324

THE COLLIERY GUARDIAN

August 13, 1915.

CURRENT SCIENCE

Drying Peat for Fuel by Electricity.

As is well known, one of the main difficulties in the
preparation of peat for commercial uses is the expulsion
of water, of which.it may contain as much as 87J or even
92 per cent. Air drying at ordinary temperatures
is unsatisfactory, because the water in peat is not
wholly in the free state, but is partly held in the
combined form to which the hypothetical name of
hydrocellulose has been applied. -Dr. Ekenberg, a
Swedish scientist, in 1909 patented a process for the
expulsion of water from peat by heating it under a
pressure of 20 to 25 atmospheres to temperatures
between 150 degs. and 200 degs., whereby he claimed
that a sufficient decomposition of the so-called hydro-
cellulose is produced to enable the extraction by pressure
of sufficient water to make the peat commercially
valuable. The heating may be accomplished by an
electric current, as has been proved in Ekenberg’s
experiments. In the meantime, in 1912, what is called
the Jameson’s patent was granted. According to this
invention, which has just been held in the Court of
Appeal to b^ valid (Reports of patent, &c., Cases, v. 32,
14, p. 377), an electric current is passed through peat
heated to a temperature of at least 100 degs. Cent,
under a pressure sufficient to prevent the formation of
steam. The electric current may be continuous or
alternating, but a continuous current is preferred, as
with it in general a lo ver temperature suffices than is
required with an alternating current to produce as good
result. The voltage may vary within wide limits, but a
voltage of about 200 has been found to be on the whole
the most economical. As stated above, the temperature
used is at least 100 degs. Cent., and the range of 100 degs.
to 120 degs. Cent, with a pressure of about 10 atmo-
spheres is preferred, but much higher temperatures
with correspondingly increased pressure may be used.
If the temperature exceeds 150 degs. Cent., which is the
lowest at which it is believed the hydrocellulose of peat
is decomposed by heating peat with water under pressure
without the passage of electric current, the electric
current so accelerates the decomposition as to make the
process economically advantageous as compared with
the case where, other conditions being the same, no
current is employed. This process is stated to depend
upon electro-osmotic action, whatever that term may
imply. By the Ekenberg process the natural water of
the peat is rendered expressible without any substantial
decomposition of the peat, and by the Jameson patent
a similar result is claimed to be produced more
economically. What actually happens when an electric
current is passed through peat under the above-
mentioned conditions is somewhat obscure; but from
laboratory experiments it has been concluded that
whereas peat pulp has small electric conductivity below
a temperature of 85 degs., above that temperature the
conductivity progressively increases so long as the
hydrocellulose is undecomposed, but when the decom-
position is complete the resistance again increases.
This seems to establish the fact that the electric current
does something more than heat the peat to the
dissociation temperature of the combined water. The
J ameson process has already passed beyond mere
laboratory experiments, and although it does not appear
to have been yet worked on a commercial scale, it has,
we believe, produced solid cakes of peat suitable for
fuel, or for distillation purposes with sulphate of
ammonia recovery.

Recent Progress in Pyrometry.

In a paper read recently before the Royal Society of
Arts, Mr. Charles R. Darling described some recent
advances in methods for the measurement of high
temperatures. Pyrometer makers, both in this country
and in the United States, have profited by the researches
carried on in the National Physical Laboratory, and in
the United States Bureau of Standards, and several
new appliances have been introduced within the past
few years. It is now established that the highest
temperature obtainable on the gas scale—viz., 1,550 degs.
Cent., and the melting point of platinum, 1,755 degs.
Ce^t., may be regarded as fixed points for the calibration
of high-reading pyrometers, and the United States
Bureau of Standards now issues materials of certified
fixed points specially adapted for the calibration of these
instruments, thus eliminating the danger of errors
resulting from the employment of materials of doubtful
purity. An advance has been made in the use of base-
metal couples developing a high E.M.F., in place of the
delicate and expensive couples of the platinum series.
Amongst these are the iron constantan couples, regis-
tering up to 900 degs. Cent., couples of iron-nickel
alloys, registering 1,000 degs. Cent., and nickel-chromium
alloys reading up to 1,200 degs. Cent. Junctions of
carbon and graphite are capable of registering up to
2,000 degs. Cent. Improvements have also been made
in methods for protecting junctions from the corrosive
action of furnace gases, and in indicators for thermo-
electric pyrometers, amongst the latter being one
specially suitable for use with superheated steam on
locomotives, and unaffected by vibrations. In resistance
pyrometers there have been few changes, although
promising lines of improvement are suggested by the
employment of molten metals, such as copper. In
radiation pyrometers an improvement has been effected
by the introduction of pivoted indicators in place of the
suspended-coil type. A new type of optical pyrometer,
based on the principle of colour extinction, has been
introduced, and other advances in this kind of pyrometer
are foreshadowed. Several new types of self-registering
recorders are described, the latest forms being Foster’s
recorder, the improved form made by the Cambridge
Scientific Instrument Company, the motor - driven
recorders of R. W. Paul and the Leeds and Northrup
Company, and the latest form of the Siemens type.

