THE UTILISATION
OF WASTE PRODUCTS
THEOOOf? HOLLER
THIRD EDITION. REVISED
THE UTILIZATION OF WASTE PRODUCTS
THE UTILIZATION OF WASTE
PRODUCTS
A TKEATISE ON THE EATIONAL UTILIZATION,
EECOVEEY, AND TEEATMENT OF WASTE
PEODUCTS OF ALL KINDS
BY
DR. THEODOR ROLLER
AUTHOR OP "COSMETICS," ETC.
TRANSLATED FROM THE SECOND REVISED GERMAN EDITION BY A
TECHNICAL CHEMIST
WITH TWENTY-TWO ILLUSTRATIONS
THIRD ENGLISH EDITION. REVISED AND ENLARGED
BY H. B. STOCKS F.I.C., F.C.S.
LONDON
SCOTT, GE KENWOOD & SON
(E. GREENWOOD)
8 BKOADWAY, LUDGATE, E.G. 4
1918
[The sole right oj Translation into English rests loith Scott, Greenwood & Son}
D. VAN NOSTRAND COMPANY
NEW YORK
~"
First English Edition . . . 1902
Second English Edition, Revised] . 1915
Third English Edition, Revised and
Enlarged .... July, 1918
PEEFACE.
IT is a matter of common knowledge that even
to-day a large number of waste products are thrown
on one side as useless, and either accumulate in
large quantities if they are inorganic, or if organic
they become exposed to the gradual decay which is
inherent in them owing to their highly complex
nature. Such substances treated in a rational
manner would no doubt be capable of yielding a
product, or in some cases a series of products, which
would not only repay the cost of treatment but
which might even equal or surpass the value of the
primary manufactured article.
As an illustration of the truth of what has just
been stated as well as the commercial or even
national importance of the utilization of waste pro-
ducts, it is only necessary to point to the chemical
industries in which the utilization of the various
wastes is of the utmost value both from a sanitary
and an economical point of view, and it is in these
industries that we find the largest number of cases
of the rational treatment of materials which at one
time were regarded to be of no value. As a concrete
example mention may be made of the rich treasures
which have been derived from coal tar, not only the
beautiful dyes which have helped to set the founda-
tions of modern German chemical industries but also
392316
VI PEEFACE.
the many synthetical drugs, essences, perfumes, and
disinfecting products which are derived by various
wonderful and ingenious processes from this very
repulsive substance.
In these days it is more than ever necessary to
give careful attention to what may at the present
time appear to be valueless. Competition is so keen
that even with the most economical and therefore
the most rational labour it is difficult to make
manufacturing operations profitable, and it is there-
fore only by utilizing to the full every product which
is handled that prosperity for all may be assured.
In the revised edition of the present work the
matter has been kept up to date ; most new and
approved methods of treating waste materials have
been touched upon, but antiquated useless processes
have not been included. It is hoped, therefore, that
the work may continue to be a practical guide to
those engaged in technical or industrial pursuits, who<
will perhaps find in its pages much that will be
useful to them.
LONDON, July, 1918.
CONTENTS.
CHAPTER PAGE
Preface . ......... v
Introduction ......... 1
I. The Waste of Towns 3
II. Blood and Slaughter-house Refuse 20
III. Fat from Waste 40
IV. Tannery Waste 47 -
V. Leather Waste 53
VI. Fur and Feather Waste 60
VII. Waste Horn 64
VIII. Fish Waste . . . . v 66
IX. Mother-of-Pearl Waste 72
X. Vegetable Ivory Waste . . . .. . . .73
XI. Waste Wood 76
XII. Cork Waste 91
XIII. Waste Paper and Bookbinders' Waste .... 94
XIV. The By-Products of Paper and Paper-Pulp Works . . 98
XV. The Waste Produced in the Manufacture of Parchment
Paper 104
XVI. Wool Waste . . .106
XVII. Silk Waste ... \ ..... 119
XVIII. The Waste Waters of Cloth Factories . 121
XIX. Cotton Spinners' Waste . . . '^_, .129
XX. Jute Waste 131
XXI. Utilization of Rags . 135
XXII. Colouring Matters from Waste 136
XXIII. Residues in the Manufacture of Aniline Dyes . . . 139
XXIV. Dyers' Waste Waters 142
XXV. Waste Produced in Butter Making 145
XXVI. Molasses . ^ 148
XXVII. The Waste Liquids from Sugar Works . . . .153
XXVIII. Fruit 164
XXIX. Waste Products of the Manufacture of Starch . . 168
XXX. Brewers' Waste 174
XXXI. Wine Residues 182
Vlll CONTENTS.
CHAPTER PAGE
XXXII. Indiarubber and Caoutchouc Waste . . . .185
XXXIII. Amber Waste 190
XXXIV. Utilization of Turf or Peat 192
XXXV. Manufactured Fuels 196
XXXVI. Illuminating Gas from Waste and the By-Products of
the Manufacture of Coal-Gas ..... 206
XXXVII. By-Products' in the Treatment of Coal-Tar Oils . . 220
XXXVIII. Ammonia Recovery . . . . .>'* . . 223
XXXIX. Petroleum Residues .232
XL. By-Products in the Manufacture of Rosin Oil . . 238
XLI. Soap-Makers' Waste ..*;.' 241
XLII. Alkali Waste and the Recovery of Soda . . .251
XLIII. Recovery of Potash Salts 260
XLIV. Sulphur 262
XLV. Salt Waste 269
XLVI. Gold and Silver Waste 272
XLVII. Platinum Residues 288
XL VIII. Iridium from Goldsmiths' Sweepings .... 292
XLIX. Metal Waste . . 293
L. Tinplate Waste k .298
LI. Calamine Slimes . . . . . . . . 305
LII. Waste Iron 307
LIII. By-Products of the Manufacture of Mineral Waters . 317
LIV. Infusorial Earth 320
LV. Meerschaum 322
LVI. Mica Waste 325
LVII. Slate Waste 326
LVIII. Broken Porcelain, Earthenware and Glass . . . 328
LIX. Utilization of Waste Glass 331
Index 333
THE UTILIZATION OF WASTE PRODUCTS.
INTKODUCTION.
THERE can be no doubt that a rational utilization of the
waste matters which are produced so frequently and abund-
antly in the manufactures and industries is of more than
ordinary importance.
Whilst we often find that some waste product is accumu-
lating in such quantity as to injure and retard the continuous
progress of a branch of industry, we also see, not rarely, that
the rational treatment and utilization of such waste products
either increases very considerably the general profits of an
industry or even forms a separate and not inconsiderable
source of gain.
The numerous communications, which have had as their
subject the profitable utilization of waste matters, are usually
only to be found scattered in the form of occasional com-
munications through the vast bulk of technical literature,
so that, under ordinary conditions, it would be impossible
for most men engaged in technical pursuits to discover, from
among the abundance of material, that which is especially
interesting to them and which touches more particularly upon
their avocations.
It is no easy matter to examine this abundant material,
arrange it, excluding all that is doubtful and superfluous,
and put the remainder in such a form that the practical
man, engaged in a particular calling, may extract what is
really useful.
Since the present work is the only one in the English
language which for the first time treats fully of waste pro-
ducts in general and from a practical standpoint, omissions
1
2 THE UTILIZATION OF WASTE PEODUCTS.
may possibly occur; it is to be hoped, however, that any fail-
ings will be criticized in a friendly and well-meaning spirit.
A smooth and well-trodden path may be traversed without
danger even by an unsteady wanderer, but where the road
must be first marked out and the rough path made smooth,
progress is of necessity slow, and each step must be made
sure before we extend to the next.
It is hoped that the present work on the Utilization of
Waste Products will point out the way to those engaged in
the various industries treated upon, and that it may act as a
stimulant to still further advancements.
CHAPTEK I.
THE WASTE OF TOWNS.
THE disposal of town refuse is one of the most important
problems of present-day municipal engineering, to which a
considerable amount of thought has been given, and which
requires unremitting care and attention in order that the
health of the community may be preserved.
Town refuse is of various kinds, most of it being included
under the headings given in the tabular scheme below. 1
1. Liquid refuse. 2. Municipal refuse. 3. Trades refuse,
{a) Sewage proper. (a) Vegetable offal or gar- (a) Soil, rock, etc., from
{b) House slops. bage from markets, excavations.
(c) Road drainage. shops and roads. (6) Old building ma-
(6) Ashpit refuse, including terials.
ashes, bottles and glass, (c) Manure from stables
old metals, old boots, and roads,
wood, paper, etc. (d) Animal offal.
(e) Dead animals.
Utilization of Town He fuse. The chief exertions were
first directed to extracting every thing in any way useful from
town refuse, and this was especially the case with regard to
fsecal matter which was and is even now in some places con-
verted into manure ; the rapid development of the large
towns, however, compelled more attention to be paid to the
quick removal of this material. Meanwhile the spread of
hygienic knowledge and the experience gained during severe
epidemics taught the municipal authorities that the health
of the dwellers in large towns, especially in regard to the
prevention of epidemic disease, depended largely on clean
soil as opposed to a soil saturated with decayed and infectious
material.
1 H. De B. Parsons, " Journal of the Society of Chemical Industry," 1908,
p. 376.
(3)
4 THE UTILIZATION OF WASTE PEODUCTS.
Thus the question of the utilization of town refuse became
of secondary importance, the question of its disposal taking
the premier place.
In some moderately-sized towns dry or earth closets are
in use in which the faecal matter is mixed with waste shoddy
or other material and after removal is allowed to dry spon-
taneously ; but so many difficulties were encountered in the
manufacture of fertilizers from faecal matter, which, moreover,
is subjected to so many precise and emphatic sanitary regula-
tions, that, especially since it requires considerable capital,
it has been superseded in large towns and cities by the water-
closet system. This is in consonance with the ideas of the
most prominent authorities on hygiene, who designate the
latter method as the most suitable. The loss to agriculture
of the manurial elements is more than counterbalanced by
the efficiency of the method and the gain to the health of the
community, while any doubts as to the advisability of the
method may be met by proofs of the automatic purification
of rivers.
In the majority of towns the sewage, house slops, and
drainage water pass together into the sewers and are purified,
either by settlement or by bacteria beds, the effluent being
turned into the nearest stream or river, or, in the case of
coastal towns, into the sea.
Attempts have been made in the past to utilize the useful
constituents which it contains, but owing to the dilute state
in which they exist this has not been attended with any
success, therefore the object at the present time is to get rid
of it as soon as possible after it has been sufficiently purified
to do away with any risk of infection.
With regard to the solid matter the case is very different,
the following methods of disposal having been tried :
1. Tipping on land. Where a sufficient area of waste
land within easy access is available, most kinds of refuse can
thus be got rid of, but with animal and vegetable offal this
method is not suitable owing to the stench which arises.
To obviate this difficulty trenches are dug in the soil and the
refuse buried.
THE WASTE OF TOWNS. 5
2. Tipping at sea. This is only available at coast towns
or those near to the mouths of large rivers, the. material being
taken out to sea in barges and there dumped.
3. Ploughing into the soil. This is suitable for manure
and garbage but not for the other materials. In some towns
manure is collected from the roads and sold at a nominal
figure.
4. Feeding to swine. Applicable to garbage, but only
locally.
5. Extraction of fat, etc. Applicable to garbage an<?
offal.
6. Destruction of organic matter by burning,.- Applicable
to practically all ordinary refuse.
In the United States of America and also to some extent
in this country the garbage is treated for the extraction of
fat either by the Arnold process, in which open steam is em-
ployed, or by the Merz and Simonin process, using a volatile
solvent, usually coal-tar naphtha or petroleum benzine. The
former method is the cheapest, though a lower yield of fat is
the result. In either case the grease is dark coloured and of
very low quality, its market value varying from 2-4-J- cents
per Ib. The extraction of fat from garbage is by no means a
remunerative operation, the only points in its favour being
the saving of the fat from destruction and the keeping of a few
" hands " in employment. According to Parsons, the follow-
ing are the products obtained :
Water and loss 85
Grease . . . . . . . .3
Tankage 9
Tailings 3
100
In Brooklyn 1 the plant for treating garbage is of the
Arnold-Egerton type and is situated at Barran Island in
Jamaica Bay, to which the material is towed in barges and
1 Edward D. Very, " Journal of the Society of Chemical Industry," 1908,
p. 378.
6 THE UTILIZATION OF WASTE PRODUCTS.
transferred by means of an elevator to the digestors. The
digesters are large tanks holding approximately 8 tons each,,
closed with a cap which is bolted on during action. In these
tanks the material is submitted to the action of open steam
at a pressure of 80 Ib. for a period which varies according to
the nature of the product undergoing treatment. The vapour
from the vats is condensed by a jet-condenser, the liquid thus
formed being conveyed by a pipe to the sewers. After steam-
ing, the pulpy mass is transferred to a tank which will hold
the contents of four digestors, and from this it is delivered to
frames covered with sacking in which it is submitted to
hydraulic pressure, the water and oil passing through the
sacking being conveyed by pipes into a settling tank below.
In this the oil and water separate, the former being skimmed
off and barrelled. The residue from the presses, or " tankage,"
is taken by a conveyer to the drying plant, and after drying it
is passed through screens and then bagged. The value of this,
material is somewhat problematical; it is used as a "filler"
for manures and contains small quantities of nitrogen, phos-
phoric acid, and potash, but burning would seem the proper
end for it.
At this plant the garbage yields :
Kubbish
. 6
Tankage
Grease
. 20
3
100
The removal and utilization of that waste of towns which
may be described as household refuse, or "dust," is an im-
portant problem. In this case a process of complete and
innocuous destruction is to be regarded as the ideal. From
the politico-economical point of view, and for the sake of
profit, it appears both desirable and justifiable to separate
material of any value from the dust. The final solution of
the problem will lie in the combination of the two endeavours :
to extract from the dust what is still of value and convert it
THE WASTE OF TOWNS. 7
\ into useful product, subsequently to destroy completely what
is valueless.
In England and America household refuse is usually
burned, the combustion taking place in special furnaces,
called " destructors," according to the system of Freyer.
Such furnaces burn all the refuse of a town, both dry and
wet. It is said that, by means of the destructor, it is possible
to burn dust to which a large quantity of inorganic, incom-
bustible matter has been added. The furnace stands in a
brick building and is fed from above. To the platform of
the building leads a stage by which the dust-carts are
brought up ; they then deliver directly over the opening of
the furnace. The dust gradually descends. It is in the first
instance lighted by means of a small coal fire, and afterwards
burns continuously. The material slowly falls farther and
farther, finally reaching the part of the furnace at which the
heat is most intense. The burnt residue passes through a
grate into an ashpit, from which it can be easily removed.
The installation consists of several furnaces in series in
most towns six, but from eight to twelve are also found.
From the hygienic point of view, it is important that the
gases given off in the process of combustion should cause no
nuisance to the neighbourhood. It has been found that the
combustion is practically complete ; however, in order to re-
move any unburnt gases which might be present, a smoke-
consumer is attached to the destructor. The temperature in
the hottest part of the furnace is very considerable ; in the
main flues it is about 300-400 C. An erection of this kind
requires no great space.
In the immediate neighbourhood of London there are
seven or eight destructors, some of which are within the
boundaries and closely surrounded by houses. In White-
chapel, for example, the destructor is only 16 ft. removed
from the wall of the nearest house, without injury to the in-
habitants. Destructors are in operation in at least twenty-
four English towns, and some have been in use for more
than fifteen years. A furnace of this kind burns per week
8 THE UTILIZATION OF WASTE PEODUCTS.
(Sundays excepted) 24-35 tons i.e. about 30,000 kilos. The
cost of the process varies : in England it is estimated that it
costs about one shilling to burn one ton of refuse, but in
isolated cases the cost is reduced to about fivepence per ton.
The products left after the combustion have many technical
uses. Mortar and stone are made from them ; at the same
time the heat which is given out by the combustion of the
dust is utilized, as, for instance, in driving compressed air
installations, electric lighting, etc.
In this connexion it may be remarked that the house-
hold refuse of English towns is quite different in composition
from that of continental towns, since in England coal is
much more extensively used for heating private houses than
in Germany.
Later, in 1894, further progress was made in the con-
struction of destructors. The system is considered the best
in which the destructor is composed of a group of furnaces
in the form of cells, generally six in number, built of fire-
brick, and covered by an arch which forms the top of the
reverberatory furnace. The dust is emptied into an immense
hopper at the top, from which it passes, after being rapidly
dried, on to grates similar to those of boilers, in the lower
part of the apparatus, where it is burnt. About every twenty
minutes a fresh charge is let down and burnt. On the
average, each cell of the destructor, in which the fire is never
extinguished, burns from 30-35 tons of refuse per week. The
ash and clinker from the furnaces are ground and mixed
with one-third of their volume of hydraulic lime, thus form-
ing a blackish cement, not of very agreeable appearance, but
selling at eight shillings per ton, and used in buildings for
staircases, and especially for drains. The specially valuable
part of the process lies, however, in the utilization of the
heat in the production of steam. With a good apparatus,
each cell of the destructor gives ten horse-power, which is
obtained from a boiler immediately attached to the destructor
and heated by the hot gases. In twenty English towns the
steam produced in this manner is used for disinfecting cloth-
THE WASTE OF TOWNS. 9
ing and bedding. At Hastings the steam thus generated is
utilized in pumping sea-water, which is used for flushing the
public urinals and sewers, and for watering the streets. At
'Southampton the steam produced by the destructor com-
presses air, by which the sewage is raised and carried away ;
at the same time it generates energy for an electric lighting
installation. In other places this power is used for driving
<jhaff-cutters, for producing mortar and artificial manures,
and for driving grinding and mixing machinery.
The table on next page by W. F. .Goodrich l shows the
working of destructors in various towns in Lancashire. The
evaporative power of the refuse varies according to the
nature of the material and the type of destructor used, rang-
ing from i to T \ of that of coal. When the evaporative
Talue is below tV that of coal the destructor cannot be re-
garded as a power producer.
The importance of the removal and utilization of dust at
the present day, in view of the rapid growth of the great
towns, is evident from the fact that in London, for example,
not less than 1000 tons have to be removed daily. The
experience of Hamburg is interesting ; after the cholera
-epidemic an attempt was made to burn the refuse, and, fol-
lowing the example of London, a furnace for dust was
erected. The experiment was favourable under the condi-
tions then prevailing; the dust burnt alone, and only a
:small quantity of coal was required to start the combustion.
Later, the dust could be burnt alone, but produced a rough
and apparently valueless clinker. In Berlin a destructor
was also erected, the experiences of London and Hamburg
being utilized, and English workmen being engaged to build
and work the furnace. Success in this case, however, was ab-
solutely wanting, for there remained an incombustible residue
amounting to 60 per cent. Thus, of 100 cwt. which were
brought to, and had to pass through, the furnace, and which
could only be kept burning by the addition of coal, 60 cwt.
had again to be taken away. The municipal authorities
1 " Gassier," 1901, 21, 99-122; also " Proc. Inst. Civil Eng.," 1902, 149 [3],
97-9.
10
THE UTILIZATION OF WASTE PRODUCTS.
THE WASTE OF TOWNS. 11
were therefore compelled definitely to abandon the experi-
ment.
In the next place, private industry stepped into the field.
Several years ago a quite new method of disposal came into
prominence, known as the " Budapest process ". It requires
large-scale arrangements for sorting the refuse, such as were
installed at Budapest, combined with the burning of the
combustible portions. The refuse is conveyed on an endless
band, on either side of which children stand to sort the
rubbish. One picks out green glass, another white glass, a
third rags, a fourth bones, all of which are thrown into separ-
ate baskets behind the pickers. Then the contents of the
particular baskets are collected, and everything still usable
is disposed of.
In Berlin this method was rejected for sanitarj r reasons.
Dr. Weil, an authority on sanitation, in a lecture to the
Society for Public Health, stated that this so-called Budapest
system, which was advanced in Berlin as quite novel, had
already been forbidden in London by law in 1892. The
advocate of the system could make no answer to Dr. Weil,
whose statement still remains unrefuted, so that it may be
accepted as correct.
The method employed for utilizing the household refuse
of Munich at the large establishment at Puchheim, on the
railway from Munich to Buchloe, is similar to the Budapest
process. The author is obliged to the managers of this large
establishment, now the third of the kind in Germany, for a
complete insight into the method.
Every day two special trains, of thirty to forty waggons
each, arrive in Puchheim from Munich. Each waggon con-
tains four large trucks known as " harritsches ". The refuse
brought by these trains amounts- to 450-500 tons daily, and
is completely treated in ten working hours. The cost of
railway carriage is about 18 per day, amounting to over
6000 per annum.
The " harritsches " are taken up by a lift from the waggons,
they are emptied by the bottoms dropping outwards and are
12 THE UTILIZATION OF WASTE PRODUCTS.
then brought back. The contents of each truck are raked by
a workman through a shoot, and then sieved. The fine
sievings are used as manure, for which purpose there is a
demand, since they contain no small amount of fertilizing
matter. The price fixed by the management must be re-
garded as extremely low. The coarse residue then passes on
to an endless band, from which, as in the Budapest process,
it is sorted by women. The sorting yields a tolerable amount
of usable material. There is, for instance, a considerable
amount of glass, rags, bones, and paper, while even hare-skins
are found in the season, and old shoes are also plentiful.
About 500 or 600 bottles are collected every day. From the
sorting band the residue passes into a sieving drum, which has
meshes of various gauge. From the sieve the finer material,
which is used as manure, is carried away by a screw con-
veyer.
The utilization of the refuse is here carried out in the
most complete and rational fashion. Unbroken glass bottles
are washed and cleaned by an iron bottle- washing machine,
and are disposed of to the brewer, wine merchant, etc.
Broken glass is also washed in an iron drum ; it then goes
to the glassworks. The countless rags are beaten in a
special rag beater, by which they are opened out and freed
from dust. They are then dried, disinfected, and sorted ac-
cording to the nature of the fibre and the quality. The fine
dust is mixed with phosphoric acid, saltpetre, and dried blood
in a special mixer. The compound is then filled into sacks
for use as a fertilizer. Old iron, which is also found in con-
siderable quantity in dust, is converted into green vitriol.
Old shoes are converted into ground leather, which is mixed
with the fertilizer. Large quantities of tinplate boxes can be
treated in order to obtain the tin.
The works are plentifully supplied with steam-power,
which is used for all the mechanical operations, and also for
the electric lighting of all the rooms. There are about 3000
metres (nearly two miles) of railway track in the works.
The residue, which is absolutely unutilizable, is carried
THE WASTE OF TOWNS. 13
away on rails in small trucks, three of which are drawn by
an ox ; hitherto it has been used for levelling the surround-
ing moor, but will shortly be destroyed by burning, the
necessary furnaces being already erected.
From the sanitary point of view, the provision of lofty
and airy working rooms, and several ventilating fans, has
satisfied the demands of health.
The process of utilizing household refuse at Puchheirn,
which is allied to the Budapest method, is doubtless more
rational, 'and may at the present time be described not only
as the most important of the kind, but also as the best
equipped and best managed.
The dust-melting process, based on the patent of Wegener,
differs entirely from the above. In this process the refuse is
fused at a temperature of about 2000 C. No sorting takes
place, the dust, as it is removed -from, the houses, being
emptied into the furnace, leaving it as a fluid glassy slag,
which very quickly solidifies after it is run out.
This process certainly satisfies all the requirements of
sanitation, but the question of cost remains to be solved.
It has, however, been shown that the dust is fusible, leav-
ing nothing but the above-mentioned slag. The cost ought
not to be unsurmountable, since the householder has already
to bear the expense of removing the dust and of its disposal.
To reduce the cost as much as possible it is necessary to
utilize the heat of the furnace gases, which reach the flue at
1250 C. Anyone acquainted with the subject knows that
this heat can be utilized. It is only necessary to measure
the temperature in order to be able to show how many horse-
power per hour are available. According to measurements
which have been made, the energy required in fusing the
total refuse of Berlin would amount to 2800 horse-power per
hour. There would be no appreciable difficulty in utilizing
the waste heat ; on the contrary, it is an important factor
in calculating the cost of the process.
Various experiments have been made with a view to
utilizing the slags, which constitute the residue in this pro-
14 THE UTILIZATION OF WASTE PRODUCTS.
cess of fusing dust. , It appears to be best to temper the slag,
which flows out, by gradual cooling, so that it is not excess-
ively brittle. The slag has been powdered under stamps, and
used as a substitute for emery. According to experiments
its hardness is 9, the same as that of flint. It is stated that
this slag binds completely with cement, therefore, since the
slag is quite fireproof, it may find employment in building
operations, particularly for foundations. Taken on the whole,
it is maintained that, according to previous experience, the
fusion of dust would not cost more than the Berlin muni-
cipality now charge at their stations to the contractors for
unloading 10 pfennigs per centner (about l^d. per cwt.). If
the excess of heat were complete"ly utilized, this cost should
he considerably diminished. It should be observed that it is
proposed to dispose of the residues or slag (which, as com-
pared with the 60 per cent of Hamburg, only amount to 12
per cent) to glassworks, where they might be ground and
mixed with the glass charge, but it is questionable if the glass
makers could use it. It could at any rate be used as road
metal.
In regard to the fuel, coal-dust firing is employed, as the
intense heat can only be obtained in this way. ' A grate is
consequently unnecessary, the coal dust being automatically
projected from above by a special appliance. The dust at
-once takes fire at the high temperature and is converted into
gases, the whole furnace being a mass of flame. No hearth
is required, but only burning gases which fuse the dust.
When this work is accomplished, they pass downwards to
the flue, where the waste heat is utilized.
Above the furnace is a large opening for charging, pro-
vided with a double cover, which fits air-tight thus preventing
loss of heat. For charging, the upper cover is taken off, the
lower remaining closed ; a box of dust is then emptied on the
latter, almost filling the space between the two. The upper
lid is closed, and the lower lid, the valves of which fall down-
wards, opened by means of a mechanism, so that the dust
drops by its own weight into a pipe leading directly to the
THE WASTE OF TOWNS.
15
furnace. In the furnace the combustion commences at a
temperature of about 800 C., the dust being dried and all
-combustible constituents gasified, thus producing fuel for the
fusion of the incombustible portion. From the furnace the
unburnt dust, containing ash, crockery, iron, tinplate, etc.,
falls gradually on to a firebridge, where at a temperature of
1200-1400 C. some of the materials are softened and the
others caused to sinter. Subsequently in the lower part of
the furnace at a temperature of 2000 C. everything present
in the dust fuses, and the liquid flows out continuously. The
furnace is built of refractory bricks.
J. T. Fetherstone has given the composition of New York
refuse as follows :
Combustible.
Carbon ....
Hydrogen . . . ,
Nitrogen ....
Oxygen ....
Incombustible.
Silica
Oxide of iron and alumina
Lime .
Magnesia .
Phosphoric acid
Carbonic acid
Lead .
Tin .
Alkalies and undetermined
Calorific Value.
Calculated
Determined (average)
Coal and Cinders. Garbage. Rubbish.
55-77
0-75
0-64
2-37
30-01
8-98
1-21
trace
nil
trace
trace sulphide
0-27
8382
8510
43-10
6-24
3-70
27-74
7-56
0-41
4-26
0-28
1-47
0-59
4-45
7970
8351
42-39
5-96
3-41
33-52
6-40
2-03
2-26
0-57
0-10
1-49
0-52
trace
1-21
7250
7251
The rubbish burns readily, developing considerable heat.
A very high temperature in the furnace is required to destroy
offensive matters, the temperature being at least 1500 F.
The weight of the incombustible residue is about 33 per cent
that of the original, but its volume is equal to 60 per cent.
Artificial draught is required for the combustion.
The approximate calorific values of the refuse in B.T.U.
per Ib. is as follows :
16 THE UTILIZATION OF WASTE PRODUCTS.
Percentage Calorific Value.
Collected. Material as Collected. Dried Material.
Garbage .... 12-3 1800 8700
Ashes .... 63-7 1800 3000
Eubbish .... 6-3 6500 7500
Street sweepings . . 17*7 3600 7000
The mixed refuse has a calorific value of about 2913,.
being about -J that of coal. Trials were made in December,.
1905, to estimate the amount of water evaporated by the
burning of this refuse, at and from 212 F., T64 and 2'16 Ib.
of water being converted into steam by 1 Ib. of the refuse.
Subsequently trials by different observers showed evaporative
powers of 2*28, 2*29, and 2'17 Ib. of water per 1 Ib. of refuse.
One or two examples of the working of ordinary de-
structors may not be out of place.
At Boun * a destructor of the type of A. Custodis and
F. A. Herbertz was installed, the trials being very satisfactory.
The installation includes seven destructor cells, the total
capacity of which is 52,500 kilos of refuse per 24 hours.
Special waggons are employed in collecting the refuse, these
having loose doors in the bottom for discharging purposes.
The refuse is taken on a transporter system to the storage
bin, which has a capacity of 126 cub. m., and from which it
is delivered to the cells by corresponding openings. The
refuse is burnt on a grate with forced draught at an air
pressure of 350 mm. water (=14 in.). The rate of burning
is equal to 313 kilos per ^q. m. grate surface per hour. The
hot gases from the cells pass into two large chambers lined
with refractory bricks in which the fine dust carried off by
the draught is consumed, and from thence pass to a water-
tube boiler of the Babcock and Wilcox type provided with
108 tubes and having a heating surface of 220 sq. m. This
boiler can also be independently heated by coal. The hot.
gases pass from the boiler to an economizer and thence to
the chimney 40 m. in height.
The steam generated by the boiler is utilized for driving
a turbine of 300 horse-power and a dynamo from which the
J S. Bondot, " Elect. Runds.," 1906, 23, pp. 331 et seq.
THE WASTE OF TOWNS. 17
power is obtained for running the destructor plant. The
two fans for producing the blast are driven by a 25 horse-
power motor ; these deliver 105 cub. m. and 130 cub. m. per
minute respectively. The clinker from the cells is ground
to a fine powder in a mill and sold.
A trial run with this plant in which 26,898 kilos of refuse
were consumed at the rate of 2782 kilos per hour resulted in
the production of 12,938 kilos of clinker and 3473 kilos of
flue dust. The evaporative power was equal to 1'13 kilos of
water per 1 kilo of refuse, the temperature of the flue gases
279 C., and the percentage of carbonic acid in the latter 8'8.
On a three months' trial the evaporative power was found to
be T05 kilos per 1 kilo of refuse.
At Burslem Electricity Works 1 a destructor of the
"Heenan" type was installed. This has three cells which
are charged from the front, their capacity being 33 tons of
refuse per 24 hours. From the cells the products of com-
bustion pass into a combustion chamber arranged at right
angles to the cells, and from thence pass to a Babcock and
Wilcox boiler, the capacity of which is 6000 Ib. of water
evaporated per hour at a pressure of 200 Ib. per sq. in. The
gases from the boiler are utilized for heating the air used in
forced draught, the latter being produced by means of a
fan driven by an electric motor. The official test carried out
on 14 November, 1905, lasted 7J hours, during which 26,572 Ib.
of refuse, mixed trade and domestic, were burned. The
total grate area is 75 sq. ft., and the heating surface of the
boiler 1966 sq. ft. The average quantity of refuse burnt was
48'8 Ib. per sq. ft. of grate area per hour and the amount of
water evaporated 49,990 Ib. or T87 Ib. per 1 Ib. of refuse
(actual) or 216 Ib. from and at 212 F. The temperature of
the feed water entering tank was 45 F. and the temperature
of the combustion chamber 2032 F. The clinker amounted
to 26'5 per cent on the refuse.
The Borough of Westmount, Canada, has a mixed refuse
destructor plant, the results after eight months' working show-
J " Elect. Engin.," 1906, 38, pp. 294-6.
2
18 THE UTILIZATION OF WASTE PBODUCTS.
ing that 2000 Ib. of refuse were equivalent to 283 Ib. of coal in
evaporative power. A trial in May, 1906, showed an evapora-
tion of 1*36 Ib. of water per 1 Ib. of refuse, which compares
with the average of eighteen European destructor plants
reported by J. T. Fetherstone, the maximum being 2'66 Ib.,
the minimum 0*88 Ib., and the average 1*62 Ib. water evaporated
per 1 Ib. of refuse.
NIGHT-SOIL AND SEWAGE MUD.
Utilization. Although there are plenty of proposals for
the rational utilization of excrement, yet hardly any process
has succeeded in surviving. Thus Leube's process the appli-
cation of sulphuric acid failed, and Petri's manufacture of
faecal stone could obtain no practical hold. The most rational
method of treatment after the removal to a suitable locality,
is to utilize it as manure. The preparation of an illuminat-
ing gas from excrement is described in the chapter on
" Illuminating Gas from Waste ".
In regard to other proposed methods, with the exception
of the manurial, we give the opinion of Fischer. 1 " As a
matter of fact, the application of human excrement as a fuel
Petri's fsecal stone is the worst imaginable use to which
it could be put since its most valuable constituents, nitrogen
compounds, are lost. For large towns there is no other
course than a well-arranged system of sewers and flushing."
Scott has patented the following process for treating
sewage : The sewage, collected in a tank, is mixed with ex-
cess of caustic lime, the clear supernatant liquid being drawn
off from the precipitate ; in a second tank an iron or aluminium
salt is added, which salt is converted into the hydrate by the
lime present in the clarified water. The precipitate in the
first tank, which contains the organic and inorganic matters
suspended in the sewage, and to some extent also substances
previously in solution, may be converted into cement or filter
coke. The precipitate in the second tank, after calcination,
gives metallic oxides which may be utilized. The water from
111 Dingler's polyt. Journ.," 213, p. 259.
THE WASTE OF TOWNS. 19
the second tank is sufficiently pure to be passed into a large
stream, and, if it has previously been filtered through the
coke obtained from the first tank, may even be run without
danger into a small stream.
The sewage mud deposited by allowing sewage to settle
in tanks is, whenever possible, pumped into vessels and sunk
right out at sea. Trials have been made by the Eoyal Com-
missioners on Sewage for using this material as a dressing on
land but without any useful results accruing. As a matter
of fact, sewage mud is so finely divided that air can only with
difficulty gain access, and on some soils, for instance clay or
peaty soils, it would act as a poison. In Germany and to
some extent in this country also the mud is treated with sol-
vents for the extraction of the fat or grease which it contains,
and quite a considerable quantity of such grease is thus
obtained; though the latter is of very inferior quality it still
has a distinct commercial value.
CHAPTEK II.
BLOOD AND SLAUGHTER-HOUSE REFUSE.
f _
Utilization of Blood. W. L. Palmer employs blood to
obtain a plastic material. It is passed through a fine sieve,
dried, pulverized, then mixed with 20 per cent of bone
meal and 10 per cent of size, placed in the required moulds
and subjected to a high pressure at 120 C. This application
of blood, and also earlier uses, in which blood and sawdust
were used in preparing plastic masses, are now of no techni-
cal importance, since cellulose can at the present day be em-
ployed much more successfully in making artificial wooden
ornaments.
Treatment of Blood. The great obstacle to the use of
blood in manufacturing processes is its tendency to decom-
position, which rapidly occurs. This drawback may be obvi-
ated by carrying out all the operations as rapidly as possible.
Heinson Huch of Brunswick has patented a simple process L
for protecting blood from decomposition and drying it. Ac-
cording to this process the blood, in the vessel in which it is
caught from the slaughtered beast, is stirred as it flows in with
about 3 per cent of ground or finely powdered quicklime, i.e.
about 450 grm. (one pound) for the blood from each bullock.
After stirring for three to five minutes the mixture is al-
lowed to stand. The lime rapidly settles to the bottom and
the blood coagulates in a few minutes. It is then removed
and placed in the sun in an airy position to dry, the drying
being accelerated by stirring at intervals. In a short time
the blood is dry ; it remains free from smell and taste, and
does not evolve ammonia. In the winter the drying must
naturally be accomplished in a kiln, or a stove if the quantity
1 "Neueste Erfindungen und Erfahrungen," 1877.
(20)
BLOOD AND SLAUGHTER-HOUSE REFUSE. 21
is small. The ground or powdered lime is brought into con-
tact with all parts of the blood during stirring, unites with
some of the water, and sinks to the bottom, leaving only
traces in the blood, which becomes somewhat more alkaline
and dries more readily, without clotting into masses, which
occurs during ordinary evaporating. Since no smell at all
is evolved, the blood retains the whole of its nitrogen, which
is of considerable importance in considering its value as a
fertilizer.
G. Thenius has also described the practical treatment of
blood. 1 Bullocks' blood is that which is obtained in the
largest quantity in slaughter-houses. In order to obtain it
in a readily fluid condition, it is stirred with a stick for some
time until the fibrin has separated in long threads, when the
stirred blood is brought on to a fine hair-sieve and washed
with water. The washed fibrin is placed on dry cloths, so
that it may rapidly be freed from water, as otherwise it
quickly decomposes. After this operation with dry cloths
has been frequently repeated, the fibrin is placed on a hair-
sieve and dried at 120 C. in an air-bath. It is to be observed
that this fibrin still encloses some globulin, and cannot there-
fore be regarded as pure. The globulin and also haemoglobin,
the colouring matter of blood, are always enclosed by the
fibrin ; they may be removed by long-continued washing in
order to obtain pure fibrin.
The blood freed from fibrin does not decompose so rapidly
and may in cold weather be kept for several days. The
author treats the fluid blood mainly by two methods :
1. By drying upon flat zinc sheets (previously oiled), the
edges of which are turned up to prevent the fluid from run-
ning off, this being done in drying-stoves, provided with
shelves, in which the temperature is maintained at 30-
35 C. The dried blood, which is now in the form of thin,
transparent sheets, is used in sugarworks, under the name
of blood albumin, for clarifying the juice. From 100 parts of
the fluid blood about 21-22 parts of the dry substance are
1 " Neueste Erfiadungen und Erfahrungen," 1878.
22
THE UTILIZATION OF WASTE PRODUCTS.
obtained ; thus 78-79 per cent of water has to be evaporated.
The author has constructed a special furnace for the drying-
stove, the arrangement of the flues in which has been found
to be very effective ; a regular heat being maintained, with
economy in the expenditure of fuel (Fig. 1).
Fn. 1. Vertical section of the furnace, with drying-stoves for heated air.
A, Furnace ; a, hearth ; &, ashpit ; c, door ; d, flues ; e, chimney; /, air
passages ; g, covering plates. B, Drying-stoves ; a, shelves ; b, pipes for
the moist air. C, Workrooms.
FIG. 2. Longitudinal section of the furnace used in making dry blood meal.
2. By thickening the fluid blood in pots with continuous
stirring, in order to obtain blood meal. The author has con-
structed for this purpose a special furnace (Fig. 2), which has
BLOOD AND SLAUGHTER-HOUSE REFUSE. 23
proved very satisfactory. In the figure, a is the fireplace, B
the grate, c the ashpit, d the flue ; the chimney, /, which re-
ceives the flue, is regulated by the damper, e. The flues are
roofed with cast-iron plates, h, upon which is a sand-bath, g,
containing the iron vessels in which the stirrers, i, can be
kept in motion by the shaft, k. Round the furnace is a
platform shown at e, to facilitate the removal of the pots and
the actuation of the stirrers by a labourer.
The fluid blood is brought into the pots, which should
only be half filled ; they are then placed in the sand-bath
and the stirrer k, i, put in position. The furnace is heated
and the stirrers set in motion, in order that the blood, which
soon coagulates, may not adhere to the walls of the pots and
char. With continuous stirring, the mass, which was at first
pasty, gradually assumes a pulverulent condition-; it acquires
thereby a dirty brown colour, which turns to reddish brown
as the drying proceeds. The vapours evolved during this
period have a peculiar odour and oxidize metals, such as
copper, very rapidly. The workman in charge of this opera-
tion is considerably affected if he should breathe these
vapours, especially when fresh blood is being treated. As
soon as the pulverulent blood has become quite dry and no
more vapours are evolved, the stirrers and pots are removed
from the sand-bath, the pots emptied into sheet-iron vessels
which can be securely closed, and the contents allowed to
cool. When quite cold the blood is perfectly dry and can
be readily ground. The average yield is 20*5-21*2 parts from
100 parts of fluid blood, so that it may be assumed that at
least 78'8 per cent of water and volatile matter are lost
during evaporation. When the blood, whilst still somewhat
moist and powdery, is filled into strong linen bags and sub-
jected to a considerable pressure in a press, there is obtained
a watery and fatty liquid, the fat of which solidifies at low
temperatures and can be separated from the water. The
quantitative yield of this liquid is 2*7-3 per cent. The aque-
ous solution contains the salts. The solid compressed residue
is more adapted for storage than the blood meal, since it does
24
THE UTILIZATION OF WASTE PRODUCTS.
not absorb moisture. The dry blood may either be used for
producing prussiate of potash, or for obtaining a very good
charcoal containing nitrogen, but more particularly for en-
riching artificial manures.
The apparatus shown below (Fig. 3) is used in making blood
charcoal. The dried and powdered blood should not more
than half fill the cylinder, since the mass swells on heating,
and' the stirrer, B, must always be kept in motion. The
cylinder (Fig. 4) is made of cast iron or thick sheet iron and
is constructed so as to be capable of removal from the furnace
FIG. 3. Longitudinal section of a blood charcoal furcace. a, hearth ; b,
ashpit ; c, door ; e, flue ; /, exit-pipe ; g, chimney.
d. The stirrer, B, can also be removed together with the
lid from the apparatus, in order to facilitate cleaning.
The vapours evolved, consisting chiefly of ammonia and
empyreumatic oils, pass away by the pipe, /, to the .receiver,
g, which contains a leaden vessel, in which is placed dilute
sulphuric acid. The ammonia combines with the acid to
form ammonium sulphate, whilst the oily substances float on
the surface and can be utilized as Dippel's oil. Fresh dilute
sulphuric acid must frequently be supplied to the receiver, g,
after drawing off the saturated ammonium sulphate solution.
BLOOD AND SLAUGHTER-HOUSE EEFUSE.
25
As soon as vapours cease to be evolved from the apparatus,
the cylinder is removed from the furnace, allowed to cool for
several hours with frequent stirring, then opened, and the
fine blood charcoal brought into a vessel which can be tightly
closed. This charcoal absorbs gases with such extraordinary
rapidity that it may spontaneously heat up and become red
hot. In medicine this preparation is known under the name
of carbo animates ; it is used principally for dusting malig-
nant wounds, which give off much bad gas and smell. When
freshly burnt, it could be used for the disinfection of hospitals
and similar buildings and is a valuable decolorizing agent.
FIG. 4. A, Cylinder for blood charcoal.
B, Lid, together with stirrer.
If blood charcoal be ignited with potash it acquires much
greater decolorizing power ; for this purpose the charcoal is
preferred in a granular form, in which state it is much more
porous.
The most important technical use of dried blood is in the
manufacture of potassium cyanide.
If dried pulverized blood or blood meal is allowed to lie
exposed to the air, it rapidly attracts moisture from the atmo-
sphere and gives off ammonia. This formation of ammonia
takes place more rapidly if the blood meal is mixed with
finely powdered aluminium silicates as, for example, brick
26 THE UTILIZATION OF WASTE PRODUCTS.
dust and at the same time freshly burnt wood charcoal in
powder is added. The mixture soon becomes warm, the*
heat increasing with the thickness of the layer. The addition
of wood charcoal prevents the loss of ammonia by condensing
the gas in its pores. On this account the addition of charcoal
to artificial manures which contain blood meal is much to be
recommended, since then no loss of nitrogen occurs. If
blood meal be mixed with dry earth, an increase in tempera-
ture and evolution of ammonia can be distinctly observed.
If moist earth be used, the blood meal is quickly decomposed,
an action which may be still more accelerated by adding
alkaline substances, such as wood ashes. Accordingly it is
advisable, before using dried blood as a fertilizer, to mix it
with wood ashes and powdered charcoal, and to apply it to
the ground in wet weather. The decomposition and action of
the fertilizer then take place very rapidly. Blood manures
are hence very valuable in agriculture, especially since the
food they contain can be very quickly conveyed to the plant
in soluble form. The author has made experiments on vines
and kitchen vegetables, in which very good results have been
obtained. For one vine 140 grms. (about 5 oz.) of dry blood
meal, mixed with double the weight of wood ashes and char-
coal, are sufficient. This mixture is mixed to some extent
with the soil of the vineyard, and is also placed in the pit,
where otherwise stable manure would be used. A great ad-
vantage of this system of manuring lies in the saving of
labour, since one man can readily manure in a day several
hundred vines.
The following is an analysis of dried blood : l
Water 10'56
Nitrogenous Organic Matter . . . 86*92
Saline Matter 2-52
100-00
Nitrogen = Ammonia .... 17-24
It should be remarked that the fertilizer, mixed with an
equal weight of sieved wood ashes, may be kept or packed in
1 Stevenson Macadam, " Journ. Soc. Chem. Indt.," 1888, p. 95.
BLOOD AND SLAUGHTER-HOUSE REFUSE. 27
well-closed vessels, e.g. in casks lined with tinfoil, biit better
still in empty petroleum or oil barrels. It should be well
pressed down, so that there are no interstices ; the atmospheric
air then cannot act on the blood meal. The mixture must also
be kept dry, in order that there may be no loss of ammonia.
Preparation of Albumin from Ox Blood. The blood
caught from the slaughtered animals is allowed to coagulate
in dishes, when the albuminous liquid rises to the surface
and can be poured off. During this process the dishes are
kept in a cool place, where the separation more readily occurs.
The so-called " blood-cakes," which separate, are transferred
to a linen filter and gently squeezed, in order to obtain the
remaining albumin which they contain. The residual fibrin
is then cut into lumps and dried in drying-chambers on zinc
plates. The blood-albumin is now treated according to the
method described for drying .the fluid blood, by bringing it in
very thin layers upon zinc plates with turned-up edges, and
freeing it from water in a drying-chamber at a temperature
which does not exceed 30-35 C. The zinc sheets are pre-
viously greased with a little olive oil, in order that the dry
albumin may be more easily removed. To free the dried
albumin as far as possible from other matters which adhere
to it, distilled water is poured over it. After some time this
is drawn off; it contains the readily soluble phosphates and
other impurities. The residue is now mixed with warm dis-
tilled water and frequently stirred, when the blood-albumin
dissolves. The solution is filtered through flannel, which re-
tains the impurities and the colouring matter of the blood>
the filtered concentrated solution being again brought on to
the zinc sheets and dried in the drying-stove at 30-35 C.
The principal applications of blood-albumin is in calico-print-
ing, for the fixation of the colours and also for leather dressing.
Edmund Campe, of Briinn, has related certain very note-
worthy experiences in the practical manufacture of blood-
albumin. 1 In order to obtain a very pale blood-albumin, it is
necessary to use the greatest care in catching the blood from
1 Wittstein's " Vierteljahrschr. f. prakt. Pharm.," 1872.
28 THE UTILIZATION OF WASTE PEODUCTS.
the slaughtered cattle and sheep, the vessels for clearing
the serum and the sieves being placed as near to the
slaughter-house as possible. When possible, the serum
should be drawn off in the slaughter-house itself, or the im-
mediate neighbourhood, and the blood should be brought on
to the sieve not longer than 30 to 60 minutes after it
is caught. The freshly-curdled blood is cut into cubes of
about 1 in. square, brought upon the sieve, and allowed to
drain for 40 to 48 hours. After the lapse of this time, the
clear serum is drawn from the clearing vessels, with the pre-
caution that none of the red colouring matter deposited at
the bottom is removed with it. In order to avoid this,
Campe employs clearing vessels with somewhat concave
bottoms, and has the orifice of the exit pipe about J in.
above the bottom.
After all the clearing vessels are emptied, the whole of
the serum is placed in a tub of soft wood, about 3 to 4 cwt.
in capacity. The tub, which is wider at the top than the
bottom, has a wooden tap about 2 to 3 in. from the bottom.
The further treatment of the serum varies, according as
" natural " albumin, i.e. without shine, or " patent " albumin
which shines is to be made.
In^order to obtain natural albumin, it is only necessary
to add J Ib. of (spirits of) turpentine to each cwt. of serum,
and stir well for an hour. For this purpose Campe uses a
circular board, about 1 ft. in diameter, perforated with holes,
and fastened to a stick. After stirring, the serum is covered
and left 24 to 36 hours at rest. The turpentine rises to the
surface, together with a greasy, greenish white fat. The
clarified serum is now drawn off through the wooden tap
near the bottom. The first runnings, which are always
somewhat turbid, are rejected, the remainder of the serum
being taken to the drying-stove for evaporation. Campe
evaporates in iron trays, 12 in. long, 6 in. wide, and f in.
deep, which are painted with enamel, varnished, and stoved.
The temperature of the drying-stove, when the serum is
poured into the trays, is about 50 C.; when the trays are
BLOOD AND SLAUGHTEB-HOUSE REFUSE. 29
full, the temperature may rise rapidly to 52 to 55 C., which is
maintained for two hours, without opening a ventilator. After
this time all the ventilators are opened, and the temperature
allowed to sink to 50 C., at which it is maintained until the
end, the ventilators being opened, in order to ensure the re-
placement of the moist air. In order to promote a rapid
renewal of air, Campe employs air-holes in the masonry at
the bottom. The exits are naturally at the top, and open
above the roof.
