefore, to prepare a fatty acid
from petroleum oils that will have the same com-
position as an acid derived from natural fats. Or
the acid formed may be so shifted by hydrogenation,
or by breaking down the carbon chain, so as to produce
finally the acids as found in natural fats.

Temperature Determination by Eutectic Alloys.

In the course of an investigation on steam turbine
alternators in the laboratories of the General Electric
Company at Schenectady, it was desired to determine
the maximum temperature arising at the rim of a
steel disc rotating at very high speeds. As the centri-
fugal forces precluded the attachment of ordinary
temperature-measuring devices to the rotors, it
occurred to Dr. C. P’. Steinmetz to drill small holes
into the rim and to fill them with metals or alloys
of known melting points. When a metal melted, it
was partly thrown out of its hole, and when one
metal melted, and another did not melt, the tempera-
ture of that part of the rim would lie between the
temperatures of the two melting points. As the
melting points of suitable metals lie rather far apart,
Steinmetz made use of eutectic alloys. They are
available in great variety, and have the advantage
that their melting points are less dependent upon
purity than those of pure metals. In his communica-

AND TECHNOLOGY.

tion to the American Chemical Society (Journal, 1918,
pages 96 to 100; abstracted in Engineering) Steinmetz
deals particularly with this feature. He points out
that a eutectic alloy, containing an excess of one or
the other constituent, would in cooling deposit crystals
of that metal, and the alloy would thus thicken before
solidifying, but the final freezing point would
practically remain that of the eutectic. Similar con-
siderations would hold for the melting point, and he
tested this by experimenting with quaternary alloys
of bismuth, lead, tin and cadmium, in various pro-
portions. The alloy containing these four metals in
the proportions 15:8:4:3 is known as Wood’s metal,
and melts at 69'5 degs. Cent.; other alloys of the
constituents have higher melting points, and by
further adding thallium and zinc to his metals,
Steinmetz obtained 12 alloys of two or more metals
ranging in melting paints up to 194 degs. Cent. It
was found that slight excesses of one or the other
constituent hardly affected the melting point of an
alloy, though the flat portion on the curve became less
long and less distinct, and a great tendency to under
cooling had to be counteracted by stirring. Thus the
limited use at present made of eutectics for tempera-
ture measurements could be considerably extended
probably. In the case of steam turbine rotors, to
which Steinmetz does not further refer, temperatures
of over 300 degs. Cent, may arise, and other alloys
would have to be used, and pressure influences might
have to be allowed for.

Protecting Iron from Corrosion.

In a paper read before the Iron and Steel Institute,
Mr. J. N. Friend summarised as follows the results
of his researches on the usefulness of paint for
protecting ironwork from atmospheric corrosion : —
(1) The practical value of acceleration tests is very
small in the present state of our knowledge. Reliable
results can only be obtained from tests carried out
under conditions closely resembling those prevailing
in practice. (2) Addition of pigment to oil increases
the efficiency of the latter as a protective paint until
a maximum is reached. After this, further addition
of pigment causes deterioration. The best results
are obtainable from paints possessing as high a
percentage of good oil as is compatible with good
body and any other working property that has to
be considered. (3) Linseed oil on setting expands
by some 3*3 per cent. This is the primary cause of
crinkling. Further oxidation causes a decrease in
volume, which in time leads to cracking. (4) Linoxyn
is permeable to moisture. The permeability is reduced
by heating in absence of air, the oil increasing in
density, viscosity, and molecular weight. (5) Poly-
merised linseed oil affords a better protection than
raw oil when used as a paint vehicle. (6) The
functions of a pigment are to toughen the film and
render it less permeable to water-vapour and oxygen.
It also reduces the expansion of the oil on setting,
and thus minimises the tendency to crinkle. (7) A
thick coat of paint protects the underlying metal
more efficiently than a thin coat, provided the coat
is not so thick that running or crinkling takes place.
(8) The very best results are obtained by multiple
coats. Two thin coats are better than one thick one
of equal weight. (9) Thinners enable thin coats of
paint to be applied. Turpentine leaves a very slight
residue behind upon evaporation, but its effect on
the efficiency of the paint is small. (10) Other things
being equal, the most permanent paints are those
containing black or red pigments, since these absorb
the shorter rays of light, and prevent them from
hastening the destructive oxidation of the linoxyn
by the air. (11) Finer pigments afford more efficient
protection than coarse pigments, since they are more
thoroughly in contact with the oil. (12) Iron struc-
tures should be painted whilst their scale is still on,
after loosely adherent 'flakes and rust have been
scraped off. The paint will last rather longer than
if applied to the pickled or sand-blasted surface, and
the labour of removing the scale is saved. (13)
Experiments with rusty plates are not conclusive, but
suggest that the rust need not be so carefully removed,
prior to painting, as is usually thought to be necessary.

Toluol from Turpentine.—It was stated at a recent meet-
ing of the Technical Association of the Pulp and Paper
Industry in New York that toluol can be produced from
spruce turpentine, which is an oil formed during the
cooking of the chips in sulphite digesters, which escapes
with the steam in the blowing-out process, and is generally
allowed to go to waste, though processes of recovering
this crude form of turpentine are carried out in a few
mills. A representative of the United States War Depart-
ment present at the meeting, explained the need for toluol
and stated that it was understood that 300,000 gals, could
be obtained from the mills in the United States at very
little expense to the mills. A committee of the Technical
Association has been appointed to co-operate with the
War Department in ascertaining the supplies of spruce
turpentine that are available for toluol manufacture.

Future of Conciliation Board.—The period for which
the Coal Conciliation Board was established under the
last agreement expired in March, and the representatives
of the workmen then gave the necessary three months’
notice with a view to the revision of the agreement.
Conferences of the men have been held in the various
districts included in the English federated area, and
certain proposals have been formulated which, after con-
sideration at a conference in June, will be submitted to
the employers. There are five principal proposals. The
first is that the existing war bonus of 18 per cent., calcu-
lated upon present rates, should be merged into wages,
and be a basis for future negotiation. The second is
that there should be no maximum wage rate in any future
agreement. The third makes it a condition that six shifts
should be paid for five to all workmen employed on the
afternoon or night shifts. The other proposals are that
the basis for securing advances should be the current
wages in force at the commencement of the agreement,
and that the existing regulation that no alteration of
wages must exceed 5 per cent, should be deleted.