AND TECHNOLOGY.

Recently, in connection with an exhibition at New-
castle-on-Tyne, which was largely devoted to furnaces
heated by coal gas, a. lecture on pyrometry was given by
Mr. Robert S. Whipple, of the Cambridge Scientific
Instrument Company, in the course of which he said :—
In the manufacture of armour plate, shells, and
cartridges, pyrometric control was of the greatest
importance. Considering the first or the expansion
group of pyrometers, he stated that though the gas
thermometer was the most important instrument in
this group from the scientific point of view, yet
commercially the only ones of importance were the
mercury ones, in which the mercury was contained in
either a glass or steel envelope. He referred briefly to
the work of Dr. Day and Mr. Sos man, in which, by
surrounding the bulb of the gas thermometer by a gas
also under high pressure, they had been able to extend
measurements with the gas thermometer up to 1,500 degs.
Cent.

In discussing thermo-couples, Mr. Whipple gave
some figures to show that if the iron constantan thermo-
couple were suitably protected, it gave reliable results
up to 1,000 degs. Cent, over* long periods of time. It
was pointed out that accurate measurements could only
be obtained with a thermo-couple if the precaution were
taken to maintain the “ cold junction ” at a constant
temperature. The best method is the employment of
Peake’s compensating leads. These leads consist of
two wires, one of which is copper and the other an alloy
of copper with nickel—these giving the same electro-
motive force one against the other as the platinum
rhodium thermo-couple. If the wires be suitably
connected to the platinum couple, the “cold junction ”
is transferred from the head of the pyrometer to the
end of the compensating leads. This junction may
then be kept at a constant temperature by.insertion in
a thermos flask filled with oil, or by burying in the
ground.

Two methods are in general use for measuring the
electro-motive forces generated by a thermo-couple;
one a direct deflection method, and the other the
balancing of the electro-motive force by* a counter
electro-motive force. The majority of instruments in
use in this country are purely deflection ones, though,
where absolute accuracy is required, the balancing or
potentio-metric method must be employed. A somewhat
similar method has been adopted by Dr. Rosenhain in
the Rosenhain and MelsOm potentiometer. This is a
simple potentiometer adapted for works use, and quite
complete in itself as a standardising unit. Works
potentiometers of this kind have recently been developed
in the United States. For temperatures up to 1,000 degs.
Cent, the platinum-resistafice thermometer has been
practically adopted as a subsidiary standard. The
resistance method of measuring temperature has several
practical advantages over other methods: (1) It is
capable of high accuracy over the range 0 to 1,000 degs.
Cent.; (2) no errors are introduced by the heating of
the thermometer head ; (3) the readings of thermometers
are independent of the distance from the galvanometer
or recorder to which they are connected; and (4) they
may be made to indicate or record on a very open scale.
Such thermometers have been employed to measure the
temperature of powder magazines, the temperature
being indicated at a distance of many hundreds of yards
from the magazines. In the case of the Fery pyrometer,
the radiation received from the furnace is concentrated
by means of a mirror on to a small thermo-couple
connected to a galvanometer ; the outfit being calibrated
so that the readings given on the galvanometer corre-
spond to degrees of temperature. A modification of
this pyrometer was introduced a few years ago by
Prof. Fery, in which he substituted a bimetallic spiral
for the thermo-electric couple. This spiral carries on
it an aluminium pointer which is moved over a dial by
the expansion or contraction of the spiral. This
pyrometer has been very generally used for the measure-
ment of the temperature in gas retorts. The majority
of pyrometers are broken mechanically and not through
over-heating. If it is possible a pyrometer should be
inserted into the muffle or furnace in such a way that it
can be left there permanently, and also that it cannot
be knocked when work is moved in or out of the furnace.
In the case of large furnaces, the method due to
Mr. Cui pan is recommended. In this method a groove
is chipped in the floor of the furnace into which a fire-
clay tube is grouted, the pyrometer being inserted into
this tube. The importance of placing the recorder near
the man who has control of the furnace cannot be too
strongly emphasised.

Problems of Mine Valuation.

A Bulletin lately issued by the State of Wisconsin
is called “ A Study of Methods of Mine Valuation and
Assessment,” by W. L. Uglow. Although referring
more particularly to the zinc mines of Wisconsin, the
principles are of general application. The author
discusses the treatment of royalty and interest upon
working capital, neither of which he thinks can
equitably be considered as an addition to working costs,
and both should, therefore, come wholly out of profits
The methods of valuation proposed by the author are
applicable only to mines of short life. He discusses
the following in detail, namely : (1) The Finlay ad
valorem method which calculates the value of a mine
as the present value of the average annual profits that
may be expected to be obtained during the life of that
mine, setting aside an annual sinking fund instalment,
the total amount of all of which instalments, at the end
of the estimated life of the mine, will amount to the
present value; (2) the Arizona method, which takes
the value of a mine for the purposes of taxation as
represented by one-eighth of the gross production of
the previous year, four times the net profit of the