In order to produce from the serum the so-called
" patent " albumin with a handsome glitter, Campe takes for
each cwt. of serum 6| drm. of oil of vitriol and 6 oz. of
strong acetic acid (sp. gr. 1*04), mixes the two, and, after
standing for one hour, dilutes with about 6 Ib. of water, and
then pours in a very thin stream into the serum, whilst con-
stantly stirring. Next J Ib. of turpentine is added per cwt.
of serum, and the mixture well stirred for 60 to 90 minutes.
After the serum has stood 24 to 36 hours at rest, the clear
portion is drawn off as before, and ammonia added to weak
alkaline reaction before placing in the drying-room, in order
to neutralize every trace of free acid. The plates are rubbed
with warm tallow, so that the finished albumin may easily be
removed from them.
By this treatment only a portion of the albumin is ex-
tracted from the blood for the preparation of the so-called
primary albumin. Now comes the manufacture of secondary
and tertiary albumin. The second variety is more an acci-
dental manufacture, for which only the serum of those ves-
sels can be used which for any reason has acquired a reddish
colour. Campe also took for it the last pale red liquids ob-
tained in drawing off the serum for primary albumin. The
treatment for secondary albumin is the same as that given
for primary. Tertiary albumin is the last product; it is
used in sugar refineries in considerable quantity. The cubes
of blood which remain upon the sieves are brought into a
vessel with a false bottom about 8 to 12 in. up and bored
with -J- in. holes ; water is poured on in sufficient quantity ;
30 THE UTILIZATION OF WASTE PKODUCTS.
also all the residues from the primary albumin are added
i.e. the red deposit which formed in the settling vessels, the
whole being well worked up with the hands. The liquid
which collects below the perforated bottom is made slightly
alkaline with a little ammonia, and brought into the drying-
stove. This product also glistens, and is the so-called tertiary
albumin.
The blood, which remains behind in the double-bottomed
vessel, is then passed (according to Campe) between two
toothed rollers, working together, so that a uniform paste is
obtained, which is dried at 60-75 C. in a stove built with
shelves. The sheet-iron drying-trays used in the stove are
2 ft. long, 1 ft. wide, and about 14- in. deep. The use of this
product is somewhat extensive. In order to improve it as a
fertilizer, Campe mixes it with solid human excrement and
.ground oak galls and moulds it into bricks, which are dried
in the air, and finally ground in the manure mill. The pro-
duct is known as blood-manure : it contains about 6 per cent
of nitrogen, and is particularly efficient for grasses and legu-
minous plants.
Preparation of Fibrin and Butyric Acid. The fibrin ob-
tained in the form of threads by whipping ox blood is washed
with distilled water until it appears quite white, and the blood
corpuscles have been removed. It is then rapidly freed from
water on linen cloths, as before described, and dried on hair-
sieves at 120-150 C.
If the moist fibrin be treated with pyrolusite and sulphuric
acid, butyric acid is formed, which may be used in the manu-
facture of butyric esters.
Butyric acid is also prepared as follows : 80 grms. of
moist fibrin, 320 grms. of starch, 20 grms. of tartaric acid,
and 5 kilos of hot 1 water are mixed together; then 1*5 kilo
of sour milk is stirred in, and the mixture left for forty-eight
hours in a warm place at 32-36 C. until fermentation com-
mences. When the fermentation has become active, 520-550
grms. of finely powdered chalk are added and the whole
frequently stirred. At first calcium lactate is formed and the
BLOOD AND SLAUGHTEK-HOUSE REFUSE. 31
mass solidifies, but after a time it liquefies, and in about
fourteen days the formation of calcium butyrate is prac-
tically complete. The process is finished when bubbles of
gas cease to be evolved. The liquid is then filtered through
cloth, and sufficient sodium carbonate added to convert the
calcium butyrate into sodium butyrate and calcium carbonate.
The latter is filtered off and the liquid evaporated. To the
residue sulphuric acid is added, equivalent in quantity to the
sodium carbonate ; the butyric acid separates while sodium
sulphate remains in solution. The butyric acid is again
neutralized with soda, and the butyrate decomposed by sul-
phuric acid in a glass retort and applied, when colourless
butyric acid distils over.
In order to obtain butyric ester from the butyric acid,
two parts of alcohol are mixed with two parts of butyric acid,
and one part of strong sulphuric acid added. An oily layer
separates upon the liquid ; it is washed with water, shaken
for some time with magnesia, filtered, and dehydrated by
means of calcium chloride. It is finally distilled from a glass
retort, when a water-white, very mobile liquid is obtained,
of a penetrating odour similar to that of pine-apples. The
specific gravity of the ester is 0*913 ; it boils at 113 C.
Butyric ester is principally used in making imitation rum.
It is mixed with the proper quantity of rectified spirit, acetic
ester, vanilla essence, and water in the last of which sugar-
candy and caramel are dissolved, in order to give the rum
the necessary colour. A very good formula is for 50 litres
of rum 500 grins, of finest rum essence, 100 grms. of butyric
^ester, 100 grms. of acetic ester, 50 grms. of essence of vanilla,
150 grms. of essence of raisins, 30 litres of high strength
spirit, and 30 litres of water. In the water dissolve 1 kilo
of sugar-candy and 250 grms. of caramel ; mix the whole
well, and allow to settle for several weeks.
Butyric ester is also much used in compounding fruit es-
sences, e.g. of raisins, apricots, strawberries, etc., which are
again mixed with spirit and other ethers in various propor-
tions.
32 THE UTILIZATION OF WASTE PBODUCTS.
Utilization of Animal Offal. Animal offal is sometimes
dried and sold as a manure. The following is the composi-
tion of a sample of this material : l
Moisture 6'48
* Nitrogenous organic matter . . . 26*77
Alkaline salts 3-42
Phosphates 45-68
Carbonate of lime 12-61
Silica 5-04
100-00
* Nitrogen equal to ammonia . . . 4-41
Fat from Animal Offal. The oldest method of obtaining
fat from animal offal consists in heating the material in a.
boiler over an open fire. With this method, in order to avoid
disagreeable odours a simple expedient may be adopted, ac-
cording to Terne. 2 When pans heated directly by fire are
employed, they must be covered by a sheet-iron lid in such a,
manner that it does not interfere with the workman stirring
and skimming off fat, and, on the other hand, the pan must
be tightly closed during the intervals. When a pipe through
the lid is brought into communication with the ashpit of
the boiler-fire in a proper manner, the disagreeable vapours
in passing through the fire will be partially decomposed, and
partially diluted with the fire gases, so that they reach the
atmosphere through the chimney unperceived. If the offal
is boiled, as is almost universally the case, by stearn in
wooden vessels, the objectional odours may be removed in
a simple manner as shown in the annexed sketch (Fig. 5)
which is self-explanatory.
The conditions are different when flesh is boiled by means
of high-pressure steam. According to Terne, the simplest
and best method for removing the objectionable gases and
vapours is the following : The mixture of gases from the
closed boiling kettle is first subjected to the full heat of the
boiler fire in a superheater, built of fireproof materials, placed
in the boiler flue. From this superheater Terne takes the
1 Macadam, " Journ. Sop. Chem. Indt.," 1888, p. 84.
s " Chemiker-Zeitung," 1879, No. 11.
BLOOD AND SLATJGHTEK-HOTJSE EEFUSE.
33
gases, when possible, along both sides of the boiler fire in a
hollow space built of fireproof materials, one side of which
forms a wall of the fireplace, the other side being in com-
munication with the atmosphere through short pipes. The
superheated gases enter this retort- like space, mix with the
atmospheric air, and then the mixture enters the firebox
of the boiler. The gases being in a highly heated condition
and well mixed with the oxygen of the air, on meeting the
fire are burnt with absolute certainty. It is to be remarked
that the best apparatus may work without effect if the gases
from the kettle are blown off suddenly under great pressure
and with the cock full open. In boiling a kettle, the exit
FIG. 5. aa, pans with perforated false bottoms and perforated pipes for direc
steam ; bb, pipes connecting with a large pipe ; c, condensing pipe carry-
ing a current of water ; d, condensing tower with water-pipe ; e, steam
injector to create the draught.
pipe must be left open until the boiling point is reached.
When boiling actually begins, the cock is closed and the
kettle raised to the pressure at which it is intended to work.
The kettle should be allowed to stand at this pressure for
about an hour ; then, whilst still admitting steam, the blow-
off cock is cautiously and partially opened. With care-
ful management it is possible to keep very near the original
pressure. If the gases are removed slowly at regular intervals
1 3
34 THE UTILIZATION OF WASTE PRODUCTS.
they may be destroyed without fail ; but if with the cock full
open they are allowed to rush suddenly, at the full pressure
of 2-3 atmospheres, into the combustion chamber, a consider-
able proportion will naturally escape unburnt into the air.
Extraction of Glue from Animal Waste. According
to Terne's communication on the manufacture of glue, 1
slaughter-house material may be arranged, according to the
proportion of glue it contains, as follows (1) ox feet, (2)
pigs' feet, (3) calves' and sheep's feet, (4) raw bones,
(5) ox and pigs' heads.
The material is freed as far as possible from blood, this
being easier the smaller the state of division. For this reason
the larger works have machinery for tearing up the fleshy
portions and breaking up the bones. The best bone-breaker,
according to Terne, is that of Baugh & Son, of Philadelphia."
When the material has passed through the breaking machine,
it is most advisable to free it from blood and dirt in a suitable
washer. After removing the blood, Terne treats the material
in suitable wooden vessels, which must be well covered, with
a saturated solution of sulphurous acid. The duration of the
action varies according to the nature of the material ; ex-
perience alone is the only guide by which it is possible to
determine the amount of action proportional to each kind
of material and the season of the year. This results in a
considerable improvement in the colour. The material, after
steaming, produces a clear, almost colourless liquid, which,
upon evaporation in vacuum pans, gives a glue in no way
inferior, either in colour or lustre, to the best hide glue.
The fat of yellowish bones is at the same time perceptibly
bleached, besides which the unpleasant smell usually accom-
panying bone fat is entirely removed.
For the production of sulphurous acid, Terne has devised
a simple apparatus, which has been found practically success-
ful (see Fig. 6). The coke towers are erected in such a
position that the outer wall is warmed by the heat of the
boiler-house, and thus the whole is protected from the frost.
1 "Dingler's Journ.," 1876, p. 253. *Ibid., 1869, p. 186.
BLOOD AND SLATJGHTEK-HOUSE BE FUSE.
35
In consequence of the treatment with sulphurous acid,
portions of hide, as well as the sinews, swell, the latter ac-
quiring a silky lustre and becoming transparent like gelatine.
The tissues which yield the glue are not only bleached, but
also become much less compact. In consequence of this
treatment it is possible both to shorten the time of the boil-
ing, and also to work at a diminished pressure.
F IG< 6. A, Sulphur burner; B, stove exit pipe; C, collecting tank; D, coke
tower, consisting of twelve earthenware pipes, each 760mm. (30 in.) long ;
E, draught regulator ; F, water tank ; G, steam pump for acid ; H, chim-
ney to sulphur burner.
The washed and bleached raw material, after treatment
with the sulphurous acid, is ready for boiling. The chief
conditions for the production of good strong liquors are low
pressure and the shortest possible duration of boiling. The
boiler erected as shown in Fig. 7 satisfies all the conditions
required for regular, gentle boiling, and affords a certainty
of obtaining a product almost free from fat. The pipe F,
36
THE UTILIZATION OF WASTE PEODUCTS.
for direct steam, is only employed for bringing the water
rapidly to the boiling point ; the closed coil E is sufficient to
keep it boiling. After boiling and settling, the fat is run off
through the pipes K^K^
r
FIG. 7. A, iron pan, lined with lead in order that the bleaching process
may be conducted in it ; B, feed opening ; C, outlet ; D, perforated
bottom ; E, steam coil connected with the steam-trap e ; F, steam pipe ;
G, drain cock, shut during boiling ; H, cock on drain pipe ; J, water out-
let ; K^-Kfr run-off cocks for fat and oil ; L, pipe conveying the noxious
gases to the boiler fire ; M, safety valve ; N, pressure gauge.
The liquor, completely free from fat, is now filtered, for
which purpose Terne employs a bone-black filter filled to a
height of about 1'22 metre (4 ft.). The bone-black is covered
with coarse sacking, and the whole filter is surrounded by a
steam jacket. Probably a filter press would be more suitable.
From the filter the liquid is taken to the vacuum pans. The
BLOOD AND SLAUGHTEK-HOUSE EEFUSE. 37
Consistency of the size obtained in the vacuum pans varies
considerably according to the purpose for which it is intended
and the temperature of the air ; it is impossible to lay down
general rules. However, the size is boiled down to such a
consistency that as soon as it sets on cooling it is capable of
being cut, or the glue, cast into plates, is readily and quickly
removable from the moulds. Strong tinned sheet-iron plates
-are the most suitable for the moulds, but they have the dis-
advantage of readily warping. In order to avoid this, glass
tables" made for the purpose are employed ; they impart to
the glue a very fine lustre, but the fragility of the glass plates
is a decided drawback.
Every manufacturer has to give the greatest attention to
the cooling of the glue ; whenever possible it is cooled to a
temperature of 0-5 C. In order to accomplish this, all the
large works in America are provided with refrigerators and
cooled working-rooms. For glue which is to be cut, Terne
has found moulds of strong galvanized iron about 3 mm.
thick (J in.) the most suitable. The moulds are about 254
mm. (10 in.) high, the upper opening is 305 x 356 mm.
{12 x 14 in.), and the bottom 290 x 330 mm. (11'5 x 13 in.).
When a refrigerator is not employed, the glue in the moulds
may, with great advantage, be cooled by placing in a tank of
Running water. Moulds constructed of bad conductors of
heat are absolutely to be rejected; since they retard the
setting and render the glue liable to decomposition.
The plates of glue, cast or cut out of the moulds, are dried
on wire netting. For the sake of economy in netting, Terne
hangs the plates, after they have attained a certain firmness,
vertically from thick iron wires.
The bones, hoofs, horns, hides, and hair of animals are
also utilized, as will be described in subsequent chapters.
There has also arisen, especially in America, quite a number
of subsidiary industries to the slaughtering of animals, or
what is known as the packing-house trade, in which a
number of therapeutical preparations are manufactured.
These include pepsin, pancreatin, trypsin, bone marrow,
38 THE UTILIZATION OF WASTE PEODUCTS.
rennet, haemoglobin, oxgall, etc., besides the cleaning and
picking of entrails to be used as sausage skins, etc., nothing-
being wasted. The residues from all these operations go
to the manure house to be converted into fertilizers.
Handling Bones for Glue Stock. According to the
"National Provision er" bones are first heated with steam
under pressure which dissolves out all the fat and glue, the
former being separated by skimming after standing. The
bones are then ground for use as a fertilizer. When the
bones are to be used for manufacture into knife handles,
buttons, etc., they are cooked with water in open vats at a
temperature of about 200 F., whereby the fat is melted out
but little of the glue is removed. Horn piths are washed and
dried and then cooked for glue, which is much esteemed for
size purposes.
The feet of oxen, after removal of the hoofs, are cooked
in water. In their fresh state they form an excellent food
known in some places as cow heel. The liquid from this
operation is allowed to stand when an oil rises to the surface.
This is skimmed off into cans, allowed to stand, then care-
fully decanted from the water and flocculent material which
has settled out. It forms an excellent oil for lubricating and
other purposes, being known by the name of neat's-foot oil.
Waste hide pieces are also treated for the preparation of
glue. If they are of fine quality and quite fresh the product
obtained from them is gelatine.
Fat and glue can also be obtained from the liquid in
which hams have been boiled. Where this is not possible,,
however, the liquid should not be thrown away, as when
mixed with solid food it forms an excellent food for pigs.
Utilizing the Offal of Animals. Very little offal from
animals is now wasted. The blood is collected and treated
in various ways. Usually it is dried and added to manures,
but some of it is treated for the manufacture of blood
albumen, the fibrin being removed and the liquid portion
evaporated. Blood is also converted into sausages.
The entrails of animals are converted into sausage skins,,
BLOOD AND SLAUGHTER-HOUSE REFUSE. 39
for which purpose they are thoroughly cleaned, scraped, and
preserved in salt brine. The entrails of sheep and goats are
converted into strings for musical instruments.
From the stomachs of oxen is obtained pepsin, from the
pylorus is produced pancreatin. Enzymes are also obtained
from the liver, kidneys, spleen, etc., while the gall (oxgall)
is used by designers for removing the greasy feel of oiled
cloth.
CHAPTEE III. ,
FAT FROM WASTE.
Recovery of Neat's-foot, Oil. The fresh feet of oxen, calves,
and pigs are boiled in a -pan with water; the boiling is
continued for fifteen minutes, after which the heating is
moderated, so that the liquid is no longer in ebullition. The
fat, which collects as an oily layer on the surface of the hot
water, is continually removed by means of a shallow spoon,
and collected in a tall, narrow vessel. The residue in the
boiling vessel the feet freed from fat is disposed of to
glue manufacturers. On long standing, the neat's-foot oil
separates on the surface of the water in this vessel as a clear
oily layer, which is poured off from the water, and brought
into small bottles of white, glass, which are exposed to direct
sunlight in order to bleach the fat. According to K. Brunner, 1
the bleaching is more rapid if a sheet of violet glass be placed
in front of the bottle, for violet light has the most powerful
action. The finest product is that which has been separated
by freezing. The neat's-foot oil is, with this object, exposed
to the intense cold of winter, and the residual liquid portion
separated in the cold from the solid portion by pressing
through fine linen cloth. In France, sheep's feet are first
immersed in water heated to 75-80 C. for about twenty
minutes, when wool and hoofs may easily be removed by
hand ; the feet are then boiled with steam. Four hundred
sheep's feet give 1-2 litres of fat (0'22-0'44 gal.) of 0'915
specific gravity.
Recovery of Bone Fat. Bones are not rendered unsuit-
able for the purposes of glue or bone-black making by the
1 " Die Fabrikation der Schmiermittel," A. Hartleben, 1897.
(40)
FAT FROM WASTE. 41
removal of the fat. For this purpose the fresh bones are
brought into a pan and covered with water, which is very
slowly heated to boiling. The boiling is continued for several
hours, and the mixture then left at rest. After five to six
hours the crude fat has collected on the surface ; it is re-
moved, whilst still fluid, into a wooden tank lined with sheet-
lead.
The best refining agent for this fat appears to be the
so-called aqua regia, which is obtained by making a mixture
in a glass vessel of one volume of white nitric acid and four
Tolumes of strong hydrochloric acid, and allowing it to stand
until it has acquired a reddish yellow colour and evolves a
penetrating smell of chlorine. Not more aqua regia should
Ibe made than can be used within a few days, since it soon
loses its activity. To 100 parts of fat contained in the above
wooden vessel is added 1-1 %5 part of aqua regia, which is
mixed with the fat by prolonged stirring, and remains in con-
tact with it for some hours. When the bleaching is finished,
warm water is added, and the acid then run off carefully
through a plug-hole at the bottom of the tank. The fat is
again mixed with warm water, well stirred, and the water
dra^n off. This washing with warm water is repeated until
the last trace of acid is removed, i.e. until the water does not
act on blue litmus paper. It should also be mentioned that
the lead sheets, with which the vessel is lined, are at first
strongly attacked. The white coating produced on the lead
lead chloride is not removed, since it protects the lead
beneath from the further action of the acid in the same
manner as a varnish.
When older bones are used, the above method for obtain-
ing the fat is somewhat altered. The bones are boiled with
water, as above described, a brown fat of unpleasant odour
being obtained, which is drawn off into wooden vats and al-
lowed to stand for several days. During the slow cooling,
a granular greyish -white mass separates, upon which floats
a brownish yellow oil. The solid portion may be used in the
manufacture of ordinary soap, the liquid in the preparation
42 THE UTILIZATION OF WASTE PRODUCTS.
of lubricants. The fluid portion of the bone fat is bleached!
with aqua regia, as above described. The older the bones,,
the larger is the quantity of aqua regia required. The ad-
dition of any larger quantity than that mentioned above is,
however, not desirable ; after 1 per cent has been added, each
fresh addition should not be more than 0'25 per cent. Fin-
ally, in order to free the bone fat from any olei'c acid which
may have been formed, it is treated with about 10 per cent
of its weight of caustic lime, which is slaked with water im-
mediately before use, and the resulting milk of lime stirred
with the fat and then allowed to settle. The olei'c acid is
thereby completely removed by the lime. Pearlash may be
used for the s.ame purpose. According to Brunner's experi-
ments, the olei'c acid may also be removed by an addition of
litharge (lead oxide), especially if the fat be warmed before
the introduction of the litharge. The lead oleate, which is
produced, remains mixed with the fat, and converts it into a
mass of the consistency of hard salve, which may be em-
ployed as a very useful lubricant for waggon axles.
A considerable amount of bone fat is also extracted by
solvents in a similar manner to that described below.
Eecovery of Oil from the Cleaning Waste of Machinery.
The most suitable method for the recovery of the oil is
founded on the fact that all the substances used as lubricants
are soluble in petroleum ether and benzene. The lubricant
is dissolved in one of these solvents, and obtained by evapora-
tion of the latter. The solvent is also regained, and may
again be used for cleaning a fresh quantity of cloths.
The used waste is squeezed fairly tight into a sheet-iron
cylinder, provided with a tap at the bottom, and with an air-
tight lid. Before the lid is put on, so much petroleum ether
or benzene is poured over the cloths that, after they are
saturated, the solvent quite covers them. The lid is then
put in place, and the vessel left at rest for 12 hours.
The solution of the lubricant is then brought into a dis-
tilling apparatus, the still of which is heated by an open or
closed steam coil. Since both the solvents mentioned have
FAT FEOM WASTE. 43
a boiling point below that of water, they distil completely,
and can be regained by cooling the vapours. The lubricant,
which was dissolved from the cloths, remains in the still in a
fluid condition and is run off from a tap at the bottom.
The waste is also heated in a still to recover the last por-
tions of the solvent, and the waste is then sent out for use
again. There are firms who will quote prices for waste to
be returned to them in its dirty state after use for the re-
covery of the oil.
In order to renovate cleaning cloths saturated with fatty
lubricants, the method of saponification may be employed.
The cloths are brought into a pan, weak caustic soda solution
poured over and heated to boiling. From time to time a few
cloths are taken out of the liquid to see whether all the fat is
yet saponified. When this is the case, the cloths are removed
from the liquid, and boiling continued, when an ordinary
soap is obtained. Cloths saturated with mineral oils or
paraffin cannot be cleaned in this manner, but must be
treated with the above-mentioned solvents.
Utilization of the Fat obtained in Glue-Making to obtain
a Soljd Lubricant. The raw material from which glue is.
made is generally waste matter, such as the waste of
slaughter-houses and tanneries, bones, rabbit and hare skins
from which the hatmakers have stripped the fur, also cat
and dog skins, ox feet, calves' and sheep's feet, sinews and
entrails. These substances receive a preliminary treatment
with lime, in order to remove particles of blood and flesh,
which would hasten decomposition and give the glue a dark
colour, and also in order to saponify the fat. For this pur-
pose the substances are treated in large pits or tanks with
thin milk of lime for 15-30 days, during which time the
lime is often renewed. When this has been done, the ad-
herent lime is removed from the animal substances, which
are worked up for glue.
The residue, which, in addition to lime, contains the fatty
matter of the substances treated, saponified by lime, is known
as " glue fat ". The cheap lime soaps, which can be bought
44 THE UTILIZATION OF WASTE PRODUCTS.
under this name, may with advantage be used in preparing
machinery greases. The process of preparing such greases
is as follows : The lime soaps are placed in a pan, which they
half fill, and then heated over a gentle fire until they melt.
The fire is then gradually increased and the boiling continued
until the mass has been so far boiled down that a sample,
brought on to a sheet of glass, can be drawn out into long
threads on touching with the finger. In order to determine
the right point, tests are frequently taken during the boiling,
since, if the mass thickens too far, it cannot be used, and
will be wasted. Thick mineral oil is now added gradually in
small portions, and with continual stirring, until the desired
consistency, which is tested by taking out portions on to a
glass plate, is reached. The mass is then run into a tub and
stirred until nearly cold.
Since glue fat contains so many impurities dirt, hairs,
etc. it must previously be cleaned, which is best combined
with the melting process the dirt swimming on the top
being skimmed off and the deposit which collects at the
bottom removed.
Utilization of Cotton Seed. At one time cotton seed was
a waste product and was either dug into the ground or burnt
and the ashes treated likewise, but now cotton seed is a valu-
able product worth about 8 10s. per ton decorticated or 5
undecorticated (pre-war prices), owing principally to the oil
it contains, which even when crude has a market value of
about 30 per ton at the present time. The oil is extracted
by hydraulic pressure from the crushed seed after steaming,
the yield being about 15 per cent. The residual cake is still
valuable for cattle feeding, yielding 4 10s. to 5 per ton (pre-
war prices). It contains about 5-10 per cent of oil and 20-
40 per cent of albuminoids. The ground seeds and other
oil seeds are, however, sometimes extracted with solvents, as
for instance carbon tetrachloride, for the removal of the
whole of the oil, when the residual meal is of no value for
cattle feeding and can only be used for manure.
The cotton seed now produced in the United States is
valued at 50 million dollars per annum.
FAT FROM WASTE. 45
Oil from Maize Germs. In the manufacture of starch
from maize or Indian corn there is an accumulation of a
large quantity of the seed germs which are removed by the
sieves after crushing the seed ; these contain about 25 per
cent of oil and were at first wasted ; they are now, however,
pressed for the recovery of oil, which appears in the market
as maize oil and is a valuable product, while the residue goes
into cattle cakes.
The residues from most oil seeds are similarly converted
into cakes either alone or mixed with other ingredients
(compound cakes), only those containing poisonous or dis-
agreeable ingredients being unfit for this purpose. This has
created an enormous trade, and is one of the best examples
of the utilization of waste products.
Oil from Wine Residues. After expressing the juice from
the grapes the residue consisting of skins and seeds is turned
out of the presses and usually dug into the ground or burnt.
The seeds can easily be removed from the skins by washing
through sieves, and as they contain oil this is worth extrac-
tion, ^cording to F. Eabak in a United States Bulletin
there are 90,000-120,000 gals, of this oil annually available,
and trials of it have shown that it is a good drying oil which
may be used in place of linseed oil.
The recovery of oil from the waste waters of wool washing
works is described on p. 121, and of oil from tanneries on
p. 50.
Reclaiming Motor Grease for Fuel. The grease removed
in the daily cleaning of the wheels, axles, and other parts of
motor-omnibuses and the paraffin which was used for clean-
ing them are utilized by the London General Omnibus Co. in
a manner described in the " Commercial Motor ". In clean-
ing with paraffin, both paraffin and grease were wasted. The
omnibus parts to be cleaned are now placed in a cradle in a
hot solution of caustic soda and boiled. This removes the
whole of the grease, which rises to the top and is collected
with a wooden rake. The cradle with the parts is then put
into a second tank of boiling water, which finishes the clean-
46 THE UTILIZATION OF WASTE PKODUCTS.
ing. The grease is treated at a central depot, and provides
sufficient fuel to drive two 80 h.p. Diesel engines and leave
some over for sale. Oil rags, instead of being thrown away,
are now put into a centrifugal steam-heated chest. This pro-
cess extracts all the grease and oil, which runs off into barrels.
The rags are then washed and used again.
CHAPTEE IV.
TANNERY WASTE.
Utilization of the Waste as a Fertilizer. Opinions have
been expressed against the use of spent tan bark as a fertil-
izer on account of the tannin it contains, which might in-
juriously affect cultivated plants. Still it may be remem-
bered that all barks used for tanning purposes are completely
^extracted. In an article in the " Mark Lane Express " the
above opinion was pertinently refuted. The tanning process,
it is there said, gives rise to a quantity of waste and residues,
ivhich may very well have unrestrained use in agriculture
in fact, i^ a much greater extent than was formerly supposed
possible. These residues are divided naturally into animal
:and non-animal. Agriculture can with advantage employ
only those residues which are not capable of being utilized
in any other way, since one could not pay the same price
for fertilizers as for a material out of which something
useful could be directly produced. The animal waste of
tanneries is much richer in manurial substances than the
non-animal. In tanneries the fresh raw hides are first
subjected to the prolonged action of milk of lime ; they
then undergo two operations, which determine the value
of the tannery waste. In the first place, the hair is re-
moved from the outside of the hide, and then remains for
& long time in contact with lime. The second manipula-
tion consists in removing the adherent flesh from th*e inner
.side of the hide, and also the thin cuticle. These waste
matters are mixed together, and lie in heaps. They contain
on an average about 75*5 per cent of water and 24'5 per cent
of dry matter; the latter is composed of 84'5 per cent of or-
ganic constituents and 15'5 per cent of mineral substances.
(47)
48 THE UTILIZATION OF WASTE PRODUCTS.
In 100 parts of the mineral matter are contained 3 '25 parts
of silicates, 17*5 parts of calcium phosphate, 69 parts of
calcium carbonate, and about 10 parts of other salts. The
mean proportion of nitrogen is about 7 per cent. Generally
these heaps are from two to three months in collecting, during
which time they lose about one-fifth of their volume of water
and three-tenths of their nitrogen. This loss is due to the
rapid decomposition of the animal matter by bacterial action
assisted by the lime. This fertilizer has then, according to-
present prices of its proximate constituents, a value of 24-
40 pfennigs. In strawberry plantations the soil is covered
by a layer of tan bark about 2 inches deep. The fruit ha&
then a clean bed, and the snails, the chief enemies of the
strawberry, are kept off.
The vegetable portion of this tannery waste is a result of
the tanning, which is only obtained after the hides have
undergone their first treatment. This process is accomplished
by using the bark of oaks or other trees rich in tannin,,
which is finely ground or powdered, and then put in alter-
nate layers with the hides in the tan-pits, water being then
run in to dissolve the tannic acid.
The loose and fibrous nature of spent tan bark leads to-
the experiment of using it in place of straw for litter.
When so used, it absorbs double its weight of liquid ; it is.
advisable for this purpose to use it together with straw. It
is not heavy, and may therefore readily be carried about.
Tan bark, however, always still contains a certain percentage
of tannin, and it is recommended to use it in combination
with lime, phosphates or ashes, materials which at the same
time hasten its decay. In combination with animal excre-
ment, tan bark accordingly forms a valuable fertilizer. In
gardens' it retards in the most marked manner the evapora-
tion and drying of the soil.
Finally, there is known the utilization of bark to form
bark cakes, which are made in a press and used as fueL
Tan bark is also used, on account of its elasticity, for covering
the floors of gymnasia, etc.
TANNERY WASTE. 49
The Waste Waters of Tanneries in their Application as
Valuable Fertilizers is advanced by J. S. Schultz in his
"Leather Manufacture". We follow here the views laid
down by Schultz, as communicated to the " Gerberzeitung "
by F. Kathreiner, of Munich.
The water used in softening, as also from the lime-pits
and tan-pits, which have become useless, and the wash
waters from the scouring and cleansing operations, are all
collected in a large tank placed below the level of the tannery,
so that all these valuable liquid fertilizers may be collected
without pumping. This reservoir may be at some distance
from the position where the washing and scraping operations
are performed ; in fact, it is an advantage if it be several
hundred feet away rather than near at hand. It should be
of sufficient size to contain, not only the waste waters, but
also the solid matters which come from the sweepings and
cuttings olf the floors of the washing and drying places.
These waste waters are so valuable that the author can see
how a small tanner could fertilize 100 acres with the waste of
a tannery treating 5000 hides Exhausted bark, fine cuttings
and scrapings, and even earth,' may be brought into this
reservoir, in order to take up the ammonia, and then be
added to the soil with great profit.
Waste, consisting of Pieces of Untanned Hide, and of
"tawed" leather, may be used in the preparation of the
finer kinds of glue. On account of the differences in the
material the waste from untanned hides and from leather is
collected in separate vessels. The waste of " tawed " leather,
if it has been sufficiently dried by exposure in thin layers,
may be stored, without further treatment, in any vessel until
a sufficient quantity has been collected. The waste from un-
tanned hides may be treated in the same manner, but it is
not dried, since the skins, being saturated with water, are
precisely in the condition which allows of their easily being
converted into glue. The glue maker would have to soften
the dried waste, and labour would be thus lost. The hide waste
is therefore left in the swollen state, care being taken that it
4
50 THE UTILIZATION OF WASTE PRODUCTS.
does not decompose. This is done by keeping it in a tub
under clear lime water, sufficient to cover the cuttings and
also containing sufficient lime. Fresh lime water is there-
fore added from time to time. When the tub containing the
cuttings is placed in a cool room, they may be kept for four
to six weeks without decomposition ; if they are then to be
worked up for glue, the lime water is ran off and the hide
washed several times with pure water.
It is still more convenient to keep the hide cuttings in a
weak solution of carbolic acid 1 in 1000. When they are
to be used, they are taken out of this solution, allowed to
drain, and washed with water. The carbolic acid solution
may be used to preserve fresh quantities of hide.
Hide clippings may be converted into glue without
further treatment. The clippings of " tawed " leather are
best treated repeatedly with cold water, and then with hot
water, in order to " untan " them and, as far as possible, to
obtain the original hide. Clippings of chamois leather can
only with far more difficulty be converted into glue, since in
them the tanning substance is far more firmly combined than
in " tawed " leather. It is best to boil these clippings with
weak caustic liquors, by 'which they are at least partially
untanned.
In order to convert into glue the clippings of leather
tanned with alumina soaps, they must first be boiled in a
liquid containing an acid, such as sulphuric, in order to de-
compose the insoluble soaps. The clippings are then
squeezed and boiled with a weak caustic lye, in order to
convert into the soluble condition the free fatty acids
thus liberated.
Recovery of Oil from Chamois Leather Manufacture.
The fatty (" stuffed ") waste of the tanner and currier is
utilized, according to J. Bergmann, 1 by the following process :
One end of an ordinary barrel, best of hardwood, is removed,
the barrel placed with the open end upwards, and a perforated
false bottom is inserted at a height of 15 cm. (6 in.) above the
1 " Neueste Briindungen und Erfahrungen," 1894.
TANNEKY WASTE. 51
bottom. A steam-pipe of 13-20 mm. bore (0'5-0'S in.), ac-
cording to the size of the barrel, passes down in the barrel to
below the perforated bottom ; a valve for regulating the supply
of steam is placed above the barrel. The waste to be ex-
tracted is filled into the barrel to one-third its height ; the
valve on the steam-pipe is opened and steam sent in, until
the leather, which is stirred two or three times during the
fifteen minutes' passage of the steam, is heated, which may
be recognized by its dark brown colour. During the boiling
the fatty matter contained in the leather becomes free, and
appears on the surface of the separate pieces, whilst the con-
densed water collects between the two bottoms, whence it
may be run off when necessary by an outflow tap.
After this treatment the leather is at once shovelled out
of the barrfc4 and put in layers of 3-4 cm. (1'2-1'6 in.) into
press cloths of equal size. The press cloths containing the
leather are now laid in piles in a vertical press (the plates of
which have been warmed), in such a manner that upon each
layer of waste comes a metal plate, and that there may be
ten or more such layers, according to the press, above one
another. As the press-plate attached to the ram descends
the fat is pressed out of the leather waste; it flows away
until it becomes thick by cooling, which may be prevented by
arranging under the bottom plate of the press a jacketed space
permanently heated by steam. As soon as the fat ceases to
ilow away, the ram is screwed back, the cakes removed from
the press, the cloths removed, and the naked cakes set out to
dry. The fat obtained by pressing, which is absolutely pure,
;and has not in any way suffered by the action of chemicals,
may at once again be used for stuffing hides and skins. As
a matter of fact, it is better than the fresh fat prepared from
tallow, degras, and cod oil, since any resinous constituents or
other injurious substances have been removed by the above
process. The dried press-cakes are subsequently ground,
producing an excellent fertilizer, which can be used without
any other addition, and finds a ready sale in the market.
In the preparation of chamois leather a considerable
52 THE UTILIZATION OF WASTE PKODUCTS.
amount of cod and whale oils is pressed into the leather;
part of this combines with or is closely held by the fibre, but
a considerable proportion is pressed out again or removed by
scraping with a blunt instrument and subsequent treatment
with alkalies, which forms an emulsion, from which the oil
is recovered by the addition of an acid. This is the English
and German method of treatment, ttfe product being known
as " sod " oil. In France the skins are fermented for a
short time, then thrown into warm water and pressed in a
hydraulic press yielding a larger proportion of oil which is of
a higher quality and is known as moellon or degras. These
oils are largely employed by curriers for stuffing leather, for
which purpose they seem eminently fitted. During the
treatment the oils undergo a remarkable change, their chemi-
cal constants being considerably altered. 1
1 Lewkowitsch, "Oils, Fats, and Waxes".
CHAPTEE V.
LEATHER WASTE.
LEATHEK cuttings are made into artificial leather, which can
be used for the welts and heels of boots. The manufacture
is very simple (according to the " Deutsche Ind.-Zeit.").
The leather waste is, with the addition of a binding medium,
made into rectangular plates, which are put one upon the
other, pressed in a hydraulic press, dried, and rolled. It is
at once evident that this leather is only suitable for cheap
work, and cannot be used where it is exposed to the action
of water.
The process of Soren Sorensen, of Copenhagen, is as fol-
lows : If the leather waste is impure, it is first freed from all
foreign constituents, after which it is converted into a uni-
form fibrous material in a machine constructed for the pur-
pose. When this finely divided leather is mixed with
ammonia solution, a gelatinous mass is formed, which, when
pressed into moulds or rolled into sheets and dried, gives a
very hard and stiff material of considerable cohesion, but
without elasticity, and soluble in water. In order to make
it elastic and resist the action of water, it is mixed with
india-rubber. The rubber, the quality of which is not impor-
tant, as finest Para or the commonest African qualities can
be used, is squeezed and washed in the washing-machine,
which consists of two grooved steel rollers, over which is led
a stream of water, which has the double effect of washing the
rubber clean and preventing it from being burnt by the heat
generated by the friction. After washing, the rubber is dried,
cut up, and dissolved by means of benzene, carbon bisulphide,
or other suitable solvent. The quantity of rubber to be dis-
(53)
54 THE UTILIZATION OF WASTE PEODUCTS.
solved varies according to its quality. Para rubber is dis-
solved, or rather gradually swollen, by 4 -parts of solvent ;
Central American scraps require 3*5 parts, Guayaquil rubber
3 parts, and African rubber 2' 5 parts. The rubber so pre-
pared is then mixed with the leather and ammonia and the
mixture well stirred. The proportions of the mixture depend
on the quality of the product to be made. For example, for
soles, 25 parts of solid rubber, 67 parts of ammonia, and 67
parts of leather ; for heels, 25 parts of rubber, 80 parts of
ammonia, and 80 parts of leather ; for welts, 25 parts of
rubber, 75 parts of ammonia, and 90 parts of leather. After
kneading until the mass is quite homogeneous, it is dried.
During the drying it is subjected to progressive pressings,
the intensity of which varies according to the destined ap-
plication of the product. For sole leather the greatest pres-
sure is used about 450 kilos per sq. cm. (about 2| tons per
sq. in.). After pressing, the substance is either painted or
lacquered, or treated in some other way to give it a similar
appearance to natural leather.
Smith and Johnson, of Huntington, dissolve the waste
leather in sulphuric acid, pyroligneous acid, and fusel oil, then
add melted wax, and mix the whole intimately with paper
pulp, which has also been previously impregnated with wax.
The mixture is then dried, ground, steamed, and pressed in
the desired moulds. Such leather is said to be waterproof
and very durable.
The leather made by the following process, published in
Ackermann's " Gew.-Zeit.," is as pliable and durable as
ordinary leather of the same thickness, may be used for the
same purposes, and is equally waterproof. The mixture
consists of 1 Ib. of india-rubber to 3-J Ib. of leather waste of
any kind in the form of raspings. In order to mix these
substances intimately, the rubber is dissolved in benzene or
carbon bisulphide ; when dissolved, 1 Ib. of ammonia is added
and the mixture well stirred. The rubber is then precipitated
with a greyish-white colour ; the leather waste is next gradu-
ally kneaded into this pasty mass. When the mixture is
LEATHEE WASTE. 55
homogeneous, the stiff paste is rolled or pressed into sheets,
cords, pipes, rings for making cold-water pumps tight, flanges,
and valves. The product is better than vulcanized rubber or
leather alone.
B. Jakel, of Berlin, has patented a machine, for producing
so-called artificial leather. In Fig. 8, A and B are two
smooth drums ; C, D, and E, three smooth massive rollers.
The bearings of the drum B, and of the rollers C, D, and E,
can be fixed by screws in any position. A and jB, also C and
D, rotate in their bearings, whilst E is fixed. The pattern
is stretched round A, B,C, E, and the ends stitched together.
FIG. 8.
The machine is driven from the drum A, which moves both
the pattern and the system of rollers.
G is a roller, upon which is wound the backing ; its spindle
rests at one side in an open bearing, and at the other in a
hole, so that it can readily be changed. A brake. acting on
the projecting spindle keeps the fabric stretched, and ensures
a regular feed. L is a sheet-iron pan with double walls,
through which hot water circulates in order to keep the mass
in the pan hot ; its width is equal to that of the machine.
The mass flows out of the pan L on to the pattern, where it
is distributed by a movable guide towards the sides, and is
then spread on in the desired thickness by means of the
rollers D and E, or, rather, by passing between D, which is
covered by the backing, and the pattern ; at the same time
the mass receives the design from the pattern. The mass
56 THE UTILIZATION OF WASTE PRODUCTS.
cools on its way to the drum A, when it is finished ; it is
then wound on the roller N, which is turned by a handle, O.
In order to obtain the negative, or pattern, of a material,
such as leather, damask, etc., the original is drawn round the
S) 7 stem A, B, C, E, in the same manner as the pattern in the
manufacture, and kept stretched by means of the screw F.
The original is then lightly coated with oil, so that the mass
may subsequently easily be removed. In the pan L is the
mixture for the pattern, consisting of glue, glycerine, and
pyroligneous acid. The mass is applied in the same manner
as described above. The surface is then hardened by treat-
ment with acetate of iron, and sufficiently dried.
The mixture for the manufacture described above consists
of glue, colour, glycerine, linseed oil, soap, gallotannic acid,
and chromic acid.
ARTIFICIAL IVORY.
Leather waste may also be used in the manufacture of
artificial .inlaid ivory, which is said to be obtained from the
bones of goats and sheep and pale or buckskin leather. The
bones are treated with bleaching powder for ten to fourteen
days, then washed in clean water and dried. When this is
done, the bones and the leather waste are dissolved together
in a pan with steam, so that a uniform fluid mass is obtained.
To 10 Ib. of this mass J Ib. of alum is added, and when this
is well mixed the scum which has risen to the surface is
skimmed off, until the mass is quite clear and pure, then
whilst still lukewarm the necessary colours are added, the
mixture strained through a clean linen cloth, and poured
into the requisite moulds. When sufficiently cooled the cast
mass is removed from the mould and laid on linen stretched
over a frame, upon which it dries in the air. When quite
dry it is soaked in a cold solution of alum for eight to ten
hours, until it has attained the required hardness ; 1 Ib. of
alum is used to 2 Ib. of inlay for this purpose. When taken
out of the alum solution the inlay is washed with fresh water,
and again dried on the frame mentioned before.
LEATHER WASTE. 57
Leather Waste for the Manufacture of Glue. In regard
to the application of waste leather in making glue, J. Repp
has constructed a machine for disintegrating the leather. It
consists of a cast-iron box 3 metres (9 ft. 10 in.) long -and
1 metre wide (3 ft. 3 in.), with rounded angles. The box is
divided by a sheet-iron partition 5 mm. thick (^ in.) into two
parts, which are connected at the round sides by the water
which circulates through. At one end the water enters under
the supply pressure, it passes through one division, and then
back through the other to the outflow. The box is made in
two pieces, at the top is a horizontal shaft with a roller studded
with knives. The middle of the shaft is 640 mm. (2 ft.) from
the bottom, the roller is 650 mm. (2 ft. 2 in.) in diameter ;
the height of the box is 1000 mm. (3 ft. 3 in.) ; it is provided
with strengthening ribs. The knife cylinder consists of a
drum in which is screwed a knife projecting 42 mm. (If in.) ;
below it is brought a long knife, which can be adjusted at
greater or less heights, according to the treatment required.
The roller is driven by a belt at a speed of 120 revolutions
per minute, thus the water and the leather which is being
washed in it circulate through the roller, where the leather
is cut to pieces. A charge of leather is 200, 150, or 120 kilos
(4 cwt., 3 cwt., or 2^ cwt.), according to the size and speed
of the apparatus. In setting the machine in motion the box
is almost filled with water, for which purpose it is connected
with a pump or water supply. The working side, in which
are the roller and the arrangements beneath, is somewhat
wider, thus the leather stands at a rather higher level on the
other side, in consequence of which it approaches with a
certain velocity, due to the difference in level. The throat
consists of a cast-iron frame with a wooden lining, upon
which the long knives are fixed and screwed. This throat at
its upper concave part occupies almost one-quarter of the cir-
cumference of the roller, with which it is concentric ; it falls
away at both sides in an inclined surface of iron or wood.
The cooled leather is well divided in this simple apparatus,
which requires little attention ; at the same time it is washed
58 THE UTILIZATION OF WASTE PRODUCTS.
clean, so that it may at once be used in glue-making. The-
apparatus works excellently, since the leather is better
purified and divided by the constant flow of clean water than
by the older methods, in which the leather was first hung ir>
the water in large baskets on a chain and then was ground
after again drying. This apparatus is termed a hollander,.
but is not to be confused with the hollanders of paper-
works.
Leather which has been tanned with a substance insoluble
in water, such as chamois or bark-tanned leather, is not at
once suitable for glue-making ; it requires a complicated:
treatment, which, however, is always profitable. In the case
of bark-tanned leather, the manufacturer has to make sure
that all the tannic acid is removed from the animal tissue,,
since only a small quantity of this substance is sufficient to
remove from the tissue its property of dissolving in water r
and thus of producing glue.
In the first place, it is important that the leather waste-
should be converted into the finest state of division, for which
a half-stuff hollander, such as is used in pasteboard and paper-
works, is the most suitable. 1 The advantage is that the
leather is not only disintegrated and washed in a manner
which renders it very suitable for glue-making, but it can also
be used in the manufacture of leather book-covers, which are
very soft and of good appearance when made from leather
stuff mixed with rag or wood pulp.
When the leather waste has been so prepared, and, in-
particular, well washed, it is chemically treated. Stenhouse
uses a boiler working at two atmospheres pressure, and
adds 15 per cent of lime to the leather mass to be treated, the-
lime being suspended in much water. Others use caustic soda
of T025 specific gravity to extract the tannin boiled with this
leather paste for twelve hours. After boiling, the water is run
off, the paste pressed, and again boiled with caustic soda of
the same strength. The soda is now carefully washed out,,
which is done in the hollander. If the caustic soda in the-
1 F. Dawidowsky, " Die Leim- und Gelatine-Fabrikation," Vienna.
LEATHER WASTE.
liquor first drawn off is neutralized, the* solution can be used
for tanning or as tannic acid for other purposes.
The following is another process: 1'5 Ib. of oxalic acid is
dissolved in 12 litres (21 pints) of water, the boiling solution
poured over 50 kilos (1 cwt.) of leather waste, and the mix-
ture kept in the water-bath at a temperature of 80-100 C.
The leather should then dissolve ; when this is the case, 15
litres (26 pints) of water are gradually added until a uniform
mass results. The paste obtained by slaking 5 Ib. of quick-
lime is then added, and the whole well mixed, when the
mass becomes friable and powdery. It is now rubbed
through a wire sieve and the still moist mass exposed to the
air. After three to four weeks the tannic acid is destroyed
and the mass becomes lighter. The lime is removed by
means of water and hydrochloric acid. If all the tannic
acid should not be destroyed by the exposure to air, in boiling
out the crude glue, 0'5 kilo (1*1 Ib.) of ammonia and 0'5 kilo-
of ground pyrolusite is added to 50 kilos (1 cwt.) of the
leather. Frequent turning over and gentle heat during the
exposure to air hasten the process of decomposing the tannic
acid.
As a final resort the leather waste is ground and used as
a manure, for which purpose, though it contains a high pro-
portion fof nitrogen, it is not eminently fitted, owing to the
fact that the nitrogenous matter has been rendered insoluble
by the tannin, and its decomposition is extremely slow.
H. P. D. Lissagaray has obtained a patent for a new pro-
cess for manufacturing an assimilable fertilizer from leather
waste. The waste is immersed for about 5 minutes in
water to which has been added about 10 per cent of strong
sulphuric acid, or a sulphate such as alum or manganese
sulphate. It is then dried in the open air, and finally in a
current of hot gases. The material has now become quite-
friable ; it is ground in a suitable mill to a fine flour, which
is readily accomplished.
CHAPTEE VI.
FUR AND FEATHER WASTE.
Utilization of Furriers Waste. Furriers produce a quan-
tity of waste, which can only partially be employed, by
neat and careful joining, to produce fur articles. A large
proportion of the smallest cuttings constitutes valuable ma-
terial for the hatmaker. No furrier, when cutting, should
neglect to have at his side a small basket, into which the
clippings can be thrown ; otherwise, after first being dirtied
on the floor, they have to be sorted out from other cuttings
of all kinds. The waste pieces may be utilized as described
below.
The waste grey pieces of monkey fur are used to fill the
star-shaped and round mosaic fur covers of opera-baskets.
The feet and heads of astrachan, carefully fitted together,
afford a material for covering gloves and hunting-mittens. .
Pieces of bear-skin of all kinds are in great demand by
brushmakers.
. Cuttings of beaver and musk, even the smallest, are sought
after by hatmakers at a good price. The forehead pieces of
beaver-skins, placed together with the hairy side outwards,
may be well used as trimmings on furs ; larger pieces are
very suitable for caps. The heads of musk, with the eyes
and ears taken out by two cuts going from the eye over the
ear, cut into triangular shape and joined together star-wise,
may be used for linings, as also may the short ends.
Long-haired pieces of badger, such, for example, as are
cut out of the middle in making covers for knapsacks, are
highly prized by brushmakers.
Fox : the tails are used in making boas, and are also the
most valuable material for ornamenting opera-baskets, foot-
warmers, gloves, etc.
(60)
FUB AND FEATHEE WASTE. 61
Goose and swan : the feathers are plucked from the waste
pieces and used for stuffing muffs. Powder-puffs may be
made from larger pieces.
Grebe : wings joined to heads, or half small wings, make
handsome ornaments for bonnets of seal and rabbit-skin, or
of seal and musk.
Considerable quantities of waste feathers of all kinds are
used for stuffing mattresses, cushions, etc.
Hare : the ears of hares are frequently set together, i.e.
stitched near together on linen, and used in making hunting-
mittens and caps. The process is, however, not to be recom-
mended. The hatmaker takes all the rest, with the exception
of the black pieces, which may occasionally be sold to toy-
makers.
Ermine scraps are frequently bought in order to make
imitation tips ; but this is only done when the pieces are fine
and of good size, and ermine skins are very dear.
Polecat : the scraps are bought by the Greeks to make
linings ; the heads, when preserved, on account of the ex-
pression, are used for ornamenting hunting-muffs ; also, when
cut into triangular pieces, for the mosaic covers of opera-
baskets. The tails are used in brushmaking.
Eabbit-skins : the heads of large skins are put together
to make wristbands, those of small skins for trimmings.
Large sides may often be put together to make collars. All
the rest, with the exception of the black portions, is used
by the hatmakers. Enormous quantities of rabbit-skins are
now converted into furs in imitation of the skins of . other
animals.
Cat-skins produce little waste. Good cat-skins when
damaged may be used as tips in white rabbit muffs. Tails
are practically of no value.
Lynx: the feet may be made into cheap trimmings.
There is practically no other waste.
Marten : the foreheads may be used for the mosaic covers
of opera-baskets, as also the throats, which may be used
together with the feet for linings similar to sable, but heavier.
62 THE UTILIZATION OF WASTE PEODUCTS.
.- "-"-^ . j
The tails are used for decorating ornaments, and also in
brush making.
Mink : the cuttings are put together by the Greeks ; the
tails, like those of the marten, are used for ornamenting
ladies' trimmings, and for borders. The foreheads are also
used for making the fur covers of opera-baskets.
Otter : fine material for hatmaking, but generally put to-
gether by the furrier, cleaned or dyed. The tails, when put
together, form handsome and durable hunting-muffs.
Sea-otter : good pieces are highly prized ; in Russia they
are principally joined together for cap-linings.
Sheep- skins : large pieces are joined together for lining
opera-baskets.
Baccoon : the hairy sides are joined together for sleeves,
or even for fur linings; the heads are used for trimmings on
black fur with raccoon borders ; the tails give durable
trimmings.
Sealskin pieces are valuable. In England the smallest
are joined together for caps, etc.
Skunk : the tails are bought by brushmakers. The white
and black foreheads, properly joined together, and often
worked in with triangular pieces of black cat-skin, make very
handsome trimmings, especially for fox-skin.
Goat- skin waste is bought by brushmakers.
Hair of all kinds can be utilized. Cow hair is employed
as a binder for plaster in building. Camel's hair is now used
for the manufacture of special clothing for cold climates.
Pigs' bristles are used for the manufacture of the best kind of
brushes, for which purpose they are distinctly valuable.
The Waste of Tanned Sheep and Lamb-skins, as produced
in the clothing industry, is mainly utilized by shaving off
the wool, which is used in cloth-making, whilst the leather
is bought by makers of prussiate of potash, hide-glue, and
artificial manures. Gawalowski has discovered a method
which makes it possible not only to separate the wool from
the leather in its original length and without loss of strength
for spinning and textile purposes, but also, when possible, to
obtain the leather in a commercially useful form.
FUR AND FEATHER WASTE. 63
If the skins are immersed in a moderately strong solution
of caustic potash or soda, the wool hairs are in a short time
entirely dissolved, and there remains a bare, slippery hide,
which, after being well washed with water, forms an excellent
raw material for the manufacture ,of prussiate of potash or
.glue. Since the wool is entirely dissolved in the alkaline
-solution, the latter can be used for the preparation of am-
monia, and especially for " animalizing " vegetable fabrics,
so that they may dye more rapidly. This process may be
applied in the manufacture of jute carpets, and in weaving
jute tapestries and hangings.
If the skins are immersed in strong ammonia, the leather
is attacked in such a manner that, on taking out after an
immersion of some duration and drying, first in the air, then
ut 30-40 C. , it is now in the form of somewhat friable pieces
of skin. It is therefore only necessary to bring the wool into
a tearing or beating machine, and next to card it, in order to
obtain, on the one hand, the wool entirely as a good textile
material, and, on the other hand, the leather waste in the
form of a hide which can be dried and ground, and like meat
meal and bone meal is an excellent fertilizer.
If the skins are immersed in a moderately strong solution
of an alkaline carbonate of soda or potash the hide swells
considerably in time and the hair may then be more com-
pletely separated by suitable apparatus from the pliable skin,
so that on the one hand it results in a leather waste as in the
first method, and, on the other, wool exactly as in the second
method. This process, accordingly, combines the advantages
of both the preceding methods, is the most simple and most
lucrative, and also, up to the stage of the mechanical separa-
tion of the wool, the cheapest. Prussiate of potash works,
which work up " dry liquor " into black potash, may combine
this minor industry with their main process in a rational and
lucrative manner, since the leather is an excellent material
for adding to the melt, and their black potash is already ob-
tained containing nitrogen. The saleable wool will then pro-
duce a not inconsiderable profit.
CHAPTEK VII.
WASTE HORN.
Utilization of Turnings and Filings. The waste materials
are mixed with a saturated solution of potash and lime, by
which the horn substance is attacked and finally transformed
into the condition of a jelly, in which state, by the application
of a gentle heat, it may be cast into moulds and pressed,
when the mass loses moisture and becomes hard and co-
herent. A final pressing, under the influence of heat, gives
the moulded mass its finished form ; it may then be worked
up into the most varied articles pipes, cigarette-holders,
stick handles, buttons, etc.
Horn waste may also be utilized in the following manner :
The turnings, raspings, and filings are moistened and pressed
into a cylindrical metal mould by a metal piston to a solid
cake, heat being applied. The mass is then rasped to a fine
powder, which is again pressed in the same manner; the
operation is repeated until the mass has acquired a sufficient
degree of hardness and solidity. Finally, it is again rasped
and carefully sieved, so that all the coarser particles are re-
moved. As a rule, horn and tortoise-shell waste are worked
up together ; the articles are then less brittle than when
made from tortoise-shell alone. From the fine powder
the finished substance is obtained as follows: The powder
is brought in layers between brass plates ; several such
layers are placed under the press, and this brought into
boiling water, when the mass becomes hard and coherent.
The plates are then further worked. Finished objects
may also be pressed out of this mass if the necessary moulds
are provided.
Horn filings may be brought by the following process
into such a condition that, from the mass, stick and umbrella
handles and many other articles may be made by casting in
(64)
WASTE HORN. 65
moulds. One kilo of quicklime, 500 grms. of potash, 40
grms. of tartar, and 30 grins, of common salt are dissolved
in water, and then one-third of the quantity of water evap-
orated off. The rasped horn or turnings is then thrown in
and boiled, until the mass becomes so thick that it can be
poured into a mould, which must be well oiled, whether it
be of metal, wood, or earthenware. If it is desired to colour
the horn, the necessary colour is stirred into the fluid mass
before casting.
The waste horn may also be boiled in a strong lye of
potash and lime, until the mixture is thick enough to be
poured out and moulded ; before casting, a colouring addition
may be given.
In order to obtain solid horn from waste, Pathe lays it
for an hour in a liquid consisting of a cold saturated solu-
tion of boric acid in water, and a cold saturated solution
of arsenious acid in dilute hydrochloric acid, the quantity
of boric acid being twice that of the arsenious acid. The
vessel containing the horn substance, swollen by this treat-
ment, is then placed for an hour in a water-bath at about
60 C. Finally, the horn substance is subjected to consider-
able pressure by means of a piston in a closed iron mould,
heated to 120 C., until all the liquid is removed. After cool-
ing, the pressed mass forms solid plates of horn, which can
be worked like natural horn, and are characterized by pli-
ability and elasticity.
WASTE HORN IN THE MANUFACTURE OF FERROGYANIDES.
At one time a considerable quantity of waste horn, hoofs,
leather, etc., was used in the manufacture of ferrocyanides,
but this is now made from the " spent " oxide of gasworks
far more cheaply.
Horn Piths in the Manufacture of Glue. The piths of
bullock's horns, when boiled as previously described, form an
excellent strong size, which is used very largely in carpet
manufacture and for other purposes under the name of pith
size.
5
CHAPTEK VIII.
FISH WASTE.
Utilization of Fish Scales. In the year 1874 a method
was discovered by which fish scales might be used in the
production of ornaments, artificial flowers, inlaid work, and
the like. Layers of fish scales, bound together by any bind-
ing medium, are now better replaced by mica waste, which is
more easily coloured and applied. E. and J. Huebner, of
Newark, in 1874, obtained a patent for the following pro-
cess : The fish scales are cleaned in a suitable manner until
they appear transparent and horny. The large scales of
fresh fish are the most suitable ; old scales are useless, since
they have lost their elasticity and transparency. In the pro-
cess of Huebner the fresh scales are first treated for 24 hours
with clean salt water, in order to loosen and remove partially
the upper layers. They are then washed in distilled or clean
rain-water, which is renewed every 2-3 hours. This is
done five or six times. The scales are then separately and
carefully rubbed with a fine linen cloth, gently squeezed in a
press to remove moisture, and finally are laid for an hour in
spirit, and again, as before, rubbed and pressed until dry.
They have now the appearance of mother-of-pearl, and are
very elastic and durable. They may either be used without
further treatment or may be coloured as required.
Fish scales are used to prepare " pearl essence," or " fish-
scale essence ". The dace (Leuciscus vulgaris), one of the
commonest fish in our waters, is washed with water to re-
move any adherent dirt, and then skilfully scaled, care being
taken to remove scales alone, and not contaminate them with
pieces of skin or blood. The scales are carefully collected
and kept in a vessel of water, until a sufficient number for the
(66)
FISH WASTE. 67
further treatment has been obtained. It is necessary to remove
the scales from almost 40,000 dace in order to obtain sufficient
to prepare 1 kilo of pearl essence, which quantity is, how-
ever, sufficient to make many thousands of artificial pearls.
The vessel in which the scales are collected is best placed in
an airy loft, since the scales very soon decompose and then
; give off a most unpleasant odour. In order to avoid this in-
convenience the following process is adopted : The scales are
covered, not with water, but with a solution of salicylic acid
obtained by dissolving 3 grms. of the acid in 1 litre of water
<3 in 1000). The salicylic acid is tied up in a little linen
bag, which is suspended in the water, so that the acid gradu-
ally dissolves. By using this simple precaution the collect-
ing vessel for the scales may be allowed to stand in the
summer without the least injury. When a sufficient quantity
of scales has been collected, the liquid above them is allowed
to run off, and a portion of the mass of scales transferred to
a large porcelain mortar, in which they are ground for a long
time with a flat pestle. In consequence of the grinding,
those particles are removed from the scales which are the
cause of their silvery appearance. After long rubbing, the
mass in the mortar is mixed with water, and the whole
poured upon a closely woven linen cloth stretched over a tub.
The colouring matter of the scales, which is suspended in
the water in the finest state of division, penetrates the cloth
together with the water. The scales are again ground and
mixed with water, when a second quantity of the colouring
matter is obtained. After the latter is entirely collected in
the tub the liquid is well stirred up, left at rest for some
time, and then drawn off into glass bottles, in which it is
allowed to stand until the colouring matter has completely
settled to the bottom. The coarser portion of the colouring
matter remaining in the tub is again stirred up with water
and allowed to settle.
The water above the colouring matter is carefully poured
off, and the latter finally collected in one bottle. In the
-moist state it has a silver-white colour and considerable
68 ' THE UTILIZATION OF WASTE PEODUCTS.
lustre ; on drying, a soft silver-grey powder is obtained.
This " fish-scale essence " can be kept for a long time un-
altered under a solution of salicylic acid.
The mass with which the pearls are filled is prepared in
the following manner : Completely colourless gelatine is
swollen in an aqueous solution of salicylic acid : the liquid is
then poured off, and the gelatine melted to a clear liquid by
cautious heating in a porcelain dish. The fish-scale essence
is now introduced and most intimately mixed with the
gelatine. No definite figures can be given for the quantities
of gelatine solution and fish-scale essence ; the rule is to take
no more of the latter than is absolutely necessary, because it
is a costly substance. Thus no more of the " essence " is
taken than is sufficient to cover the mass after it is intro-
duced into the glass pearl.
The mixture is kept melted on a water-bath, and intro-
duced into the glass pearls by sucking it up into a glass tube
drawn out to a point, allowing a drop to fall inside the glass
pearl, and turning the latter until the inner surface appears
to be quite covered by the pearl essence.
In order to prevent the solidified mass from becoming
detached from the glass wall, and to give the pearls a greater
weight, they are filled with melted wax or a mixture of wax
and paraffin. Pear-shaped pearls, which have only one open-
ing, are filled with wax, and the opening closed by a small
drop of melted pearl essence.
J. Loreau, at his works at Kernevel, near LT Orient, uses
fish in the preparation of sardines in oil. A large quantity
of waste is produced, consisting of heads, bones, entrails,
bloody salt liquors, etc. This waste is collected, drained,
heated in a pan and pressed ; the cakes are dried and ground,
when a fertilizer is produced. If treated with sulphuric acid,
this fish guano would be very suitable for beetroot. l
Substitute for Isinglass, also Gelatine and Glue from
Fishes and Fish Waste. A substitute for isinglass, also for
gelatine and glue, is prepared by C. A. Sahlstrom of Stock-
1(4 Bull. Soc. Encouragement," 1877; " Dingier' s Journ.," 227, p. 511.
FISH WASTE. 69
holm, according to his patent, from fish and fish waste, by
treatment with bleaching powder, potassium permanganate,
and nitrous and sulphurous gases.
For this purpose the fishes, or portions of fishes, are
first well washed in fresh water, and then left for from three
to four hours in a solution of about 85 grins, of bleaching
powder in 25-30 litres of water (1 in 300 to 1 in 350). After
washing, they, are treated with a solution of about 5 grms.
of potassium permanganate in 25-30 litres of water (1 in
5000-6000), and then exposed to the action of the nitrous
gases produced by heating 300-400 grms. of nitric acid for
every 40 kilos of raw material (about 1 per cent). This gas
may be first absorbed by water, or sulphur dioxide may be
used instead of nitrous gases ; the former would be obtained
by burning about 200 grms. of sulphur for every 40 kilos of
raw material (about 0'5 per cent).
The material, after this treatment, is washed ; those
portions intended for the production of the isinglass substi-
tute are freed from their outer skins and dried and pressed
at a gentle heat. The portions destined to produce gela-
tine or glue are, on the contrary, exposed to a temperature of
40-50 C. for from ten to twelve hours, by which the material is
'mainly dissolved. The mass is then forced through a strainer
or sieve, allowed to stand for some hours, and finally dried,
as is usual in the manufacture of glue or gelatine.
A considerable amount of fish scrap is produced during
the extraction of the various fish oils. This is dried and
converted into fertilizers. In the Menhaden industry the
fish scrap from the presses falls into the buckets of a con-
veyor from which it is delivered to the drying room. 100 Ib.
of* the mass from the cookers contains 22 Ib. of dry matter
and 78 Ib. of water. In the press 56 Ib. of oil and water are
removed, leaving a mass of 44 Ib. consisting of 22 Ib. of dry
matter and 22 Ib. of water. The hot air drier for drying the
fish scrap is almost universally employed. This consists of
an insulated iron cylinder about 6 ft. diameter and 30 or
40 ft. long. It is provided inside with a series of iron flanges
70
THE UTILIZATION OF WASTE PEODUCTS.
or shelves, about 8 ins. wide, running the whole length. These
are for the purpose of lifting the scrap and dropping it
through the hot air. The cylinder is rotated by an electric
motor, a forced draught of hot air being induced in it by
means of a fan. The wet fish scrap is charged in at one
end, while the dry scrap falls out of the other into a brick
chamber, from which elevators convey it to the bagging
room. The transit of the material through the drier occupies,
from 3-20 minutes, by w T hich time the moisture is reduced
to 7 per cent. A million fish will yield 75-85 tons of dry
scrap.
Dry fish scrap is known as fish guano and is of consider-
able value as a fertilizer. The following are analyses of these
manures as well as that of raw fish offal : x
Moisture
Oil ....
* Nitrogenous organic matter
Alkaline salts
Phosphates .
Carbonate of lime
Silica .
Raw Fish
Fish Guanos.
Offal.
Anchovy.
Herring.
Cod.
50-58
8-06
6-14
6-24
15-51
__
18-54
66-18
70-18
57-68
10-93
4-54
1-56
2-12
3-84
14-92
7-92
26-17
0-48
3-28
3-68
6-35
0-12
3-02
10-52
1-44
100-00 100-00 100-00 100-00
10-13
* Nitrogen equal to ammonia . 3'31 8-62 10'42
Fish Meal. Quite a considerable quantity of offals is
produced in dressing and boning fish, heads, tails, skins,
entrails, and bones ; this is usually carted away to the de-
structor, but where it can be quickly applied to land it forms
an exceptionally good fertilizer.
A new industry has, however, been developed in which
these offals and also any fish which cannot be disposed of
is dried in a current of hot air; it is then ground to powder
in a disintegrator and is sold as " fish meal ''.
This fish meal has been found to be a very valuable food
for cattle. It was first made in Norway ; subsequently the
manufacture was taken up in this country, but the farmers
were at first extremely reluctant to give it a trial so that large
Uvison Macadam, " Journ. Soc. Chem. Indt.," 1888, p. 83.
FISH WASTE. 71
quantities were shipped to Germany. Now that the price
of feeding-stuffs is so extremely high more attention is being
given to this material, and no doubt in a short time all that
is made here will find a ready market amongst the farmers.
Fish meal contains about 55 per cent of albuminoids, there-
fore it is an extremely concentrated food. It should, of course,
not be fed to cattle alone, but should be judiciously mixed
with other materials such as oilcake or grain.
CHAPTEE IX.
MOTHEK-OF-PEARL WASTE.
Utilization of the Waste of Button-making. A substance
which formerly could not be utilized, is the lining cut out by
button-makers from the shells, the innermost layer of which
is the so-called " mother-of-pearl ". The suggestion was
made to convert this waste into a fine powder, when a soft
bronze powder, of a silky, metallic lustre, was obtained,
which could be employed in many ways, especially since it
can be coloured to any shade. The pulverization of the
mother-of-pearl waste is accomplished in the same manner as
that of wood which is to be worked up into wood-pulp, i.e.
the waste is ground by a suitable rotating grindstone, in such
a manner that it is first beaten to pieces and then brought
into a cylinder, in which it is pressed on the grindstone by
means of a piston. The powdered mother-of-pearl obtained
in this manner is then levigated, and, after drying, brought
on the market, with or without previous dyeing. In order to
convert mother-of-pearl into a glittering powder, suitable for
makers of artificial flowers, the shells are first treated in
closed vessels with high-pressure steam, after which they
can readily be powdered. The use of this powder in mak-
ing wall-papers is said to be profitable : 1 sq. metre of the
paper requires 3'5 grras. ; thus, a roll of paper 9'5 x 0'5
metre (31 ft. x 20 in.) would require about 14 grms. (-J- oz.)
of powdered mother-of-pearl, the cost of which would be
1 pfennig per grm., or 10 marks per kilo (4s. 5d. per lb.).
The chemical works of M. Hess, at Neufunfhaus, Vienna,
produce " pearl silver " from such waste.
(72)
CHAPTEE X.
VEGETABLE IVORY WASTE.
Utilization of the Waste of Ivory-nuts. Guild, of New
York, makes moulded objects of all kinds, especially buttons,
from the waste of ivory-nuts. The process is as follows :
The waste is ground to a fine powder and the mineral par-
ticles removed by stirring up the powder with much water,
when the mineral constituents rapidly sink to the bottom,
whilst particles derived from the nuts remain suspended.
The water is then drawn off together with the suspended
powder, which is separated by filtering and pressing, and
then dried in any suitable manner. The dry powder is sieved
and mixed with enough water to make the separate particles
cohere. The process may also be simplified by drying the
powder only to such an extent that it retains the proper
quantity of water. The mass obtained is filled into moulds,
which give the shape of the desired article, and pressed in a
press whilst subjected to a temperature of 125-150 C. Ac-
cording to the size of the article the mould containing it is
subjected to the action of pressure and heat for a period of
3-10 minutes. The pressed articles are then taken out
of the moulds, dried, and finished. In making coloured
articles, a colouring matter is added to the mass before it is
filled into the moulds.
Brolik employs ivory-nut waste as a hardening material
for Bessemer steel and iron. The hardening powder is made
from the sawdust and the smaller turnings and filings. The
larger pieces can be ground in a drug mill or other similar
apparatus, yet it is advisable to employ instead a suitable
rasping arrangement, since there is then a considerable saving
(73)
74 THE UTILIZATION OF WASTE PKODUCTS.
in cost ten to twelve shillings per cwt. being charged for
grinding the shavings. The powder obtained in this manner
may also be mixed with other hardening agents. The latter
substances can also, if they are soluble in water or at least
able to impart their special properties to it, be made to pene-
trate the powdered portions of the nut, by placing the
powdered nut, which strongly attracts water, in water con-
taining the requisite substances, removing it after twenty-
four hours, and thoroughly drying it. Hardening experiments-
were conducted in the following manner with unmixed ivory-
nut powder, ground to the size of fine sand : A cementation
box, filled in the ordinary manner with Bessemer steel plates
and iron to be hardened, and with leather charcoal, received
at the top at one narrow end a layer of the ivory-nut powder,
in which were placed a disc about 5 cm. (2 in.) in diameter
and then a piece of steel about 12 mm. (-in.) thick. The lid
was then placed on the box and the joints luted with clay..
After heating in a coal fire for three hours the box was-
opened. When cold it was found that, in consequence of in-
sufficient or irregular heating, insufficient time or bad leather
charcoal, the iron placed in the latter was irregularly hard,
so that it could not be used and had to be hardened again ;
whilst the two pieces in the ivory-nut powder were of uniform
hardness and could not be attacked in any place by a good
new file without blunting it. The disc was then broken ; it
showed on all sides a completely regular hardened crust about
1 mrn. ('04 in.) thick. The hardening experiment was then
repeated with fresh ivory-nut powder ; in regard to the hard-
ness, exactly the same results were obtained. Although the
hardness of the iron immersed in the ivory-nut was faultless-
and of a regularity not hitherto obtained, it was found that
ivory-nut powder of too fine grain was not suitable for
hardening steel which was required to be of good appearance.
The surface of the hardened steel was covered with spots,,
which were presumably produced by the penetration of the
exceptionally fine grains of powder into the pores of the iron
when enlarged by heat, where they remained and were fixed
VEGETABLE IVOKY WASTE. 75
by the contraction during or after cooling. It is not impos-
sible that with coarser powder, as from the sawdust and
raspings, or by mixing or saturating the ivory-nut powder
with other suitable ingredients, this hindrance to the general
use may be avoided.
CHAPTEK XI.
WASTE WOOD.
THE utilization of waste wood is worthy of attention for two
reasons. In the first place, from a purely technical point of
view, through the production of more or less valuable pro-
ducts from small and objectionable waste ; in the second
place, from the economic point of view, since nothing should
be lost, and material once introduced in the manufacture
must be worked up into new forms.
Perhaps, in a certain sense, necessity was the cause of
the endeavours to utilize wood waste, as, for -example, was
also the case with blast-furnace slags, which, by their im-
mense accumulations, diminished the working spaces of the
works to such an extent that the removal of these by-products
became a question of life and existence to the smelters.
It is true that there is nothing to hinder the technical
utilization of waste wood, but, unfortunately, it is a hindrance
that the waste is locally produced and must be utilized on
the spot. Carriage of waste wood to any considerable dis-
tance renders its conversion into new products quite un-
profitable.
In districts where waste wood is produced in large quan-
tity and what is equally important regularly, its utilization
is very profitable, especially when, by the development of
special processes, products can be obtained which possess the
natural good qualities of the wood, and also valuable qualities
artificially added. On the ground of many years' experience,
the author is strictly of the opinion that valuable imitations
and complete substitutes can only be obtained by using the
less valuable waste of the original substance. Imitations of,
(76)
WASTE WOOD. 77
and substitutes for, leather can practically only be obtained
by suitable treatment of waste leather; imitations of, and
substitutes for, wood can only be produced from wood
waste.
The industries which produce imitations and, substitutes
should abide by this principle; they would then be spared
many disappointments, and we should read fewer patent
specifications, of which it can at once be said that they are
practically worthless.
Waste wood may be utilized in a variety of ways, but it
would be unjust to designate all as equally good. Neither in
execution nor in profit are they of equal value.
In regard to the appliances employed in utilizing waste
wood it appears to be very difficult to give any accurate and
particular statement, since the manner of working and the
products obtained are too varied. Generally speaking, it will
be sufficient, to say that the necessary appliances are similar
to those used in producing plastic masses mixing and knead-
ing machines, moulds and presses.
If it be intended to consider seriously the manufacture of
products from waste wood, it is first necessary to obtain clear
ideas on certain points. The first question is always, Is there
a certainty of a sufficient, reliable, and lasting -supply of suit-
able waste wood ? This question favourably answered, and
the raw material thus secured in a sufficient and permanent
supply, then comes the second question : Does the existing
or main business possess any of the appliances or the neces-
sary conditions for the manufacture of particular products
from waste wood ? This question appears very important ;
it affects the question of profit. The last question to be
raised is, Does the article which is to be made meet an actual
need, and do time and circumstances appear to favour an
abundant sale of the article, so far as human estimates go,
as the sum of the deliberations, comparisons, and experiences
of the manufacturer and others ?
These questions must first be drawn up, considered, and
answered. The more thoroughly and practically they are
78 THE UTILIZATION OF WASTE PEODUCTS.
examined, and the more precisely the answers are drawn up,
the more solid will be the foundation for the manufacture arid
the better prospects will the intended process have.
Special instructions for answering the first two questions
cannot be given, because they are of a personal or local
nature. Hints may be given in regard to the answer to the
last question, which will render possible a rapid and practical
survey and a course of action.
An important wood waste is sawdust, both on account of
the quantity and frequence of its production. This is to-day
utilized on a large scale. The most obvious and simplest
method of use is as a fuel, for which it has often been pro-
posed, but the first attempts were unsuccessful on account of
the lack of suitable apparatus for burning. Now, however,
these difficulties have been completely removed lay a rational
construction of furnaces and grates, which enable fuels in
powder or dust to be employed without difficulty.
Another method of utilization, the first to touch on a real
branch of manufacture, was to prepare artificial wood from
sawdust, the binding medium used for the sawdust being
glue solution and water-glass, also colophony, blood, and
: glue with potassium bichromate. The best binding medium
for sawdust is glue, to which bichromate of potash is added
in order to make the compound waterproof. On exposure to
light, chrome glue, insoluble in water, is formed. The glue
solution is prepared from five parts of good pale glue and one
part of isinglass by softening, slow heating with water, and
careful straining. The quantity of water is decided by the
nature of the glue ; it ought not to be too small, being such
that the liquid does not form a jelly on cooling, but only just
begins to set. Moulds of metal, gypsum, or sulphur, after
thoroughly oiling or even of wood, if previously varnished
with a spirit shellac varnish, may be used for shaping the
wood mass mixed with glue. A thin layer of the mass may be
first applied, pressed well into the mould with the fingers, then
the remaining space filled with mass prepared from coarser
-sawdust, the surface covered by a large plate, .and weighted.
WASTE WOOD. 79
JBefore taking out, which is easily done as soon as the mass
is somewhat dry and coherent, the superfluous matter is cut
off with a broad, thin knife, and the under surface of the re-
lief thus made level. The articles can then be varnished or
gilded, and treated just as ornaments cut out of wood.
The wood paste prepared by the method of Kletzinsky is
very well -worth attention : 160 parts of sawdust best from
soft woods are well boiled in a solution of 100 parts of
sulphate of alumina in the necessary quantity of water, and
then allowed to cool ; 50 parts of glue are dissolved at the
boiling point in 100 parts of water. The glue solution is
well mixed with the sawdust paste ; the mixture is kneaded,
rolled in press sheets, and pressed under a very powerful
pressure. The pressed material, which is at first very brittle,
on gradual drying in the air acquires a surprising degree of
hardness. When sufficiently firm, it is moistened from three
to five times with a dilute solution of potassium carbonate
in water, after which it is finally dried. In this manner the
separate particles of wood become united by a kind of alum-
tanned glue, which is no longer soluble in water, and is of
horny hardness. Any desired colouring matter may be added
to the alumina mordant, and also ground dye woods, in order
to obtain coloured wood pastes. By adding coarse mixtures
of wood meals of different colours beautiful mosaic plates for
parquetry may be produced.
The property of sawdust to act as a non-conductor of
heat has naturally been utilized. It has been recommended
for lining ice safes, and is now used for this purpose. There
is, however, no doubt that in this respect it leaves much to be
desired, apart from the fact that a regular supply depends on
local conditions, and that it is far from being the best for this
purpose. (Cf. Infusorial Earth and Slag Wool.)
Sawdust is used for burning Hack clay pipes. A layer of
sawdust and a layer of pipes, 300-500 in number, according
to size, are placed in a large muffle. The muffle is then
luted up, brought into the furnace, which is built up, with
the exception of the firing doors. The sawdust is carbonized
80 THE UTILIZATION OF WASTE PKODUCTS.
by exposure to a red heat for 10-12 hours, and colours the
pipes black. The pipes are next, in numbers of 20-50,
placed on a round sieve with an equal number of holes, kept
over a straw fire, when they become intensely black ; they
are finally polished by means of wax and a stiff brush.
Among the further processes in which wood waste is used
is the manufacture of oxalic acid. In this case the operation
is conducted on a large scale, and requires, besides some
chemico-technical knowledge, also suitable appliances, so
that it appears advisable to introduce this application of
sawdust only where a suitable manufacture already exists,
to which that of oxalic acid can conveniently be added.
In view of the many applications of oxalic acid and its salts,
there is no doubt of the demand.
The process is commenced by prpearing the lyes. Potash
and soda are mixed in such quantities that, after causticizing,
the proportion of the potassium hydroxide to the sodium
hydroxide may be as 40 : 60. The mixture of the two salts,
is dissolved in about eight times the quantity of water, and
made caustic by boiling in an iron pan with slaked lime.
After deposition of the calcium carbonate thus produced, the
lye is drawn off into another iron pan, in which it is evap-
orated to a specific gravity of 1 '3-1*4. The sawdust, which
is to be used, must be freed from large pieces of wood by
sieving ; it is then mixed with such a quantity of the caustic
lye that there are two parts by weight of alkali to one part
of sawdust. Since it is important that the whole mass of
the wood should be uniformly saturated by the alkali, the
concentration of the latter is arranged so that, after thorough
mixing, the whole of the liquid has been absorbed by the
sawdust. The mass is then at once brought into the vessel
in which the heating is to take place.
The yield of oxalic acid is the largest when the mass is-
spread out in thin layers ; thus it is best to use for the heat-
ing very shallow dishes of about 2 metres (6 ft. 6 ins.) diameter,
with rims about 5 cm. (2 ins.) high, in which the mass is-
spread out to a depth of 1^-2 cm. (0'6-0'8 in.). It is continu-
WASTE WOOD. 81
ously turned over by a stirrer, which at each revolution lifts
tne mass from the dish, and allows it to fall back.
It is of the greatest importance that the temperature of
the whole mass should be brought to 240 C., but should not
exceed this limit. It therefore appears to be advisable to
heat the pans, not by direct fire, but by the hot gases drawn
off from the fire. This condition is attained by connecting a
fire-grate by flues with a low chamber, the roof of which is
formed by the pans ; in each flue is a damper, of careful con-
struction, which renders it possible to regulate the admission
of the fire gases or to cut them off altogether. By using an
arrangement of this description, it is not difficult to keep the
temperature of the mass within the desired limits. The saw-
dust, saturated with lye, is brought into the pan by means of
flat shovels, by which it is spread out, the stirrer put in
motion, and at the same time the pans heated by opening
the dampers. At first only evaporation of water takes place,
the mass gradually darkening until it becomes deep brown ;
at the same time a peculiar odour is perceived. When the
temperature reaches about 180 C. the mass becomes paler
again, finally acquiring a greenish-yellow colour. The tem-
perature is now very gradually increased to 240 C., at which
the mass is kept until particles of wood can no longer be
seen when a sample is withdrawn. The dampers are then
closed, the melted mass removed with flat shovels, and
allowed to cool, or further treated whilst still hot.
In the latter case the melt is thrown into a pan contain-
ing hot water, in which it rapidly dissolves and heats the
water almost to boiling. The heating is continued until the
concentration of the liquor reaches 38 B., when it is run out
into small crystallizing vessels, in which, during the rapid
cooling, nearly all the sodium oxalate separates, this salt
being only slightly soluble. Very little of this salt remains
dissolved in the liquid, which contains potassium carbonate,
caustic soda and potash, and humus compounds. In order
to free the crystals of sodium oxalate from the mother liquor,
they are brought into a tall tub with a false bottom, where
6
82 THE UTILIZATION OF WASTE PEODUCTS.
the mother liquor drains away, the remainder being then dis-
placed by water. The mother liquors are evaporated to dry-
ness, the residue freed from the humus compounds by
roasting in the air, and the residual mixture of sodium and
potassium carbonates again causticized.
In order that the soda united to the oxalic acid may again
be immediately used in the form of caustic soda for the
treatment of new quantities of wood, the sodium oxalate is
treated in the following manner : It is dissolved in a very
little boiling water in a vessel heated by steam, and then thin
milk of lime run into the hot solution, which is kept in con-
stant motion by means of a stirrer, until the decomposition
is complete, i.e. until insoluble oxalate of lime and soluble
caustic soda have been formed. The quantity of lime to be
employed is calculated from the weight of sodium oxalate
taken ; since, however, both substances are not quite pure,
the calculated quantity of lime does not agree with that really
used. It is, however, important to bring no excess of lime
into the precipitate, since otherwise in a later operation a
larger quantity of sulphuric acid would be required than is
needed to decompose the oxalate of lime. The precaution is
therefore taken, after the greater part of the lime has been
introduced, of taking repeated samples, which are filtered,
acidified with acetic acid, and calcium chloride added ; .so
long as a turbidity is produced, undecomposed sodium oxalate
is still present.
The milky liquid is then run from the decomposing vessel
into another, where it is allowed to settle, and the clear
caustic soda solution drawn off from the precipitate. The
latter is washed with water, and the first wash water, which
still contains much caustic soda in solution, is added to the
caustic solution ; the further washings are, however, used to
dissolve new quantities of the crude melt. The oxalate of
lime, when sufficiently washed, is transferred to a tank lined
with lead, stirred to a paste with water, and then with the
calculated quantity of sulphuric acid previously diluted down
to 15-20 B. The quantity of the sulphuric acid should be
WASTE WOOD. 83
equivalent to that of the lime used in the decomposition ;
when two parts of sulphuric acid are used to one part of lime
the sulphuric acid preponderates, and there is obtained a
solution of oxalic acid containing free sulphuric acid. How-
ever, it is advisable to work in this manner, since the excess
of acid accelerates the decomposition of the oxalate of lime,
the sulphuric acid being utilized again in a later operation.
In order to hasten the decomposition of the oxalate of
lime, steam is continuously introduced through a small lead
pipe, which reaches to the bottom of the decomposing vessel.
The solid compound is thus kept always suspended in the
liquid ; the heating also assists the decomposition. After the
.-addition of the whole of the sulphuric acid the liquid is al-
lowed to rest, the solution of oxalic acid drawn off after the
deposition of the gypsum, and the latter washed with water
in a lead funnel lined with linen, the first washings being
added to the oxalic acid solution ; the remainder are used in
place of pure water to mix with the oxalate of lime in a fresh
decomposition. The residual gypsum is an excellent fertilizer
for clover, but may, since it is very pure, be dehydrated and
utilized as plaster of Paris.
The solution of the oxalic acid is concentrated in a shallow
lead pan, standing on a sand-bath, which is heated by an
open fire, or better, by steam, until, in the summer, it is
15 B., in the winter, 10 B. It is then cooled to the ordin-
ary temperature, when the dissolved gypsum separates in
crystals. The liquid poured away from the gypsum is then
further evaporated to 30 B., and set to crystallize in shallow
lead vessels.
The mother liquors, separated from the crystals, contain
the excess of sulphuric acid in addition to the oxalic acid ; the
sulphuric acid is estimated, and the liquors added in the next
decomposition of oxalate of lime, the amount of sulphuric
acid added being decreased by the corresponding quantity.
The oxalic acid crystals are washed with cold water to
remove adherent mother liquor, and are then purified by
solution in boiling water and rapid cooling, so that only small
84 THE UTILIZATION OF WASTE PRODUCTS.
crystals may form. The compound is then sufficiently pure
for commercial purposes ; it contains a very small quantity of
sulphuric acid and an equally small quantity of oxalate of
soda or potash.
The manufacture of pyroligneous acid from sawdust may
be applied in all cases where the production of acetic acid
from alcohol is not profitable. One hundred kilos of saw-
dust give 45-54 litres of a liquid, which contains 4 per cent
of acetic acid, and also 6-8 litres of tar.
The dry distillation of sawdust begins at a temperature
of 100-130 C., at first only water coming over, the quan-
tity of which naturally depends on the condition of the
sawdust. According to whether it has been kept in the
open or in closed rooms, it will contain a larger or smaller
quantity of moisture, which influences the quantity of water
distilling over, and also the consumption of fuel. It is there-
fore advisable, when possible, to give the sawdust a prelimin-
ary drying, before bringing it into the distilling apparatus.
The temperature rises from 145-500 C. ; the products of
distillation are water, pyroligneous acid, wood spirit, and tar,
also various gaseous substances, whilst charcoal remains.
The acid products form the chief quantity when the tem-
perature is rapidly raised ; they must be rapidly removed if
they are not to undergo a further decomposition.
In North America a very considerable amount of waste
pine wood, twigs, chips, etc., is first distilled with super-
heated steam for the production of " wood " turpentine, and
subsequently carbonized in the retorts for the production of
wood alcohol, pyroligneous acid, wood tar, and charcoal.
New Source of Turpentine. In view of the constant up-
ward tendency of prices in turpentine any possibility of a
fresh source of supply deserves the fullest investigation. A
paper presented to the Newcastle section of the Society of
Chemical Industry by Paterson and Forbester quotes some
promising results obtained from what is at present a waste
material, viz. the residue and waste cuttings from the very
large quantity of pine woods used in the shipbuilding industry,
WASTE WOOD. 85
which at present is carted away and destroyed. The investi-
gators set up an experimental plant for converting 'this waste
material into a source of revenue by submitting it to frac-
tional distillation. For this purpose they used an experi-
mental still, consisting of a cylindrical iron retort 6 ft. long
and 14 ins. in diameter, heated by hot air in such a manner
that they could maintain it for any desired time at a constant
temperature varying from 100-400 C. This retort was
connected with condensers and scrubbers for collecting and
recovering the products of distillation. The various products
obtained as the result of experiments, calculated on one ton
of dried wood, are given as follows :
Pitch Pin,
Turpentine oil . . . . 14 gals. 8 gals.
Tar . . . . , . : . 97 49
Acetate of lime . . ! . . . 30 Ib. 50 Ib.
Alcohol and acetone . . ." ' . ' 1J gals. 2 gals.
Charcoal -. ,. . ' . . '. 500 Ib. 370 Ib.
The authors state that the turpentine referred to in the
above table is identical with American turpentine in all its
properties, having a sweet pine-like odour quite free from
any smell of creosote, and a specific gravity of 0*846. It
may here be remarked in parenthesis that this gravity does
not agree with the claim that the material is identical with
American turpentine, the specific gravity of which is con-
siderably higher than this, *867 being recognized as a normal
figure. In fact, the product is obviously more of the nature
of that produced in a somewhat similar manner in the United
States under the name of " wood turpentine," and it is
doubtful if, as the authors claim, it could compete on equal
terms with genuine American turpentine, although there is
not the slightest doubt that it would prove a valuable sub-
stitute. A further point of interest in this paper is the pro-
duction of a large quantity of polymerizable oils which come
off with the tar, and which, as the authors suggest, might
86 THE UTILIZATION OF WASTE PEODUCTS.
profitably be extracted and find extensive use as wood pre-
servatives and in the preparation of priming paints. 1
In a certain sense artificial vanillin is a product obtained
from waste matters. In the year 1861 T. Hartig found a
crystalline substance in the cambial sap of the coniferse,.
which he termed "laricin," but later, after he had ascer-
tained its presence in the majority of coniferous trees, he
named it " coniferin ". It is obtained in the following
manner : Pines, firs, larches, felled between the middle of
May and the middle of July, are gradually stripped of their
bark and bast layers ; the young wood fibres, swollen with
sap, are scraped off by means of pieces of glass from the hard
woody layers, and collected in vessels beneath. The scraped-
off material is at once separated from the sap by fine press-
cloths, and the sap immediately boiled. The coagulated
albumin and the solid substances it encloses (cell nuclei,,
starch grains) remain behind on filtering through paper,,
whilst a clear filtrate is obtained, which, when carefully
evaporated to about one-fifth of the original volume, separates
the cambial sugar and also the coniferin in crystalline form.
By treatment with cold water the difficultly soluble coniferin
is separated from the sugar ; it then crystallizes in white
needles, generally united to form rosettes, which give a deep
violet coloration with strong sulphuric acid.
Dr. Haarmann, of Holzminden, has given an account of
the preparation of artificial vanillin in Post's " Zeits. fur d.
chem. Grossgew." The raw material for the preparation of
artificial vanillin, says Haarmann, is coniferin, a glucoside
contained in the cambial sap of coniferous trees. It is ob-
tained in the districts where the trees are felled during the
sap period Thuringia, the Baden and Wiirtemburg Black
Forest. The coniferse red and white firs are barked, the
sap lying below the bark, together with part of the bast,
scraped off by means of a piece of glass or a knife, and col-
lected in a vessel. The sap is filtered from the bast as rapidly
as possible and boiled, since it readily ferments and com-
pletely decomposes. The liquid is then separated from
1 " Oil and Colour Trades Journal."
WASTE WOOD. 87
the coagulated albumin, evaporated down to one-fifth its
volume, and set aside to crystallize. After a short time the
crystals produced are pressed to remove the mother liquor ;
100 litres of the sap, which is very difficult to obtain, produce
O'5-l kilo of coniferin. For the production of vanillin the
coniferin is treated with oxidizing agents (sulphuric acid and
potassium bichromate), and the vanillin either distilled in
steam or extracted by ether. In order to separate the vanillic
acid produced, the substance is subjected to purification by
sodium bisulphite solution and then recrystallized. After
this operation, vanillin forms an almost white crystalline
powder, which melts at 80-81 C. Twenty grms. of vanillin
are equivalent to 1 kilo of the best vanilla, since the latter
contains on an average only 2 per cent of this compound.
The application of sawdust as an addition to cement, in
order to prevent the formation of small cracks, is technically
interesting. The sawdust is well dried, then sieved in an
ordinary sieve so that only the small woolly flocks are used.
The mortar is mixed from one part of cement, two parts
of lime, two parts, of sawdust, and three parts of sharp sand.
The sawdust is first mixed dry with the cement and sand,
and the lime then added.
Sawdust is also mixed with cementing agents such as
magnesia and magnesium chloride, and Jaid on concrete
floors with a trowel. It yields a durable and pliable coating
which is very pleasing in appearance. It may be coloured
by the addition of common mineral pigments, e.g. red oxide,
ochre, umber, etc.
Wood waste finds another application in the manufacture
of casks. The outer skin of the stems, removed when the
tree is sawn up, is cut up by an ordinary circular saw into
lengths equal to the length of the staves required. These
lengths are now cut up into proper widths by means of a
circular saw with two to three blades, which can rapidly and
easily be put in motion. The wood is fed to the saw by
means of rollers with deep grooves and running in elastic
bearings. The pieces now come to a circular saw with a
88 THE UTILIZATION OF WASTE PBODUCTS.
vertical spindle and horizontal roller feed, by which they are
cut to shape. The saw blade has a diameter of 23-24 ins.
In the middle of the spindle above the table is a guide, to
right and left of which, in front of the saw, and thus diagon-
ally opposite, are grooved rollers in elastic bearings. By
means of this arrangement two pieces can simultaneously
be cut to different thicknesses. The staves now go to a
trimming and slitting machine, in which they are cut into
exact lengths and bevelled towards the inside, and the slits
cut for the reception of the ends. This machine has a shaft
upon which the slit-cutting tool runs, and two other shafts
upon which run the circular saws which trim the staves.
The saws and tools can be fixed at different distances apart
to allow for varying lengths of the staves.
The staves are fed in by hand, each being laid with its
hinder end against a guide, which can be moved backwards
and forwards. The pieces of wood after this treatment come
to the jointing machine, in which the staves are carried in a
segment-shaped guide over a slit below which is a small stout
circular saw. The staves receive in this machine an accurate
joint, which make subsequent working by hand unnecessary,
and enables the body of the cask to be at once built up. For
the sake of easier carriage, which is important, the staves are
tied up in a bundle. The ends of the casks are cut from
smaller waste pieces in a similar manner to the staves. For
this purpose wood is used which, by its structure, is unsuitable
for staves. The separate pieces are pegged together, and
finished on a machine which cuts out the round end. All
the machinery may be tended by youths. With one set of
machines several hundred casks can readily be made in a
day. The sale of these casks, made from outer skins of trees
and waste pieces, should be almost without limit ; cement
makers, millers, nail makers, and fruit dealers in particular
buy them readily.
The application of the waste of saw-works in manufactur-
ing parquetry must not be overlooked. Parquetry sheets are
made in sizes of 59 cm. and 64 cm. square (24 and 26 ins.
WASTE WOOD. 89
square). The foundations for inlaid parquetry are made by
gluing together strips of wood somewhat shorter than the
dimensions of the sheet, cutting these glued pieces into the
right length, grooving at the ends, and finally grooving and
tonguing. In Eussia another method is adopted ; the founda-
tions are made from a frame with two middle pieces and four
panels. The frames are so morticed and tenoned that each
piece has a mortice at one end and a tenon at the other. The
four panels are grooved and tongued into the frames and the
cross pieces, only the tenons of the whole work being glued.
The panels are inserted so that the grain of the wood may
run in one at right angles to the direction in the other. By
this arrangement warping is made impossible and shrinkage
is reduced to a minimum, since only the two parallel frame
pieces in a total width of at most 25 cm. (10 ins.), under
the most unfavourable conditions of temperature, can swell
or dry to a small extent. All wood waste may be used' in
making these foundations, since the panels have at most a
length of 20 cm. (8 ins.). These parquetry foundations
<3an easily be made my means of a few circular saws and a
very simple boring machine for making the holes.
Sawdust for the Production of Stoppers. F. Koeller, of
Neulengbach, in Lower Austria, has obtained a patent for
a method of making stoppers from sawdust. The sawdust
is rolled upon a round wooden rod, being made to adhere to
the surface of the rod by means of some binding medium
such as rosin or india-rubber cement. The rod has the same
length as the layer of sawdust ; the stopper furnishes a safe
hold of the cockscrew in removing it from the neck of the
bottle. Finally the stoppers are dipped to half their depth
in pure melted paraffin, and are then ready for use.