previous year and the value of the improvements; (3)
the Colorado method, which takes the value as one-
fourth of the value of the gross output of the preceding
year, unless the net exceeds one-fourth of the gross, in
which case the net output is taken to be the assessable
value, except in the case of mines of the precious
metals, where the value is taken to be half the value of
the gross output plus the entire net output; (4) the
equated income method, which takes the value as the
present value of all future profits, these latter being
taken as equal to the actual profits of the preceding
year, excluding royalty, interest, and amortisation
charges, assuming the same average length of life for
all the mines of a district. The last named method is
favoured by the author, who very rightly insists upon
the fact that mining property is a wasting asset, and
should not, therefore, be taxed on the same basis as
ordinary real estate. The views of the author are
necessarily controlled somewhat by the special circum-
stances obtaining in Wisconsin, where owing to
conditions of tenure there are generally three separate
parties interested in the mining property, viz., the
Jessees, the royalty owners and thebanks advancing the
working capital.

*

THE GERMAN AND AUSTRIAN COAL
AND IRON TRAPES.

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 :—

New Temporary Coal Syndicate for Rhenish Westphalia.

At the meeting of the Coal Syndicate on July 29, the
question of forming a temporary syndicate for the period
between January 1, 1916, and March 31, 1917, was
under discussion. The negotiations carried on with the
Minister of Commerce, and in connection with the
renewal of the existing syndicate, in view of the Federal
Decree for establishing compulsory syndicates, led the
committee to regard the voluntary renewal for a period
of five years as impracticable. Consequently, it con-
sidered that the only way to avoid the formation of a
compulsory syndicate—which is disliked on all sides—
would be to form a temporary syndicate for the above
period, on the basis of the new syndicate agreement
already decided on.. By adopting this proposal, the
committee believed that there would be few difficulties
to overcome, because during the continuance of the war
the amount of participation will not play the important
part it does in ordinary times. At present the output is
only between 60 and 75 per cent, of the participation,
and therefore there could hardly be any dispute on this
point. It therefore recommended the meeting to agree
to the formation of the temporary syndicate, and adopt
the participation suggested for 1916 by the committee.
On the whole, the old members of the syndicate
expressed their agreement with this proposal. The
Bochumer Bergwerks A.G. and the Heinrich and Victor
collieries were not represented, and therefore their
opinion could not be ascertained; and the following
withheld full concurrence until the question of how
existing contracts will be dealt with has been settled :—
Borussia, Oespel, Deutscher Kaiser (which has sold its
output for 25 years to Thyssen und Company), and
Langenbrahm. The same reservation was made by the
outside collieries : Freie Vogel und Unverhofft, Lohberg,
Rhein I., Sachsen, und Wilhelmine Mevissen. Freie
Vogel and Furst Leopold also wanted a larger allotment
than that proposed by the committee. It was decided
to call another meeting on August 7 to discuss further
proposals for settling the matter of existing contracts.
The State Mining Board agreed to the formation of the
temporary syndicate, with the reservations given below :
The State shall have the right to sever its connection
with the syndicate at any time, by giving four weeks’
notice, to terminate at the beginning of a quarter, and
may begin to sell its products for delivery during said
quarter not earlier than 14 days before the expiry of the
notice. These rights shall also apply to the Hibernia
Colliery if acquired by the State. The Minister of
Commerce may impose his veto if 30 per cent, of the
total voting power (excluding that of the State) is in
favour of lowering, or against increasing, the settling
prices. The State shall have the right to supply 450,Q00
tons per annum, out of its sales allotment, for State
purposes free of syndicate assessment except* tonnage
dues. This quantity may be exceeded if the public
interest necessitates an unexpected increase in the supply
of fuel for State purposes, but in such case the full dues
shall be payable. The manner in which the maintenance
of the State’s trading organisation is to be secured shall
be regulated by conditions still to be agreed upon. The
State shall receive a transport allotment in the Kohlen-
kontor, commensurate with the quantities it has shipped
through a Rhine shipping group during a past period,
the duration of which is still to be settled. The
syndicate shall appoint a representative of the State
mining administration as a member of the board of the
kohlenkontor.

With regard to the agreement with the outsiders, the
committee reported that all covenants subject to rati-
fication by the members of the syndicate have been
rendered nugatory by the new situation, with the excep-
tion of those unanimously ratified at the meetings on
January 23 and February 8 last. The question of prior
contracts with merchants has been disposed of, so far
as compulsory syndicates are concerned, by the minis-
terial Decree, which treats such contracts as dissolved.
In the temporary syndicate, therefore, the same condi-
tion will have to be observed; but, on the other hand,
an arrangement should be entered into whereby mer-
chants should have a share in selling the syndicate’s
products. The committee also recommend that the
Deutsch-Luxemburgische Bergwerks und Hiitten A.G.