Finally the manufacture of fuel briquettes from sawdust
is to be mentioned. Molasses is recommended as an excellent
binding medium for the production of briquettes from saw-
dust. The latter is moistened with the dilute molasses, the
whole intimately mixed, then brought into cylindrical, rect-
angular, or other shape by means of suitable presses, and
90 THE UTILIZATION OF WASTE PRODUCTS.
dried. Colophony and tar may also be mentioned as binding
agents. The prospects for the success of the manufacture of
briquettes naturally depehd, in the first place, on local con-
ditions, especially on the regular supply of the waste material.
Both waste sawdust anii wood are used in the manufacture
of firelighters. The sawdust is mixed with melted rosin, or
what is cheaper commok naphthaline and pressed in
moulds. Waste wood is cut into small strips which are tied
or wired together in various ways, and also dipped in melted
naphthaline to render them more easily combustible.
See also "Wood Products: Distillates and Extracts," by
Duinesny and Noyer ; and " The Utilization of Wood Waste,""
by E. Hubbard. (Scott, Greenwood & Son.)
CHAPTEE XII.
CORK WASTE.
Utilization of the Waste of Cork-cutting. The waste i&
either at once used for stuffing mattresses, for upholstery, or
ships' fenders ; or it is sorted, the adhering bark removed and
applied to the same purposes ; or it is converted into powders
of varying degrees of fineness. The waste is first, by hand
labour and sharp knives, freed from the outer rough and dark
layer of the bark, then cut into sheets of different thick-
nesses, and finally into cubes of different dimensions.
The waste is also treated by filing or rasping, by which
means a more or less fine dust is produced. It is easily com-
prehensible that increasing fineness of the cork dust con-
siderably increases its price.
The woody portions of the waste, as well as the peculiar
hard, sandy powder found in the cork, are partly separated
by picking, partly by sieving, so that the remainder is, as far
as possible, free from these impurities. Special machines
are used for grinding cork waste, among which is to be men-
tioned the patented " Favorita " mill of H. E. Glaser, of
Berlin. This machine consists of a cast-iron base, upon
which is the real mill, with the grinding arrangements, the
feeding arrangement, the transmitting disc, and the regulator.
The mill works by reason of two conical surfaces, one solid>
the other hollow, each provided with teeth of triangular sec-
tion concentrically arranged, and engaging together. One of
the cones rotates, whilst the other is stationary and fastened
to the framework. The grinding teeth pass by one another
in such a manner that the material^ introduced at the apex
of the cone and driven by centrifugal force towards the base,
is cut as if by shears, and crushed. The grinding surfaces
(91)
92 THE UTILIZATION OF WASTE PKODUCTS.
may be moved nearer together or farther apart by a hand
wheel while the mill is working, so that the cork may be
ground to different degrees of fineness. The teeth are fixed
in segment-like plates, which are so arranged as to be cap-
able of renewal ; and according as the teeth on these seg-
ments are smaller or larger, near together or wide apart, the
mill delivers finer or coarser cork. The velocity of the rotat-
ing cone also affects the fineness of the product.
Utilization of Cork Waste for Gas-making. Illuminating
gas may be made in the usual manner, in closed retorts, from
cork waste, 100 kilos (2 cwt.) of which give 50 cub. metres
(1850 cub. ft.) of gas. The distillation is naturally much
more rapid than that of coal. The illuminating power of the
gas, with a consumption of 150 litres (5J cub. ft.) per hour
in the bat's wing burner No. 10, is thirty-six candles, so that
there would be a saving of 50 per cent, in comparison with
coal-gas at the same price, in view of the greater illuminating
power. The cork tar produced as a by-product is of the con-
sistency of ordinary tar, and reddish-brown in colour : on
fractional distillation it gives 27 per cent of light oil passing
over at 210 C., which consists mainly of benzol and toluol
with a little naphthalene. The heavy oil contains anthracene
and a little phenol. The liquid condensed in the gas manu-
facture contains methyl alcohol, acetic acid, and ammonia.
Cork Waste for Cork Mattresses. In making these mat-
tresses a fabric as waterproof as possible is sewed or glued
together so that it forms a large sack, which is then filled
with cork waste or coarse ground cork, sewn up, and then
given the shape of a mattress by quilting. In order to make
it quite impenetrable by water, the seams, and especially the
quilted portions, are coated with an india-rubber solution,
after the drying of which the mattress may be used. Mat-
tresses for gymnasia are made in the same manner, but using
an ordinary coarse fabric. Ships' fenders are bags or baskets
filled with cork waste.
Use of Cork Waste in the Vinegar Manufacture. It has
been recommended to replace wood shavings in the manu-
COBK WASTE. 93
facture of vinegar by the much lighter cork waste. The
elasticity of cork is made still greater by wetting, so that a
sinking together of the filling material is not to be feared even
in tall vinegar vessels. In the pores of cork are countless
small organisms, and among them the acetifying bacteria
exist in great quantity, so that the vinegar-making vessels
filled with cork rapidly cause the formation of acid.
One of the chief uses of cork raspings is in the manufac-
ture of linoleum and cork lino, for which purpose it is mixed
with oxidized linseed oil and gum kauri in special kneading
machines and is then spread upon cloth.
It is employed on a considerable scale for packing grapes
in Spain and other countries where it is abundant.
Cork raspings also form an excellent non-conducting
material, and for this reason are especially prized for filling
the lining of refrigerator chambers and also as a non-conduct-
ing coating for pipes.
During the last few years cork raspings have also been
made up into corks for bottles and for other purposes by
mixing with a small quantity of a shellac solution in methyl-
ated spirit or in ammonia, or with a pyroxylin varnish, and
pressing in moulds. These corks are excellent for many
purposes owing to their regularity in size and outline.
CHAPTER XIII.
WASTE PAPER AND BOOKBINDERS' WASTE.
Utilization of Waste Paper. The waste paper 1 is thrown
into a conical drum, about 10 ft. long and 3 ft. in medium
diameter, covered by wire netting of three-quarter inch
mesh ; in passing through this drum the greater portion
of the adherent dust is removed. Bones, pieces of wood, and
other large hard objects, which announce their presence
by striking the drum, can be removed by the workman who
takes away the waste paper which has gone through the
drum. On account of the dust, this sieve works in a casing
lined with boards ; it may be fed through the open narrower
end or through a hopper; thirteen to twenty revolutions per
minute are sufficient. The paper is next ground under edge-
runners, and is then passed through a second sieving drum,
somewhat smaller and covered with a No. 5 or 6 sieve. This
drum is closed at the wider end (the exit) by a wooden bot-
tom, which has two openings closed by slides. By this
means the ground paper waste may be kept in the drum
until all the particles of paper have passed through the sieve.
The residue, containing rags, thread, etc., which may be
sorted and worked up, comes out when the slides are opened.
This sieve, like the first, works in a wooden casing, one side
of which is open, so that the sieved paper particles may
be removed. It is driven at the side by bevel cog-wheels,
so that it may be easily emptied ; ' the speed is forty to fifty
revolutions per minute. There is no loss of fibres in this
method of purification.
Utilization of Bookbinders' Be/use. The waste produced
1 " Papierzeitung," 1886; " Neueste Erfindungen und Erfahrungen,"
1886.
(94)
WASTE PAPER AND BOOKBINDEES' WASTE. 95
in bookbinding may well be used to prepare papier-mache for
foas-reliefs, dishes, urns, picture frames, clock' cases, etc.
For this purpose all kinds of paper cuttings and waste card-
board may be employed. A second constituent is well-sieved
wood ashes, especially those of hard wood ; finally a third
constituent is flour paste. The papier-mache is prepared
from these substances in the following manner: The paper
clippings and other bookbinders' waste are torn up small,
thrown into a vessel filled with water, and left to disintegrate.
Frequent stirring accelerates the dissolution. The -disinte-
grated mass of paper is finally removed from the vessel, the
water is lightly squeezed out, and the mass then comes into
a mortar, where it is well pounded. Next it is taken out,
laid on a strong linen cloth, and the water squeezed out
as completely as possible. The balls of material obtained
are then dried in the sun, near a fire, or in a stove. When
dry, the balls are rubbed on a grater, when the particles of
paper become similar in feel to cotton. They are then mixed
on a board by means of a wooden spatula with ordinary flour
paste and spread out with the rolling-pin, just as dough is
worked.
This mixture with flour paste, which must amount to
one-third of the w T hole quantity of material to be made, is
formed into a ring on a board or table. Two parts of fine
sieved wood ashes (best from hard wood) are placed in the
middle, water is gradually added and mixed in until the ashes
are thoroughly moistened. Finally the paper pulp is worked
up with the wet ashes.
The mixture of the three constituents is now brought
into the mortar and well pounded ; it then forms papier-
mache, and can at once be used. If the mass is to be kept
.moist for a length of time, it is filled into glazed earthenware
vessels, which are placed in pairs, one upon the other, and
protected from sun and heat.
From this papier-mache bas-reliefs can easily be made,
the mass being used in place of the wax which otherwise
is employed in embossing. For this purpose a portion is
96 THE UTILIZATION OF WASTE PKODUCTS.
taken out of the earthenware vessel, in which it is preserved,
spread out flat to the requisite dimensions for the bas-relief,
one side of the sheet so' obtained is covered with flour paste
and the mass then pressed upon a smooth surface slate,
polished wood, metal, or smooth pasteboard. Then a linen
cloth folded in two is laid on the mass and superfluous
moisture removed by repeated applications of the cloth.
After this treatment the design of the low or high relief
can very easily be engraved on the mass by the embossing
style ; hollows can be dug out, and projections formed by
adding fresh material where required.
This mixture has certain advantages over embossing wax.
In the first place the style works much more easily in the
soft paste, since the mass may be depressed, moved to all
sides, raised, and moulded as desired. Should some spot
begin to dry somewhat too soon, it is brushed over with
a brush dipped in water, when the mass may be worked
as before.
If the work is quite dry before it is finished, it may be
moistened over a portion, or the whole, of the surface and
further worked with the style.
After the finished relief is quite dry it is pasted over with
thin flour paste by means of a camel's-hair brush, and then
again allowed to dry, when the whole object is polished with
a bone polishing-style. The object is now in a condition in
which impressions of it in wax may be taken. It is then
coated with thin size, again dried and polished as before.
This last treatment of the surface permits of the application
of oils or water paints, and of gold leaf simply by breathing
on the surface or by using oil varnish. After painting or
gilding the object it is usual to give it several coats of spirit,
varnish. After the latter is dry, neither heat nor cold,
moisture, dust, or fly-spots can harm the work, for the var-
nished surface entirely protects the material beneath from
injury. Dust is removed with a soft brush and fly-spots by
a damp cloth.
Utilization of used Paper Cases. By paper cases in this.
WASTE PAPEE AND BOOKBIKDEKS' WASTE. 97
instance are understood the small conical hollow cylinders of
hard paper, similar in shape to cigar holders, which are used
in the textile industries as yarn spools by weavers and
stocking-knitters, and which are made in hundreds of sizes
for various purposes and in different forms.
E. Hofel, of Gruna in Saxony, has patented a process for
utilizing the large quantities of these paper cases in prepar-
ing articles of utility and ornament umbrella and walking-
sticks, fire-screens, baskets, card-tables, toy-furniture, picture
frames, etc. The cylindrical, or rather conical, form of the
cases makes their utilization easy. Just as the spindles on
the spinning-frame must be exactly alike, so also the paper
cases originally intended and solely used for the spindles are
also exactly similar. One fits over another ; the pointed
cases may be pushed easily one into the other, and so form
a rod already firm and of any required length.
After a number of the cases have been pushed one into
the other, and a rod of the desired length obtained, a wooden
stick or a wire of sufficient strength is drawn through the
tube, in order to give it more solidity and afford a means of
attaching the ferrule and handle. The ferrule and handle
are screwed on the core at the bottom and top, and confine
the bottom and top cases. The stick may then be painted
and varnished. A pen-case is simply made from a large
paper case, which is altered to fit its purpose by fitting a
stamped metal bottom and a similar lid, and then ornamented
by paint and varnish. In making containing vessels out of
the cases, the so-called "ring-ousel" cases are laid near to-
gether and united at top and bottom by a ring of wire. They
can then be ornamented in any required colour and a de-
corated top and bottom, preferably of sheet iron, applied.
CHAPTEE XIV.
THE BY-PRODUCTS OF PAPER AND PAPER- PULP WORKS.
Utilization of Waste Matters in Paper and Paper-pulp
Works. The waste waters, produced in boiling, washing,
bleaching, in the paper-machine and also in certain subsidiary
operations, constitute the greater part of the by-products and
require the most attention. 1 Fibres of all kinds, fine sus-
pended mineral and vegetable substances, organic matter and
colours in solution, and the chemicals employed constitute
the impurities which are carried away in the waters. The
most valuable of these substances are the fibres which origin-
ate in the various raw materials. In order to retain them,
pulp-catchers of the most varied construction, settling-tanks,
and also filters are used. The most convenient and the
cheapest process consists in first allowing the waste waters
to pass an efficient pulp-catcher and then to deposit in
settling-tanks of sufficient size, of which several must always
be provided, for alternate use and cleaning. These should
be so arranged that the water can rise to a considerable
height, and flow away smoothly over a considerable breadth,
so that everything may be deposited in the almost motionless
water. The separate compartments should be emptied at
fairly frequent intervals, since, in consequence of the presence
of the various organic matters in the deposit, decomposition
readily sets in, which may extend to the fibres, with conse-
quent loss of strength, or even destruction. The regained
material is especially suitable for grey or dark packing paper.
Since it consists of the finest fibres, it requires no preparation,
but can at once be introduced into the paper-machine. If
suitable papers are not made, this recovered fibre can readily
1 J. B. Hohn, " Anzeiger fiir Papierindustrie," 1894.
(98)
THE BY-PRODUCTS OF PAPER AND PAPER-PULP WORKS. 99
be sold at a good price to pasteboard-makers. In this case
it is rendered more suitable for transport by being pressed.
The waste waters of cellulose works in particular carry away
much good pulp, so that some arrangement of the kind
described is very essential. As regards the separate divisions
of the manufacture from which the waste waters are derived,
the liquors of the rag-boiler are first to be considered ; they
contain so little fibre that they may be excluded from the
fibre recovery. On the other hand, they are very rich in
nitrogen, which results from the fat, perspiration, and other
matters extracted from the rags, and since they also contain
lime they produce an excellent fertilizer. For this purpose
they are run into a pit, from which they can be withdrawn
as required. The offensive odour is removed by gypsum,
which also results from by-products. These waters may also
be used for moistening the heaps of fertilizers which are
composed of other waste products.
The waste liquors of cellulose works may differ in com-
position according to whether soda or sulphite-cellulose is
made. In the former case the usual method for regaining
the soda is employed, the very dilute liquors, which cannot
profitably be calcined, being used to dissolve fresh portions
of soda. For sulphite liquors there is not yet known a really
useful and practicable process of recovery or of further treat-
ment, in order to obtain tannic acid, sugar, or other sub-
stances. They can, however, be used for manurial purposes,
after the free acid has been neutralized by alkaline or lime
waste, which is always simultaneously produced. This is an
inexpensive process, if conducted as mentioned above for the
liquors from the rag-boiler. Where it has been tried, it has
been found that all the liquors could be disposed of in this
manner, and thus the nuisance of the waste waters entirely
removed. Also this liquor, in consequence of the bisulphite
and tannic acid it contains, is -an excellent substitute for
alum and sulphate of alumina in rosin sizing. It may also
be used for the manufacture of brown and black colours.
The waters from the beating-engine are those from which
100 THE UTILIZATION OF WASTE PRODUCTS.
it is most important to recover the fibre. Those from the
paper-machine, however, which contain clay, size, colouring-
matters, and the like, which it may be necessary to con-
serve as far as possible, are best used over again several
times by taking them back repeatedly to fill the beating-
engine, to dissolve starch and clay, or to the rag-boiler.
Since a certain quantity of water can only take up a definite
quantity of foreign matter under given conditions, it is easily
seen that the loss is considerably reduced in this manner.
The composition of the paper is naturally very important.
With paper which is not sized, coloured, or weighted, such a
mode of treatment is unnecessary. In the case of the water
from highly coloured paper, which would strongly contami-
nate the river into which it might flow, it would be advisable
to beat and wash the rags from the boiler with it, by which
means the colouring matter would be partially fixed and
partially destroyed. The bleaching-powder residue is also to
be considered along with the waste waters. It cannot be
employed as manure. It is best collected in a pit and con-
verted by stirring with soda solution into calcium carbonate,
or with sulphuric acid into gypsum, either of which may be
employed as a fertilizer, especially when mixed with the
above-mentioned liquors, or they may be used as fillers if the
residue is pure. Carbonate of lime, which is less suitable for
use as a filler, may be converted into quicklime in a small
lime-kiln.
According to Siedel, the waste liquors from the sulphite-
pulp works, in which the Eittner-Kellner process is employed ,
have a sp. gr. of 1*050 and contain 11*44 per cent of solids ;
the total sulphur is 9*54 per cent, 93 per cent being present
in organic combination. The amount of potash in these
liquids is about 1 part in 5000. The liquids are evaporated
and incinerated for the recovery of the soda, of which, ac-
cording to F. Briggs, 85-90 per cent is obtained.
According to K. Lorentz, 1 the waste resin obtained by
treating the waste lyes of paper-pulp works with acids, a
1 " Seifensieder Zeit.," 1916, 43, 501-502.
THE BY-PRODUCTS OF PAPEE AND 'PAPER-PULP WORKS. 101
product which at one time was quite unsaleable, now finds
a market at about 4-^d. per Ib. It can be purified by treat-
ment with acid or with lime, and can be saponified or distilled.
It is of no value for soapmaking, but can be used for paper-
sizing and possibly in varnish manufacture.
Of less importance are the residues of rosin, colour, and
china clay, but if they have accumulated or are produced in
large quantity, they are mixed, allowed to dry in the air,
ground with a suitable filler on an edge-runner mill, and used
as a substitute for earth pigments for common papers. An
excellent earth pigment, as a substitute for dark ochres and
umber, may be obtained in sulphite-cellulose works by treat-
ing the burnt or spent pyrites, which consists to a great extent
of ferric oxide. The material is first broken up under stamps
to the size of hazel-nuts, the finer portion being then sieved
off and levigated. There results a very fine, soft colour of
great staining power. In view of the quality of the material,
the levigating apparatus may be of very primitive construc-
tion, the cost of working consisting only of the labour, the
process being quite remunerative. The larger pieces which
remain are composed mostly of unburnt pyrites* these are
taken back to the furnace.
The grey arsenic sublimate is to be regarded as an un-
important by-product of cellulose works ; it is deposited in
the gas flues and is generally disposed of in the wash waters.
This is extremely destructive to fish, even at very great dilu-
tions far more so than any other substance in the waste
liquors. The deposit is formed in the pipes in solid form, so
that it can readily be collected ; in large parcels it always finds
purchasers. As a result of the frequent blowpipe solderings
there is gradually formed in the gas-producing apparatus a
residue of cadmium, an uncommon and dear metal which,
in other branches of industry, is collected for utilization.
Finally, calcium monosulphite and gypsum separate from
the sulphite liquor on standing, and also on boiling. The
former can be used as a solid "antichlor," when it is con-
verted into gypsum, or it may be mixed with the fertilizers
102 THE UTILIZATION OF WASTE PRODUCTS.
already mentioned ; also it may be converted by sulphuric
acid or a warm solution of sodium sulphate into gypsum, or
by soda into calcium carbonate, in which last case it is again
used in preparing fresh boiling liquor ; it is also used for this
purpose without treatment, but since it is not finely divided,
but is generally caked together and encrusted, it has not been
found very suitable.
The residues of the soda recovery, i.e. of causticizing, in
the soda-cellulose works are of particular importance in the
first place, because of their great quantity. This by-product
consists essentially of carbonate of lime, contaminated by soda,
carbon, and other matters. It is best utilized by burning
after it has dried to a certain extent, the requisite quicklime
being thus reproduced. In consequence of the large quantity
to be dealt with, continuous working is necessary, and thus
fresh lime is continually produced. For conversion into gyp-
sum the by-product is treated with sulphuric acid ; the soda
salt must be completely neutralized if the gypsum is to be
used as a fertilizer.
Certain by-products, which do not come in contact with
water, are produced in wood-pulp and cellulose factories, viz.
the waste sawdust, bark, and other pieces of wood obtained
in cutting and dressing the wood. The sawdust constitutes
an excellent fuel when burnt in specially constructed grates ;
the bark is used as litter for cattle, and is in demand for this
purpose by farmers. The two substances together can be
worked into a species of cellulose, an operation which is only
found profitable when collected in boilers specially con-
structed for the purpose. Chance pieces of bark, larger
pieces of wood, the waste from the grinding apparatus, and
the dust from the sieves cannot profitably be separately
treated.
As previously stated, however, waste wood is best distilled
for the production of wood spirit, acetic acid, wood tar, and
charcoal.
The last waste product to be mentioned, but the first in
the actual manufacture, is the rag dust, which by itself con-
THE BY-PRODUCTS OF PAPER AND PAPER-PULP WORKS. 103
stitutes an excellent fertilizer. The fibre it contains may be
extracted by agitating with water and running off the liquid
after a short time, when the fibre is carried away, but the
dust, sand, and heavier particles remain behind.
The damaged paper is also to be reckoned as a by-pro-
duct. It is unnecessary to say much concerning its utiliza-
tion, except that it is taken back to the beating engine : it
is always produced in every process ; it is only mentioned
as an example to demonstrate that the further treatment of
waste matters is usually profitable, and occasionally dis-
tinctly so. Utilization of all waste products is an important
factor in the balance sheet of a paper or paper-pulp works,
and increases in importance as time goes on.
Paper from Corn Stalks, etc. It is estimated by C. J.
Brand that the following wastes are available for paper-
making :
Tons.
Cornstalks . , ' . .' * 30,000,000
Rice straw. . , . . . 1,500,000
but in addition there is flax straw, megasse, or bagasse (sugar-
cane refuse), cotton-seed hulls, etc., to a very large amount. 1
Recovery of Wax. After preparing the fibre from raffia,
esparto, and sugar cane, the residues are extracted with
solvents and waxes obtained thereby.
See also " The Paper Mill Chemist," by H. P. Stevens ;
and "The Treatment of Paper for Special Purposes," by
L . K Andes (Scott, Greenwood & Son) .
] C. F. Cross, "Lectures on Cellulose," Institute of Chemistry, 1912.
CHAPTEK XV.
THE WASTE PRODUCED IN THE MANUFACTURE OF PARCHMENT
PAPER.
Utilization of Parchment Paper Waste. C. D. Cech has
given an account of the utilization of the waste from parch-
ment paper- works in the preparation of oxalic acid. He
remarks that the chief attention in making oxalic acid from
parchment paper waste must be devoted to a thorough wash-
ing of the latter. According to the method of manufacturing
oxalic acid introduced by Roberts, Dale & Co., of Warrington,
by fusing sawdust with caustic potash (see p. 80) , parchment
paper waste will not only give a sufficient yield of oxalic acid,
but its preparation from this material would not suffer any
drawback such as occurs with the colouring matters which
arise in the treatment of hard woods.
The process of manufacture is the same as in the prepara-
tion of oxalic acid from sawdust (compare the details of this ap-
plication of sawdust) .* J. Upmann remarks, with regard to
Cech's proposal, that the process of converting cellulose into
oxalic acid by fusion with alkali is no novelty, since it had
already been confirmed by experiments on the small scale,
before the introduction of the present method of making
oxalic acid from sawdust ; on the other hand, it must be
admitted there had been no previous published proposal to
utilize cellulose in this manner. Now, Upmann considers
that the question whether parchment paper waste may really
be a suitable substance to replace sawdust cannot be decided
a priori, since, even if sufficient raw material could be ob-
tained, which is doubtful, it would have to be compressed for
transport to a distance : whilst the complete washing would
1 Post's " Zeits. f. d. chem. Grossgew.," II, 4.
(104)
WASTE PKODUCED IN PAECHMENT PAPEB MANUFACTUEE. 105
be attended with more -difficulty than would appear, at first
sight. Also, the subsequent drying of the paper could not
very well be obviated ; thus an expense would be incurred
which is lacking in the case of sawdust ; this might, how-
ever, be compensated for by a larger yield of oxalic acid.
CHAPTEK XVI.
WOOL WASTE.
Utilization of Waste Wool in making Shoddy, etc. 1
For this purpose rags and other waste containing woollen
fibre, as well as mixed fabrics of cotton 'and wool, are em-
ployed. The rags and" waste are first subjected to certain
preliminary operations in order to remove buttons, seams,
string, etc., when about 20 per cent of waste is produced,
which is used in agriculture. The rags are then cut into
pieces of suitable size, and sorted, first into pure woollen and
mixed fabrics, and subsequently according to the character
of the wool fibres, whether those are short or long. The
short-fibred rags consist mainly of cloth and similar materials
of carded yarn, milled or otherwise ; the long-fibred consist
of the unmilled, and especially of worsted, fabrics. The
names mungo and shoddy are used respectively for the
materials thus differentiated, after they have been torn up.
Finally, the rags are sorted according to colour.
In the following description we proceed exactly according
to the authorities quoted. Since rags come into commerce
unsorted, or only superficially sorted, it falls to the manufac-
turer to undertake the operation. This operation is, how-
ever, a very necessary one as it loosens the dust in the rags,
the air of the sorting-room soon becoming more than saturated
with it ; good ventilation is accordingly requisite, unless the
rags are first cleaned. Breton, of Pont de Claix, accomplishes
this purpose by arranging the rags in a layer 30 cm. (1 ft.)
deep and moistening them with bleaching-powder solution,
0*5 litre per sq. metre (1 gal. per 100 sq. ft.). They are then
brought into a species of corn-sifter provided with a fan,
1 Grothe, " Technologie der Gespinnstfasern," vol. i., p. 209 et seq. ; Mus-
pratt, " Prakt. Chemie," vol. vi.
(106)
WOOL WASTE.
107
which drives out the dust into a flue 5-6 metres (16-20 ft.)
long, where it deposits. Leading into the outlet is a water-
pipe, which yields a fine spray of water which throws down
all the dust. Dirty rags are boiled with milk of lime and a
little soda, washed in a washing-machine, and then dried.
A rag- washer, which works very well, has been constructed
108
THE UTILIZATION OF WASTE PKODUCTS.
by Planche & Rieter. 1 This machine, which is made by
Seraph in, of Paris, consists of two spherical vessels for the
reception of the rags ; these may be worked together or
separately, for which purpose the driving mechanism is
provided with the requisite clutches.
Fig. 9 is a .vertical section through the axes of both
vessels, Fig. 10 a ground plan, and Fig. 11 an elevation, of
the driving mechanism. In Fig. 9 is shown the different
systems used for introducing the steam and the cleansing
liquid, the various possible modifications being represented
at the same time.
FIG. 10.
Each of the spherical vessels A and A 1 is about 6 ft. in
diameter, holding about 1300 Ib. of rags, and is constructed
of f-inch boiler-plate, so that it is capable of resisting a steam
pressure of five atmospheres. Each also contains a double
perforated bottom of thinner plate a, fastened to the outer
walls by angle irons b. The holes in these double bottoms
are fV in. wide, placed at distances of 1 in. apart. Over this
bottom are scrapers B or rods 18 ins. long, which separate the
rags and keep them in motion. The steam enters the ring-
shaped space a between the perforated bottom and the outer
a "Polyt. Centralbl."
WOOL WASTE.
109
wall. The manhole C attached to the vessel serves for the
admission of the rags and for necessary repairs ; it is closed
by a cover fastened down either by ordinary bolts as shown
on the vessel on the left, or, as seen on the vessel at the right
and in Fig. 12, by a swinging nut c moving on a hinge. The
valve D, shown magnified and in section in Fig. 13, is also
affixed to the exterior of each vessel ; it serves as a safety-
valve against too strong pressures, and may also be used to
FIG. 11.
admit air in case a partial vacuum should be produced. It
has a brass seating, fitting on to the spherical vessel, in which
moves the real safety-valve d, provided with a conical face
tapering downwards and pressed down by a strong spring e,
which works against the plate /of the arch D, which again
carries a screw /' for regulating the pressure of the spring.
The valve d is again in its turn perforated and carries the
second valve d', opening inwards, which is kept pressed into
its seat by the weak spring e.
A tap E on each vessel, opposite to the manhole, serves
110 THE UTILIZATION OF WASTE PEODUCTS.
to run off the liquor or washing liquid. Each vessel has two
pinions F and F', which are carried by the columns G bolted
to the brick-work G'. The longer axis F' carries a large
cog-wheel H, which is actuated by the cog-wheel h. Both
the wheels h are on the shaft J", which has its bearings in
the columns G and in a third and lower one. The main
shaft 0, with the pulleys P and P', moves the shafts I, etc.,
by means of the cog-wheels i and % . In order that each
vessel may be revolved separately, the cog-wheels i are not
attached to the shaft 0, but are made to rotate by means of
the clutches j and /, worked by the levers J and J'. Further,
in order to be able to move the vessels by hand so that the
manhole may be exactly at the highest or lowest point, in
order that the rags can be introduced or removed, the conical
FIG. 12. FIG, 13.
cog-wheel k is also attached to the shaft 0. It is moved
from the subsidiary shaft Ef to which a handle can be at-,
tached, and which is supported on bearings in the supports k' 2 .
From Fig. 9 it will be seen that the steam and the various
washjng liquids can be conducted through the hollow axes F
and F' in various ways. On the left side of Fig. 9 there is
a central pipe L which rests in a small support and divides
into two branches, provided with the taps I and V (Figs. 9
and 11), in order to be able to cut off the supply to either.
In the interior of the vessel is seen the pipe L, continued
downwards by the pipe L', which terminates between the
outer wall and the perforated bottom and rotates with the
vessel. The fixed pipe M enters through the other axle F' ;
it also divides outside into two branches with taps m and m',
whilst the other end is continued inside by the arm M, which
WOOL WASTE. Ill
points upwards. A perforated diaphragm a at the side pro-
tects the pipe from contact with the rags. The steam enters
through this pipe at a pressure which can be regulated as
required.
The pipes affixed to the vessel on the right are differently
arranged. The steam there enters on the left through a
rose n. On the opposite side are to be seen two fixed pipes
M and N ; M being directed upwards introduces the steam,
N downwards and introduces or removes the washing liquid.
Both these pipes are connected by a T-piece with the central
pipe M which passes through the axle F, and is separated
by a diaphragm into two divisions. The inside pipes M and
N are here also protected from the rags by a perforated wall
almost concentric with the spherical vessel and somewhat
differently fixed. A tank N perforated by many small holes
is placed under each vessel. It may be fixed on wheels so
that it can readily be moved on a tramway. It is intended
to receive and drain the washed rags when they are turned
out of the boiler.
These machines work in an exactly similar manner to the
ordinary cylindrical form. When in the position of Fig. 12
they can be filled through the manhole, which is then closed
tightly. When the washing is finished, the liquid is first run
off through the cock E ; the sphere is then turned so that the
manhole is at the bottom. The latter is then opened, and
the rags fall out.
It is necessary to produce a constant uniform steam pres-
sure, which is effected by means of the regulator, shown
separately in Fig. 14. It consists of a vessel A with a cylinder
C cast on at the top, and with two side pipes B and B r placed
opposite to one another, of which B' is used to carry away
the steam, whilst a safety-valve S is attached to B. The
cylinder G is provided with a bored metallic lining, in which
works the double piston pp l . Between the two discs of the
piston communication is made with the vessel A by means
of the side passage a, the opening of which is opposite to the
pipe c. The top of the piston is connected by the rod Z with
112 THE UTILIZATION OF WASTE PRODUCTS.
the lever L, on the end of which is an arc s to carry the
weight P. When, for example, the safety-valve is loaded to
four atmospheres pressure, and this is not to be exceeded, the
weight of the lever L must be so regulated that the space
between the two dies of the piston provides a full communica-
tion between the channel a and the entry pipe c. If, say,
steam of six atmospheres enters, the piston rises, and the
openings of c and a are shut off to some extent so that little
steam can enter the vessel A. The safety-valve S serves to
prevent any accidental accumulation of pressure.
FIG. 14.
Grothe states that according to the mode of operation
there are four different methods of manufacturing mungo and
shoddy :
1. The woollen rags, unwashed but slightly moistened,
are torn up, and without further treatment in the carding-
machine are at once put on the market. The loosened mass
thus still contains all the dust and dirt.
2. The woollen rags, without being washed before tearing,
are afterwards treated dry in the carding-machine, by which
treatment a quantity of dust is removed.
3. The woollen rags, without washing before tearing,
are afterwards slightly oiled and carded. This system affords
WOOL WASTE. 113
the greatest opportunities for fraud. In the first place, the
oil fastens the dust on the fibres, besides which it serves to
retain the fibres which are too short for further treatment,
these being like dust as compared with the longer fibres.
When this carded mungo comes into the market it generally
deceives the purchaser. It is different when the mungo
manufacturer spins it himself.
4. The woollen rags are well washed before tearing, and
afterwards are not oiled or carded. This method always
produces a very clean and unmixed fibre, free from all im-
purities. It also avoids the production of dust, which injuri-
ously affects the workpeople in the other methods.
The process of treatment has now been outlined. After
freeing from buttons and seams, the rags are put through a
rag-shaker which removes dust and dirt ; they are then sorted
into different qualities, cut into small pieces, and fed into
the " devil," which tears them into fibres. This procedure
is adopted in methods 1, 2, and 3 ; but in method 4 the rags
are washed before tearing, and again afterwards, then centri-
fuged and dried. The " devil," or tearing-machine, consists
of a large drum, the exterior surface of which is thickly studded
with iron teeth, and which moves with considerable velocity
about 550-700 revolutions per minute. The rags are fed to
the drum between two rollers of small diameter provided
with longitudinal grooves. These rollers revolve very slowly
and, since the upper is pressed very hard on the lower by
means of a lever and weight, the rags are held fast and the
teeth of the drum comb out only the cross threads. This
operation produces a fibrous mass, which is termed mungo
when it originates in cloth or carded yarn fabrics, and shoddy
when it is produced from worsted and long-fibred materials.
In the above methods a treatment in the willy carding
engine follows after the tearing by the " devil ". The rollers
of the former have strong wire points with an elastic attach-
ment to the surface. Mungo is generally not subsequently
treated in the willy and the following carding-machine, but
is at once packed and afterwards carded mixed with natural
8
114 THE UTILIZATION OF WASTE PEODUCTS.
wool in proper proportions, since it is too short in the fibre
to be spun alone. The proportion of mungo varies from 20-
70 per cent to 30-80 per cent of natural wool. The subsequent
spinning offers no further difficulties. Shoddy wool is at
once carded on the willy and the following machines, and is
generally spun without further additions.
There is a great quantity of rags composed of mixed fibres.
Generally the warp is of vegetable fibre and the weft of
animal fibre. For mungo-spinning, the vegetable fibre must
be removed. Usually the two textile fibres are separated by
treating the rags with acids, which destroy the vegetable
fibres, but do not attack the wool. For this purpose sulphuric
acid diluted to about 18 B. is used, and also hydrochloric
acid. After the acid bath the material is brought into al-
kaline solutions, in order to neutralize the acid remaining
in the fibre ; it is then well dried. In consequence of this
treatment, the vegetable fibre becomes converted into a
friable condition, whilst the wool fibres remain uninjured, and
can be isolated simply by rubbing. For this operation, many
different methods are now employed, which will be mentioned
below.
Newmann separates the wool from mixed woollen fabrics
as follows : In order to protect the wool from the action of
the acid, it is saturated with a solution of sulphate of alumina
or alum (1-5 parts to 100 parts of water), and then dipped in
a warm soap solution containing l*5-7'5 parts in 100 parts of
water. The material to be treated, after this preparation, is
brought into sulphuric acid (1-5 parts diluted with water to
100 parts). The moist fabric is then subjected to a tempera-
ture of 95 C. The vegetable fibre is thus thoroughly dis-
integrated and can be removed by rubbing or washing in hot
water, the wool fibre, however, remaining unimpaired.
R. Bottger omits the preliminary treatment with alum,
but applies a soda bath after the treatment of the fabric, in
order to neutralize the acid. The carbonic acid, thereby
evolved, considerably loosens the residual wool.
Ward gives a process for separating cotton from wool,
WOOL WASTE. 115
which has for its object the recovery of the cotton for paper-
making. He subjects the mixed fabric to the action of water
under a pressure of from three to four atmospheres in a
Papin's digester. The cotton then remains quite unaltered,
whilst the wool is converted into a friable substance.
In order to recover the woollen fibre from a fabric com-
posed of wool and vegetable fibre, Schaller immerses it for
12 hours in a bath composed of 3 per cent of sulphuric acid
(66 B.) and 97 per cent of water, and then dries. If this
solution should not act sufficiently energetically, the rags are
exposed for from 4-5 hours to a temperature of 60-70 C.,
when the vegetable fibre becomes friable.
Kowley recovers the wool from mixtures with vegetable
fibres by treating the rags with dilute sulphuric acid, subse-
quently bringing them into a rotating wire sieve, in which
they are dried by a current of hot air. The rags are then
packed in boxes with sand, where they remain for a longer or
shorter time, according to their nature ; they are again separ-
ated from the sand by the rotatory action of the wire sieve.
This method is so complicated, and its effective action ap-
pears so questionable, that it can in no way be recommended.
Grothe calls attention to the fact that the greatest care
must be given to the strength of the acid bath, in order that
the wool hairs may not be attacked.
Extracted mungo wool is mixed with mungo obtained by
the mechanical methods, and the two worked up together.
The shoddy or mungo is mixed on a floor with varying
quantities of fresh wool and with considerable quantities of
oil, usually recovered oil, then put through the usual carding,
spinning, and weaving operations for the manufacture of
cloths to be sold at lower prices than would be possible when
using all new wool.
Manufacture of Yellow Prussiate of Potash from Wool
(horn and blood). J. J. Hess, of Vienna, has given a
very full account of his own experience of this manufacture. 1
The proper preliminary treatment is exceedingly im-
1 " Deutsche Gewerbe-Zeit."
116 THE UTILIZATION OF WASTE PRODUCTS.
portant to lucrative working, consisting in a cautious drying
at a high temperature, or rather in gently calcining the
nitrogenous material, in order, in the first place, to drive
out all moisture and, in the second, to render the nitrogenous
matter more easily pulverizable and also richer in nitrogen.
This process of concentration is best conducted in a kind of
"fig-coffee" drum, or in a large rotatory apparatus, capable
of being heated. One axle of this machine must be hollow,
and be connected, by means of a bent pipe, with a cooling
tank, which condenses the vapours evolved, since these are
also valuable, consisting as they do of combustible oils and
ammonium carbonate.
The dried, roasted, and concentrated mass, when the
operation has succeeded, must be frothy, brown, transparent,
interspersed with bubbles, of a slight, peculiar odour, and
very easily friable. If too strongly burnt, the mass appears
black, is very light, very frothy, and very poor in nitrogen ;
on this account every attention must be given to the drying
process, in order that heavy loss may not result.
The next important material is the potash, which is fre-
quently, through false economy, bought at the lowest price >
and, being of poor quality, adds a good deal of inconvenience
to the manufacture. The potash should be as pure as possible.
Next comes the third raw material, the iron, which can
be used in the form of hammer scale, dull-coloured ferric
oxide, or iron filings and turnings, in fine powder.
All the substances should be dried and kept in that con-
dition, and in a state of fine powder ; they are then mixed
for use in the following proportions : 10 kilos of dried horn,
etc., 6-8 kilos of potash, 4 kilos of hammer scale, etc., the
average yield from these quantities being 3-3^ kilos of yellow
prussiate.
The intimate mixture is now heated in clay crucibles
lined with sheet iron, in a muffle furnace very similar to an
ultramarine furnace. After about 24 hours the furnace is
opened, the crucible removed, and the coherent mass, which
readily falls out, thrown at once into cold water in order to
WOOL WASTE. 117
prevent oxidation. As soon as the mass falls into the water
a hissing is heard, and frequently sparks momentarily fly out,
which is a sign of a successful operation. The mass soon
falls to a fine, black powder, leaving a clear, pale yellow
solution, which becomes dull in colour when subsequently
boiled, and deposits fine crystals of ferrocyanide of potassium
on standing.
In addition to other advantages, Hess's process also
utilizes the resulting fine powder. The black deposit con-
tains pure iron and carbon ; the iron can be extracted by
nitric acid and used in the preparation of Prussian blue, or
it can be transformed into ferric oxide by burning in the air,
and used over again. The nitrate of iron, which is thus ob-
tained, may be acidified and used to act on the mother
liquors, when Prussian blue and potassium nitrate are ob-
tained. The carbon left in very fine powder, after the iron
has been dissolved out, yields an excellent pigment ; after
washing and grinding it has a fine colour with great covering
power.
Recovery of Oil from Wool. Preparation of Suint.
There are two methods of extracting oil from wool, the one
by means of solvents, the other by soap or alkalies and water.
In the former process the wool is treated in large closed
tanks, in the same way as bones, with volatile solvents such
as benzine, benzol, and carbon bisulphide. In recent years
carbon tetrachloride has come much into favour as a solvent
owing to its non-inflammability, freedom from odour, and
easy volatility, as well as other similar substances, trichlor-
ethylene, dichlorethylene, etc. The solvent is evaporated
from the fat in a still leaving a residue consisting of " suint "
or wool fat mixed with dirt, etc., which latter is removed by
pressing in bags at a moderate temperature.
The wool fat or " suint " thus obtained is further purified
and is used as an ointment mass under the name of " adeps
lanse," or mixed with about 25 per cent of water as " lano-
line," very useful in preparations for the skin.
Suint and also the potash contained in the wool can- also
118 THE UTILIZATION OF WASTE PKODUCTS.
be recovered by the Smith Leach process from wool-scouring
waters by evaporation and centrifugalization.
Potash from Wool Sweat. According to the patent of
Prof. K. Kraut, of Hanover, wool is washed in the ordinary
washing-machine with warm water, to which potash (pearl-
ash) is added. The wash waters are allowed to settle in
tanks, the residual liquid being evaporated to dryness, and
heated on the hearth of a reverberatory furnace. The residue
contains the potash used in washing, and the potassium which
was present in the sweat, also mainly in the form of carbon-
ate of potash. A portion of the potash solution obtained by
lixiviating this residue is again used for washing wool, whilst
the remainder may be evaporated, and the residue calcined,
forming crude potash from which pearl-ash can be obtained.
The residual waste from shoddy which cannot be other-
wise utilized is converted into manures. A sample of
" Ground Wool" gave the following figures "on analysis : *
Moisture 7-92
Organic matter 70'52
Alkaline salts 0-56
Phosphates 0-92
Oxide of iron ) nc
. . . [ . . . . . . 6 9b
Alumina )
Carbonate of lime 5-54
Sand 10-54
100-00
N = to Ammonia . .,,/, = ," * 7'56
1 Ivison Macadam, " Jour. Soc. Chem. Indt.," 1888, p. 95.
CHAPTER XVII.
SILK WASTE.
The Utilization of Silk Waste. The patented machine of
Grothe and Heller remains the only one hitherto made for
the manufacture of silk shoddy from silk rags, since it has
been found that the quantity of silk rags is not great, and
that the fabric cannot be entirely unravelled on account of
the strength of the fibre. (Compare also the article on
Shoddy, p. 106.)
Broadly speaking, there are three branches of silk-waste
spinning, which involve the manufacture of " floret " silk
from first waste, noil yarn or " bourette " silk, and silk
shoddy.
The first raw material to be mentioned is the strusa, i.e.
the clean waste obtained in unreeling the cocoons, which
were unreeled from fire or steam-heated basins. Strusa a
vapeur is accordingly the more valuable, and in greater de-
mand, to which also the fact contributes that it is produced
in larger quantities of uniform quality, since it is made in the
larger works.
Perforated cocoons and whole cocoons which cannot be
unreeled are not included in the strusa ; these are brought
into commerce under the term of " cocoons ".
Strazza is the name of the waste produced in spinning
raw silk, through the breaking or spoiling of the threads.
These materials also occur in a slightly decayed condition,
the decay being said to improve the quality.
The second commercial raw material is decayed waste-
stami, peignees, the stami being somewhat decayed cocoons.
Marseilles is the principal market for silk waste, the follow-
ing commercial qualities being sold there at prices rising from
(119)
120 THE UTILIZATION OF WASTE PKODUCTS.
1 franc to 16*5 francs per kilo (4-d. to 6s. per Ib.) : Bassinets,
Moorish, frisons de nouca, de Rhorassan, Syrian, Accoulys
(Greece), French, Italian, Persian, Broussa, Oshio, Yama en
Flottes, Kibisso Yama, Bourre de Chine, Levant, Spanish,
Adrianople, Salonica.
The damaged cocoons are placed in deep vats, hot
water is added, and the mixture allowed to stand for several
days. The dead pupae quickly cause putrefaction, which
attacks and destroys the gummy and resinous matters. The
material is then smoothed and cleaned by a combing-machine,
and brought into the market under the name of peignee, the
fibres of which are from 5-16 cms. (2-6 ins.) in length.
The flocks and unspinnable waste obtained in spinning
the first waste have been utilized by Pasquay for spinning
into round hemp cords, and plaiting the cords, thus obtaining
long bands, which can be used for wrapping steam-pipes to
prevent loss of heat.
CHAPTEE XVIII.
THE WASTE WATERS OF CLOTH FACTORIES.
Utilization of the Waste Waters in Cloth Factories. It is
well known that the waste waters cause the fouling of the
streams into which they run, and are, on that account, often
a source of great inconvenience, and frequently a restraint
on the manufacture. This is especially the case in flat
countries, such as Holland, where as, for example, at Til-
burg the endeavours to remove the stagnant waste waters,
in this case on sanitary grounds, have been extraordinary.
According to the method of E. Schwamborn, of Aix, 1 the
waste waters of cloth factories are used to prepare lime soaps,
the process being as follows :
Attempts at clarification, by means of sand or cinder
filters, in the so-called clarifying vats, have proved unsuccess-
ful, on account of the mechanical difficulties in separating the
soap, though they may have succeeded with the solid sus-
pended impurities. The soap may be removed by chemical
means, when not only is the water rendered clear, but the
fatty matters contained in it may also be regained. Schwam-
born's process is applied in a similar manner to the recovery
of the wool-fat from the waste waters of wool- washing. The
waters used in fulling and rinsing the cloth are included under
the head of waste waters. They contain the oil used in spin-
ning, to the extent of 15 per cent of the weight of the yarn ;
the soap used in fulling, up to 30 per cent of the weight of the
cloth ; also the size used for strengthening the warp, and, in
addition, dissolved colouring matters and wool fibres. The
clarification of these wash waters depends upon their decom-
position by means of milk of lime, the following being a
description of the method of treatment :
1 " Dingler's Journ.," 216, p. 517.
(121)
122 THE UTILIZATION OF WASTE PKODUCTS.
The washing-machines are provided with two waste-pipes
the one to conduct the first thick liquid, which is gradually
becoming more dilute, into the collecting-tank ; the other,,
for the direct removal of the next clear waters, which are fit
to run direct into a stream. When the collecting-tank, the-
capacity of which is assumed at 150 cub. metres (5295 cub.
ft.), is full, which takes about fourteen days with a con-
sumption of 2000 Ib. of soap, corresponding to the washing
of about 8000 Ib. of cloth, its contents are run off through
a pipe at the bottom, into a tank of equal size at a lower
level. At the same time a thin stream of milk of lime is run
from a vessel (a vat provided with a tap) at a higher level,,
into the outflow pipe, so that an intimate mixture is obtained.
Sloping ground is an advantage for this arrangement ; but
when no slope is available its place must be taken by pumps.
The bottom of the second tank the decomposing tank
is made of three layers of bricks. The lowest is continuous ;
in the next, the bricks are laid with as great interspaces a&
the third layer, which is also continuous and united with
mortar. This system of drains has an inclination towards
one corner of the tank, where it communicates with a
wooden funnel reaching to the top of the tank, and pro-
vided with a slanting series of holes, which are closed with
wooden plugs whilst the suds are being admitted.
The decomposition takes place immediately the liquids
enter the tank ; the lime soap separating in flocculent form
surrounds the solid suspended substances, such as colouring
matters, wool fibres, etc., partly sinking with them gradually
to the bottom, where it finally unites to form a precipitate.
Even a few minutes after mixing the uppermost layer of the
liquid is free from the precipitate, and not only clear, but also
colourless. This clarification, which extends to the dissolved
as well as the suspended colouring matters, is so energetic
that considerable quantities of some dye waters may be added
and simultaneously purified. The characteristic appearance
of the flocks in the clear water affords a sign of a sufficient
THE WASTE WATERS OF CLOTH FACTOEIES. 12&
proportion of lime : slight excess, however, does not hinder
the purification. For 150 cub. metres (5295 cub. ft.) of the
suds, there is required approximately 0'3 cub. metre (1O6
cub. ft.) of lime paste, in the condition in which it occurs in
wet slaked lime, the quantity naturally varying according ta
the amount of soap in the suds.
The clear water is run off by drawing the wooden plugs,,
fixed in the funnel, from above down to the point to which
the thick lime soap is found to have settled. The manipula-
tion is easier if a board partition, also provided with plugs,,
be placed transversely in front of the funnel, up to half the
height of the tank. More water is removed, partly by eva-
poration, which is assisted by the cracking and shrinking of
the mud, and partly by filtration in the system of drains
at the bottom. After several days, the substance lying at
the bottom is a dried fissured paste, which is thrown out on
the edge of the tank, and spread, in order that it may dry
further. In winter, when necessary, the final drying takes
place under cover on suitable supports. If the space at dis-
posal permits a second decomposing tank to be laid down,
the drying is made considerably easier, by reason of the
double time allowed.
The lime soap retains the last portions of liquid for a long
time, whilst, on account of its greasy nature, i.e. its want of
incompatibility with water, it does not again take up water,
such as rain, which may reach it. A lump, after drying in
the air, may lie for days under water without appreciably
gaining in weight. The residue from a tank T5 metre (4 ft.
11 ins.) deep, is about 6 cms. (2'4 ins.) thick, which corres-
ponds to 4 per cent of the liquid.
From statistics it is calculated that the yearly quantity
of cloth washed in Europe is about 10,000,000 cwt. Now,
8000 Ib. correspond, as stated above, to 5295 cub. ft. of
water, or to 2000 Ib. of soap, and include 800 Ib. of oil used
in the spinning (calculated at 10 per cent of the weight of the
cloth). There are obtained on the average about 1600 Ib. of
lime soap. Accordingly the soap waters of Europe corre-
124 THE UTILIZATION OP WASTE PRODUCTS.
spond to about 2,000,000 cwt. of lime soap per annum, which
is produced from 2,500,000 cwt. of soap, containing 45 per
cent, or 1,125,000 cwt. of fatty acids, and from the oil used in
spinning, 10 per cent of the weight of the wool, or 1,000,000
cwt. of fatty acids. Thus, there is a total of 2,125,000 cwt.
of fats annually used in European cloth factories.
The lime soap is insoluble in water ; it dries to a pale
dark-grey substance, which can easily be cut, has a fatty
feel, and burns with a flame when lighted. By decomposing
the lime soap with acid, and then washing with hot water, a
fatty substance is obtained, which may be directly subjected
to distillation, the distillate separating on pressing into solid
and liquid fatty acids.
For the treatment of the suds of wool-washing and cloth
fulling, E. Neumann, of Kosswein, has obtained a patent. 1
In this case the whole apparatus consists of two tanks dug
in the ground (even for large factories two oil-vats of 12-15
cwt. capacity are sufficient), into which the suds are run by
sluices or pipes from the washing-machines or cylinders, and
also of a lift and force-pump, and a filter-press with waste
channel.
Crude calcium chloride (or some substitute, which forms,
with fats, soaps insoluble in water) is dissolved in an equal
weight of water and the solution, to the extent of 1, 1*5, or
2 per cent of the total capacity, according to the amount of
fat in the suds, poured into tank No. 1. The suds are then
run in, the ensuing commotion ensuring a thorough admix-
ture with the calcium chloride solution ; the lime soaps are
at once formed and separate in flocks, which remain sus-
pended in the water. When the first tank is full, the con-
tents are pumped into the filter-press, whilst in the meanwhile
the suds are being run into the second tank, which has just
previously been charged with the necessary amount of calcium
chloride.
In the filter-press there remain lime soaps, dirt, hair, etc.,
whilst the clear water, carrying with it chiefly potassium and
1 "Neueste Erfindungen und Erfahrungen."
THE WASTE WATEES OF CLOTH FACTOEIES. 125
sodium salts and a little excess of calcium chloride in solution,
runs away by the waste pipe. After tank No. 1 is emptied,
tank No. 2 is pumped out, No. 1 again filled, and so on, until
after about eight to twelve hours' work the press is full, a
condition readily recognized when the taps almost cease to
drip. The press is opened, and the cakes, when they do not
fall out unassisted, removed by a wooden spatula. The press
is then closed, and the pump again started, when the process
again commences. Only the introduction of the calcium
chloride, the opening and closing of the feed-cocks, the re-
moval of the press-cakes, and the starting of the pump, re-
quire manual attention ; these operations are the work of but
a few minutes, consequently a special workman is not requisite.
The press-cakes obtained are either dried in the air and
used to prepare an oil-gas, or they are more profitably treated
to recover the fat, which is a separate part of the treatment
of the suds. It may be undertaken by large mills and wool-
washing establishments ; smaller works find it more advan-
tageous to sell the press-cakes to the grease-extractors.
In recovering the fat, the press-cakes are stirred with
very dilute hydrochloric acid to a thin paste : if necessary,
more hydrochloric acid is added to produce a weak acid re-
action. The mass is then forced through a filter-press heated
by steam. The fat and the reformed calcium chloride run
into small vats, from which, after some time, the calcium
chloride solution, containing excess of hydrochloric acid, is
drawn off into a vat containing carbonate of lime, which on
neutralizing the hydrochloric acid again produces calcium
chloride, and this is used to produce fresh quantities of lime
soaps. Thus it is only requisite to procure a supply of calcium
chloride once for all. The fat is heated in a pan over an open
fire to 70 C. with 10 per cent of sulphuric acid of 10 B. ;
after standing some time it forms a clear layer on the top,
which is skimmed off into barrels, and is then ready for sale.
Treatment of Wool-washing Waters with Baryta.
Daudenart and Verbert, of Schaerbeck, near Brussels, 1
1 " Deutsche Industrie-Zeit."
126 THE UTILIZATION OF WASTE PEODUCTS.
mix a solution of barium chloride in a closed vessel with
magnesium carbonate, carbon dioxide being at the same
time introduced ; barium carbonate is then obtained. The
magnesium chloride, which remains in solution, is con-
verted by superheated steam into hydrated magnesia, when
hydrochloric acid is obtained as a by-product. This pro-
cess is designed for the utilization of wool-washing waters,
which are mixed with baryta solution, the precipitate pressed
and decomposed with hot dilute hydrochloric acid. The
separated fat is skimmed off, the liquid evaporated, and the
residue of barium chloride converted into barium carbonate
by the method described above.
The liquid from which the barium soap has been removed
is evaporated to dryness, the residue, consisting mainly of
potash, is calcined, and converted into refined potassium
carbonate in the usual manner.
Utilization of the Eesidues of Wool-washing. Into the
fatty waters, which are contained in large masonry tanks,
sulphurous acid enters direct from the furnaces in which
the sulphur or pyrites is burnt. 1 After the mass has become
.acid, it is allowed to stand for twenty-four hours. The tank
then contains three separate layers the uppermost consist-
ing of impure fat, the bottom of an earthy deposit, whilst the
middle layer contains the sulphites of soda, potash, and
ammonia. This middle layer is concentrated by evaporation,
and the residue burnt in a furnace. The sulphites are then
converted into sulphates, which are obtained by solution and
-crystallization. The upper layer is heated and pressed in
bags, in order to obtain the fatty acids.
A. Gawalowski, of Briinn, has obtained a patent for a
process for the recovery of the fat from wool-scouring waters,
and other industrial waste waters containing soap. The
essential features of this process are : Sulphurization of the
suds and acidification ; the sulphuretted hydrogen, at the
moment of its production, acts on the resulting scum, destroy-
ing the aniline dyes to a great extent. The decanted scum
1 Chaudet, " Muster-Zeit.," 1873.
THE WASTE WATERS OF CLOTH 'FACTORIES. 127
is impregnated with chromates, by which the size, starch,
and dextrine are partially oxidized ; this process takes place
slowly, but is more complete on standing. The scum, after
this treatment, is washed, by which the dyes, the oxidized
mineral pigment, and also the glutin and oxalate products
;are removed. The wash water is deep red to brown. At the
same time, the scum, already oily, can be kneaded in water
like butter or lard, but can no longer be mixed with it to
-a liquid similar to the original suds. It still contains an
excess of chromates and traces of free acid, and would there-
fore easily destroy press cloth. Gawalowski accordingly stirs
it with a reducing solution, which changes the chromate to
chromium oxide, and then presses out the neutral green
liquid in the cold, after which the cake of scum is pressed
warm. This method of treatment results in the highest yield
of fat being obtained, a purer product moreover, which can
well be used, after the acid has been removed, in spinning dark
coarse yarn.
In the Yorkshire district l the wool-scouring liquors are run
into a large brick-lined tank, in which they are treated with
a sufficiency of oil of vitriol diluted with water to render them
slightly acid. From the first tank the mixture runs into a
second where the grease rises to the surface in the form of a
scum, the liquid is filtered through coarse clinker in the bottom
of the tank, the grease remaining on the surface being scraped
off and wrapped in squares of canvas which are then hot
pressed in a hydraulic press at 400-500 Ib. pressure per
square inch. The grease runs through the bags into tanks
or barrels placed below. It is a brown solid grease melting
at about 105 F. and worth from 8 to 12 per ton. It is
used in very large quantities in the woollen districts for
working up shoddy and mungo. The liquid from the tanks
is sufficiently pure to turn into the streams. Most manu-
facturers are averse to treating their waters, but where it has
been done there is a considerable profit. The grease is also
-distilled with superheated steam yielding " distilled grease
1 " The Wool Year Book," 1914, p. 252.
128 THE UTILIZATION OF WASTE PRODUCTS.
oleine " and "distilled grease stearine," both of which are
valuable products, the former being employed for oiling wool,
and the latter as a sizing tallow. The following is an analysis
of recovered or Yorkshire grease by Lewkowitsch :
Volatile acids 1-28
Insoluble free fatty acids .... 20-22
Combined fatty acids 48*47
Alcohols . . . . . . 36-47
106-44
The excess over 100 in this analysis is due to the water
taken up by the fatty acid and alcoholic radicles as a re-
sult of the hydrolysis. The alcohols are cholesterol and iso-
cholesterol principally.
CHAPTEE XTX.
COTTON-SPINNERS' WASTE.
COTTON waste l consists of soft waste and hard waste. The
former, being the waste from opening and carding machines,
is in an open condition, the latter is from the spinning frames,
cop bottoms, etc., and is more or less twisted.
The soft waste is moderately easy to treat, being worked
up in a similar manner to ordinary cotton and spun for the
manufacture of sheetings, flannelettes, towels, and quilts, or it
is converted into wadding, and also into guncotton. In the
manufacture of wadding it is put through a wadding plant
consisting of carding engine, travelling chain creeper, lap-
forming apparatus, gumming machine, and drying chest.
The hard waste requires stronger treatment, being put
through a waste machine consisting of an iron cylinder pro-
vided with strong steel teeth and an iron doffer similarly
provided which opens out the waste ; after which it passes
through a breaker and a scutcher which cleans it and forms
it into a uniform lap, which passes to the carding engine,
Derby doubler, a second carding engine, and then to the mule
or ring-spinning machine.
Waste which is too hard spun to be utilized by either of
the above methods is opened up by means of a very powerful
opening machine and is then sold as engine-cleaning waste.
As previously mentioned, this waste, even after use, is still
valuable, being treated for the extraction of the oil and then
again used for a similar purpose.
Cotton-spinners' Waste in the Manufacture of Gun-
cotton. According to the English patent of Mackie, the
waste of cotton-spinning is treated with superheated steam
^ee " The Cotton Year Book," 1914, p. 232.
(129) 9
130 THE UTILIZATION OF WASTE PEODUCTS.
in order to remove the oil, then carded and immersed in
the usual acid mixture 300 parts of a mixture of 1 part of
nitric acid (specific gravity, T52) and 3 parts of sulphuric acid
(1'85), cooled to 5-25 C. The guncotton produced is carefully
washed, cut to pieces by means of a rapidly rotating circular
knife, and finally passed between rollers, from which it issues
in a very finely divided state. This cutting and squeezing
are said to have the advantage over the usual pulping in the
beating machine, in that all the capillary tubes are completely
destroyed, and thus any residual acid can readily be washed out.
The succeeding operations consist in mixing the nitrated
cotton with saltpetre and sugar (67 parts of guncotton, 28
parts of sugar, and 5 parts of saltpetre), granulating the mix-
ture by means of wire sieves, and drying in tightly closed
pans heated to about 38 C., in which a vacuum is maintained
by a pump. An increased addition of sugar and saltpetre
decreases the violence of the explosion of the guncotton.
According to the English patent of J. Hall, rags and
other linen waste are brought into a bath composed of equal
volumes of nitric acid (specific gravity, 1'5) and sulphuric
acid (specific gravity, 1*84), and diligently stirred in it for
12-24 hours. The mass is then allowed to drain, pressed,
carefully washed for 7-14 days, and dried. For purposes
for which a violent explosion is not required, the guncotton,
whilst still moist, is mixed with starch paste.
Heddebault has discovered a method by which wool can
be removed in the dissolved state from fabrics in which it is
contained in admixture with cotton or other vegetable fibres.
When these fabrics are subjected to the action of superheated
steam under a pressure of five atmospheres, the wool dissolves,
and falls to the bottom of the vessel, whilst the cotton, flax,
or other plant fibre resists the action, remaining in a condition
suitable for the manufacture of paper. The fluid mass, in
which the dissolved wool is contained, is evaporated to dry-
ness ; it is completely soluble in water. Bags treated in this
manner gain in value to a sufficient extent to cover the cost
of the process.
CHAPTEB XX.
JUTE WASTE.
Treatment. The softening, beating, and carding machines
are used in treating jute waste. 1
1. Jute Cord and Fabric. Both these are collected and
go into the store as the first waste product. The latter is
used for packing purposes. The former is first unknotted by
hand-labour outside the factory, then untwisted or unravelled,
and cut into lengths of about a yard, which are laid parallel
to one another, made up into bundles of about 45 lb., and
tied together. A large number of these bundles go into the
softening house, where they are sprinkled with water and fish
oil or mineral oil emulsion, allowed to lie in layers, and then
taken to the breaker card. The jute cord is treated either
alone or mixed with other jute.
2. The root ends, which have been cut off, are worked up
in the same manner as the cord into the lowest yarn numbers,
and are spread out on the feeding-table of the corresponding
breaker card. Other waste, which is formed at times, is, in-
stead, taken to the finisher card, which treats the correspond-
ing qualities. In order that markedly different slivers may
not be produced by too rapid supply, these tow slivers must
be introduced slowly and as thin as possible over the feeding-
rollers. The moment of passing the rollers is the best for
adding faulty slivers.
3. (a) Carding Tow. In the first place, the shorter strips
of fibre are sorted out by hand, and again subjected to the
carding operation, after which they are given a beating or
shaking treatment. The lower qualities of this tow are sepa-
X E. Pfuhl, " Dingler's Journ.," 222, p. 573.
(131)
132 THE UTILIZATION OF WASTE PRODUCTS.
rately collected and stored in suitable places in the open;
they are removed by cartloads for manure. The better
qualities are compressed in box-presses to bales weighing
2-4 cwt., which are tied up and sold to paper or pasteboard
makers.
(b) Spinning Tow is not subjected to a special treat-
ment ; either alone or mixed in the shaking machine with
the breaker tow, it is pressed into bales, packed, and sold to
paperrnakers.
(c) Roving Tow can be readily introduced into the spin-
ning process. It is either placed on the cloth of the breaker
card together with long jute, or, preferably, it is passed through
the softening machine, and then taken to the finisher card
for further treatment, for which purpose this machine must
be supplied with a feed-table, the fibres thus produced being
longer. The roving tow should, however, never be added for
re-treatment to medium or better qualities.
(d) Good Tow from the Fine-spinning. The dropped
threads of the rovings are sorted, mixed with the roving tow,
and spun together with it. A second sorting of the tow then
takes place in the softening house, after which it is sent once
through the softening machine and then over the tow carder,
when a loose and very soft cleaning material is obtained,
which is packed in sacks, or, better, compressed into bales,
and sold to railway workshops, etc. This tow is not suitable
for spinning.
(e) Clean Thread Waste. This is passed once or twice
through the softening machine, when it also gives a very
fine cleaning material, which, however, is somewhat less
soft than the preceding substance. The waste, after this
treatment, is frequently used for stuffing ordinary mattresses,
sofas, etc., 'in place of flax tow, in comparison with which it
has the advantages of cleanness and purity, but it has, how-
ever, the smell of fish oil.
(/) Ordinary Sweepings. From the sweepings any good
waste, such as sliver, roving tow, etc., is sorted out ; then
follows the search for oily cleaning waste, which, owing to
JUTE WASTE. 133
the presence of oil is regarded as liable to produce danger by
fire, is sent to light the fires in the boilerhouse, for which no
better utilization can be found. The remainder is either at
once mixed with the beating ordinary carding-tow, or is
previously beaten, when the better-class fibres remaining in
the machine are united with the tow from the breaker card.
The tow-cleaning machines may be divided, according to
the nature of the beating apparatus, into (a) simple beating
or shaking machines, (b) conical shaking machines, and (c)
double shaking machines. Of these three machines, the
most practical jare the first and last.
Simple Beating or Shaking Machine. In a cylindrical
vessel, the upper half of which consists of a tight casing with
a door for admitting and removing the material, and the
lower half a grating of laths, moves a horizontal shaft pro-
vided with fast and loose pulleys. On the shaft are found
six series of round iron rods as beaters. As the shaft rotates,
the beaters move between two other series of fixed rods. The
side walls of the machine are well boarded, so that the dust-
chamber is formed under the grating. After the waste (card-
ing tow) has been introduced through the above-mentioned
door, and distributed throughout the machine, the door is
closed, the shaft set in motion, and the beating operation
allowed to proceed for 10-15 minutes. The shaft with the
beaters is then removed, and the machine emptied of the
cleansed waste through the door. The dust, sand, bast
particles, etc., beaten out, fall through the grate into the
dust-chamber. They are most readily and conveniently re-
moved from the workroom if the machine is erected over a
brickwork pit, connected by means of a passage with a special
dust-shed in the open. If the drainage conditions do not
permit such a pit and connection with a shed, the shaking
machine must be erected in an elevated position, a large box
running on wheels being brought under the dust-chamber,
in which the ordinary refuse shaken out can collect. If the
dust-chamber is connected with a fan which carries away the
lighter dust to deposit it in a suitable position, it is still
necessary to have an arrangement of this kind for collecting
134 THE UTILIZATION OF WASTE PRODUCTS.
the heavy particles. The beater-shaft usually has a speed of
260-280 revolutions per minute.
Double Beating Machine. Two horizontal shafts, each
with six series of iron beaters, are so arranged in a cylin-
drical casing that the rods of one move through the spaces
between the rods of the other. The casing also in this
machine consists of an upper tight cover and a grating below.
The beaters in addition strike through another series of rods.
The opening for charging is closed by a counterpoised door
during use. The dust-chamber communicates either with a
pit or with a closed box ; a fan may also be used. The feed is
fixed in the upper part of the cover ; it consists of an endless
cloth, a small loose roller, and a roller, studded with needles,
moving at a high speed both in a tight-fitting casing. The
needle roller is designed to introduce the material, as far as
possible, into the beater in an unravelled and divided state.
A certain quantity of waste is brought into the machine and
the feed set in motion. In a few minutes the door is opened,
so that the cleaned material may be thrown out and caught
in a box placed to receive it. The door is then closed and
a fresh quantity introduced. This repeated change can
readily be worked automatically by suitable mechanism.
The Tow Carding Machine or Teaser Card. A rotating
drum, to which the material is brought by the feeding apron
and grooved rollers, is surrounded on the upper half by three
pairs of turning and squeezing rollers working together.
These rollers treat the material in the known manner ; it
then goes to the delivery roller, from which it is drawn off
by smooth rollers as a coherent fleece and carried on to the
delivery apron. The machine is therefore a semi-circular
card, with an upper working half. In order to prevent the
production of dust, the rollers are all protected by a sheet-
iron cover. The diameter of the drum is generally 3-4 feet ;
it is about the same in length, and runs at 100-120 revolu-
tions per minute. The rollers move at various velocities,
which have to be adjusted to the needs of the moment. The
ratio of the velocity of feed to that of delivery should be at
the most 1 : 15.
CHAPTEK XXL
UTILIZATION OF BAGS.
A VEEY large quantity of rags of various kinds are collected
from ashpits, and from the marine store dealers. These rags
are sorted into different heaps according to the nature of the
fibre and their colour. Woollen rags, as before stated, are
used in the manufacture of shoddy and mungo ; cotton and
linen rags go to the papermaker ; silk rags to the manufacturer ;
while old rope and string, old canvas bags, etc., are all utilized
in some way or another.
Woollen rags or cuttings are also made into carpets. For
this purpose they are cut into strips about f in. wide and
6-8 ins. long, and drawn through a piece of coarse canvas
or hessian so that both ends are on the same side. Simple
patterns are made with rags of different colours. These
carpets are very warm and durable, and, owing to their
cheapness, are eminently suited for kitchens. Printed cotton
and silk cuttings are cut into -various patterns and stitched
together to form quilts and bedcovers. Both these were
home industries at one time, but the modern tendency of
buying everything ready made is gradually replacing them
by factory-made goods which though more showy are not
necessarily more durable.
(135)
CHAPTEE XXII.
COLOURING MATTERS FROM WASTE.
Utilization of the Waste from Dye-wood Extracts. Croissant
and Bretoniere, of Lavalle, gave a detailed account of their
work in this direction in 1875. x In the first place, this con-
cerns the solid dye-wood extracts, each of which contains its
own peculiar tannin or colouring matter. Now gallic acid, a
product of the decomposition of tannic acid, on heating to
about 250 Ci, gives metagallic acid. The chemists named
therefore treated logwood extract by the same reaction,
when they obtained an evolution of carbon dioxide and a
black voluminous substance, insoluble in water, but readily
soluble in alkalies, and precipitated from these solutions by
acids in the form of brown flocks. With solutions of different
metallic salts it gave variously coloured precipitates. This
decomposition of logwood extract, accompanied by the evolu-
tion of carbonic acid gas, also takes place at 200 C. in the
presence of caustic alkalies. In the latter case is obtained the
soluble alkali salt of an acid analogous to metagallic acid,
which is precipitated from its solutions on the addition of
other acids or of metallic salts. One important point is that
the alkaline solution of this compound has a very strong direct
dyeing power for vegetable fibres. If instead of the natural
colouring matters the same process is applied to other organic
substances, there is known to result by the action of alkalies a
salt of oxalic acid, e.g. from sawdust. The reaction, how-
ever, takes quite a different course if sulphur be at the same
time introduced into the compounds. Either the sulphur
enters into direct combination with the substance without
J Bull. Soc. Ind. Mulhouse; " Dingler's Journ., " 215, p. 363.
(136)
COLOURING MATTERS FROM WASTE. 137
the elimination of any element, as in the case of the aloe, or,
as more frequently happens, the sulphur unites with a por-
tion of the hydrogen of the organic substance to form sul-
phuretted hydrogen, which is volatilized, the organic substance
thus becoming reduced. In both cases, however, and from
many organic materials, there are produced in this manner
new substances, which act as substantive dye-stuffs for animal
and vegetable fibres, which produce intense and fast shades
without the assistance of a mordant.
The discoverers have heated a series of the most diverse
organic substances in closed vessels with sodium mono- and
poly-sulphide, and in every case find confirmed the correctness
and general applicability of their discovery.
The colouring matters are readily and certainly produced
in the form of a swollen voluminous mass, more or less dark
in colour according to whether the temperature of preparation
was higher or lower, between the limits of 200-300 C., and
according to the longer or shorter duration of the heating.
The solubility of the product also increases with the tem-
perature arid duration of heating, as also the fastness of the
effects produced on fibres, especially in regard to the action
of light. All the products are very hygroscopic, and therefore
require to be kept in well-closed sheet-iron boxes; it is also
necessary to guard against oxidation by the air, by the action
of which the colouring matter is converted into an insoluble
substance. Without this precaution they become quite use-
less in four to five months. In a freshly prepared dye-bath
the colouring matter has such affinity for vegetable and animal
fibres that, when the dyeing is sufficiently protracted, the whole
may be withdrawn from the bath and a colourless liquid left.
Of particular importance to the productiveness of this colour-
ing matter is the nature of the water employed. In waters
containing lime it dissolves only incompletely ; if only such
water is available it requires to be purified before use by
boiling with soda. The colouring matter is also separated
from its solution by acids, but the precipitate readily redis-
solves in dilute alkaline liquids. This behaviour affords a
138 THE UTILIZATION OF WASTE PRODUCTS.
means of purifying the colouring matter, and obtaining it in-
the form of a dry unalterable powder, soluble in alkaline-
liquids. Other precipitants are alum and metallic salts ; the
precipitates vary in colour according to the metal contained
in the salt. The most useful precipitant for dyeing pur-
poses, however, is potassium bichromate, owing to the oxidiz-
ing action of the chromic acid it contains, and because the
precipitates which it produces, with few exceptions, are quite
unacted upon by most solvents, even by boiling caustic
liquors ; therefore this salt is a most valuable means for fixing
the colour upon the yarn or fabric.
CHAPTEK XXIII.
RESIDUES IN THE MANUFACTURE OF ANILINE DYES.
Utilization of the Residues. In the manufacture of magenta,
resinous residues are produced, which contain, in addition to
organic matter, almost the whole of the arsenic originally
employed.
According to Bersch, this arsenic may be regained by
various methods. The arsenious and arsenic acids in the
residues are first brought into solution by boiling with hydro-
chloric acid, and extracting the undissolved residue with
water. The two solutions are mixed and neutralized with
soda, when a dark green precipitate is produced. The liquid
filtered from the precipitate, consisting of a solution of sodium
arsenite and arsenate, is mixed with milk of lime, which pre-
cipitates calcium arsenate. The precipitate is decomposed
in lead-lined vats by means of sulphuric acid, to which a
little nitric acid has been added. The solution of arsenic
acid is drawn off from the deposited sulphate of lime and
again used, after concentration, for the oxidation of aniline
oil.
In order to work up the mother liquors of the magenta
manufacture for arsenic acid, the acids of arsenic are pre-
cipitated by lime, the precipitate washed and dried, and the
arsenic reduced by ignition with coal. The arsenic vapours
evolved are allowed to come in contact with hot air, by
which they are burnt to arsenious acid, which is condensed,
and again oxidized by nitric acid to arsenic acid. This pro-
cess is, however, only suitable if concentrated liquors are in
question. Weak liquors have to be evaporated in shallow
pans, which are heated by the flue gases from other ap-
(139)
140 THE UTILIZATION OF WASTE PBODUCTS.
paratus ; after this concentration they are treated by the
former process.
Another method, which (according to Bersch) is suitable
for works where very cheap fuel is obtainable and for work-
ing on a very large scale, consists in mixing the very con-
centrated solution of sodium arsenate with powdered chalk
and lignite, drying, and heating the mass in a furnace. The
vapours of the (reduced) arsenic passing from the furnace
are, by contact with the air, burnt to arsenic trioxide, which
is condensed and deposited in long flues. The residue in the
furnace consisting of soda mixed with calcium carbonate is
extracted with water ; thus the two substances are separ-
ated, to be again used in succeeding operations for recover-
ing arsenic.
In order to obtain magenta from the mother liquors left
after the crystallization of the dye-stuff, soda solution is added
to them, which separates the magenta base. From the re-
sidual liquid the arsenic is regained by one of the methods
described.
When the mother liquors are worked up systematically,
shallow leaden pans are employed, these being closed and
provided with vapour pipes leading into a chimney with a
good draught. When possible, the pans are heated by the
flue gases from the vessel in which aniline is transformed into
magenta. The very concentrated mother liquors yield a
considerable quantity of sodium arsenate, and the liquid still
remaining may, in order to obtain the rest of the arsenic, be
precipitated with lime, and the precipitate converted into
arsenic acid, as previously described.
By systematic treatment of the impure mother liquors
from the manufacture of magenta, several firms have suc-
ceeded in producing certain definite shades of reddish-brown
and brownish-red, passing into the deepest brown. It is of
the first importance always to produce these of the same
nature, so that the same shade of colour may always be pro-
duced by a dye which has once been known in commerce
under a certain name. This object may be attained, accord-
KESIDUES IN THE MANUFACTURE OF ANILINE DYES. 141
ing to Bersch, by always working by one and the same pro-
cess in the manufacture of magenta, and by always treating
the mother liquors by the same process of evaporation.
Treatment of the Residues produced in the Manufacture
of Aniline Red. The methods with arsenic acid and mer-
curic nitrate, as also Coupier's process with nitrobenzene,
iron, and hydrochloric acid, give only a yield of 30-40 per
cent of the aniline employed in the manufacture as saleable
dye. The Actiengesellschaft fiir Anilin-Fabrikation, of
Berlin, has now found, according to a patented process, that
the air-dried residues give, on dry distillation from horizontal
retorts, a distillate which, together with water and ammonia,
also contains aniline, toluidine, xylidine, and their horno-
logues, which can again be directly employed in the manu-
facture of aniline red ; in addition to this there is produced a
high-boiling oil, consisting principally of diphenylamine, but
containing also naphthylamine and acridine. The residual
coke is used as fuel.
Treating with a Solvent Waste Acids from Nitrations.
No. 15,455 of 1915. J. W. Leitch, B.Sc., of Somerville,
Edgerton, Huddersfield, claims: (1) A process of continu-
ously extracting by means of solvent nitro-compounds from
waste acids from nitration by running together in suitable
proportions the solvent and acid into a mixing vessel while
maintaining the conditions of temperature and concentration
suitable for the extraction, and allowing the mixture to flow
into settling tanks from the vessel through an overflow pipe.
(2) The apparatus for the process referred to injclaim 1, com-
prising a closed vessel containing a vertical stirring shaft
having propeller blades, surrounded in known manner by a-
cylinder open at each end, these blades being adapted to
draw the liquid upwards into the sphere of action of other
propeller blades on the shaft which throw the liquid out-
wardly and downwardly, the cover of the vessel having a
trough for distributing the liquid continuously charged into
the vessel, an overflow pipe to the vessel for continuously
discharging the liquid to settling vessels, and devices for
internally or externally heating or cooling the vessel.
CHAPTEE XXIV.
DYERS' WASTE WATERS.
Recovery of Ar senates and Phosphates. For the recovery of
arsenates and phosphates from the solutions used in fixing
the mordants the so-called " dunging" the following pro-
cess has been patented by Higgins and Stenhouse : The
waste liquors are mixed with an iron or manganese salt, the
mixture made alkaline by milk of lime, and allowed to settle.
The precipitate, which contains the arsenic and phosphorus,
after removal of the clear liquid, is brought on to cloth
strainers. A portion is examined for the percentage of bases
it contains, and an equivalent quantity of sodium mono-
sulphide added to the whole bulk. The mixture is then
boiled with water in a steam-jacketed pan for two hours.
The resulting clear solution contains sodium arsenite,
arsenate, and phosphate ; if a little sodium sulphide should
be present, it is oxidized by means of sodium hypochlorite.
The solution is now again available for "dunging," but if it
should be found too alkaline it is neutralized by a mineral
acid.
Recovery of Dyes from the Waste Liquors. This patented
discovery is due to Remmers, of Glasgow. It accomplishes
the recovery of alizarine and purpurine from the waste
liquors obtained in dyeing Turkey reds and other shades, for
which madder or artificial alizarine is employed. For this
purpose the waste liquors are run into a large tank, into
which hydrochloric or sulphuric acid is run in quantity suffi-
cient to precipitate the whole of the colouring matter from
the solution. The reaction is accelerated by stirring. After
settling, the clear liquid is drawn off from the precipitate, the
(142)
DYERS' WASTE WATERS. 143
latter being boiled for some minutes, when necessary, with a
little acid, until the liquid acquires a yellow colour. After
cooling, the precipitate is separated from the liquid by means
of a filter press, and washed until neutral, when it may again
be used in the same way as the original material.
Recovery of Tin from the Waste Waters of Dyeworks.
Mogret has given an account of the recovery of tin from the
waste liquors of dyeworks. 1 To a greater extent than ever, tin
preparations, in the form of stannic or stannous salts, play an
important part in dyeing, both as mordants and for weighting
silk. Hardly half the quantity of tin used is really utilized,
the other half being lost in the used mordanting or dyeing
baths or in the wash waters of yarns and fabrics. Since this
metal is expensive, the wash waters and used liquors re-
present a considerable sum. In order to regain a portion of
the valuable constituents, which run into the drains and
'Contaminate the rivers, the dye-baths and wash waters are
collected in tanks. In these the tin is precipitated by the
addition of granulated zinc, or, better, of zinc dust known
under the name of "preparation". The precipitated tin,
mixed with stannic oxide, is filtered through woollen cloth, the
precipitate washed, dried, and melted at a white heat, with
the addition of borax and a little granulated zinc. The
stannic oxide is reduced to metal by the zinc, the excess of
zinc being volatilized at the high temperature employed. In
this manner pure metallic tin is obtained, which is poured
into moulds, and is of considerably higher value than
the zinc used in its recovery. This method is said to be
employed in several large works in France.
With regard to dyers' waste waters generally, they are,
whenever convenient, turned into the nearest stream or river.
'This is, however, not always possible, besides which it is
never desirable to turn out impure liquids in this way. In
ome works large brick tanks are constructed into which the
liquors are run. Acid liquids are neutralized with lime or
alkaline liquids with sulphuric acid, in some cases with de-
1 " Moniteur de la Teinture," 1889 ; " Farber-Zeit.," 1889.
144 THE UTILIZATION OF WASTE PEODUCTS.
position of the colouring matters. Sometimes dyes mutually
precipitate each other. After standing, the liquid is passed
through sand niters or bacteria beds and is then sufficiently
pure to be run into a stream. Alkaline bleaching liquids are
purified by the septic or closed tank treatment and then
passed through sand or coke.
CHAPTEE XXV.
WASTE PRODUCED IN BUTTER-MAKING.
IN creameries where butter is produced the cream is separ-
ated from fresh milk by centrifugal means more completely
than can be done by hand, and is either sold in that state or
converted into butter. This leaves as a residue a consider-
able proportion of skim milk containing only about 0*3 per
cent of fat. The following analyses show the composition of
whole and skim milk :
Whole Milk. Skim Milk.
Fat . . . . . ... . . 3-50 0-46
Casein and albumin . . '. , .'. ' 4 -7 5 3-37
Sugar. . :- . . / . ; . * 4-17 5'34
Ash . . . .'.,'' . . 0-70 0-72
Water. 86-88 90-11
100-00 100-00
Several methods of utilizing this skim milk have been
devised. In Ireland a considerable proportion of it is con-
verted into condensed skim milk, for which purpose it is
evaporated in a vacuum pan at 100-120 F. until sufficiently
concentrated and the requisite quantity of sugar added.
The composition of such milk is as follows (Dold & Gar-
ratt) :
Fat . . . .,- , 4 _ . -. . 0-78
Casein, etc. . r^=^ . . . 10'33
Ash 2-16
Cane sugar ....... 50*35
. Milk sugar . . . . . ... . 10 92
Water . . . . . . . 25-46
100-00
This condensed skim milk is a useful article of diet, parti-
cularly where cheapness is important, but, as pointed out by
(145) 10
146 THE UTILIZATION OF WASTE PEODUCTS.
many medical men, it is not at all suitable for infant feeding
owing to its deficiency in fat.
The skim milk has also in America been converted into
cheese, and although such cheese may not be easily digestible,
its sale is quite legitimate provided that it is labelled in a
proper manner. Certain manufacturers of this commodity
were at one time not content with this, but replaced the
butter fat with margarine or lard, and sent it to this country
to pass muster as genuine cheese and thus command a higher
price.
A proportion, of the skim milk is treated for the separa-
tion of casein. For this purpose it is slightly acidified or
treated with rennet, the curd which separates being washed
to free it from soluble impurities and then dried by centrifugal
means, followed by hot air with or without a partial vacuum.
The casein thus produced forms a very light flocculent
powder which is easily dissolved, or rendered fluid by am-
monia or borax, the paste thus formed being used as an ad-
hesive also in the dressing of cloth and surfacing of paper.
Casein is also mixed with zinc oxide and other pigments and
moulded into various articles. This is known as galalith,
etc. Some of these products resemble natural ivory so closely
as to be with difficulty distinguished from it.
Another use for casein is as a food product. It is highly
nitrogenous and is a valuable dietetic substance. It is mixed
with flour and made into biscuits, also with cocoa, etc. A
well-known blood enricher is also casein in an almost pure
condition. 1
The liquid or whey drained from the casein contains the
milk sugar. The following is an analysis of such whey :
Fat 0-10
Proteids 0'27
Milk sugar 505
Ash 0-47
Water 94-11
100-00
1 " Casein : its Preparation and Technical Utilization," by Robert Scherer.
WASTE PRODUCED IN BUTTER-MAKING. 147
For the separation of the milk sugar it is necessary that
the whey should be fresh, as fermentation destroys it, yield-
ing lactic acid, alcohol, etc.
The whey is neutralized and evaporated considerably
when impure milk sugar separates in hard crystals. These
are dissolved in water, purified by passing through animal
charcoal, and the solution again evaporated, yielding prac-
tically pure milk sugar. The sugar thus produced has the
same composition as cane sugar (C^H^On), but quite different
properties, for instance it is scarcely sweet. It differs also
from glucose or grape sugar. It is used principally for add-
ing to cow's milk for making " humanized " milk, also for the
preparation of lozenges and medical tablets, for which pur-
pose it is eminently well fitted.
CHAPTEE XXVI.
MOLASSES.
Utilization of Molasses. One of the uses of molasses is in the
manufacture of spirit. For this purpose its value depends on
the percentage of sugar : in order to estimate the value the
molasses are diluted, say to 18 on an ordinary saccharometer,
the solution mixed with an excess of yeast at 24-25 C.>
brought into a warm place, and allowed to ferment. If now
the saccharometer shows 3 unfermented, there was in the
18 solution apparently (since the spirit present in the fer-
mented liquid affects the saccharometer reading) 15 of sugar ;
thus in molasses which showed 45 originally, 37*5. In order
to find the true amount of sugar, the fermented liquid is
boiled, the alcohol driven off, and the loss in boiling replaced
by distilled water ; a polariscope reading is again taken,
when the percentage of sugar indicated by the instrument is
the true unfermented. For example, if the saccharometer
shows 19 before fermentation, in the unboiled fermented
liquid 4 C , in the boiled fermented 5-J, then there are really
13^ fermentable. 1
Usually, however, the percentage of crystallizable and
uncrystallizable sugar are determined by means of the polari-
scope and Fehling's solution.
Molasses contain sugar, salts, nitrogenous and nitrogen-
free compounds, alkalies, and alkaline earths. The latter
hinder fermentation. In order to neutralize the alkalinity
which retards fermentation, 0'5-1*5 per cent of sulphuric acid,
as required, is added to the molasses. Molasses do not need
mashing, but they are somewhat diluted in the mash-tun, ac-
ll( Populates Handbuch der Spiritus- und Presshefe-Fabrikation," A.
Schonberg, 4th ed., Vienna, Hartleben.
(148)
MOLASSES. 149
cording to their thickness, and the sulphuric acid, previously
mixed with water, added. The mixture is then heated until
the sour | smell disappears. Acid is only to be used when the
molasses have an alkaline reaction ; if this be the case, acid
is added until blue litmus paper dipped in it is coloured a
weak wine-red. It is preferable to add the water in the
mash-tun, and to prepare the liquid there, for if the water is
added in the fermenting vat there is difficulty in stirring the
liquid. The molasses is intimately mixed with the water;
and since cold molasses mix with water with great difficulty,
heat is applied whilst mixing in the mash-tun. A cooler is
necessary in molasses works. Whether sulphuric or hydro-
chloric acid is employed for neutralizing depends on the
success with which the liquid ferments. Generally, after
neutralization with sulphuric acid, 1-2 Ib. of hydrochloric acid
are added to a tun containing 90-100 buckets (say 300 gals.).
Many samples of molasses require no hydrochloric acid ;
those which require it are generally the produce of works
using beet from wet, heavy soil, or from uncultivated ground.
As a rule, the quantity of hydrochloric acid is 5-10 per cent
of that of the sulphuric acid.
An intense green malt yeast is generally used for molasses
wort, to 'which beer yeast or pressed yeast is added every
day, since molasses worts require a very heavy fermentation ;
10 per cent of yeast is employed as a rule. It is also very
advantageous to initiate a very strong preliminary fermenta-
tion. The wort after adding the yeast soon acquires a layer
on the top 3-4 ins. thick, below which, if the treatment has
been successful, a very intense fermentation proceeds. The
fermenting vessels are filled to within 2-3 ins. of the top, and
the wort pitched at 30-44 C.
If beet juice is available, it is used for diluting the
molasses. If a vat -does not commence fermentation pro-
perly it is assisted by an addition of beer yeast or fermenting
wort. Care has to be taken that the fermenting room is al-
ways at a temperature of 18-20 C. Since these worts rapidly
cool and ferment with difficulty, it is necessary to have one
150 THE UTILIZATION OF WASTE PKODTJCTS.
or two stoves in the room, so that it can be warmed during
the winter months.
After distillation the spent wash of country distilleries is
used as food for cattle, mixed with more or less other
materials ; it is also ^used as manure. In large distilleries
the wash is evaporated in the " thickening pans," and then
brought into calcining furnaces built like black- ash furnaces.
As a rule three furnaces are arranged in steps one below the
other ; as the wash becomes concentrated it is allowed to flow
from one to the other, being carbonized in the last. Accord-
ing to the quality of the molasses, 11-12 per cent of carbon-
aceous residue is obtained, containing about 50 per cent of
potassium carbonate. The free acid in the wash is frequently
neutralized with lime, the sulphate of lime is then allowed to
deposit, and the wash, after evaporation in the pans, brought
into the above-mentioned calcining furnace in order to destroy
the organic matter.
When given in large quantities to cattle, molasses wash
causes sickness.
If potatoes are to be worked together with molasses, it is
most convenient to mash the two together, and to mix them
in the inverting vessel. The prepared molasses wort is run
into the inverting vessel during the grinding of the potatoes.
If, however, there is no vessel in which the molasses wort
can be made, it is done in the inverting vessel, and the
ground potatoes added. The best proportion is 25 cwt. of
potatoes to 2'5-3 cwt. of molasses of 42. The manipula-
tion is the same as with potato worts, except that the yeast
must be increased in proportion to the molasses. With these
proportions the wash may be used as fodder without fear.
C. Vincent has introduced & process for the more rational
utilization of vinasse the residue left after distilling the
alcohol from fermented beet molasses ("Chemical News").
Formerly the vinasse was calcined in open hearth furnaces
for the recovery of the potash salts. The idea of utilizing
the gaseous compounds produced in this process had been
mooted years ago, but has only recently been realized by
MOLASSES. 151
Vincent. In this process the calcination is performed in
cast-iron retorts ; the products of distillation, which condense
at the ordinary temperature (tar and ammonia water), are
caught, whilst the gaseous products are led away to heat
the retorts. The ammonia water is practically similar to
that obtained in making gas by the dry distillation of coal,
but contains, in addition to the ordinary constituents, methyl
alcohol, methyl cyanide, methyl sulphide, and, what is parti-
cularly remarkable, a large quantity of trimethylamine salts.
The aqueous alkaline product of the distillation is, ac-
cording to a further account in the " Pharmaceutische
Zeitung," first over-neutralized with sulphuric acid and then
distilled. Methyl alcohol comes over ; on cooling, ammonium
sulphate crystallizes from the residue. The mother liquid
contains much trimethylamine sulphate.
Trimethylamine has at present no particular commercial
value ; it is, however, very suitable for the production of
methyl chloride. When trimethylamine hydrochloride is
heated, it decomposes into ammonia, free trimethylamine, and
methyl chloride. The decomposition begins when the boil-
ing point of the concentrated mother liquor of the trimethyl-
amine salt has reached 260 C., and is complete at 325 C.
The gaseous products are conducted through hydrochloric
acid, which retains the alkaline compounds ; after sal-am-
moniac has been separated from this solution by evaporation
and recrystallization, the solution is again subjected to dis-
tillation. The methyl chloride which passes over, after puri-
fication by washing with dilute caustic soda solution, is dried
by strong sulphuric acid, and pumped into iron or copper
cylinders closed by screw-cocks. The gas is liquefied by
pressure in these cylinders, in which state it is sold.
Methyl chloride has two technical applications ; it is very
suitable for the production of " artificial cold," and it is used
in manufacturing methylated aniline dye-stuffs, which have
previously been very costly owing to the use of methyl iodide.
When methyl chloride evaporates, its temperature falls to
- 13 C. ; but if the rate of evaporation be increased by the
152 THE UTILIZATION OF WASTE PRODUCTS.
passage of a current of dry air, the temperature sinks to
- 55 C. Methyl chloride is thus an excellent material for
ice-machines.
At the large distillery of Tilloy, Delaume & Co., at
Courrieres, which was managed by Vincent, 90,000 kilos
(90 tons) of molasses were treated daily ; 25,000 litres (5500
gals.) of pure alcohol of 90 (Gay-Lussac) were obtained,
leaving 40 tons of vinasse, which yielded 10,000 kilos (10 tons)
of potash salts, and as condensation products, 1600 kilos
(32 cwt.) of ammonium sulphate, 100 kilos (2 cwt.) of methyl
alcohol, and 1800 kilos (36 cwt.) of concentrated mother
liquors, of trimethylamine salts ; the vinasse also yielded
4000 kilos (4 tons) of tar, from which 360 kilos (7-J cwt.) of
oil and 2000 kilos (2 tons) of ammonia water were distilled
off.
Other Uses of Molasses. A very considerable amount of
molasses is purified and sold as treacle or golden syrup for
food purposes. The remainder, especially the crude beet
molasses, is an important ingredient in the manufacture of
shoe-blackings.
During the last few years a very large trade has been
built up in the preparation of cattle foods containing mo-
lasses, usually crude beet molasses. This is mixed with
various materials, e.g. peat moss, ground hay, etc., and forms
an excellent feeding-stuff.
The residues from beet-sugar manufacture are usually
sent back to the farmers, but they are sometimes dried for
use as cattle food. Two samples of such material, analysed
by Smetham, gave the following figures :
Dried Beet Pulp. Beet Fodder (Spanish).
Water 11-80 12-00
Oil .
Albuminoids
Digestible carbohydrates
Woody fibre .
Mineral matters
Sand and silica
0-83 0-60
8-75 8-87
'58-92 61-52
16-45 10-21
3-25 6-80
0-05 0-05
100-00 100-00
Food units ... 83 85
CHAPTEK XXVII.
THE WASTE LIQUIDS FROM SUGAR-WORKS.
Utilization of the Waste Water. W. Eiehn has described a
process } by means of which it is possible to remove the in-
jurious effects of the waste waters, and to recover them again
with little loss, not, indeed, in the form of a potable water, but
in such a condition that they give no trouble in the neighbour-
hood, and are quite suitable to be used over again in the works
or elsewhere. In using this process, in order to avoid a false
impression of the extent of the purification it affords, it must
not be neglected to remove entirely the deposits in the drains
and other legacies of the past. The process may be carried out
without any considerable outlay, this being covered by the
value of the fertilizer obtained, the work being done by the
labour of one man, under careful supervision. The purifica-
tion is said to attain three objects : prevention of conditions
dangerous to health, production of a valuable fertilizer, and
recovery of the water. In regard to the operations to be
performed, the impure waste waters may be divided into
(1) water used for washing the beet, and from the crude juice
station ; (2) water from the bone-black treatment, and from
washing filters and cloths ; and (3) condensation and con-
densed water from boiling the juice.
The condensed water from the steam engines and other
apparatus, which is collected separately and carefully, the
water from the evaporators, and the waste juice from the
filters, do not need special treatment here ; they are already
employed to the best advantage in any properly conducted
works for feeding the boilers, treating the bone-black,
1 " Dingler's Polyt. Journ.," 223, p. 402.
(153)
154
THE UTILIZATION OF WASTE PRODUCTS.
slaking lime, washing and give rise to no further incon-
veniences.
1. Water Used for Washing the Beet, and from the
Crude Juice Station. The temperature of these liquids in-
the waste-pipes varies between 18 and 32 C. ; their im-
purities are largely earth, carried in suspension, other dirt
and particles of beet, also juice in small quantity, i.e. sugar,,
salts, etc. The purification of these waters is very simple ;
FIG. 17.
the settling-tanks a l and 2 (Figs. 15-17) are quite sufficient
for removal of the impurities just mentioned, the small
quantities of sugar, etc., being also completely removed by
the contents of the niters c, d and d%, after the liquid has-
passed through the tanks and undergone the reactions which
THE WASTE LIQUIDS FKOM SUGAB-WORKS. 155-
take place there, as described under the next section (2)..
The water received in the collecting tank e is at least as pure
as the original water used, and the necessary cooling has
been obtained in the open tanks and conduits. The settling
or mud-tanks, a and a 2 , are of masonry, sunk more or less in
the ground according to the local conditions ; for the daily
treatment of 100 tons of beet, each tank is 8 "8-9*5 metres
(29-31- ft.) long, 3-8-4-4 metres (12'5-14'5 ft.) wide, and 1-9
metre (4;2 ft.) deep. In the case of larger quantities, or very
dirty beef, a third such tank is provided. The tanks 6 X and
b 2 , also of masonry, are together as large as % or a 2 : they
are merely divided by an overflow partition. It is necessary
that the valves shown in the figures should be properly ar-
ranged, and that all the pipes should have the correct fall.
The manipulation is simple : at the commencement all the
waste waters run to a lf thence through the pipe g to the tank
b lt etc. When a x is filled with deposit the valves are re-
versed ; the waste waters then go to a 2 , whilst a-^ is emptied.
From the tanks &j or 6 2 , in which the last settlings are de-
posited, the liquid comes to the first filter c, which is l'9-2'5
metres (6'2-8'2 ft.) square or in diameter, and is the same
depth as the previous tanks ; it is filled with layers of various
grades of cinders, sand, or other material suitable for the
complete mechanical purification of the water. The filling
material may be suitably mixed with alum mud, iron
chloride, potassium permanganate, etc., if such substances
are to be obtained cheap in the neighbourhood of the works.
From the filter c the water enters the filter ^ at the bottom ,
from which it flows over into d% (1 '6-1*9 metres square or in
diameter, i.e. 5*3-6'2 ft.), and finally through a ground pipe
into the collecting-tank e (3'2-3'8 metres in diameter, i.e.
10'5-12'5 ft.), whence the purified water is removed to the
works by the suction-pipe /.
The contents of the filter are changed as soon as it is so
choked that it no longer works. Turf coke is the most suit-
able filling for d^ and d 2 ; when it cannot be obtained, waste
bone-black is used, or the prepared wood charcoal of June-
156 THE UTILIZATION OF WASTE PRODUCTS.
mann charcoal in coarse grains, boiled with a solution of
five parts of acid calcium phosphate and five parts of sulphate
of alumina, then dried and ignited. This charge is renewed
during the season only once, or several times at the most, as
soon as the diminished purity of the filtered water makes it
necessary. The pipes are laid down in a manner convenient
for cleaning, which is necessary only once before and after
the season, if they are given sufficient fall. Before the mud-
tanks and the filters there is a channel or pipe h leading to
the tank e, and provided with the necessary valves, so that
the waters run off direct at the end of the season, or for
repairs.
2. Waters from the Bone-black Treatment, and from
Washing Filters and Cloths. The purification of these
waters offers great difficulties, and the temperature in the
waste-pipes varies from 20-60 C. ; the quantity and vari-
ability of the suspended or dissolved impurities are very
considerable. These impurities are organic matters, albumin,
alkalies, and alkaline compounds, salts, acids, products of fer-
mentation, etc. A large number of experiments have been
conducted to find a universal means for removing these mis-
cellaneous impurities. The author has used turf coke, which
is cheap and may be obtained on the large scale by burning
in heaps, with the best results for filling the filters d l and d 2 .
It was found that, by reason of the great porosity and con-
sequent absorptive properties of this material, every trace of
sugar, and organic impurities, was removed from the waste
waters which passed through. The mineral constituents of
the turf coke iron, gypsum, lime impart to it even to some
extent a disinfecting action ; and there is a considerable ad-
vantage in that the absorbed matter loses none of its fertilizing
value for plants, so that the turf coke, together with these
absorbed matters, forms an addition to soil which is most
valuable in every respect. In regard to a complete disinfection
of these waste waters, according to the author's experiments,
only the compound of acid magnesium phosphate with basic
iron salt the double salt of magnesia and iron already re-
THE WASTE LIQUIDS FROM SUGAK-WOEKS.
157
commended by Blanchard and Chateau has been found
satisfactory. By means of this compound the whole of the
nitrogen is fixed, with formation of ammonium magnesium
phosphate ; the other organic matters are also precipitated,
the sulphur compounds, sulphuretted hydrogen, etc., by the
basic iron salt, so that the water is so far prepared for com-
plete purification that, after passing the settling-tank, it only
requires filtering through turf coke.
A similar precipitant to Blanchard 's magnesium sul-
FIG. 18.
FIG. 19.
phate, calcium phosphate, and ferric phosphate has also,
according to the author, been made for several years by
Frank, of Stassfurt, and sold at the very low price of 2s. 6d.
per cwt. This preparation is used for the purification under
consideration in the following manner : 100 parts are stirred
with 66 parts of ordinary hydrochloric acid in a tank or tub
and allowed to stand two to three days, 300-400 parts of
water are then added. The vessel i (Figs. 18 and 19) is filled
with this mixture ; as much as may be required is run through
the exit-pipe into the waste water contained in the first section
158 THE UTILIZATION OF WASTE PRODUCTS.
of the apparatus y, where it is well mixed by means of the
stirrer. Milk of lime from the second vessel k is run into
the second section of the apparatus, which is also provided
with a stirrer, in sufficient quantity to render the liquid
alkaline, so that any free phosphoric acid present may be re-
covered as tribasic phosphate of lime. The settling of the
precipitate, which is generally voluminous, takes place in
the sections of the settling-tank n-^n^ which are connected
together two and two and used in turn. According to the
position of the valves, the liquid flows either into the tank ^
and thence runs over into w 2 , or into n^ and thence into n^.
'The clarified water then goes through the drain z to the
settling-tanks a lt b lt or a 2 , 6 2 (Figs. 18-19), is mixed with the
contents of these tanks, enters into reaction with them, and
then runs away for the final purification in the filters, c, d lt d^
In regard to the construction of this purifying plant, the
tanks y l and y 2 are built of wooden planks or bricks ; they
;are about 63 cm. (2 ft.) wide and 95 cm. (3 ft.) high, with
two divisions, each 63 cm. (2 ft.) long (round or rectangular).
The stirrers are driven in the most convenient manner from
the nearest shafting. The liquor is fed in at the bottom and
runs away at the top ; in the hinder wall of each division is
a valve just above the bottom for running off the contents.
'The vessels i and k are of wood or iron, 79 cin. (2 ft. 7 ins.)
wide and 95 cm. (3 ft.) high. The settling-tanks n r n 4 are
of brickwork, open or covered, and connected two arid two
in such a manner that the water runs over from one into the
other ; each tank is about 1*3 metres (4 ft. 3 ins.) square and
1*6 metres (5 ft. 6 ins.) deep.
The precipitate collected in the tanks n^n possesses great
fertilizing value ; it has been found by several analyses to
contain ammonium magnesium phosphate equivalent to 28
per cent of phosphoric acid and 10 per cent of ammonia, also
varying quantities of readily soluble basic phosphate of lime,
the sulphur compounds combined by the iron salt, and various
nitrogenous and organic substances. Together with the de-
posits in the settling-tanks and the contents of the filters, it
THE WASTE LIQUIDS FROM SUGAR-WORKS. 159
produces an excellent fertilizer, the value of which covers all
expenses.
3. The Water of Condensation and the Condensed Water
from the Evaporation of the Juice. The temperature of this
water varies in the waste-pipe from 30-60 C. ; it is con-
taminated by small quantities of volatile organic matter,
ammonia, juice, also fats, fatty acids, etc. Since, as a rule,
well-water, containing more or less lime, is used at the low-
est possible temperature for condensing purposes, and the
lime is partially separated owing to the heating by the
vapours from the juice, this waste water is in this respect
more pure than the original water. A portion of this large
quantity of water is used for preparing the lime ; it may also
be used without hesitation for feeding the boilers, and, if
necessary, for treating the bone-black, also, in very frosty
weather, for washing the beet. The remainder, in case the
quantity is considerable, must be cooled as much as possible
by a suitable simple cooling-tower or terrace cooler, in which
the heat should be regained, or by one of the surface coolers
used in breweries ; the water is then to be completely puri-
fied by the method of section 1 or 2, according to the locality.
If the excess of water is not great, it will require no separate
'Cooling.
Napravil, in order to recover the fertilizing matters and
to purify the waste waters, allows milk of lime to run in con-
tinuously. 1 The precipitate obtained settles in large flocks'
whilst the water runs away quite clear. In 119 working days
3053 cwt. of lime, at a cost of 1005 fl. 95 kr. (91 12s.),
were used ; the cost in wages was 190 fl. 89 kr. (17 7s.) ;
26,228 cwt. of slime were obtained. The best method of
removing and utilizing these waste waters is to employ them
lor irrigation.
The separation or saturation mud is the most abundant
residue produced in sugar-works ; several factories obtain in
one season 15,000,000-20,000,000 kilos (15,000-20,000 tons).
1 Kohlrausch, "Organ fur Riibenzucker- Industrie "; Fischer, " Ver-
werthung der Stadtischen und Industrie-Abfallstoffe ".
160 THE UTILIZATION OF WASTE PKODUCTS.
This residue frequently forms great heaps near the works,
which, by reason of the decomposition which sets in, give
rise to many inconveniences and complaints in the neighbour-
hood, and even damage the manufacture itself. This mud
has only found one use on the large scale as a fertilizer ; yet
it is rather harmful to calcareous soils, since it only contains
0*04 part of phosphoric acid and 0'35 part of nitrogen to 35
parts of lime. The author supposed that by carbonization a
black substance could be obtained, which would find various
uses. 1 The heating must be so conducted that the organic
matter leaves behind carbon after its decomposition. This
carbon has the advantage of being in a very fine state of divi-
sion similar to a true chemical precipitate, so that the
material, when squeezed between the fingers, feels like talc
or soap. If it is attempted to carbonize the mass in large
crucibles the portion in the middle is not sufficiently heated,
whilst the portions at the sides are overheated ; also at
temperatures higher than a dark red heat the carbonate of
lime is decomposed, the carbon being at the same time oxi-
dized, so that only white lime remains.
It is therefore necessary to use another apparatus, the
rotatory furnace of Casalonga being the best. This consists
of a revolving cast-iron cylinder, which has a hollow axis,
through which the tar and gas can escape. The cylinder
makes only a few revolutions per minute. The dried mud
is fed in at one end, and escapes at the other by a suitable
arrangement after it has been carbonized. The substance
obtained consists of an impalpable powder and of small
harder particles, which are easily crushed. It is thoroughly
powdered and may then be used as a black pigment. Its
composition is as follows :
1 " Journ. des Fabr. de Sucre," 20, No. 36.
THE WASTE LIQUIDS FKOM STJGAR-WOKKS. 161
Calcium carbonate 78-500
Phosphoric acid 0-950
Ammonia 0-168
Ferric oxide and alumina . . . 6*509
Silica . . 3-205
Carbon 7-500
Undetermined 3-168
100-000
The percentage of carbon varies according to the com-
position of the mud in particular, according to the quantity
of sugar it contains. The latter usually soon disappears
owing to the fermentation which arises ; it is therefore well
to add to the mud before carbonization about 10 per cent of
waste molasses. The shade of the black is more or less good
according to the quantity of this addition.
The volatile products evolved during the carbonization
deposit ammonia-water and tar in the condensers, whilst the
gas is drawn off into the fires, where it burns with the pro-
duction of much heat. The tar may also be burnt if a De-
ville furnace is used. The termination of the process is
readily recognized by the blue flame which appears when the
decomposition commences to yield carbon monoxide. The
condensed water contains much ammonium carbonate, am-
monia, and other nitrogenous compounds, including pyridine
and picoline. In order to separate these products from one
another the liquid is distilled with caustic soda solution, the
distillate saturated with hydrochloric acid, and evaporated,
when crystalline ammonium chloride is obtained. The
mother liquor is precipitated by alcohol, which retains in
solution the hydrochlorides of the organic bases, which are
then set free by potash.
Further investigations of these products have been made
by Etard ; l they are similar to those obtained by Vincent
from distillers' refuse. The principal product is naturally
the black, which is suitable for use in size, oil-paints, and
1 Zeits. d. Ver. f. Riibenzucker-Industrie," 16, p. 916.
11
162 THE UTILIZATION OF WASTE PEODUCTS.
printing inks. The cost is only 10 francs per 100 kilos (4s.
per cwt.).
Skene, of Breslau, has given an account of the arrange-
ments he employs for the waste matters. 1 The whole of the
waste water goes on to 17*5 hectares (43*2 acres) of land,
surrounded by banks ; here the water cools ; it is then
drained off, and again filtered by passing through a meadow
of 3 '25 hectares (8 acres). The drainage is laid down in the
ordinary system and is cut off by a valve, which is not opened
until all the conduits have been pumped full. The irrigation
works are so large that the water is only run off once in the
season.
Purification of the Alumina which has been used for
Clarification in the Manufacture of Sugar, in order to re-
cover the Matter it contains. The Brothers Lowig have
patented four processes for this purpose. 2
1. The used alumina is mixed with one equivalent of
lime and ignited. Calcium aluminate is formed, the organic
matter first leaves carbon or burns entirely on further heat-
ing. Ammonia, which can be recovered, is formed from the
nitrogen in the organic matter.
2. The alumina is heated with magnesium chloride ; mag-
nesium aluminate is then formed, whilst the organic matter
is destroyed by the hydrochloric acid produced, which can
also be condensed and used later to dissolve the magnesium
aluminate. The aluminates obtained in these processes (1
and 2) are converted into alumina by known methods.
3. The alumina is dissolved in the least possible quantity
of hydrochloric acid, and the solution filtered from insoluble
organic matter, e.g. albumin from plant juices containing
sugar. Many of the organic substances which remain in
solution can then be precipitated by the addition of alumina,
or by the precipitation of a portion of the dissolved alumina,
and then filtering off. The aluminium chloride may also be
1 " Zeits. d. Ver. f. Riibenzucker-Industrie," 16, p. 916 ; Post's " Zeits. f.
d. chem. Grossgew."
2 Ibid.
THE WASTE LIQUIDS FROM SUGAR-WORKS. 163
ignited, and the organic compounds destroyed by the hydro-
chloric acid which is formed ; but care must be taken that
too violent heating does not result in the production of in-
soluble alumina.
4. The impure alumina may further be dissolved in
caustic alkalies and thus freed, for example, from ferric
oxide ; then, if necessary, it may be purified by igniting the
evaporated solution, and finally again be precipitated as the
aluminate of an alkaline earth. The albuminous matters
obtained in method 3 may be used as fertilizers or in the
manufacture of ammonia.
See also " The Technology of Sugar," by J. G. Mclntosh
(Scott, Greenwood & Son).
CHAPTEK XXVIII.
FRUIT.
Conversion of Fruit into Jelly. Several recipes for this pro-
cess are given in the following pages : x
Recipe of Siemens, of Hohenheim : Pears are crushed and
pressed, the fresh sweet juice is boiled down to one-third of
its volume in a clean copper pan, the scum removed, and the
liquid cooled ; it is then strained through washed flannel.
Whilst this is being done, about the same quantity of apples
as of pears is well boiled with only a little water. The
apples have previously been washed clean, but not pared or
cut. When boiled soft they are rubbed through a hair-sieve
of average mesh by means of a stiff brush, in order to separate
the pulp from the skins and cores. The apple pulp is then
mixed with the purified pear juice in the pan, and the two
boiled together under constant stirring, until the mass adheres
to a spoon in large lumps and, on cooling, has the consistency
of a stiff paste. A slight addition of lemon peel, cinnamon,
and cloves improves the flavour. In order to give the jelly
a fine colour, about 0*5 litre of bilberry or elderberry juice is
added to 100 kilos (1 lb.-2001b.); a few green walnuts are
also suitable.
All the jelly, whilst still hot, is brought into the vessels in
which it is to be kept ; these, which should be previously
warmed, are best of earthenware ; the jelly is not again dis-
turbed before use. When the jars are full it is found advisable
to bring them for some time into a very hot room, e.g. a baking
oven, so that the jelly becomes covered with a very thick,
hard crust. In order to protect the surface from the entry of
1 Lucas, " Die Obstbeniitzung Deutsche allg. Zeits. f. Landw.," No. 26.
(164)
FRUIT. 165
air, the jars are to be closed by a moist bladder. They are
kept in a cool but dry place.
For fruit jelly all our sweet or less acid summer and
autumn pears are suitable ; of apples, baking apples, " rose
apples," and other varieties ripening in the autumn. There
need be no hesitation in using sourish-sweet or sweetish-sour
apples, but a moderate addition of sugar is requisite. It
seems to be established that the jelly from pure sweet a.pples
and pear juice keeps longer than that in which sour apples
are used.
Recipe for Lower Ehine fruit jelly : Equal parts of apples
and common beet are separately half-boiled, then brought
under a press together and the juice squeezed out. This
juice is then placed on the fire and boiled down to a thick
jelly. Pears may also be used without any different treat-
ment being necessary : the juice is brought into a condition
suitable for boiling, then freed from stalks, skins, cores, etc.,
and evaporated until it becomes a solid mass.
Sweet apples are generally used for such apple jelly ; two
of the best varieties are the h'drteling, which is the most
productive apple for jelly, producing 15-18 per cent of jelly,
and the Jcernling. Neither freezes readily ; they are kept
through the winter on the ground in the open, later they are
squeezed and boiled down to jelly. The fruit must be ripe
for storing if it is to produce an abundance of fine jelly.
Manufacture of pure beet jelly, especially valuable in poor
fruit-growing districts and in districts in which there has
been a bad season. The apparatus next described and the
manipulations may also be used for pure fruit jellies. After
the beet has been freed from the cluster of leaves, it is
washed in large tubs, or, better, in rotating lathwork drums ;
it then goes into a round copper pan, widening out above, in
which it is boiled. In order to prevent burning upon the
bottom, the pan is provided with a false bottom of strong
wire cloth. During boiling the beet is continuously beaten
and stirred to break it down. The size of the pan is arranged
according to the quantity of beet to be worked. The quantity
166 THE UTILIZATION OF WASTE PRODUCTS.
of water is 8 litres to 100 kilos of beet (1 gal. to 125 lb.). The
beet, boiled, and broken down, is tben shovelled with iron
spades into the press tub, which is provided with a grating or
false bottom, so that the sap can readily flow away. This-
grating and the sides of the tub are lined with filter-cloth,
which is also placed between the layers of beet pulp at in-
tervals of about 6 ins. ; old coffee-bags can be employed in
place of the filter-cloth. When all the contents of the pan
have been introduced, they are covered over with filter-cloth,
the wooden cover is put in position, and the vessel subjected
to the action of (hydraulic) pressure. The expressed juice
runs into a receiver, from which it is pumped back into the
pan. The pan which was used for the first process is now
used for boiling down the juice, or, on a larger scale, a second
pan is employed, but in the former case the pan is very care-
fully cleaned by scouring with sharp sand. The evaporation
then proceeds regularly ; towards the end a little oil or lard is
added, in order to prevent frothing and burning on the bot-
tom, the fire being also slackened. The consistency of the
syrup is judged by the " thread " test : it is stiff enough when
a thread 5 cm. (2 ins.) long can be drawn out between the in-
dex finger and thumb. A small spoonful of the syrup, placed
in a shallow iron vessel and cooled in cold water, allows of the
consistency being judged. One press is required for every
two pans, one of which is used for boiling the beet, the other
for thickening the juice. The whole process requires on the
average a period of seven working hours. The finished jelly
is, as a rule, first brought into earthenware pots, and then,
when it has half-cooled, into the vessels in which it is to be
kept.
The utilization of fallen fruit has been treated by a prac-
tical fruit-grower. 1 In the first place, it is not desirable to
allow any fallen apples to spoil. The author collected the
fallen apples in July, boiled them soft with much water, and
then stirred up to a paste in order subsequently to obtain a
jelly. The mass, which was obtained from quite green, un-
1 " Praktischer Eathgeber im Obst- und Gartenbau," 1898.
FKUIT. 167
ripe apples, had a very unpromising appearance; however,
the requisite sugar was added. The whole process therefore
was as follows : The unripe apples were cleaned, brought
into the boiling-pan, water added to cover them, and the
contents then boiled and stirred until a fluid paste was pro-
duced. This paste was transferred to a coarse linen cloth
and allowed to drain. The juice was then boiled with sugar
to a jelly : 400 grins, of sugar to 1 litre of syrup (4 Ib. to 1
gal.), the boiling being continued for about forty-five minutes.
The jelly from unripe apples had a fine red-gold colour and a
good flavour ; its cost was quite low i.e. rather less than
3d. per Ib.
Preparing Dried Fruits. A considerable amount of fruit
such as apples, pears, plums, apricots, etc., is now dried or
desiccated, in which condition it will keep indefinitely. Such
fruit as apples and pears are first peeled, cored, and cut into
thin slices, while from fruit containing large stones the
latter are removed. The fruit thus prepared is then placed
on wire gauze frames, preferably galvanized, or of aluminium,
which are arranged one above another in a room through
which a current of warm air is passed by means of a fan.
In large installations the drying may be done in appar-
atus provided with moving endless bands or in vacuum
drying machines.
See also " Kecipes for the Preserving of Fruit, etc.," by
E. Wagner; and " The Manufacture of Preserved Foods and
Sweetmeats," by A. Hausner (Scott, Greenwood & Son).
CHAPTEK XXIX.
WASTE PRODUCTS OF THE MANUFACTURE OF STARCH. 1
Utilization of the "Fruit Water". In working by the or-
dinary process by which starch is obtained, the potato pulp
coining from the grinding machine is diluted with so much
water that the proportion of valuable constituents is reduced
to such an extent that they cannot be utilized. This "fruit-
water," if it has not fermented, may be suitably employed as
a direct addition to pigs' food. If steam be available, it may
be passed into the "fruit water" until the albuminous
matters are coagulated into flocks, which are separated by
running off the clear liquid into the drain, and using the
residue as cattle food.
Utilization of the Pulp. This mass is most suitably
mixed with other cattle foods ; since it is somewhat difficult
of digestion, however, it is advisable to break it up by heating
to boiling. The pulp still contains some starch which it
may be profitable to recover. By suitable treatment 2-2*5 or
even 3 per cent of the total quantity of starch may be re-
covered from the pulp, thus increasing the profits very
materially. The pulp still contains many uninjured cells
filled with starch which have escaped the grinding, and in
order to break up these cells a simple arrangement is em-
ployed which drags the cells lengthway and thus ruptures
them. The apparatus is constructed as follows : A roller of
polished marble or granite is connected with a cog-wheel.
Below this roller, but very near to it, lies a second one, also
connected to a very much larger cog-wheel. Thus the upper
roller makes three revolutions whilst the lower is making
1 F. Rehwald, " Die Starke Fabrikation," Vienna, Hartleben.
(168)
WASTE PKODUCTS OF THE MANUFACTURE OF STARCH. 169
one. The pulp in passing between the rollers is at the same
time squeezed and drawn out in consequence of the unequal
speeds, by which means almost all the starch-containing cells
are ruptured. When the rolled mass is brought into the
cylindrical brush apparatus starch can be obtained from it in
the same way as from the original material.
The process is generally conducted by collecting a quan-
tity of the pulp, then rolling it and treating it alone. The
starch which has been semi-dried and purified by settling also
produces in this case a certain quantity of starch mud, which
is treated either separately or together with -similar material.
In places where there is a distillery it is advisable to work up
the residual pulp with the other material for the manufacture
of spirit ; by this means the whole of the starch is extracted,
the cellular tissue going into the distillery wash.
If the pulp is collected into heaps, which are kept moist,
a process of decomposition soon sets in which gradually but
completely destroys the cellular tissue. The whole changes
to a soft, cheesy mass, consisting of the decomposed cellular
substance, starch and cellulose. If it be then brought into
the apparatus for obtaining starch, the latter is obtained pure.
For this purpose the pulp is allowed to lie in thin layers for
-a time, and, while still moist at the top, heaps are formed,
60-80 cm. high (24-32 ins.), resting on a layer of boards and
covered by twigs or boards. After a few days the tempera-
ture of the whole heap rises (the covering of boards protecting
it from cooling) and rapid fermentation sets in. In order to
allow the air as much access as possible, it is advisable, in
building the heaps, to insert poles and to draw these out care-
fully, so that channels may be formed into the interior of the
mass. Repeated turning over with shovels and, if necessary,
moistening with water, greatly accelerate the fermentation
of the mass.
If the formation of gases of bad odour is remarked dur-
ing this process, it is a sign that putrefactive fermentation is
taking place in addition to the ordinary decomposition, by
which the yield of starch would be diminished. A buttery or
170 THE UTILIZATION OF WASTE PEODUCTS.
cheesy smell denotes the occurrence of the butyric fermenta-
tion, by which the starch itself is attacked. This incorrect
course of the reaction is due to the entrance into the mass of
too little air, the mass being either too compact or too wet..
This evil may be overcome by working the mass by shovel-
ling, or by allowing it to dry somewhat.
Utilization of the Gluten. In the process of fermentation
just described the gluten is dissolved or destroyed with the
exception of a small quantity, which rarely exceeds 25 per cent,,
but in the process without fermentation the yield of gluten
may amount to more than 90 per cent of the total quantity-
present. In addition to the use of gluten as cattle fodder, for
which purpose the gluten obtained by the process without
fermentation is stirred with water and heated to 70 C., it is
also used in the manufacture of foods. In the latter case-
the first operation is to obtain gluten-flour, as described by
F. Eehwald (loc. cit.).
Wheat, from which the husk has been removed, is
thoroughly washed ; the starch layers obtained are not sub-
jected to a further washing, but are partially dried by the
air-pump and mixed with gluten. The mass is then rendered'
plastic by an admixture of potato-flour, or, in place of this,,
dark-coloured wheat-flour or pea or bean-flour may be used.
It is of great importance to mix the gluten most intimately
with the starchy substances, for which purpose a kneading
machine, such as that used by bakers, is employed. The
mixing may also be done by means of rollers, in which case a
first pair of rollers produces a band of a certain thickness,
which is stretched out more and more by the succeeding pairs
of rollers. The thinnest band is collected, pressed together,
and again subjected to the action of the rollers ; by this means,
there is obtained by repetitions of the process a more and
more uniform mixture of gluten and starch. It is advisable
to add to the mass, before kneading, y^o of its weight of
sodium phosphate and T o 2 oo to TCTOO ^ common salt. The
paste is filled into a shallow rectangular box, with a narrow slit
at one end, through which it is expelled by a piston. Below the
WASTE PRODUCTS OF THE MANUFACTURE OF STARCH. 171
box is a long endless belt of linen cloth, running over rollers.
When the paste is expelled through the slit in the box by
means of the piston, it leaves in the form of a thin band,
which is carried away by the endless cloth, from which it is
taken on to boards. It is then dried in the sun to a thin,
horny mass, which can be easily broken and ground to flour.
This gluten-flour far surpasses beans in nutritive value ; a
food is obtained from it by stirring into boiling water, to
which salt has been added.
The following process is used in order to obtain gluten
in the form of groats. The gluten, made into a paste with
potato-flour in the above-mentioned manner, is brought into
a cylinder fitted with a piston, and closed at the bottom by a
metal plate perforated by the largest possible number of holes.
The holes are slightly conical, being about 1;5 mm. in diameter
at the top and 1 mm. at the bottom. By applying pressure
to the piston, the paste is made to issue in the form of thin
threads, which are then cut up into small pieces by a knife
below. The apparatus is arranged so that pressure is only
applied intermittently, in order that the grains may be as far
as possible of equal size. Below the cylinder there moves
slowly a stretched endless cloth, which catches the grains
and carries them away ; they are then lightly dusted with
flour. In order to round the grains, they are brought, to-
gether with 5 per cent of potato-flour, into a barrel, through
the bottom of which passes an axle, and which is closed by
a door in place of the bung-hole. The grains are rounded
by the slow rotation of the barrel; finally they are sorted
through sieves of different meshes, and dried in thin layers
on boards.
Utilization of the Residues. G. Thenius recommends a
new method for the utilization of the residues obtained in the
manufacture of starch, 1 which consists in evaporating the
wash waters the " softening " waters which have previ-
ously been run to waste. By evaporating 10 grms. of this
liquid, Thenius obtained 2'09 grms. of extract, which was
1 " Chem. Zeit.," 150 ; Post's " Zeits. f. d. chem. Grossgew.," Ill, 2, 280.
172 THE UTILIZATION OF WASTE PKODUCTS.
of a pale brown colour, had a sweetish, salty taste, and an
odour similar to that of malt extract. If the extract is dis-
solved in a little water, the less soluble salts sulphates,
phosphates, sodium and potassium chlorides separate. The
portion soluble in water is again evaporated to dryness on
the water-bath ; it then possesses a pleasant, sweetish taste,
but is not salty. One hundred parts of the extract con-
tained 25*6 parts of salts and 7 '44 parts of pure extract.
From a vessel of 15 hectolitres (330 gals.) capacity, 30 kilos
(67*5 Ib.) of extract are obtained. The extract can be profit-
ably employed in bread-baking or in making cattle foods.
The bread prepared with it is said to have an agreeable
flavour, and to keep moist for a long time. The purified
extract can be used medicinally, and as a substitute for malt
extract. The extract is obtained by evaporating the liquor
in shallow pans by means of the waste steam from the boiler.
Utilization of the Waste Waters. In most cases the waste
waters are run into a stream or sewer ; they then frequently
give rise to complaints, since the decomposable matter they
contain ferments, and may thus taint the neighbourhood and
injure the fish in the rivers.
As long ago as 1835, Burggraf made successful experiments
on the use of this water for irrigating meadows and arable
land, 1 and in 1877 Marcker gave an account of comprehen-
sive experiments on the irrigation of meadows by its means. 2
The waste water, which is first run through two settling- tanks,
in order that the fine grains of starch still suspended in it
may be deposited, is conducted for a distance of 170 metres
(185 yards) through a pipe 15 cm. (6 ins.) wide, with a fall of
33 mm. per metre (3'3 in 100). The water is received from
the pipe in an open ditch 1 metre (39 ins.) wide and 30 metres
(33 yards) long, which conveys it to a small storage pond.
It is here mixed with pure well-water, in order to avoid the
strong concentration of the original waste water, and to ob-
1 " Polyt. Journ.," 56, p. 464.
2 " Zeits. d. landw. Centralver. d. Provinz Sachsen " ; " Dingler's Journ.,"
25, p. 395.
WASTE PRODUCTS OF THE MANUFACTURE OF STARCH. 173
tain larger volumes of waters for regular distribution over the
meadows. The mixed waters are then carried to a large
meadow of 7-J- hectares (18-j- acres), over which it is distributed
by a system of large and small ditches, and retained by dams.
The water is conveyed away by a system of drains, which
can be put in or out of action by sluices as required. The
drainage then goes to a second meadow of 5 acres, and thence
to a third of 6 acres. The crops obtained are described by
Marcker as excellent.
Marcker observes, in conclusion, that the waste waters of
starch-works may be applied to the irrigation of meadows
with the greatest advantage, because there is not only an
increase in the crop, but the composition of the hay is also
considerably improved.
CHAPTEK XXX.
BREWERS' WASTE.
Utilization of Malt " Combs". These are an excellent food
for cattle.
Utilization of Brewers Grains. 'They are used as food
for cattle. For this purpose they should be employed as fresh
as possible, since lactic acid readily forms, which then later
produces butyric acid, acetic acid, etc. This objectionable
alteration of the grains is recognized by the loss of the pure
malt odour, the smell becoming distinctly sour. In feeding
with grains it is necessary to add chopped hay or straw in
order to cause the cattle to masticate. For a short period
about fourteen days the grains may be kept in tanks, in
which they are weighted down with boards and stones, and
covered with water to a depth of several inches. The tanks
must be kept very clean, and, when emptied, must be lime-
washed until the coating does not turn grey which is a sign
that acid is present but remains white. When required to
be kept longer, brewers' grains are deposited in a pit in the
ground and covered by a thick layer of earth. The pits
should be of such a size that the grains in each are used in
eight or, at the most, fourteen days. Fermenting grains
are a valuable manure.
The following are analyses of two samples of dried grains
'from distilleries by A. H. Allen :
i. 2.
Moisture . . . 10-32 8-00
Oil
* Proteids or albuminoids
Sugar, starch, and digestible carbohy
drates . . . .
Woody fibre ...
Mineral matter
6-70 5-07
19-88 19-80
41-06 49-66
19-00 13-16
3-04 4-31
100-00 100-00
* Containing nitrogen . . . *V 3'14 3'13
(174)
BEEWEKS' WASTE. 175
There are four methods of preserving grains to be con-
sidered. The first, drying in the kiln, gives very good re-
sults, but the process is too expensive. The second, which is
coming into use in England, consists in expelling the moisture
in centrifugals, into which live steam is conducted ; the
.grains then become pressed into solid cakes, which are re-
commended as a most excellent food for cattle. In another
method, the grains, mixed with other suitable foods, such as
bran, meal, peas, beans, etc., are mixed up to a paste, and
baked into a kind of bread. The product is brown, porous
and friable, smells and tastes similarly to fresh rye bread, mixes
witl} water, and may be given dry mixed with other chopped
fodder, and also as a drink. Finally storage, with an addition
of common salt in pits with cemented brick walls, is said to
have been effective.
Utilization of the Yeast. Pressed yeast, commonly known
in England as German yeast, is produced from distillers'
yeast, but not from brewers' yeast, which is difficult to purify
and does not keep so we'll. H. Kiidinger gives the following
account of its preparation : x
After the termination of the main fermentation, the yeast
which has separated in the fermenting vats is collected in a
large tub, provided with a series of plugged holes in the side.
The mass is left at rest for some hours, when the yeast
settles, and, by opening the upper holes, a quantity of raw
beer may be obtained, which is either put into a barrel or
added to the fermenting vat in the next fermentation. After
this beer has run off the tub is filled up with clean water,
the whole well stirred and allowed to deposit. After about
an hour the liquid again begins to run off. The upper holes
are opened ; the liquid, which is at first clear, is removed,
but when it begins to be somewhat turbid it is run through
a sieve, on which a wet coarse linen cloth is spread. The
linen retains the greater portion of the yeast ; but after some
time the pores of the cloth are so filled by it, that the liquid
1 " Die Bierbrauerei und Malzextract-Fabrikation," H. Riidinger, published
by A. Hartleben, Vienna, 1887.
176 THE UTILIZATION OF WASTE PRODUCTS.
runs away very slowly. It is therefore necessary to have
several sieves in readiness so that the operation may not be
stopped.
The removal of the liquid, by opening the lower holes,,
is continued until the yeast begins to appear as a thick
liquid, when the holes are again closed. The yeast on the
linen is removed and returned to the tub, which is again filled
with water, and the yeast treated exactly as before. This
washing is continued so long as the yeast on the linen has a
perceptibly bitter taste. In most cases three or four treat-
ments of the yeast, with fresh quantities of water, are suffi-
cient to remove the bitter taste to the required extent.
The washed yeast is now collected and freed from water,
for which purpose a system of filters is arranged near the
yeast-tub. The uppermost part of this apparatus is a fine
hair-sieve ; below this are placed several frames, across which
linen cloth is stretched, being hung at the four corners of the
frame to wooden pegs by means of stitched-on loops. The
turbid liquid coming from the uppermost cloth leaves a por-
tion of its yeast on the next, also on the third, and so on,
finally leaving the last cloth with only a slight turbidity ; it
is received in a tub, where it deposits the remainder of the
yeast as a fine, slimy residue, whilst the supernatant liquid is
quite clear.
The pores of the filter cloths soon become filled to such
an extent by the fine particles of the yeast that only a little
liquid can pass through; frames in this condition are re-
moved, allowed to drain spontaneously, and replaced by fresh
frames. When finally all the liquid has been brought from
the tub on to the filter frames, the latter are allowed to stand
until no more liquid drips from them. The yeast now ap-
pears upon the cloths as a brownish-coloured soft mud, which
is removed by spreading the cloths out flat, and scraping off
the yeast with a blunt wooden blade.
The paste is now brought into a very strong cloth (press
cloth), this is surrounded by a second cloth, and the whole
brought under a screw press, where at first a gentle pressure
BEEWEKS' WASTE. 177
the liquid should not run away turbid and then gradually
a considerable pressure is applied. When once a consider-
able quantity of water has been pressed out of the yeast, the
pressure may be allowed to rise tolerably high, so that the
compressed yeast taken out of the press cloths is a mass
which may be compared in consistency with new cheese.
In order to be able to keep the pressed yeast without al-
teration, it is found advisable at once to divide it into rect-
angular blocks of definite weight (500, 250 grms., i.e. about
18 or 9 oz.), which are then wrapped in oiled paper, tinfoil,
or canvas, and kept in a cool place.
Utilization of the Bottom Yeast. If bottom yeast is to be
converted into useful bakers' yeast, it requires to be washed.
It is first run through a fine hair-sieve into a vat, which is
somewhat deeper in front than behind. In the front wall of
this vessel, in the middle stave, which is somewhat thicker
than the others, in order not to lose strength, are bored
holes at intervals of 5 cm. (2 ins.) at the top, and at smaller
intervals below ; the holes are now closed with plugs. The
yeast is stirred with water, to which a teaspoonful of
powdered ammonium carbonate is added per hectolitre of
yeast (22 gals.). When the yeast has settled the plugs are
drawn one after the other, and the water allowed to run off.
The yeast after this treatment is rarely sufficiently pure, so
that the process must be repeated a second and third time.
The second time less ammonium carbonate is added ; the
third time, none.
This process is occasionally also used for top fermentation
yeast, in which case two additions of water, without the salt,
are generally sufficient. When the yeast is white enough,
it is filled into press bags and well pressed ; it is also fre-
quently kneaded with starch, partly to improve the colour,
partly to give it more the nature of a so-called short or
crumbly yeast, but this is now regarded as an adulteration ;
such yeast keeps better but it is naturally weaker in its
action.
Some little time ago a yeast extract was prepared by boil-
12
178 THE UTILIZATION OF WASTE PRODUCTS.
ing yeast with water, straining and evaporating the liquid.
This was remarkably like extract of beef in odour and taste,
and was used for adulterating the latter ; its detection and ex-
posure, however, soon put an end to this form of sophistica-
tion. It is, however, particularly rich in nitrogenous matter,
and therefore there is no reason why it should not be used
in a legitimate manner as a food product.
Dried Yeast as Food Jor Farm Stock. According to C.
Crowther, 1 dried brewers' yeast is used on a large scale in
Germany for feeding cattle, and in England there are several
places at which yeast is dried, principally for export, the
amount being from 2000-3000 tons annually. The average
composition of the material is :
Moisture 4*8 per cent.
Proteins , 48-5 ,,
Oil 0-5
Fibre 0'5
Ash 10-7
Soluble carbohydrates . . . 35'5 ,, ,,
100-0
Feeding experiments have been carried on with this
material in Yorkshire, which show that it is quite safe to use
for cows, calves, and pigs, but cows do not seem to take to
it owing probably to its bitter flavour. Owing to its high
content of proteins it should be mixed with other feeding-
stuffs such as grain or oil-cake.
Utilization of the After-worts. These are advantage-
ously employed, instead of water, for mashing the malt of the
next mash, if that takes place immediately after the one from
which the after- worts were obtained. If it would be neces-
sary to wait only several hours, it is advisable to use the
after-worts together with the wash-water of the grain for
preparing malt vinegar. For the same purpose, i.e. vinegar,
' all other residual liquors the last portions of the beer, which
are turbid owing to the presence of_ yeast, etc. may be em-
ployed.
1 J. Board Agric., 1915, 22, 1-10.
BKEWEKS' WASTE. 179
For the last-mentioned purpose a wide but low vat, pro-
vided with a cover, is brought near the brewing vessel, the
liquids enumerated above being brought into this vat. In order
to commence the formation of vinegar, a few glasses of sour
beer or some " mother of vinegar " are added. After the
liquid has stood for some hours in this vat, it 'is drawn off
into smaller vessels, placed in an airy situation at an ordinary
room temperature. If the vinegar is found to be too weak,
one-hundredth of its volume of distilled spirit may be added,
for which purpose the crude distillate is quite suitable.
Utilization of the Deposit in the Coolers. This deposit
may be used as fodder in conjunction with brewers' grains or
distillery wash.
The Utilization of Spent Hops as Cattle Food has been
treated upon by 0. Kellner. 1
The spent hops (according to Kellner), on account of their
composition, which corresponds to that of red clover hay of
medium quality, have recently been much recommended for
fodder. Since, on the one hand, this refuse is produced in
large quantity and has hitherto been utilized to an inadequate
extent, and, on the other hand, it was of great interest to
learn the behaviour of such an extracted vegetable substance
towards the digestive juices, Kellner undertook to ascertain
the digestibility of spent hops by a direct nutritive experi-
ment. The results showed that the digestive coefficients of
the constituents of hops, with the exception of that of the
crude fat, are lower than have hitherto been found for any
food directly tested for digestibility. Since the extraction in
the brewing did not afford a sufficient explanation of this re-
markable result, other conditions were included in the scope
of the observations. It was then found that about 24 per
cent of the crude fibre is lignin, which, being in intimate
admixture with the cellulose, considerably decreases the
digestibility of the latter. Also in spent hops a portion of
the protein is found in combination with tannic acid, which
1 " Deutsche Landwirthschaftliche Presse," 1879, No. 55, pp. 332, 333 ;
Biedermann's " Centralbl. fur Agriculturchemie," 1879, No. 9.
180 THE UTILIZATION OF WASTE PBODUCTS.
is known to hinder the action of the digestive juices. Only
the crude fat had a normal digestive value. Since this con-
stituent of hops is certainly composed of substances which
have not the chemical constitution of ordinary fats, it may
also be assumed that the digestibility of the hop fat is not
equal to that of the ordinary fats.
Thus, in consequence of the low digestibility and the re-
luctance with which cattle eat spent hops, this substance
cannot find any extensive use as fodder.
The residues in question are best employed in preparing
compost, perhaps after the residual portions of the wort have
been removed by water, to be further utilized in beer. Small
additions of hops to the daily food are not to be rejected,
since the appetite of the animal is increased thereby. The
proposal of Pott, to add spent hops in place of the usual
straw to the cakes of distillery and brewers' grains, appears
to be worthy of attention, especially since the tannin in the
hops has probably a preservative action. For the same reason
spent hops might perhaps be used with advantage in storing
sliced beet, etc.
The best method for treating malt "combs" for use as
food or manure consists in grinding to a coarse meal, after
well cleaning and removing dust. This substance must always
be mixed with other foods ; it is most suitable for improv-
ing a ration of chopped straw. After grinding, the " combs "
are more easily acted upon, and hence are more digestible.
The same reason holds good when malt " combs " are to be
used as a fertilizer. From experiments of A. Fericka it
appears that the differences in the vegetation obtained with
different manures are very considerable, and that ground
malt "combs" treated with sulphuric acid afford the best
means of increasing the growth of grass. The process of
treating the ground "combs" with sulphuric acid is as fol-
lows: In a large tub, 5 cwt. of the ground "combs" are
steamed, with a gradual addition of boiling water, until a
paste is produced, which is left at rest for two hours, after
which the whole mass swells up considerably ; it is then found
BKEWEKS' WASTE. 181
that the meal has absorbed the whole of the water, no more
remaining at the bottom of the tub. Then the mass is again
scalded, this time with an addition of about 10 Ib. of sul-
phuric acid to the boiling water. After cooling, the material
can be at once used for manure ; it is especially suitable for
incorporation in poor composts.
Waste Waters of Distilleries. The spent wash or " pot
ale " left in the stills after evaporation of the spirit contains
a considerable amount of organic matter with a comparatively
high percentage of nitrogen. Wherever possible this is run
into the sewers or streams, but such a proceeding is not
desirable. It is somewhat difficult to purify, and some little
time ago a valuable prize was offered by the Scotch distillers
for a method of utilizing it. It could be purified by the
septic process or evaporated, and the residue mixed with the
spent grains for cattle feeding, but would scarcely repay the
cost of fuel.
Separation of the Fusel Oil. In the fermentation of
sugar and saccharine matters, especially that which is ob-
tained from potatoes, a certain proportion of higher alcohols
particularly amyl alcohol are formed. These are separated
from the ethyl alcohol and water by rectification or fractional
distillation, and form fusel oil. This is redistilled, the portion
passing over at about 131 C. being crude amyl alcohol.
Amyl alcohol is used to a certain extent in the manufacture
of varnish stains and also for the production of amyl acetate
or pear essence, which is now used very largely as a solvent
for nitrocellulose in the manufacture of celluloid varnishes.
See also " Industrial Alcohol," by J. G. Mclntosh (Scott,
Greenwood & Son).
CHAPTER XXXI.
WINE RESIDUES.
Utilization of the Marc. This is the residue from the wine-
presses, consisting of the skins and seeds of the grapes to-
gether with more or less stalk. The utilization of this
material extends to the production of tartaric acid, the pre-
paration of marc brandy and osnanthylic ethers, the produc-
tion of illuminating gas, Frankfort black, and grape-seed oil.
To these are to be added the methods used by wine-growers
for utilizing the marc : the production of marc brandy and
after-wine, the preparation of wine vinegar from the marc,
the use of the marc in making verdigris, the consumption of
the marc by cattle, its use as fuel, and the recovery of potash
from the ash.
Utilization of the Crude Tartar. To this division belong
the preparation of tartaric acid from crude tartar and calcium
tartrate, the preparation of cream of tartar and the more im-
portant tartartic acid compounds.
Utilization of the Lees. The principal products are :
lees brandy and oenanthylic ether, calcium tartrate and
cream of tartar, Frankfort black, and lees wine.
We must here abstain from dealing further with this
highly important industry of waste products, which is so
extremely profitable in wine-growing districts, since a special
work on the subject has just been published, which is highly
to be recommended. In it the utilization of all the wine
residues is described in so thorough a manner, easy to under-
stand and highly practical, that the whole work would have
to be reproduced if we were to deal with the subject. We
therefore refer anyone who intends to undertake the treat-
ment of wine residues, which is extremely profitable in
(182)
WINE RESIDUES. 183
wine-producing districts, for instruction in the necessary
arrangements and method to the book " Verwerthung der
Weinriickstande," etc., by Antonio dal Piaz, Vienna, Hartle-
ben. To this practical work we add here, in regard to the
treatment of wine lees, 'only the process by which the firm
of Wagemann, Seybel & Co , of Liesing, near Vienna, pro-
duces tartar and tartaric acid from the substance.
According to E. Kopp, 1 4000 cwt. of tartaric acid are
produced by this firm. The wine lees, which deposit separ-
ately in the spring after the main fermentation, amount
to about 5 per cent of the wine. They were at one time used
only as manure. Since 1854 Seybel has successfully en-
deavoured to facilitate the utilization. The process begins
by subjecting the lees to high pressure in filter presses, 100
eimer (58 hectolitres or 1276 gals.) then produce 40 hectolitres
(880 gals.) of wine and 20 cwt. of dry lees. With the yearly
production of about 4,000,000 eimer of wine in Austria, the
lees deposited amount to 60,000 cwt., and represent a value
of over 4,000,000 francs (160,000). The pressed lees con-
tain organic matter, yeast cells, etc., tartar, tartrate of lime,
colouring matter, clay, and sand ; they are treated with hot
dilute hydrochloric acid, which dissolves principally the tartar
and tartrate of lime. The liquid, after filtering through
woollen cloth, gives, on cooling, crystals of tartar, which can
be purified by recrystallization. The mother liquors, when
neutralized by milk of lime, give a precipitate of tartrate of
lime, which is converted into tartaric acid. From the last
impure mother liquors of the tartaric acid a further quantity
of tartar is obtained by the addition of potassium chloride.
A process introduced by Miiller and Schlosser, of Vienna,
for the recovery of tartaric acid from the deposits in dis-
charging vats, is allied to the above treatment of wine lees.
It is well known that tartaric acid is used in considerable
quantity for discharging printed Turkey-red fabrics ; it is
then precipitated in a bleaching powder vat as tartrate of
lime. The method of treatment is not known, but is readily
1 " Naturf. Ges. in Zurich " ; " Neueste Erfindungen und Erfahrungen ".
184 THE UTILIZATION OF WASTE PRODUCTS.
imagined. It would be very convenient to combine it with
the treatment of wine lees. The calcium tartrate from the
discharging vats contains excess of lime, which could serve
for neutralizing the hydrochloric acid decoction of the lees.
Among the applications of grape marc Pasque gives at-
tention to the production of oil, 1 which, according to Pezeyre,
is very simple and profitable. The well-dried marc is stirred
to a paste, brought into a pan, frequently well stirred, boiling
water added 1 gal. to 4 gals, of marc and, as soon as the
oil exudes, the whole mass is brought to the press. The oil
obtained is pale yellow and odourless ; it can be used for
burning purposes, and, when sufficiently purified, for culin-
ary use, but it should not be long kept, since it soon becomes
brown and rancid. The oil-cakes may find application as fuel
in distilleries ; the ash forms an excellent manure for vine-
yards, being very rich in potash.
The firm of D. Savalle fils et Cie., of Paris, has constructed
a special portable apparatus for the production of alcohol
from grape marc. 2 Although this apparatus cannot be taken
to every vineyard on an ordinary wagon, yet it can be taken
to some one vineyard, to which the marc from the neigh-
bouring vineyards can be inexpensively and simply removed.
Not only is the pressed grape marc to be distilled, but also
the fluid residues obtained after the fermentation and repose
of the wine, the deposit and the lees. With such a method
the co-operative spirit is a necessity, for several, or many,
vine-growers would have to combine to obtain the apparatus ;
they would then treat their residues in turn according to
agreement.
1 " Giorn. agr. Ital."
2 " Oesterreich-ungarische Brennerei-Zeitung."
CHAPTEK XXXII.
INDIA-RUBBER AND CAOUTCHOUC WASTE.
Utilization of the Waste. According to Grote, in Muspratt's
41 Chemie," Goodyear grinds the waste from vulcanized caout-
chouc in a rag engine, mixes with it pure caoutchouc similarly
divided, passes the mixture between heated rollers in order
to obtain thorough incorporation, then adds a quantity of
sulphur corresponding to the pure caoutchouc, and afterwards
proceeds as in the manufacture of vulcanized caoutchouc.
Bacon disintegrates the waste of vulcanized or hardened
caoutchouc or gutta-percha, then pours 10 kilos of carbon
bisulphide and 250 grms. of spirits of wine over 100 kilos
of the waste, and allows the whole to stand for two hours in
closed vessels, when the mass is found to be so soft that it can
be ground and used again in the manufacture of new objects.
The degree of softening can be regulated by the quantity
of the carbon bisulphide mixture and the duration of the
action.
Parkes (according to Grote in Muspratt's " Chemie ") boils
8-10 kilos of the disintegrated waste in a strong solution
of 20 kilos of calcium chloride until the gutta-percha or
caoutchouc has become soft, and two pieces can be readily
united by kneading. The lumps taken out of the liquid are
washed first in a hot alkaline liquor, then in hot water, after
which, according to the statements of the patentee, they can
again be worked up.
Newton desulphurizes caoutchouc waste by softening it
in camphine (distilled turpentine) for two to fourteen days,
according to the extent of the vulcanization. If much sulphur
was used in vulcanizing, or if lead compounds are present, it
(185)
186 THE UTILIZATION OF WASTE PEODUCTS.
offers considerable resistance to the camphine. The treatment
is in every case continued until the waste is well softened
throughout, when it is heated in a still at 65-71 C., adding
camphine from time to time, so that the waste is always
covered with liquid. It is convenient to add in this operation
15-25 kilos of ether and 5 per cent of spirits of wine, and
then continue the heating until the waste has regained its
natural condition, for which one to two hours are requisite ;.
the whole is then dried at a gentle heat. The addition of
spirits of wine prevents the residues from remaining sticky,
but may be omitted if this is immaterial. The use of a still
effects the recovery of the evaporated solvent.
Later, Dodge recommended to disintegrate the waste as
completely as possible and then expose it to a temperature of
150 C. in a cylinder surrounded by another cylinder, steam
being supplied to the space between, until it had become quite
plastic, when it was mixed with fresh rubber mass, or to 25
kilos of waste, 100 grms. of palm oil, 170 grms. of sulphur,
and 1*5 kilo of white lead, zinc white, magnesia or clay may
be added, and the whole well kneaded.
A new and improved process for utilizing the caoutchouc-
contained in the waste of caoutchouc goods, and for recovering
the zinc present in them, is due to Burghardt, of Manchester^
and has been patented in England. In this process the waste
is thrown into a vessel of wood or lead, and covered with the
requisite quantity of hydrochloric acid of a strength sufficient
to destroy adherent cloth and fibres completely ; the mixture
is then boiled until the caoutchouc is freed from all fibres.
The solution contains zinc and calcium chlorides, and occa-
sionally also lead chloride ; it is treated as described below.
The vulcanized rubber is now brought into a vessel contain-
ing water, which is boiled until all the acid and zinc, calcium,
or other chlorides are removed from the rubber. The caout-
chouc thus purified is now dried, and mixed with sufficient
spirit, coal-tar naphtha, wood-naphtha, petroleum, turpentine,,
carbon bisulphide, benzene, or other solvent for rubber, in
a jacketed vessel of wood, copper, iron, or lead, the vessel
closed, and the whole brought to a temperature of about 115
INDIA-EUBBEE AND. CAOUTCHOUC WASTE. 187
C. by means of steam, gas, or hot air, until the caoutchouc-
is dissolved or converted into a thick pasty mass. When
this is the case, the naphtha is distilled off at a temperature
not exceeding 100 C. The above-mentioned solution is-
treated in a vessel with sodium bicarbonate, soda crystals,
anhydrous sodium carbonate, ammonium carbonate, potas-
sium carbonate, the carbonates of the alkaline earths, caustic
soda, caustic lime or its solution, or caustic potash, in quan-
tity sufficient to precipitate the zinc, calcium, or lead from
their solutions. The precipitate is ground in a current of
water, by which the calcium carbonate, which is specifically
lighter than the zinc carbonate, is carried away. The zinc
carbonate is either dried and sold as such, or dissolved in
hydrochloric acid, sulphuric acid, or other acid, and sold as
zinc chloride, sulphate, or other salt. Or the solution can
also be concentrated to a suitable extent and used as a
mordant for cotton.
Ludwig Heyer, a rubber manufacturer of Berlin, applies
the following method to the recovery of old vulcanized
caoutchouc: Old discarded buffer rings of railway wagons-
are heated in the presence of steam. The sulphur distils off,
the caoutchouc melts and flows into hot water, where it col-
lects at the bottom of the vessel. The steam prevents the
material from burning. The melted caoutchouc has acquired
essentially different properties ; it has become a tolerably
fluid dark mass, which also remains liquid at the ordinary
temperature, soon dries in the air, and has retained the pro-
perty of being waterproof. On the other hand, it has lost the
elasticity, at least in thick pieces. Heyer employs this fluid
caoutchouc principally for preparing waterproof sheets for
wagons, railway trucks, ships, etc. It may also be recom-
mended as a waterproof varnish for ironwork. 1
Dankwerth and Kohler, of Petersburg, have patented a
process for the treatment of old or perished caoutchouc, in
order to obtain from it oils, varnish, and materials for mix-
ing with caoutchouc and other substances. Old or perished
caoutchouc is subjected to dry distillation in a retort by means
1 " Chemiker-Zeitung," 1880.
188 THE UTILIZATION OF WASTE PEODUCTS.
of fire and superheated steam. Volatile constituents of the
caoutchouc pass over, which, when condensed, form oils and
a substance which has, after vulcanization, to a great extent
the properties of natural caoutchouc. The lighter oils, dis-
tilling at 60-105 C., are separated from the heavier oils. The
former serve directly for the preparation of varnish, the latter
are mixed with hempseed, linseed, or other vegetable oils, and
then converted into boiled oils by boiling or chemical action.
The mass still to be subjected to vulcanization is intimately
mixed by means of rollers, and then 7-20 per cent of sulphur
added.
A very durable varnish from old rubber waste can be pre-
pared for various purposes J by heating 2 kilos of old rubber,
4 kilos of colophony, 4 kilos of boiled linseed oil, and 0'5
kilo of sulphur in an iron pan until all are equally dissolved.
When this is the case, whilst the liquid is still hot, 4 kilos
of rectified American spirits of turpentine are added, and then
the liquid is diluted with about 10-12 kilos of boiled lin-
seed oil. The varnish may be coloured with earth pigments
as desired, or left in its original state. When uncoloured the
varnish has a honey-yellow colour, similar to a dark copal
varnish. It is particularly recommended for varnishing the
lead roofs of bleaching-powder chambers ; its resistance to
free chlorine has been tested for years. The varnish is very
brilliant ; when good boiled oil is used in its preparation it
dries within several days.
One of the latest processes for the recovery of india-rubber
is that in which terpineol is employed. India-rubber, both
vulcanized and unvulcanized, is soluble in terpineol, which
also dissolves the resins, etc. By addition of alcohol to this
solution fairly pure india-rubber is precipitated, while the
alcohol and terpineol can be recovered from the residue.
This is probably the only process in existence for successfully
treating waste rubber.
As a rule waste rubber is utilized by grinding it up and
adding it to fresh rubber with the other ingredients. It can-
^ampe, " Oel- urid Fettindustrie," 1890; " Neueste Erfindungen und
Erfahrungen ".
INDIA-KUBBEK AND CAOUTCHOUC WASTE. 189
not be regarded as improving the material, but it simply
serves the purpose of a "filler ".
Artificial caoutchouc is made in the following manner :
In an iron pan about 10 Ib. of sulphur or flowers of sulphur
are heated with 20 Ib. of rape oil, with constant stirring, until
the sulphur is melted and a point is reached at which the
mass swells up. At this instant the mass must be rapidly
poured out, either into a mould dusted with any kind of
flour, or on to stone plates wetted with water. The mass
solidifies and has similar properties to caoutchouc ; it is
soluble in linseed oil. The mass may also be prepared from
linseed oil, but less sulphur must then be taken. The pan
should only be half filled, otherwise the mass would boil over.
The rubber substitutes or surrogates are, however, usually
prepared by mixing linseed or rapeseed oil with sulphur
chloride, which immediately combines with them to form
solid gelatinous elastic substances, which are largely used for
mixing with india-rubber in order to cheapen that product.
White substitute is prepared by treating the oils in the
cold, and brown substitute under the influence of heat, the
proportions being about 100 parts of oil to 25 parts of sulphur
chloride.
Extraction of Eesins from Crude India-rubber. India-
rubber always contains a proportion of oxidized substances
which owing to their properties are known as resins. They
do not resemble ordinary resin as their acid and saponifica-
tion values are very low, but they have some properties in
common. The amount of resin in rubber varies from 3 per
cent in Para to 50 or more per cent in the crude African
rubbers. For the purpose of purifying the latter and thus in-
creasing their value the resins are extracted in some form of
closed extraction apparatus by means of acetone. The ace-
tone is distilled off in a current of steam and the melted resin
run into barrels. At present there is not much demand for
this product, but as it becomes better known no doubt a
variety of uses will be found for it.
See also " India-rubber and Gutta-percha," by T. Seelig-
mann, etc. (Scott, Greenwood & Son).
CHAPTEE XXXIII.
AMBER WASTE.
Utilization of the Waste. Attempts have been made to weld
amber cuttings together by heat, but never with great suc-
cess, the mass obtained having lost somewhat in beauty of
colour by being browned by the heat. A better process is
the following: After the cuttings have been sorted accord-
ing to size, they are treated for several hours by solvents
such as carbon bisulphide, ether, etc. A plastic mass is ob-
tained, which is spread out on a table so that the excess of
solvent may evaporate, when it is compressed under great
pressure into the requisite moulds.
In certain cases it is found advisable in this process to
apply a gentle heat in order to unite the isolated parts, and
to press them better into the moulds.
The pieces obtained, which have already the general
shape of their final form, are further worked in the ordinary
manner and then polished.
Whilst the lumps of amber welded together by the old
process are very brittle, those obtained by the process just
described are characterized by great elasticity. Holes may
be bored in them without fear of cracks or chips, which
often occur in the pieces amalgamated by heat alone.
In order to obtain articles of a cloudy or speckled appear-
ance, small pieces of hard amber are mixed with the plastic
mass ; these pieces, when they differ in colour from the
general mass, give the article a novel appearance.
The waste amber turnings, etc., and the dark and small
pieces are sold to varnish manufacturers for the manufacture
of amber varnish, probably the most durable varnish known.
(190)
AMBEE WASTE. 191
Legend has it that the old violins were varnished with amber
varnish which is regarded as imparting the purity of tone for
which some of these instruments are famous ; it is also sup-
posed that the method of making this amber varnish is a lost
secret.
On distillation of amber an oil is obtained known as " oil
of amber " together with succinic acid which has some claims
to be regarded as a preservative.
See also " The Manufacture of Varnishes," Vols. II. and
III, by J. G. Mclntosh (Scott, Greenwood & Son).
CHAPTEE XXXIV.
UTILIZATION OF TURF OR PEAT.
TURF or peat occurs in very large quantity in various local-
ities in boggy places. It is the product of the slow decay of
vegetable matter under water, and in some respects resembles
coal. Peat is a dark brown solid varying in appearance from
a loose friable earthy product to a hard tough mass very
nearly approaching coal, the former being found on the sur-
face, the latter at depths of several feet. In Ireland, in
Yorkshire, and parts of Scotland, etc., the peat is regularly
cut every year into the form of blocks which are air dried and
used as household fuel.
Peat varies very considerably in composition, but it in-
variably contains a large percentage of water and mineral
matter and hence has not a very high calorific value. The
following is an analysis of a sample peat dried at 100 C.
(Johnstone) :
Carbon . -, . . . / .- 59-00
Hydrogen. , . . , . . . 5'50
Oxygen . . . . . . '. 19-50
Nitrogen . ' * ' '. .- .' . . 1-50
Mineral matter . . . .-,-. '> 14-50
100-00
In the wet state peat will contain 60-65 per cent of
water and in the air-dried state 25 per cent, so that difficulty
is found in drying, whilst on burning the evaporation of this
water requires a considerable amount of heat, hence as com-
pared with coal, peat is a poor fuel.
Many attempts have been made to utilize peat, and in
this connection a very able paper by Dr. Dvorkovitz on the
" Distillation of Peat " l may be consulted.
1 " Journal of the Soc. of Chem. Indt.," 1894, p. 596.
(192)
UTILIZATION OF TUEF OE PEAT. 193
The lighter and more flocculent peat is baled and sold as
" peat moss litter," used as bedding for horses and cattle, for
which purpose it is very well suited.
Peat moss is also ground up and saturated with common
beet molasses, passing under proprietary names as a cattle
food.
By suitable treatment peat can be spun into yarn, while
a proportion of it is available as a low-class papermaking
material.
Peat is also compressed into briquettes and used as fuel.
The distillation of peat is also carried out in the same way
as coal yielding illuminating gas and other products. Both
these processes will be considered in subsequent chapters.
Utilization of Turf Waste. G. Gercke, jun., of Hamburg,
has patented a process for producing plastic objects from
turf as a substitute for wood, pasteboard, paper, etc. This
process is based upon obtaining the turf without damage to
the fibres, which are easily injured whilst moist. In remov-
ing the turf, in order not to cut through the fibres, the longi-
tudinal layers must be followed, which occasionally form flat
sheets.
After the raw material has been cut to the desired dimen-
sions, it is dried upon boards or a framework of laths, during
which it is protected from the sun in order to prevent the
plates from warping. When completely dry, the material is
subjected to a special treatment, the essential part of which
is strong compression, according to the particular purpose for
which it is required. The very hygroscopic constituents of
the product must be removed if it is to be exposed to the
action of the weather. For example, in order to make a
roofing material, the dry turf plates, compressed to 10-20 per
cent of their original thickness, are protected from moisture
by saturation with a heated mixture of tar and asphalt. The
excess of tar is removed by squeezing between rollers and
the plates then dusted with sand in order to prevent them
from sticking together.
Another method consists in saturating the turf plates with
13
194 THE UTILIZATION OF WASTE PRODUCTS.
milk of lime, drying, pressing or rolling, soaking in water-
glass and then coating with water-glass paint.
In order to increase the strength of the plates, which is
already considerable, materials of various kinds are inserted
and fastened between two or more of the layers by means of
a suitable adhesive agent. For this purpose bast, tow, cord,
long turf fibres, heather, twigs, metal or waste wood are
suitable, the binding and impregnating materials being tar,
asphalt, wood cement, glue, water-glass, varnish, pitch, clay
and resin cement.
The compressed turf may be subjected to any required
treatment ; it is suitable for replacing papier-mache and
wood-pulp, wood, horn, bones, etc. 1
Obtaining, Oils, Spirits, and Gases from Peat, etc. No.
11481 of 1915. A. N. Hacnicol, 31 Queen St., Melbourne,
Australia, claims: (1) A process for the extraction of oils,
spirits, and gases from peat or other materials or substances
consisting in first grinding the material and continuously or
intermittently feeding the substance by pressure or otherwise
into a retort, and applying a heat gradually and regularly
externally of the retort, subjecting the material in the retort
to the action of steam which may be superheated, the sub-
stance being passed over the heated surface by a moving
rabble, the retort being partitioned to provide heat sections,
and the volatilized substances emanating from the material
treated being led off by pipe connections to a condenser or
condensers, the oils and spirits being collected in a reservoir
or reservoirs by condensation, the non-condensable gases
being returned to the furnace to be used as fuel, and the hot
gases flowing from one part of the apparatus to another part
being utilized for drying the substances before they are fed into
the retort. (2) Apparatus for the extraction of oils, spirits,
and gases from peat or other materials or substances by the
process set out in claim 1, having in combination a retort
chamber, rabbles within the retort chamber, and arranged
to pass over the surface of the retort, means for dividing
1 Compare T. Koller, "Die Torf-Industrie," Vienna, Hartleben, pp. 109
et seq.
UTILIZATION OF TURF OR PEAT. 195
the retort into neat sections, a feeding hopper at one end of
the retort, a feeding conveyor adjacent to the hopper, means
at the opposite end of the retort adapted to expel the material
after being treated, means dividing the retort chamber below
the floor into a plurality of flue compartments, a source of
heat adapted to heat said compartments, means for driving
the rabbles over the floor of the retort and pipe connections,
and a fan or blower between the retort and condensers.
(3) An apparatus for the extraction of oils, spirits, and gases
as claimed in claim 2, wherein the retort chamber is con-
structed of refractory material, partitions divide the retort
into heat sections, and the plurality of flue compartments
receive heat independent of each other and extend longi-
tudinally to the floor of the retort within the chamber of
refractory material. (4) An apparatus for the extraction of
oils, spirits, and gases as claimed in claim 2, wherein the
rabbles passing through said heat sections progressively
carry material to be treated over one end of the retort to the
other, and the source of heat is connected with said flues
adjacent to the delivery end of the retort, means being pro-
vided for withdrawing the gases independently from the
several heat sections, and for conducting the non-condensable
gases to the said source of heat where they are used as fuel.
(5) An apparatus for the extraction of oils, spirits, and gases
as claimed in claim 2, wherein the rabbles extending trans-
versely across the retort carry rollers at their end separated
from the heat sections of the retort. (6) An apparatus for
the extraction of oils, spirits, and gases as claimed in claim
2, wherein the rabbles are adapted to pass over a relatively
cool surface between the platform and the roof of the retort
and above the heat sections. (7) An apparatus for the ex-
traction of oils, spirits, and gases as claimed in claims 2 and
3, wherein the partitions forming heat sections are carried
down to the surface of the material under treatment. (8)
An apparatus for the extraction of oils, spirits, and gases as
claimed in claim 5, wherein the rollers of the rabbles are
adapted to operate in a cooler zone formed by an extension
of the retort and a partition.
CHAPTEE XXXV.
MANUFACTURED FUELS.
Artificial Fuel. In the year 1874, Ney, at a meeting of the
Aix-la-Chapelle Society of Engineers, confirmed the statement
which originated in Belgium, that a mixture of 80 Ib. of soil
with 20 Ib. of small coal, moistened with a solution in water
of 1 Ib. of soda or common salt, burnt well. This amount of
coal, which by itself would only last fifteen minutes, in com-
bination with the other materials burnt for an hour. This is,
however, merely a retardation of burning, there is no gain in
the actual heating value. It is explained by the fusion of the
soda and the earthy constituents of the soil, to form a slag
below which, owing to the impeded circulation of the air, the
fire burnt for a long time. Naturally, direct action of the
soda on the fuel is not to be imagined. E. Hasenclever, on
this occasion, called attention to the high proportion of com-
bustible matters in certain soils. Thus street mud from
Stolberg, near Aix, according to his researches, contained not
less than 20-21 per cent of combustible material ; whilst dirt
from the Bomerstrasse, in Aix, only contained 6 per cent.
The choice of the soil is therefore of importance. At Hasselt,
in Belgium, where the discovery of the above artificial fuel
was made, there are many = cavities filled with turf -like soil.
When such soils are not at hand, the process is devoid of
importance. The mixture, as might be anticipated, has
been found quite suitable for firing boilers.
Manufactured Fuel. Loiseau x prepares a fuel, in lumps of
the size of a hen's egg, from 95 per cent of coal dust, 5 per cent
of clay, and a binding substance made from rye flour and
slaked lime. Subsequently the lumps are soaked with paraffin
1 " Zeits. f. d. chem. Grossgew.," v. Post, 1877, 1.
(196)
MANUFACTURED FUELS. 197
residue dissolved in benzine, in order to protect them from
the weather. The clay is dried on iron plates over a movable
fire and ground, then mixed with sieved coal dust by means
of a special appliance, which measures off the necessary
quantity of each constituent, and delivers them into a re-
ceiver, where they are mixed with the binding medium
which drips over them. In a second large iron tank the
mass is kneaded between iron rollers covered with teeth ; it
then goes to the hopper of the press, the two rollers (29 ins.
in diameter) of which are each hollowed out into 870 large and
56 small moulds. When the moulds meet in the rotation
of the rollers, the soft mass is pressed in, and falls in egg-
shaped lumps upon a moving band of woven wire. The large
lumps weigh 3 oz., the smaller about | oz. They are dried
on moving woven wire belts in an oven at 250 C., and then
fall on to another belt with wire sides which carries them
through a bath composed of paraffin residues and benzine.
The volatile benzine is then distilled off in the " evaporator,"
when the briquettes are ready for use. The apparatus turns
out 150 tons of briquettes daily. The product is considerably
cheaper than ordinary coal.
Briquettes from Lignite. At the lignite mine at Frielen-
dorf , near Cassel, in 1876, a new briquette works was erected, 1
the arrangement of which was as follows : The lignite was
drawn up from the bottom of the open working in half-ton
wagons in a winding shaft, by means of steam power, to the top,
whence it was transported on a covered tramway, either to the
hoppers from which the boilers were fed, or to the hoppers of
the rotatory sorting apparatus, and there emptied out. A short
screw conveyer carried the lignite, which was to be compressed,
to a sorting cylinder, which passed all the pieces above 7 mm.
partly through the large openings in the latter half of the
sieve, and partly through the end of the cylinder, whence
they fell upon a pair of rollers below. The material, which
was here ground below a maximum size of 7 mm., together
with the small which had fallen through the finer part of the
1 " Preuss. Zeits. f. Bergwesen," 1876.
198 THE UTILIZATION OF WASTE PRODUCTS.
sieve, passed into a horizontal screw conveyer, which now
carried the fine coal to an elevator. The latter raised the
coal through a height of 8 ft. to a horizontal screw conveyer,
passing over the drying-ovens, which were thus furnished
with the necessary quantity of moist ground lignite. After
the material had passed through the interior of one of the
four sections of the automatic oven, and had left the delivery
apparatus, the now dry coal was taken by an elevator, cased
with sheet-iron, to the level of the hoppers of the two presses,
from which it fell spontaneously through a regulator, and
finally left the presses in the form of briquettes. These now
went to a wooden trough, through which the machine forced
them in a compact string, into the store to be stalked, if they
were not loaded for transport direct from the trough. The
presses did not differ materially in construction from other
coal presses which have recently been found satisfactory.
Each consisted essentially of a thirty horse-power horizontal
engine, together with the stamp and the press head, which
was rigidly connected with the bed-plate of the engine. The
press head a cast-iron cube carried the orifice through
which the lignite was supplied, and was traversed by a
chamber 62 ins. long, containing the press feeder, which con-
sisted of top, bottom, and two side wedges, between which
the stamp moved and effected the compression of the material.
A wrought-iron plate resting upon the upper wedge, pressed
by a screw at the front, and moving on a strong spindle,
served to close the top of the press chamber and to regulate
the pressure or friction in the mould. The lignite already
in the press chamber, which had been solidified, provided
the resistance for the next following briquette. At both sides
of the press block were hollow pieces, through which hot
steam was sent to heat the block. The compressed lignite,
as previously remarked, from the press entered a wooden
trough in front in a continuous stream, and was then pushed
outside the building into wagons, or to the store. Without
overloading the machine, the stream of briquettes might be
from twenty to forty yards long. One great advantage of the
MANUFACTURED FUELS. 199
Frielendorf apparatus, as opposed to the ordinary trough and
plate machine, was that, within the former, there were no
moving parts, which in the latter cause so many stoppages
and repairs, and also give rise to the formation of much dust
and danger 'of explosion.
Compressed Fuel from Lignite-coke and Peat. F. Mathey
states that a compressed coal may also be made from lig-
nite-coke and peat ; yet these roquire a somewhat greater
addition of saltpetre than charcoal. The latter, obtained
from different works, contained 2-4*5 per cent of potassium
nitrate. 1 The Chemnitz works use as binding medium gum-
arabic waste ; Knorr, of Weissenfels, uses rye flour ; others,
dextrine. Of gum-arabic, as much as 4 per cent is added ;
of dextrine and rye flour, 4-8 per cent. Instead of rye flour,
gluten a waste product of starch- works would be better.
Practical Experiences in Briquette-making. At the Aix
District Association of German Engineers, Hilt read a paper
concerning the local development of the briquette manu-
facture. 2 In the first place, he maintained that this industry
could only take root where small coal was to be obtained at
one-quarter of the price of large coal. Coking is the best
method to use with very bituminous small coal. For briquet-
ting the small of non-caking coals, there may be used (1)
mineral binding agents, such as clay, loam, gypsum, cement,
and lime ; the resulting coke naturally contains much ash and
is not hard; (2) carbonaceous binding agents, such as glue,
starch, tar, and coal-tar pitch. The briquettes obtained are
impervious to weather, may be readily transported or stored
without crumbling, and possess a heating effect similar to
that of large coal. The first species of briquettes, made with
mineral substances, is much used for domestic purposes, but is
unsuitable for boiler firing. The second kind, made with or-
ganic substances, may also be used as boiler fuel, with a good
draught and care in firing, without producing excessive smoke.
1 " Deutsche Industrie-Zeitg.," 1876, p. 125 ; " Dingler's Journ.," 1878,
p. 90.
2 Wieck's " Gwb.-Zeitg.," 1878, No. 39 ; " Zeits. f. d. chem. Grossgew.," v.
Post, III, I, 1878.
200 THE UTILIZATION OF WASTE PRODUCTS.
The somewhat slow combustion of these briquettes may be
counteracted by using a thicker layer of fuel, by breaking
them up, and by more frequent raking of the fire. In making
the briquettes the coal and binding medium are nrxed in the
proper proportions in a suitable apparatus, provided with a
mechanical stirrer, in which the mass is softened by hot air
entering the apparatus or by heated steam. The briquettes
are then moulded, under a high pressure, in closed moulds,
or in an apparatus similar to the well-known brick press.
Drying apparatus for briquettes has been made of many
forms. Most of these considerably increase the cost of
manufacture. The cheaper drying apparatus of A. Wilcke is
here described. 1 Upon a solid foundation, 3*25 metres (12
feet) square, in which are two flues for supplying and removing
the heating gases, are built two walls containing flues, 1 metre
(39 ins.) thick and 1 metre apart. Between these two walls
floors are built in, consisting each of two iron plates, which
floors are closed at the short ends by plates, so that the fire
gases introduced by the flues into the closed boxes must heat
the plates. Thus, when the flues are connected to a fire, they
bring the gases to the second floor, which they pass through,
then through the third, and so on, until they are drawn off to the
chimney and reach the atmosphere. If eight such floors, each
3 metres long, are placed one above the other, the fire gases
have an opportunity of giving up their heat to the 24 metres
length of iron plates which they touch, to the full extent
allowable in view of the necessity of producing a sufficient
draught in the chimney. The gable-ends of the iron floors
are protected from cooling in a suitable manner. The separate
floors are so arranged as to project in turn, so that the pro-
jecting part catches the coal falling down from the floor above.
Similarly, in order to shut off the open space between the
separate floors from the outside, movable flaps are provided.
The upper plate of each floor is surrounded on three sides
by a ridge ; on the open side the* coal is brought down to
the next floor. Thus, as stated above, the coal goes from
1 "Dingler's Journ.," 221, p. 523.
MANUFACTURED FUELS. 201
floor 1 to floor 2 ; the narrow edge of floor 2, protected by
the ridge, projects 250 mm. (10 ins.) beyond floor 1. If
now some arrangement be provided by which the coal, which
reaches floor 1 from a hopper, is moved over the plate of
floor 1 to that of floor 2, and so on, and if this motion be so
regulated that the coal is heated to about 60 C. when it
arrives at the delivery-shoot, coal quite suitable for briquetting
will be obtained.
The movement of the coal over the plates is accomplished
by means of a lattice provided with scrapers, and moved by
mechanical power. Two _i_-shaped rails are connected by two
cross-bands and two transverse rails ; this grating is provided
on the flat under-surface with flat scrapers 100 mm. (4 ins.)
apart, and is coupled to cranks on the shafting. When the
shaft rotates, the grating is moved backwards and forwards
over the plates. This motion to and fro would, however, not
move the coal lying on the plates, which can only be done if
the grating, in moving back, is raised over the coal without
touching it. Projecting pieces are arranged on the shaft,
which act so as to raise the grating in the reverse movement.
This rise is naturally at first gradual, so that the scrapers
level the ridges into which the coal w^s brought in the for-
ward movement. Thus the coal is stirred, which is a neces-
sary condition for the uniform drying of coal intended for
briquettes. The grating is supported by a foot running on
a small wheel, so that it may keep at the greatest height until
the end of the reverse stroke ; when the reverse stroke is
finished the grating falls, and then again moves the coal
forward.
The rails run upon rollers, in order to prevent the scrapers
from grinding on the plates during the forward movement,
and stays are used in the floors to prevent the plates from
buckling. The grating also runs upon three wheels in the
middle.
If now coal is continuously brought upon floor 1 from
the hopper, when the grating is put in motion the coal is
regularly moved forward. As soon as the grating commences
I
202 THE UTILIZATION OF WASTE PEODUCTS.
the retrograde motion a valve closes the hopper, and feeding
ceases until this motion is finished. If this were not done,.
too much coal would be piled up in the hopper, and some
would be thrown over the edge. The coal is gradually carried
over floor 1, then falls to floor 2, and so on, until it finally
reaches the press, whither it is carried by elevators or con-
veyers. During the passage of the coal it is uninterruptedly
exposed to the heat radiated by the plates, which is prevented
from escaping too rapidly by the flaps before-mentioned. The
fresh coal is subjected to the greatest heat, since the fire gases
are conducted into the apparatus from above.
Clayton has constructed a machine for compressing small
coal into briquettes. 1 A horizontal plate carrying moulds of the
required size is placed between two cast-iron columns. Upon
the plates moves the filling-box, to which the material, pre-
pared in the proper manner, is conveyed from the mixing-drum.
The filling-box obtains its movement to and fro by means of
a bent lever from the cross-head. The briquettes are com-
pressed from two opposite sides. The lower pistons are
driven by cogs on the wrought-iron shaft supported by the
framework. The upper pistons of the press are actuated
from the shaft by cranks and strong connecting rods, sus-
pended from the cross-head which moves in the framework.
In order to avoid excessive pressure on the mechanism, the
upper pistons are provided with strong springs.
When the moulds are filled with coal, the upper and
lower pistons at once move and compress it to a solid brick.
The upper pistons then rise, and are followed by the lower
pistons, the finished briquette being thus raised out of the
mould to the level of the plate. The filling-box in its return
with fresh material removes the briquette. The reversal of
the lower pistons, which also affect the lubrication of the
moulds in a well-known manner, is brought about by cog-
wheels on the shaft.
A two horse-power steam-engine is sufficient to drive a
press which can produce per day about 10,000 briquettes.
1 " Dingier' s Journ.," 203, p. 27L
MANUFACTURED FUELS. 203
each weighing 5 Ib. The space required is very small ; a
ground space 5 ft. long by 4 ft. wide, with a clear height of
6 ft., is sufficient.
Finally, E. F. Loiseau has constructed a machine for
converting anthracite dust into an artificial fuel. 1 The
coal dust is moistened on a platform and then scraped
into the hopper of a stationary cylinder, in which a shaft
rotates. On the shaft are six radial plates which divide
the interior of the cylinder into six equal spaces. The
coal dust fills these spaces, and the rotation of the plates
drives it into an opening beneath, through which it leaves.
A smaller hopper, placed close against the first, receives clay
previously dried and ground. This passes through a smaller
cylinder, also provided with rotating partitions, and is then
emptied into the same channel as the coal dust, with which
it mixes.
The space between the partitions of the clay cylinder is
calculated regularly to take and deliver 5 parts of clay, whilst
the larger cylinder delivers 95 parts of coal dust. The mix-
ture of coal and clay is sprinkled with milk of lime whilst it is
falling below a chain elevator, which now raises the moist
mixture to the hopper of a conveyer. The Archimedean
screw rotating in the latter drives the material into a mixing
apparatus, where it is rapidly transformed to a plastic mass
by means of seven vertical shafts, to each of which four toothed
arms are screwed. These arms cross one another in all
directions, and intimately mix the coal and clay together.
Through suitable openings at the bottom of the mixer, the
plastic mass falls along a shoot into the kneading machine, in
which, by a series of knives attached to the central shaft and
a propeller, it is forced through an opening at the bottom be-
tween two rollers, in the periphery of which are a series of
oval moulds. These rollers, moving in opposite directions,
take the material presented to them in the form of a coherent
band, and mould it into oval lumps. An endless wire band
l4< Journ. Franklin Institute," 1873, p. 266; " Dingier' s Journ.," 210,
p. 437.
204 THE UTILIZATION OF WASTE PRODUCTS.
<
carries the lumps away, and delivers them into a hopper
placed above the drying-flue.
The drying-flue is heated from a fireplace at each end.
It contains five endless wire belts, one above the other, which
move in opposite directions over rollers placed at the ends of
the stove, and which have an arrangement for preventing the
lumps from falling down. The compressed lumps of coal fall
upon the topmost wire belt, are carried by it through the
whole length of ijhe stove, and then slide along a shoot which
carries them on to the second endless belt beneath. This belt
carries them in the opposite direction through the whole
length of the flue to a second shoot, from which they pass
down to the third belt, upon which they are carried forward,
and so on. The last wire belt carries the coal out of the
stove and empties it into the buckets of an elevator, by. which
it is raised and then delivere'd to another endless band, which
passes through an open tank, fed continuously from a neigh-
bouring larger tank, by which the smaller tank is kept filled
with the waterproofing composition. The endless band is pro-
vided with small partitions, which prevent the oval lumps from
suddenly falling down into the composition. The continuous
immersion of the coal in the waterproofing mixture is brought
about by small balls at each side of the belt, which run in
narrow grooves on the walls of the tank. On leaving the
tank the excess of liquid drips from the lumps of coal through
the wire belt into a gutter beneath, from which it flows away
by a pipe to a convenient tank.
The waterproofing composition employed by Loiseau is a
solution of colophony or some other resin in benzine. In
order rapidly to evaporate this benzine, the lumps of coal
coming from the bath are emptied into the hopper of a stove
of smaller dimensions than the drying-flue, in which only
three endless belts are placed one above another. In this
flue a strong current of air, driven by a fan, rapidly
evaporates the benzine, whilst the coal goes from one belt to
another. From the last belt it falls through a shoot into the
coal truck outside. The end of the shoot may be raised so
MANUFACTUBED FUELS. 205
that a filled truck may be taken away and an empty one
brought in its place.
During the passage of the material through the flue the
hot air acts on all the lumps and rapidly dries them. The
whole process of manufacture, from the passage of the coal
dust into the first hopper, proceeds automatically ; coal dust
and clay are mixed in the proper proportions with milk of
lime, this mixture is kneaded, compressed into oval lumps,
which are dried and waterproofed, the benzine is evaporated,
and the finished products delivered to the trucks, all mechani-
cally. During the whole process the coal is continuously in
motion.
CHAPTEK XXXVI.
ILLUMINATING GAS FROM WASTE AND THE BY-PRODUCTS OF
THE MANUFACTURE OF COAL GAS.
Utilization of Waste Products in Making Illuminating Gas.
Gas from Suint. 1 In addition to the waste products con-
taining fat bones, oil-cake, etc. soap waters produced in
washing the grease out of wool and the gum from silk may
be used with advantage for the production of an illuminating
gas. It contains the original grease of the wool, oleates
and stearates of soda and lime, and also nitrogenous organic
matters from the wool and silk. The fatty acids are
separated from the suds either by inorganic acids, or they
are combined with lime and the product subjected to
distillation, (a) Distillation of the separated fatty acids.
According to Knapp, at Kheims, 300 cwt. of wool-washing
suds are mixed with 2 per - cent of sulphuric acid or 4
per cent of hydrochloric acid and equal quantities of water,
and allowed to stand for twelve to eighteen hours, when
the impure greyish mass of fat which has risen to the
surface is mechanically cleaned, melted in a copper pan,
and, whilst fluid, treated again with 2 per cent of sulphuric
acid. The clear oil obtained is used for soap-making,
and the black, solid, fatty residue employed for produc-
ing gas. The tar which separates in the distillation is
-always again used to dissolve the solid residue, (b) Dis-
tillation of the separated lime soaps. At the spinning-mills
in Miihlhausen and Augsburg, according to Altgelt, the water
containing the sweat of the wool and the used soap is
allowed to stand with milk of lime for twelve hours, the
clear liquid drawn off, the deposit sieved through coarse
1 " Dingler's Journ.," 195, pp. 175, 216, 517.
(206)
ILLUMINATING GAS FROM WASTE. 207
linen cloths, and the mass which passes through allowed to
stand for six to eight days in a cellar until it forms a pasty
mass, which is then cut up with a spade into rectangular
lumps of the size of half a brick. These lumps are dried
for several weeks on frames, and the dried mass, which is
termed suiter, subjected to distillation. A gas is obtained
which it is not usual to purify, and which has three times
the illuminating power of coal gas. The soap liquors in
which silk has been boiled, according to Jeannency, are
heated with slaked lime to 70-75 C., allowed to clarify
during two to three days, the clear liquid decanted off, the
deposit filtered, spread out to dry in the air, and then used
for gas-making. One hectolitre (22 gals.) of the soap liquor
requires 0'75-1'5 kilo (l'68-3'37 Ib.) of quicklime, and gives
1200-1600 litres (42-56 cub. ft.) of gas. The gas .is not
purified or washed, but is 'taken direct from the retorts to
the gasometer.
Illuminating Gas from Wool Waste. Liebau, of Magde-
burg, 1 employs wool waste from spinning mills either alone
or, better, mixed with coal to produce illuminating gas. A
layer of coal 52 mm. deep (2 ins.), then a layer of wool waste
157 mm. (6'3 ft.) deep, and finally a little more coal, are
brought into the scoop used for filling the retorts, and the
contents quickly emptied into the retort, which is at a low
red heat. With a retort of 30 kilos (67 Ib. capacity) the
distillation is finished in one and a half to two hours. Fifty
kilos (1 cwt.) of waste produce 21 '63 cub. metres (800 cub.
ft.) of gas, whilst the coal also gives about 17 cub. metres
(630 cub. ft.) of gas per 50 kilos (1 cwt.). The carbonic acid
is removed by purifying. It is advisable to use the wool
waste mixed with coal rather than alone, since a saleable
coke is produced, the cheaper clay retorts can be used, and
the purification is also less expensive.
Illuminating Gas from Beet Molasses, Wine Lees, and
'Grape Marc. 12 From 100 kilos (2 cwt.) of dried, or 111
.kilos (250 Ib.) of crude molasses, Stammer has obtained
1 " Dingler's Journ.," 184, p. 380. 2 " Deutsche Industrie-Zeit."
208 THE UTILIZATION OF WASTE PRODUCTS.
61'8 cub. metres (230 cub. ft.) of unparified illuminating
gas. The residues from the maceration of dried beet, after
pressing and drying, give 24'72-37*08 cub. metres (916-1375
cub. ft.) of gas per 100 kilos (2 cwt.). The gas contains.
23-24 per cent of carbonic acid. Three kilos (6| Ib.) of
10 per cent ammonia liquor or 1'2 kilos (2'6 Ib.) of sulphate
of ammonia are also produced.
The grape marc, which has already been used for
producing tartaric acid and marc brandy, may further be
used with profit for gas-making. 1 No other appliances are
necessary for producing gas from the grape marc than those
used for coal or wood gas. Grape marc may therefore be
treated in any well-arranged coal-gas works. The by-pro-
ducts obtained by condensation from the gas produced by
grape marc are essentially the same as those obtained from
wood gas, viz. acetic acid, ammonia solution, and a mixture
of hydrocarbons similar to wood tar, which may .very well
be utilized for the preparation of creosote, photogene, and
paraffin. It is absolutely necessary that the marc used for
producing gas should be fre'e from alcohol, i.e. only marc can
be used from which brandy has been prepared or from which
the alcohol has evaporated by long lying in the air ; it must
also be air dried, and should not be mouldy. The marc, as
it comes from the brandy distillery, is pressed in order to
remove the greater part of the liquid. It is then dried, for
which purpose it is pressed, into moulds, which may be either
rectarigular boxes, open at top and bottom, or circular rings ;
rectangular bricks or round cakes are thus produced in the
same manner as the bricks of tan-bark. The bricks or cakes
are quickly dried in the open air on hurdles or frames. Dry-
ing the marc by the aid of artificial heat is not advisable,
since if the drying be carried only a little too far, not only is
much less gas obtained, but also gas of lower illuminating
power. The dried bricks may be kept for years before use,
if they are piled one above another in open layers so that the
air can always pass between them. The retorts are charged
1 " Die Verwerthung der Weinriickstande," A. dal Piaz, Vienna.
ILLUMINATING GAS FROM WASTE. 209
in the same manner as with coal. At each charging 20-50
kilos (42-112 Ib.) of the marc bricks are introduced, according
to the size of the retorts, so that five- or six-tenths of the in-
ternal volume is occupied. The quantity of marc cakes re-
quired for one charge is distributed in a charging scoop, of the
same length as the retort and of semi-circular section. The
scoop is then quickly pushed into the retort and turned
over, so that its contents are emptied on the bottom of the
retort. The empty scoop, is rapidly withdrawn and the retort
lid, the edge of which is well smeared with clay paste,
screwed on. When the retort is closed a violent distillation
and evolution of gas take place as soon as the retort is suffi-
ciently heated. As in making wood gas, a charge of grape
marc is completely gasified in two hours at the most, whilst
coal requires five to seven hours before it is. entirely ex-
hausted. The treatment of the grape marc has thus the ad-
vantage over that of coal that a large quantity of gas can be
rapidly made without large furnaces and gasometers being
necessary. The gas is also of greater illuminating power than
ordinary coal gas, but particular care has to be taken that the
grape marc used is thoroughly air dried, and quite free from
alcohol and mould. If the intention in gasifying grape marc
is to obtain good Frankfort black, then no higher tempera-
ture is used in the distillation than is required to maintain
the retorts at a dark red heat. Thus it is advisable to use for
heating the retorts or gas furnaces, in place of the usual
coke, a fuel of less heating power, such as turf, lignite, or
wood, especially when coke is the more valuable. When
grape marc is gasified with the retorts at a dark red heat, a
coaly residue of a dull, deep bluish-black colour is obtained,
which produces Frankfort black of a very fine shade. If, on
the contrary, the retorts are almost at a white heat, the re-
sidue is dark grey and shining like graphite, to which when
ground it is quite similar ; it may be used ground in linseed
oil as " furnace black," a greyish-black paint of good covering
power.
After the distillation has continued one to two hours, ac-
14
210 THE UTILIZATION OF WASTE PRODUCTS.
cording to the size of the retorts, the evolution of gas slackens,
the gasification of the charge is then regarded as finished, and
the hot residue at once withdrawn from the retort. When
the retort lid is opened, the gases issuing from the retort are
lighted, as in making coal gas, in order to avoid an explosion.
The withdrawal of the red-hot charge, similarly to the charg-
ing, is carried out as rapidly as possible, in order that the
residue may not be partially burnt, which would result in
the product being contaminated with a fine white ash.
It is therefore necessary to use a broad rake in emptying
the retorts, to rake the contents into a sheet-iron box with a
well-fitting lid, placed below, and at once to close the box
with the lid in order to exclude the air. It is, however,
better and simpler partially to fill the box with water, so that
the glowing contents of the retort are quenched immediately
they are drawn.
In making gas from grape marc similar condensing ap-
paratus is required to that used for coal or wood gas ; as
with the latter, dry lime is used for purifying. The gas lime
obtained in the purification, and also the other by-products
of the condensation, can be utilized in the same manner as
those obtained from wood gas or coal gas. Experiments
made at the Griinstadt gasworks have shown that when the
retorts are almost white-hot, from a 50 kilo (1 cwt.) charge
of completely air-dried grape marc about 17 '5 cub. metres
(648 cub. ft.) of gas are obtained of a considerably higher
illuminating power than ordinary coal gas. At a dark red
heat the yield of gas is smaller thus, from a 50 kilo charge,
about 15'6 cub. metres (577 cub. ft.) of gas of the same
illuminating power as ordinary coal gas are obtained.
The grape seeds, separated from the marc and dried, in
consequence of the oil they contain, yield almost twice as
much gas as the marc, this gas far surpassing that from
marc in illuminating power. The carbonaceous residue ob-
tained in gasifying the seeds also gives Frankfort black. In
gasifying grape marc the residue, i.e. the Frankfort black,
amounts to one-quarter of the weight of the dried marc;
ILLUMINATING GAS FEOM WASTE. 211
therefore it is possible to reckon with certainty on obtaining
20-25 per cent of grey or black pigment.
Illuminating Gas from Fusel Oil. 1 The fusel oil from
potato spirit is generally preferred in the manufacture of
perfumes to fusel oil from beet or molasses distilleries, since
it contains more arnyl alcohol. H. Briem recommends that
this by-product of the molasses distillery, which has little
commercial value, should be used for preparing illuminating
gas, for which purpose it is passed through a heated pipe.
The iron pipe required for decomposing the fusel oil has a
diameter of about 10 cm. (4 ins.) for lighting 100-200 burners ;
it is laid in the fireplaces of the furnaces used for evaporating
the wash.
Illuminating Gas from Sewage Deposits and Excrement.
The first experiments with this object date back to 1827,
when Keimann, of Berlin, made illuminating gas from faeces.
The price of the new gas was, however, higher than that of
coal gas, and thus this method of utilizing excrement had to
be abandoned. Of the more modern processes, two in parti-
cular are worthy of notice : the first, for the production of
illuminating gas and hydrogen from sewage deposits, is due
to E. G. Hickey ; the second, of illuminating gas from excre-
ment, to Sindermann, of Breslau.
Hickey has published a description of this process, 2
according to one modification of which hydrogen, for il-
luminating purposes, is obtained by passing superheated
steam over sewage deposit, heated in a retort. Another
modification consists in producing a gas for lighting and
heating from sewage deposits. Hickey intended to make
excrement of all kinds innocuous ia this manner, by car-
bonizing it in closed retorts, and using the residue in the
retorts for removing the smell of fresh matter before its in-
troduction into the apparatus, and also, together with the
distilled products, as manure ; the gas was to be used either
1 " Zeits. d. Ver. f. Biibenzucker-Industrie."
*" Dingler's Journ.," 195, p. 378.
212 THE UTILIZATION OF WASTE PKODUCTS.
for lighting or heating, or for both purposes. The process
differs somewhat according to the result desired. For the
transport of the sewage deposit to the gasworks, buckets of
circular or elliptical section are used ; they narrow at the
top to a neck from 3-4 in. wide, which is filled with the
ignited excrement, and may also be closed by a water-lute r
to prevent the escape of smell. The fluid constituents
are partially removed from the matter before it is brought
into the retorts, and are also made odourless by means of the
ignited residue. For this purpose the mixture is brought
into a cylinder with a perforated bottom, covered by a layer
of ignited residue. When full, a tight-fitting plate is laid on
at the top, and then, by a screw mechanism, a gentle pres-
sure is applied, which expresses a large part of the liquid in
a completely innocuous condition.
The retorts in which the pressed matter is heated are
either of clay or wrought iron ; they are best Q -shaped, and
have at each end an opening, closed during use by a tight-
fitting lid, smeared with clay ; the retorts are laid at an angle
of 15-20. If the gas is to be used for heating only, the gases
and vapours are allowed to rise through pipes, and then
through a water-tank divided into several compartments ; in
this manner they are completely washed, and the ammonia
salts mostly separated. The gas then passes through a con-
denser, and thence into a small gasometer, from which it
passes through a pipe, furnished with a regulating valve and
ending in a head provided with slits, to the furnace, where it
is burnt with the addition of partially carbonized excrement.
If the gas is to be used for lighting it requires to be more
carefully purified. It leaves the retort, as does coal gas, to
enter the main pipe, which must be of relatively large size ;
it goes thence to the condensers, in which the ammonium
and other salts are removed by repeated passage through
water. It then goes through a scrubber a cylinder filled
with bricks, stones, charcoal, or large lumps of the retort
residue and finally through a dry purifier, which contains
alternate layers of lime and retort residue, spread on
ILLUMINATING GAS FROM WASTE. 213
frames one above another, which it leaves for the gaso-
meter.
If the gas produced in the retorts is to be used for heat-
ing, and, at the same time, hydrogen gas is to be made for
lighting purposes, the gas which is first evolved is conducted
away, as in the first case ; as soon as the evolution of gas has
ceased, the connection with the pipes leading to the condenser
is cut off by a tap, and then superheated steam, from a small
boiler built in the furnace, and which may be fed with the
liquid expressed from the excrement, is passed through a
perforated pipe over the red-hot residue in the retort. Pure
hydrogen and carbonic acid are formed almost entirely ; the
latter is removed in a dry lime purifier, whilst the hydrogen
is burnt in an Argand burner, provided with platinum
gauze.
The gas produced from human excrement burns with a
very bright flame. The residue remaining in the retorts is
an odourless black powder, which is very suitable for remov-
ing the odour from solid and liquid sewage matters, and, like
the deposit in the condenser, produces an excellent manure.
From the liquid condensed in the main pipe, by evaporation
with hydrochloric acid in pans on the top of the furnace, sal-
ammoniac is obtained in large quantity.
A very favourable report on Sindermann's process was
given in 1875 by the Breslau Common Council, which had
appointed a special commission to examine it. The faeces are
brought in small quantities with the apparatus then used
2-3 kilos (4^-6f Ib.) every fifteen to twenty minutes into a
heated retort. One hundred kilos (2 cwt.) of faeces require
50 kilos (1 cwt.) of coal, and produce 7'8-9 cub. metres (290-
333 cub. ft.) of gas, and with the addition of 1 kilo (2J Ib.)
of iron turnings, 24 cub. metres (888 cub. ft.) of gas. In
addition, there are said to be obtained 6 '66 kilos (15 Ib.) of
coke, which may be used as manure; 3*33 kilos (7*5 Ib.) of
tar ; 3'33 kilos of fat, which is used for protecting the collect-
ing barrels ; and large quantities of ammonia liquor.
The process just described can hardly exist in actual
214 THE UTILIZATION OF WASTE PEODUCTS.
practice ; in a critical examination by Fischer, 1 it is entirely
rejected. Therefore it may here be mentioned that, according
to Gintl, faeces contain an average of 92'5 per cent of water
and 1'6 per cent of ash. Thus, in order to obtain 5 "9 kilos
of organic matter, from which gas can be made, 92*5 kilos
of water have to be evaporated, which again must be con-
densed in a gigantic cooling apparatus. Whilst a coal-gas
works consumes barely half the coke it produces from the
coal, in treating faecal matter large quantities of fuel must
be purchased. The production of larger quantities of gas
by an addition of iron turnings can, at least in substance,
only result from the decomposition of water by heated iron.
Now
3Fe + 4H 2 O = Fe 3 4 + 4H 2
168 72 232 8
therefore 168 kilos of iron give 8 kilos or 89*5 cub. metres
of hydrogen ; thus 1 kilo of iron, even when it is completely
transformed into Fe 3 O 4 , can only give 0*5 cub. metre. Sin-
dermann's statement, that an addition of 1 per cent of iron
turnings can increase the yield from 8-24 cub. metre.s,
must therefore rest on error. The gas liquor will, as a rule,
barely contain 0*5 per cent of ammonia, and is therefore far
more difficult to utilize than that from coal. Also, the tar
and the fat apparently obtained seem to have a low value.
Since, further, the tending of the apparatus requires relatively
much labour, the process cannot be profitable.
Utilization of the Ferric Oxide Used for the Purification
of Coal Gas. Various methods have been proposed. Ac-
cording to an English patent of H, Griineberg, the spent
purifying mass, after extraction with water and alkali, is
treated with hydrochloric acid in order to separate part of the
sulphur, and is then converted into Prussian blue by means
of a ferric salt and bleaching powder. 2
Gerlach proposes to grind the purifying mass fine, and
then to extract first with water, next with caustic soda solu-
1 " Dingler's Journ.," 217, p. 425. 2 Ibid., 227, p. 212.
BY-PRODUCTS OF COAL-GAS MANUFACTURE. 215
tion. From the last extract, sulphur and cyanides are pre-
cipitated on the addition of acid to slight acid reaction ; ferric
chloride is then added to the solution, drawn off from the
precipitate, and filtered if necessary. The residue remaining
after the two extractions yields its sulphur on distillation in
an iron or clay retort in a current of superheated steam.
The extracted and desulphurized mass is converted into col-
cothar by heating with access of air.
P. Spence uses the following process : The spent iron
oxide is first washed with water in a suitable tank, in order
to remove any ammonia compounds present. The mass is
then again dried in the air, a quantity of quicklime equal to
half the weight of the oxide is slaked, and the dry hydrate
intimately mixed with it. The mixture is lixiviated with
warm water not above 70 C. in iron vessels with double
bottoms. The solution when slightly acidified gives, with
ferric chloride, a precipitate of Prussian blue. This precipi-
tate is used as such, or employed to prepare yellow prus-
siate of potash. After the ferric oxide has given up all the
potassium ferrocyanide, it is heated in the same vessels
with water to boiling. A solution of calcium polysulphides
is obtained, from which hydrochloric acid precipitates sul-
phur. The ferric oxide thus extracted is again used for
purifying coal gas. 1
The oxide used for removing the sulphur from coal gas is
a natural hydrated oxide of iron, known as bog iron ore, con-
taining about 30 per cent of ferric oxide or an artificial pro-
duct known as "Lux" prepared from bauxite. Sometimes
Weldon mud or impure hydrated oxide of manganese is used
in place of it. When a purifier shows that sulphuretted
hydrogen is ceasing to be absorbed it is thrown out of the
series, opened up, and the oxide of iron removed. On ex-
posure to air rapid oxidation takes place with re-formation of
oxide of iron and liberation of free sulphur. It is used in
this way again and again until it contains about 50 per cent
of free sulphur, when it is sent to the sulphuric acid works
1 Eng. Pat. 4118 ; " Chem. Centralblatt," 1879, No. 28.
216 THE UTILIZATION OF WASTE PRODUCTS.
and burnt for the production of sulphur dioxide in a similar
manner to iron pyrites.
In small gas works the sulphuretted hydrogen is absorbed
by lime, forming sulphide of lime, from which the sulphur
cannot be removed, but this also has a use, as it can be em-
ployed by farmers for digging into the land as a dressing for
crops, in place; of quicklime, and is no doubt of benefit in de-
stroying insects and worms.
Prussian Blue from the By-Products of the Manufacture
of Coal Gas. According to the English patent of -Valentin,
ferric hydroxide, which has been used for purifying coal gas,
is washed with water, digested with magnesia or chalk at a
high temperature, and then extracted with water. The pale
yellow, somewhat alkaline solution contains calcium or mag-
nesium ferrocyanide ; on the addition of a little acid and an
iron salt it deposits fine Prussian blue.
Treatment of the Used Laming's Mixture of the Gas-
works. For many years the chemical works of Kunheim,
Berlin, have worked up the Laming's mixture from gasworks. 1
The mixture of ferric oxide and lime, which are the essen-
tial constituents, soon absorbs a large quantity of ammonia,
sulphur, and cyanogen compounds. By washing with water
the ammonia salts are extracted and isolated. The residue,
when decomposed with lime, gives a soluble double cyanide,
from which yellow prussiate of potash may be obtained by
precipitation with potassium sulphate. The insoluble por-
tion, when roasted, gives up the whole of its sulphur, which
is .utilized in vitriol chambers ; there remains ferric oxide in
a condition very suitable for the purification of gas. In
addition, ammonium sulphide, and, by direct treatment with
hydrochloric acid, Prussian blue may be prepared.
There are two methods of extracting the cyanogen from
coal gas in. successful working, the first being that intro-
duced at the Beckton gasworks in 1892, in which the gas is
washed by passing it through a solution of ferrous sulphate
" F. Beilstein, "Die chemische Grossindustrie " ; " Dingler's Journ.,"
211, p. 76.
BY-PRODUCTS OF COAL-GAS MANUFACTURE. 217
or of sulphide of iron suspended in water. In this way the
bulk of the cyanogen removed is obtained as ammonium
f errocyanide. In Germany a similar process was patented by
J. Bueb, but the process is carried only so far that the cy-
anogen compounds are left in an insoluble form in the sludge
from which they are subsequently recovered.
The polysulphide process depends on the fact that
ammonium polysulphide formed by treating spent oxide with
-ammonium sulphide absorbs cyanogen yielding ammonium
cyanide, ammonium sulphocyanide, and ammonium sulphide.
This process is due to the British Cyanides Company, and
also to P. E. Williams, who patented it in 1909. 1
Recovery of Sulphur from Laming's Mixture. The sul-
phur deposited in the mixture may either be extracted with
carbon bisulphide, or may be industrially utilized by burning
the mixture in the sulphur burners to sulphur dioxide, when
1 ton produces 1J tons of sulphuric acid.' 2 G. Pelouze re-
commends to utilize the solubility of sulphur in coal-tar oils
for its extraction from Laming's mixture. 3
Simultaneous Utilization of Coke Dust and Gas Tar. In
large gas works coke dust is produced in considerable quanti-
ties ; it has hitherto been utilized only by a somewhat la-
borious process with little profit. It is mixed with small
quantities of coal tar, or tar freed from its volatile constituents
by distillation, or even with loam or clay, and moulded into
briquettes by special machinery. The briquettes form a good
fuel, but they require to be made by powerful machinery, and
are consequently expensive. Coal tar, in consequence of its
chemical composition, is by itself a valuable raw material for
the production of illuminating gas, but all attempts to utilize
it in this manner have failed owing to various technical diffi-
culties. The engineers of the Paris Gas Company have pro-
posed to utilize coke dust and coal tar by the simultaneous
production of a good fuel from the former and of illuminating
144 Lectures on Chemistry in Gas Works," W. J. A. Butterfield, Institute
of Chemistry, 1913.
2 " Dingler's Journ.," 196, p. 372. 3 Ibid.
218 THE UTILIZATION OF WASTE PRODUCTS.
gas from the latter by-product, and have obtained a patent
for the process.
In any simple mixing apparatus, 50 parts by weight of
tar are well mixed with 40 parts of coke dust, brought into
the retorts by means of the ordinary semi-cylindrical scoop,
and heated for three or four hours at a temperature of about
1200 C. After this lapse of time, the distillation of the
admixed tar is finished, and the solid coked residue has
sintered with the coke dust to a solid mass, which has only
to be cooled by water or steam and broken up, in order to
yield an excellent fuel, burning readily in a grate with a slight
draught, and especially suitable for household use, etc. 1
Utilization of Lignite Coke. It is well known that, in
the dry distillation of lignite, coke is obtained in considerable
quantities as a by-product which is difficult to utilize. For-
merly it was only applied as road material, but later- it
has begun to be used in the so-called ashpit stoves. The
" Wochenschrift fiir Oel- und Fettwaarenhandel " calls atten-
tion to other uses for this by-product. Coleman has (loc. cit.)
made successful experiments with a view to using lignite
clinker for disinfecting the latrines of two large hospitals in
Glasgow. Two parts of the contents of the latrines, mixed
with one part of bone-black or powdered lignite coke were
temporarily, and when mixed with an equal quantity per-
manently, deordorized. Coleman accordingly proposes to use
lignite coke for disinfecting the contents of the sewers of
towns and to utilize the product as manure.
There have also been several communications in this con-
nection to the " Zeits. f. Paraff." in regard to the utilization
of the lignite coke of oil distilleries for the same purpose,,
by the use of which equally favourable results have been
obtained. However, more may be expected from the appli-
cation of lignite coke as fuel, if only suitable fire grates can
be constructed for the purpose.
1 Armengaud's " Publication industrielle," 22, p. 491 ; " Dingler's Journ.,"'
219, p. 470.
2 Post's "Zeits. f. d. chem. Grossgew.," Ill, 1.
BY-PKODTJCTS OF COAL-GAS MANUFACTUBE. 219
(In regard to working up the tar, which is an industry in
itself, and to describe which would be to overstep the limits-
of this work, the reader is referred to the excellent and
practical work of Dr. J. Bersch, " Die Fabrikation der Anilin-
farbstoffe," Hartleben, Vienna, and to Dr. Lunge's work on
" Coal Tar and Ammonia ".)
CHAPTEK XXXVII.
BY-PRODUCTS IN THE TREATMENT OF COAL-TAft OILS.
IT would be impossible in a single work to give details of the
methods employed in treating coal tar for the recovery or
production .of the whole of the valuable substances. By
simple distillation it is separated into benzene, toluene, car-
bolic acid, neutral tar oils, naphthaline, anthracene, and pitch
or coke.
From it are obtained various grades of carbolic acid rang-
ing from the common brown disinfecting fluids to the per-
fectly pure medicinal phenol. From phenol is obtained picric
acid and from toluene is obtained trinitrotoluol, which are.
amongst the best of the modern explosives.
By various processes are obtained an enormous number
of dyes derived from aniline and other coal-tar bases, from
phenol, naphthalene, anthracene, nap"hthols, etc., besides
which we have a whole range of synthetic perfumes and
drugs.
Blast-furnace' tars and also coke-oven tars are similarly
treated for the production of oils and disinfectants, pitch and
other products.
Coal tar and pitch are largely used for paving purposes in
the production of artificial asphalt, and also in the newer tar
macadam. The oils obtained from tar are employed in
enormous quantities for creosoting or preserving timber.
Utilization of the By-products. The caustic soda solu-
tion used in refining oils containing creosote is partly used
directly as soda-creosote for impregnating mine timbers, and
is partly worked up into carbolic acid. For this purpose
the liquors are mixed with the sulphuric acid, which has
(220)
BY-PKODUCTS IN THE TREATMENT OF COAL-TAE OILS. 221
also been used for refining the oils, until the reaction is
strongly acid. In this case, acid sodium sulphate is produced,
which is more soluble, and hinders less the separation of the
creosote than the more difficultly soluble neutral salt. The
salt liquor is set aside to crystallize, and the separated salt
sold to the soda or glass-works.
In decomposing with carbonic acid, which, according to
L. Grotowsky, 1 is obtained from burning coal, the mixture of
soda-creosote and water in equal parts must be cold. Carbonic
acid is passed in until the liquid is saturated and froths iip
violently for about an hour. The separated soda solution is
evaporated to dryness, ignited, dissolved in water, causticized
with lime, the caustic liquor drawn off from the chalk mud,
and concentrated to 35-38 B. The caustic soda solution thus
obtained still contains impurities, and therefore can only be
used to separate the creosote from crude oils.
The creosote, separated by one or the other process, after
washing with water, may be brought into the market ; it is
used for soaking telegraph poles', railway sleepers, etc., also
as a disinfectant. When distilled, ,it gives a fluid oil of
O965 specific gravity with a strong odour, which is used as a
disinfectant under the name of creosote oil, or in the manu-
facture of phenol dyjss. By repeated solution in caustic
soda, decomposition with sulphuric acid, distillation over iron
filings, and finally over green vitriol, a quite white oil is ,
obtained. The substance produced under the name of creo-
sote by the mineral oil works in Saxony is, according to
Grotowsky, simply phenol and cresol.
The acid resin drawn off from the refining apparatus is
mixed with hot water in suitable vessels, and washed by direct
steam; on standing, the empyreumatic resin separates out at
the surface. The recovered acid, which is coloured black by
organic matter, is sold at a strength of 40-50 B. to super-
phosphate works, where it is used for dissolving phosphates
and bones. The resin is well washed, mixed with any un-
1 " Zeits. f. Paraffin Ind." ; also see p. 186.
222 THE UTILIZATION OF WASTE PRODUCTS.
utilized creosote, and subjected to distillation, when, according
as tar or pitch is required, little or much creosote oil is dis-
tilled off.
The bone-black used in refining paraffin is boiled out with
water, then heated in horizontal retorts to drive off the re-
sidual paraffin, and finally converted into superphosphate with
the above acid.
CHAPTEK XXXVIII.
AMMONIA RECOVERY.
Preparation of Ammonia Solution from the Ammoniacal
Liquor of the Gasworks. The patented process of Watson was
carried out in the following manner : l The crude ammoniacal
liquor, together with a quantity of lime, which varies ac-
cording to the quality of the liquor, is brought into a roomy
retort or a boiler connected with a cooling apparatus. On
warming, the gas is soon driven off, and is absorbed by the
water in the receiver. On longer heating, much water distils
over with the ammonia. As soon as this is observed, the
receiver is changed and the later portions of the liquid
caught separately, since the last portions are not alkaline, or
only very slightly. This portion is brought back into the
retort in a following operation, in order that it may be con-
centrated by a second distillation. The first portion dis-
tilled over is also not yet sufficiently pure ; it generally
contains certain oily substances which can be mechanically
separated, and, in addition, a tolerably considerable excess
of water; it must, therefore, be subjected to a second dis-
tillation alone. The ammonia gas is, as before, caught in a
little water, and the receiver changed when too much water
.goes over with it. Thus a solution of ammonia is obtained,
which is sufficiently pure for almost all technical operations.
The second portion of the distillate is reserved for the next
operation, when it is again brought into the still.
Concerning this process, Stohmann 2 remarks with justice
that it is quite unpractical, since several distillations are re-
quired in order to produce a commercial product. This may
1 Muspratt's " Chemie," 3rd ed., 1874, Vol. I. 2 Ibid.
(223)
224 THE UTILIZATION OF WASTE PEODUCTS.
be avoided, he continues, by a methodical distillation, in which,,
during the operation itself, the quantity of ammonia contained
in the vapours is increased, and the foreign constituents-
separated. The apparatus used for this purpose is really an
improved spirit still. 1
Ammonia frqm Gas Liquor. According to a patent of
Braby and Baggs, ammonia is obtained from gas liquor by
adding caustic lime, heating in a boiler to a temperature
between 40 and 100 C., and then forcing air through a pipe
reaching to the bottom of the boiler, the air being further
distributed by a perforated bottom. The air, carrying
ammonia and a little steam, leaves the upper part of the
boiler and passes into a receiver filled with water, hydro-
chloric or sulphuric acid. At Deptford, where this process-
was employed, the air, laden with ammonia, first goes through
a lime purifier containing milk of lime kept in constant
motion by a stirrer, and then through a cooled coil to the
receiver, which consists of three vessels. Two of these
vessels -are one-third filled with cold water, the last is filled
with a strong solution of ferric chloride, which is converted
into a solution of sal-ammoniac with precipitation of ferric
oxide, which, after ignition, can be used as a painter's
colour.
Ammonium Sulphate from Gas Liquor is made by P.
St. Brown, in Ireland, 2 by incompletely neutralizing with
sulphuric acid, thus leaving the liquor sligHtly alkaline, and
evaporating in iron vessels until ammonium sulphate crys-
tallizes out. The product is somewhat impure, and can
only be purified by complex and repeated recrystallizations.
H. Kratzer has accordingly recommended a new method
1 Newton used for this purpose, according to a patent in 1841, the still
devised by Coffey, by means of which ammonia solution of any required
strength, even to the strongest, can be obtained. Rose has also constructed an
apparatus for the distillation of gas liquor. Compare Fleck, " Fabrikation
chemischer Producte aus thierischen Abfallen," p. 150 ; Knapp, " Chem.
Technologic," 3rd ed., Vols. I and II, p. 534; Muspratt's " Chemie," 3rd ed.,
Vol. I, p. 648.
2 Post's " Zeits. f. d. chem. Grossgew.," IV, 1.
AMMONIA EECOVEKY. 225
for the preparation of ammonium sulphate, which has been
adopted in several chemical works, and which produces an
almost completely pure salt. A little lime is added to the
gas liquor in order to decompose the ammonium salts it
contains ; a rapid current of steam is then passed through the
mixture. The whole of the ammonia is expelled, and when
conducted into a water-tank gives at once ammonia solution
of any required strength, from which by neutralization with
sulphuric acid a product can be obtained far more pure than
by previous methods. One hundred parts by weight of gas
liquor give 1-2 parts of the salt. This method is particularly
to be recommended to those works which make ammonium
sulphate for use as a fertilizer, since the product is free from
sulphocyanides and hence is harmless for agricultural pur-
poses. Kratzer showed, as a result of many experiments
undertaken when director of the Agricultural Institute at
Brandis, that sulphate of ammonia, made by older methods,
generally contains ammonium sulphocyanide, and then injures
the crops instead of improving them.
The following process l was patented in England by W. M.
Brown, for J. H. Elvert, of Geneva, and J. J. M. Pack, of Basle,
for the preparation of pure ammonia from gas liquor. The
liquor is mixed in a closed vessel cylinder or boiler with the
proper quantity of lime drawn off into a second vessel, and
there heated. The steam containing ammonia, etc., is con-
ducted to the bottom of the first vessel, which has mean-
while been recharged with gas liquor and lime, and from
thence the gases, containing more ammonia, pass to a con-
densing chamber, from which the more readily condensable
constituents flow back through a connecting pipe to the first-
mentioned vessel, whilst the more volatile constituents pass
through a cooling coil into a second condensing chamber,
where hydrocarbons, sal-ammoniac, and a small quantity of
free ammonia are retained. The purified vapours, consisting
now almost entirely of ammonia, are conducted through
several vertical pipes filled with charcoal and thence to
1 " Ber. d. d. chem. Ges.," 1873, 1553.
15
226 THE UTILIZATION OF WASTE PKODUCTS.
receivers containing distilled water, which are changed as
soon as they become saturated. As soon as all the ammonia
has been driven out of still No. 2, it is emptied, filled with
the contents of No. 1, the latter charged with fresh liquor as
before, and the operation recommenced. Treated in this
manner, 1000 litres of crude liquor at 3 B. give, in the course
of from four to five hours, 100-110 kilos of commercially
pure ammonia of 22 3 B.
The apparatus hitherto used for the distillation of the
ammoniacal liquor of gasworks consists either of a still, in
which the liquor is distilled alone or with lime, or two vessels
are used, one of which serves to heat the charge, and the other
serves as the still. If no lime is added, only the ammonia
combined with volatile acids is obtained ; in the other case
the lime introduced into the apparatus causes danger of over-
heating the still, a danger only imperfectly removed by the
introduction of a stirrer.
This evil is removed by an arrangement invented by H.
Griineberg, of Kalk, near Deutz, 1 which enables lime to be
used without a mechanical stirrer, and thus brings about the
recovery of the whole of the ammonia, including that com-
bined with the non-volatile acids, without causing injury to
the apparatus.
The fresh ammoniacal liquor runs from the tank into
a boiler 7-8 metres long (23-26 feet), where it is heated ; it
then passes into the second boiler, heated by direct fire,
thence to the third boiler, which is not in contact with the
fire gases, where it is treated with lime to decompose the
non- volatile ammonia compounds ; finally, after exhaustion,
it is run off. In regular working, the second boiler is heated ;
the fire gases which leave it surround the first boiler, and
bring its' contents to the boiling point. The vapours evolved
in the second boiler pass into the third through a pipe which
has a rake-shaped end ; in this boiler they drive out the
ammonia set free by the milk of lime, which is introduced
through a funnel. The ammonia, together with steam, passes
through a pipe into the preliminary heater, where it takes
1 " Polyt. Journ.," Vol. CCXXIX, 1878; Ger. Pat. 351, of 13 July, 1877.
AMMONIA RECOVERY. 227
up the volatile ammonia compounds, and, with these, passes
through pipes into covered leaden boxes, filled with 50 per
cent sulphuric acid. The gases evolved here, principally
sulphuretted hydrogen and carbonic acid, are taken through
a" flue to the fireplace of the second boiler, and so rendered
harmless.
When the acid in the saturators is neutralized, the liquor
obtained is allowed to cool and the crystallized salt collected
on drainers, whilst the proper quantity of sulphuric acid is
added to the mother liquor and the mixture again treated
with ammonia vapours, so that a separate evaporation is not
required.
If sal-ammoniac is to be made, the leaden boxes are re-
placed by stone tanks filled with hydrochloric acid ; in this
case evaporation of the liquid cannot be avoided.
This apparatus has already been introduced into the
ammonia works at Cologne, Hamburg, Stettin, and Leipzig.
It has been found easy to work, the necessary repairs are
small, and the gas liquor is completely utilized.
Sal-ammoniac from Gas Liquor. The liquor is treated 1
either by distilling with a quantity of lime, proportioned ac-
cording to the quantity of ammonium chloride or sulphate to
be produced, and the evolved ammonia led into hydrochloric
acid, or the gas liquor is immediately neutralized by acid.
The finest product, almost chemically pure, is obtained by
the former process.
In this process the liquor is heated with quicklime in a
capacious still to boiling, the vapours taken through a coil
cooled by water, in order to condense the greater quantity of
the water, and the distillate allowed to flow into a tank con-
taining hydrochloric acid. This tank is a wooden box lined
with thick sheet lead, and closed by a cover. A pipe con-
ducts the unabsorbed gases sulphuretted hydrogen, etc.
under the fire grate of the still, where they are burnt and
from whence they pass into the chimney. The end of .the
1 Stohmann, Muspratt's " Chemie," 3rd ed., Vol. I.
228 THE UTILIZATION OF WASTE PEODUCTS.
coil dips into the acid, so that the ammonia, which is only
partially condensed in the coil, may be entirely absorbed.
After about one-tenth of the liquid in the still has
evaporated, all the ammonia appears to be driven out, a
point which is recognized when a red litmus paper, held in
the steam issuing from a test-cock, is no longer, or only
slightly, turned blue. This tap is then opened and the still
emptied, the air entering through the tap thus preventing
the sal-ammoniac solution from rushing back.
The ammonia gas is allowed to pass into the acid until
the latter is just neutralized, when the salt solution is drawn
off and the receiver charged with fresh acid. Generally the
sal-ammoniac solution is so concentrated that it requires but
little evaporation in order to attain the strength requisite
for crystallization. It is then allowed to cool, when a fine
crop of crystals, almost white in colour and completely free
from tarry matters, is obtained.
The distillation can be more conveniently conducted if
two boilers are connected together by pipes and cocks in such
a manner that the vapours from one can be passed into the
other. The first boiler is then heated by direct fire; the
latent heat of the steam brings the liquor in the second to
boiling and volatilizes the greater part of the ammonia, so
that the ammonia from both quantities of liquid passes in the
vapours through the second boiler into the acid. As soon as
the first boiler is exhausted, its contents are run off; it is
then refilled and fire made under the second boiler, in order
to drive steam from it into the first and the ammonia thence
into the acid, until the second vessel is exhausted, when it
is again filled. Great economy in fuel is thus effected, since
double the quantity. of ammonia can be obtained by using
very little more fuel than would be required for the distilla-
tion of the liquid in one boiler. There is also the advantage
that much less steam passes over with the ammonia gas, and
thus a much more concentrated sal-ammoniac solution is
obtained.
Quite a number of methods of recovering ammonia from
AMMONIA RECOVERY. 229
gas liquor have been patented, the usual process being per-
fectly automatic. The still is an upright cylindrical cast-iron
vessel divided into shallow compartments communicating
one with another at opposite sides. The gas liquor is pumped
in at the top and flows from one compartment to another,
meeting on its way a current of steam passing in the opposite
direction. In the upper half of the still the free ammonia
and the volatile ammonium salts are driven off. At about
half the height of the still a graduated quantity of rnilk of
lime is pumped in by a small pump at the side. This de-
composes the fixed ammonia salts. The spent wash passes
out at the bottom of the still. The vapours containing am-
monia and volatile ammonium salts pass over by a lead pipe
into a bell-shaped device suspended in a lead-lined tank con-
taining sulphuric acid which absorbs all the ammonia, de-
composing the salts. To prevent any nuisance from the
sulphuretted hydrogen, etc., which is evolved, a small pipe
passes from the bell into an oxide of iron purifier which
absorbs the sulphuretted hydrogen. The sulphate of ammonia
separates in fine crystals wHen the acid is saturated. It is
scraped out and laid on a lead floor to drain and usually shows
a greyish or bluish colour. It is in this state used directly as
a fertilizer and forms one of the most concentrated sources
of nitrogen in an easily available condition.
The amount of ammonia recovered from coal is now very
considerable, as will be seen from the following figures taken
from the Annual Eeport of the Chief Alkali Inspector for
1915 :-
AMOUNT OF AMMONIA RECOVERED IN THE UNITED KINGDOM
(Expressed in Terms of Sulphate). Tons.
Gasworks
.
1913.
173,675
15,142
58,826
145,406
33,218
426.267
1914.
175,930
16,008
62,749
137,430
34,295
426.412
1915.
182,180
19,956
63,061
133,816
33,695
432.618
Shaleworks
Coke ovenworks ....
Producer, gas, and carbonizing works
(bone and coal) ....
Total
230 THE UTILIZATION OF WASTE PRODUCTS.
The most recent development for the recovery of ammonia
from coal gas is that known as the " direct " method, in which ,
instead of treating the liquor condensed from the gas, the gas
itself is passed through dilute sulphuric acid contained in an
apparatus known as an acid " bubbler," but many difficulties
have been encountered, and the process cannot yet be re-
garded as a perfect success in gasworks although at coke
ovens it has proved to be advantageous.
In the patent granted to the Deutsche Continental Gas
Gesellschaft, Dessau and K. Fritz, Darmstadt (Ger. Pat.
291,038), it is proposed to recover the combined ammonia
from gas liquor by heating it with the mineral constituents
of solid fuel, such as wood, peat, coal, etc., employed in the
form of ash, clinker, or coke breeze in place of lime. The
action of these materials is stated to be due to the action of
iron oxide, magnesia, and lime in combination with silica or
alumina. The gas liquor may either be run through a layer
of the material, or else treated with an aqueous extract of the
same, the liberated ammonia being expelled and recovered
in the usual manner. The process can be made continuous
by employing a number of boxes, adapted to be out of the
main circulation for recharging.
Preparation of Ammonia from Guano. In 1841 Young
took out a patent for obtaining ammonia from guano. 1 Vertical
cylindrical retorts are filled with two parts of guano and one
part of slaked lime or any other caustic alkali. The two sub-
stances are mixed with a stirrer, then gently heated, and the
temperature slowly raised to a red heat. Through the com-
bined action of heat and the alkali, the whole of the
nitrogen in the guano is converted into ammonia. Thus not
only the ammonium salts already present, but also the
nitrogen of the organic compounds, always present in guano,
are obtained in the form of ammonia. It would not, how-
ever, be economical to use guano as a source of ammonia,
since it contains phosphates which would be wasted. It is
best used as a manure, as in this case both the ammonia
and the phosphates are utilized.
1 Muspratt's " Chemie," 3rd ed., 1874, Vol. I.
AMMONIA RECOVERY. 231
The Dry Distillation of Bones produces a liquid which
contains a large quantity of ammonium carbonate. Laming
obtained ammonia solution from this liquid by first adding
calcium chloride, insoluble calcium carbonate and ammonium
chloride (sal-ammoniac) being formed. The liquid was then
separated from the precipitate and boiled for an hour. All
the volatile and gaseous impurities were thus removed. As
soon as the liquid had cooled, it was mixed with a sufficient
quantity of ferric hydroxide, by which all the sulphur com-
pounds were converted into insoluble sulphide of iron. Milk
of lime was then added in order to set the ammonia free, and
the liquid finally distilled.
L. 1'Hote 1 utilized the waste of wool, hides, leather, horn,
feathers, and sponges, which contains 6-15 per cent of
nitrogen, in order to obtain ammonium sulphate. When
these waste matters are treated with a solution of caustic
soda in from nine to ten times its weight of water, preferably
in the cold or at a gentle heat in order to avoid loss of am-
monia, some are dissolved, whilst some entirely lose coher-
ence. The slimy liquid so obtained is mixed with slaked
lime to a paste, which is brought into an iron retort, con-
nected to receivers, in which is placed chamber sulphuric
acid. The mass is then distilled at the lowest possible tem-
perature, in order to prevent the dissociation of the ammonia ;
when the evolution of gas has ceased, the retorts are heated
to a red heat. After the operation there is left in the retorts
a white powdery residue, consisting only of sodium carbonate
and quicklime. On treating this with water caustic soda is
again formed, which can be used for the next operation.
The ammonium sulphate obtained is coloured, but it may be
purified by crystallization.
1 " Compt. rend.," 76, p. 1085 ; "Dingler's Journ.," 209, 1873.
CHAPTEK XXXIX.
PETROLEUM RESIDUES.
Preparation of a Resin-like Substance from the Sulphuric
Acid Used in Refining Petroleum. W. P. Jenny, of Boston,
has obtained a patent for the preparation of a substance
similar to resin from the waste sulphuric acid of petroleum-
refining. The sulphuric acid, which has been used for re-
fining petroleum or shale oil, is mixed with an equal volume
of water, when two layers form, the upper consisting of a
thick oil of objectionable odour, the lower of dilute sulphuric
acid. The oil is repeatedly washed with boiling water,
finally with the addition of a little soda, and is then distilled.
After the oil distilling below 250 C. has passed over, a
current of air is blown by means of a suitable arrangement
for forty-eight hours through the residual oil, the operation
being conducted in the retort used for the distillation. Dur-
ing this process the oxygen of the air is eagerly absorbed by
the oil, which, on cooling, solidifies to a deep brown mass
similar to resin.
Another method for obtaining this resin consists in heat-
ing the residual acid, which contains the oil in solution, for
several days at 100-150 C., until a test portion sinks when
poured into water. The mass is then poured into water and
washed with a large quantity of water, or, if necessary, an
equal volume of petroleum ether is first added. In the
former case the resin separates on the bottom of the washing
vessel ; in the latter case it remains dissolved in the naphtha,
and floats on the surface of the acid.
The product, which is more or less hard in its nature ac-
cording to the extent of the oxidation, is insoluble in water,
(232)
PETKOLEUM RESIDUES. 233
alkalies, and alcohol, but dissolves readily in 'fats, animal and
vegetable oils, naphtha, benzol, chloroform, ether, carbon
bisulphide, amyl alcohol, spirits of turpentine, and in sul-
phuric acid of 66 B. When melted with gutta-percha or
caoutchouc in varying proportions, it forms an elastic sub-
stance which can be used for insulating purposes.
Tar and Other Products from Petroleum Residues.
Letny has investigated the composition of tar obtained in
making illuminating gas from petroleum residues. 1 In
this method of making gas the petroleum residues are
subjected to dry distillation in retorts filled with wood,
when they produce illuminating gas and a tar of specific
gravity 1'015. If the latter is passed through the retorts
a second time, only a very small quantity of gas is pro-
duced, and the tar is but little altered ; it has now a
specific gravity of 1*207, and possesses all the properties of
coal tar. It begins to distil at 80 C., and gives fluid dis-
tillates below 200 C. ; at higher temperature solid substances
are formed, but later, above 300 C., oils again come over,
which, however, separate crystalline compounds. A more ex-
act examination of the distillate gave below 200 C., 13*9 per
cent, containing 4'6 per cent of benzene, 5*2 per cent of
toluene and xylene ; from 200-270 C., 26 '9 percent; from
270-340 C., 8'6 per cent, containing naphthalene, cumene,
and petroleum ; above 340 C., 27*5 per cent, containing 3*1
per cent of pure anthracene ; the ,residue in the retort was
20-6 per cent.
This tar affords the possibility of utilizing the petroleum
residues in districts which are rich in petroleum, to produce
substances which can be used in the manufacture of aniline
dyes and alizarine. The quantity of petroleum residues pro-
duced in Kussia alone was estimated by Letny at 98,000 tons
in the year 1878. Of this only a small portion was used for
heating the distilling apparatus, another portion went into
the interior of Eussia for gas-making, whilst more than half
1 " Polyt. Journ.," 229, p. 353; Post's " Zeits. f. d. chem. Grossgew.," Ill,
30, 244, 506.
234 THE UTILIZATION OF WASTE PBODUCTS.
remained, and was burnt up outside the works, owing to lack
of storage. There is no doubt that in the future there will 1
be found in these petroleum residues a valuable material for
the production of aniline, alizarine, etc.
In order to ascertain the conditions most favourable to-
the formation of tar, petroleum residue of specific gravity
0*872, and boiling at 270 C., was passed through red-hot
iron pipes 1*24 metres (4 ft. 1 in.) long and 5 cms. (2 ins.)
wide, filled with carbon. Irregular heating gave rise to very
different results. In one case 100 grms. gave 23'9 grms. of
tar and 30' 1 litres of gas ; another experiment yielded 46'4
grms. of tar and 59 litres of gas. At higher temperatures the
yield of gas was higher up to a certain temperature, above
which the yield again became less. Without carbon the
decomposition in the pipes proceeded irregularly, until a car-
bonaceous deposit had formed by the destruction of a portion
of the petroleum, which deposit then facilitated the decom-
position. The action is the same when the pipe is filled with
broken brick, asbestos, etc. Very porous carbon, platinized,
was still better than ordinary carbon ; those catalytic sub-
stances which most readily absorb gases cause the production
of the most tar. If the tar produced be again passed through
the pipe under pressure it is considerably decomposed, carbon
being deposited. Without increase of pressure, however, it
suffers practically no alteration. The specific gravity of the tar
never exceeds 0'8889 ; it contains a mixture of amylene and
benzene, 6'28 per cent ; benzene, 12*56 per cent ; toluene,
10*5 per cent; mixture of toluene and xylene, 6*8 per
cent in all 52*5 per cent boiling below 320 C., and 35*0
per cent above 320 C. Solid hydrocarbons, such as naphtha-
lene and anthracene, could not be detected, which is
ascribed by Letny to the fact that the petroleum vapours*
have passed through too short a layer of carbon. In fact,
when gas retorts are used, the yield of tar is lower the less
coal is present in the retorts ; accordingly the quantitative
yield of tar, and the percentage of solid hydrocarbons in it,,
is proportional to the dimensions of the layer of carbon;
PETKQLEUM RESIDUES. '235
through which the petroleum vapour is passed. In working
on the small scale, amylene, hexylene, etc., were always
formed ; but not when gas retorts were used. Steam passed ,
through the retort together with the petroleum residues was
without action ; and, on the other hand, by the application of
pressure the yield of tar was always reduced. Similarly to the
tar, the gas differed in composition according as it was made
on the large or small scale. In the latter case it contained,
in addition to hydrogen and marsh gas, ethylene, propylene,.
butylene, acetylene, and crotonylene.
Petroleum Residues as Fuel for Cupola Furnaces. The
introduction of pulverized fuel in cupola furnace practice
effects, on the one hand, the oxidizing action of the excess of
blast, and, on the other hand, prevents the formation of pro-
tuberances on the tuyeres, and the attendant inconveniences.
The carbon deposited on the walls of gas retorts, and the
residues obtained in petroleum refining, are the most suitable
fuels to be used in the pulverized state, since they are com-
pletely free from ash. W. Batty, of New York, injects these
substances, in a state of fine dust, with the blast, and obtains,
the following advantages : (1) The whole of the oxygen, as
it enters the zone of fusion, can at once combine with carbon,
by which means a powerful neutral or reducing flame is pro-
duced the quantity of carbon introduced can readily be
regulated as may be necessary ; (2) the iron becomes hotter,
and instead of oxidation occurring through the presence of
an excess of air, the iron readily takes up carbon in the
atmosphere of carbonic oxide impregnated with heated carbon ;
(3) in consequence of the higher temperature, the slag is more
fluid ; hence (4) the formation of protuberances on the tuyeres
is avoided ; (5) the loss of metal is lower. On account of the
partial carbonization of the iron, the possibility of selecting
scrap-iron, which is, as far as possible, free from sulphur and
phosphorus, is of especial importance to the quality of the
castings.
Utilization of the By- Products and Chemicals of Mineral
Oil Works. Grotowsky has made certain noteworthy obser-
236 THE UTILIZATION OF WASTE PEODUCTS.
vations on this subject, 1 according to which the carbolic acid
may be separated from the so-called creosote-soda, produced in
refining the crude oils, either by means of the dilute sulphuric
acid, also produced in refining, or by means of carbonic
acid made for the purpose. In the former case Glauber's
salt, in the latter soda, or, in the event of again causticizing
by lime, caustic soda, are produced. The separated carbolic
acid is either merely washed with water and then brought
into the market to be used for disinfecting purposes and- for
saturating wood, or it is converted by distillation into the so-
called creosote oil. The latter is then used for making
phenol dyes or for disinfection. By repeated solution in
caustic soda, decomposition by sulphuric acid, distillation
over iron filings, and finally over green vitriol, a quite pure
pale oil is obtained. The empyreumatic resin, which dis-
solves in the sulphuric acid during refining, is separated from
the acid again by high-pressure steam. The dilute sulphuric
acid then obtained may be applied in the manufacture of
superphosphate, or as indicated above. The separated
empyreumatic resin is washed with water and subjected to
distillation either alone or together with creosote. In the
distillation more or less is removed according to the purpose
for which the product is intended : in the case of tar for
roofing felt, only until the residue forms a stiff paste, but for
asphalt, to be used as the binding medium for coal briquettes,
until the mass, when cold, has a shining, brittle fracture.
Regenerating Spent Sulphuric Acid from Refining Tar
Oil or Petroleum (Ger. Pat. 291,775, C. Still, Eeckling-
hausen). The crude, recovered acid, whilst still warm and
fluid, or after dilution to the desired degree, can be im-
mediately regenerated to pure liquid sulphuric acid by spraying
it through a nozzle with high-pressure steam or hot com-
pressed gas. A friable solid residue is left, and all the volatile
constituents, such as residual traces of oil, and the malodorous
decomposition products formed during the treatment of the
acid, escape with the outgoing steam or gas. For this pur-
1 Post's " Zeits. f. d. chem. Grossgew.," Ill, 2, p. 345.
PETKOLEUM EESIDUES. 237
pose the crude acid is run into a collector, which is heated by
an internal steam coil. From this vessel the fluid acid is run
into a pulverizing nozzle, which is built into the wall of a
closed chamber and fed with steam. The bottom of this
chamber slopes down toward the opposite side, so that the
liquid condensed during the process can drain away to an
open pocket outside, for which it forms a seal, so that none
of the gaseous contents of the chamber can escape. When
this liquid reaches a certain level it is drawn off automatically
into a collecting vessel. The cover of the chamber carries
a flue, fitted with baffle plates to retain particles of liquid
carried upward with the steam, etc., the latter being aspirated,
by means of an injector nozzle, into the condenser, which
discharges into a collector. The permanent gases are led
from this latter into a washer charged with an alkaline
washing liquor, which eliminates any injurious acid fumes,
such as sulphur dioxide. The solid residue from the crude
acid falls on to the sloping floor of the chamber and slides
down into the pocket outside for removal.
CHAPTEE XL.
BY-PRODUCTS IN THE MANUFACTURE OF ROSIN OIL.
Recovery of Acetate of Lime from the Acetic Water of the
Rosin Distillation. 1 The acetic liquor is neutralized with
lime in large wooden vessels, when acetate of lime is
formed, and a brown insoluble compound of lime with
resinous matters separates at the surface and is removed.
The clear liquid, obtained by filtering, is evaporated to 5 B.,
and then a strong solution of Glauber's salt added so long as
a precipitate of sulphate of lime is formed. The whole of
the acetate of lime is not, however, converted into sulphate
of lime, accordingly the undecomposed remainder is preci-
pitated as carbonate of lime by means of carbonate of soda.
The liquid, freed from the precipitate by filtering, and now
containing only sodium acetate and a little calcium sulphate
in solution, is evaporated in shallow cast-iron pans to crystal-
lization ; the resinous matters which separate during the
evaporation are removed. The crystallizing point is reached
at 15 B., the liquid is then drawn off into the crystallizing
tubs, in which, after four days, it deposits the sodium acetate
in large crystals, which are once or twice recrystallized.
The sodium acetate obtained is subsequently fused in flat
cast-iron pans. It first melts in its water of crystallization,
sifter the evaporation of which the salt again becomes solid ;
it is then fused a second time at a higher temperature. The
mass of salt swells up, evolves oily vapours, and finally
melts quietly; it is next removed from the pan, dissolved
whilst still hot, and the solution filtered. The filtrate is left
to crystallize, the sodium acetate decomposed by strong
sulphuric acid in an iron pan lined with lead, with a copper
1 " Die Harze und ihre Producte," G. Thenius. Vienna, Hartleben, 1895.
(238)
BY-PBODUCTS IN THE MANUFACTURE OF ROSIN OIL. 239
or lead head, and the acetic acid distilled over ; it is again
rectified in a glass retort with a little pyrolusite. It is then
water- white, and free from foreign odour.
Preparation of Acetate of Iron from the Acetic Water of
the Rosin Distillation. The acid liquor obtained in the
distillation of colophony is brought into barrels filled with
small particles of iron sheet-iron clippings, iron turnings and
borings. In about eight to fourteen days the saturation of the
^icid is complete ; it is accelerated by frequently drawing off
the liquid, so that the iron in the barrels may come into
-contact with the atmosphere, which hastens the oxidation.
The dilute acid in the barrels is also kept at a temperature
of 25-31 C. by frequently injecting steam. However, the
saturation is not always complete in the barrels ; the solution
is therefore drawn off, and heated to boiling in iron pans
similarly filled with iron. The resinous matter which rises
to the surface is skimmed off, and the process continued until
the acid is completely saturated. The liquid is evaporated
down to 10-15 B., and allowed to settle thoroughly before
use. It forms a dark, blackish-green solution. Acetate of
iron is extensively used in the calico-printing industry.
Utilization of Rosin Oil and the Residue of the Distilla-
tion in the Manufacture of Soot-blacks. Kosin oil gives,
when burnt in special stoves, a very fine soot, highly prized
by manufacturers of lithographic and printing inks. In order
to obtain the black from rosin oil, the latter is allowed to
flow from a separate tank through a narrow pipe, whence it
falls upon a red-hot plate contained in the stove ; the oil is
decomposed, the soot drawn into the depositing chambers,
where it settles in various qualities. As soon as a certain
quantity of oil has been burnt, and the stove, having stood
for a sufficient time, is quite cold, the separate collecting
chambers are opened, and the soot removed. The finest
.soot for lithographic purposes is always found in the
furthest chamber, whilst a less fine black, used for letter-
press inks, collects in the nearer chambers. The soot is
.graded by sieving.
240 THE UTILIZATION OF WASTE PEODUCTS.
The residue of the distillation, containing much rosin,,
is burnt in a special soot-stove ; it produces lower qualities,
of black, which are similar in value to the soot of ordinary
flames. From the burnt residues the sodium carbonate
may be regained by extracting with water, filtering, and
evaporating.
See also " The Distillation of Eesins," by V. Schweizer
(Scott, Greenwood & Son).
CHAPTEE XLI.
SOAP-MAKERS' WASTE.
THEEE is a considerable amount of waste soap cuttings pro-
duced in all soaperies. These are added to the pan in the
next boiling and facilitate saponifi cation by 'bringing the oil
and alkali into more intimate contact.
Toilet-Soap Cuttings ("Neue Seifensieder-Zeitung ").
Manufacturers, who possess a pan heated by steam or in a
water-bath, can readily melt together and again press the
cuttings of toilet soap. The soap to be melted is cut up
into shavings by means of a wire or plane, and brought in
small quantities at a time into a pan heated by steam or on
the water-bath. The soap is there allowed to melt, with the
addition of a little water, or, if the soap becomes too thick
and viscid, of spirit. The quantity of water to be used is
determined by the condition of the soap ; if it be dry more
is added than if it were wet. If water-glass has been used
in making the soap, it is necessary to add a few pounds of
lye at 20-22 B. to prevent the separation of silicic acid.
Naturally,. care must be taken that the soap does not froth,
which is accomplished by stirring diligently, and adding
water if required. The water is only added in order to
facilitate the melting of the soap, but not to dissolve it.
When the soap is completely melted, the colouring matter is
stirred in, and then the perfume, before pouring into the
mould. These soaps are generally coloured yellow, red, or
brown, and made into household, Windsor, mottled, coal-tar,
and also sand and pumice soaps.
In melting the cuttings, if the soap should froth or be-
come too thick and lumpy, and if a small addition of spirit
(241) 16
242 THE UTILIZATION OF WASTE PEODUCTS.
is without result, the following method is adopted : Whilst
stirring, sufficient water is poured into the pan to dissolve
the soap completely to a thin liquor ; it is then salted out
with a strong hot solution of salt, the salt liquor removed,
and the soap brought together by potash lye of 2-3 B. or hot
water. After the soap has stood for some time, it is drawn
off down to the deposit at the bottom, coloured, crutched in
the cold, perfumed, and poured into the mould.
The following directions for making brown Windsor soap
by melting together cuttings may serve as an example of this
method of treatment. For a brown soap are taken the cut-
tings of such coloured soaps as yellow, blue, and brown.
50 Ib. of soap are coloured brown by 120 grms. (4 oz.) of
caramel, and then scented with 40 grms. of oil of lavender,.
30 grms. of oil of thyme, 30 grms. of cumin oil, 30 grms. of
oil of cloves, and 30 grms. of cinnamon oil. The caramel is
obtained by carefully melting ordinary sugar in a pan, with
constant stirring, until it has changed into a mass, which runs
from the stirrer in dark golden-yellow threads.
Utilization of Waste Soapy Waters. The utilization of
the waste soapy waters produced in such large quantities in
public laundries and in many industries, i.e. the separation of
the fatty acids which are combined with alkali in these waters,
has been many times attempted, but with little success. The
methods often recommended collection of the soap-suds in
tanks, decomposition of the soap, allowing to deposit, etc. 1
can only be applied to small quantities of strong soap
liquors, such as are produced in wool- washing. In the
case of public laundries, which use daily 150-200 kilos
(3-4 cwt.) of soap in 60,000-70,000 litres (13,200-15,400
gals.) of water, tne application of such methods is quite
impossible. In such cases, in order to collect the suds,
the waste waters should be run, together with a regular
stream of lime water, through the apparatus shown in
Fig. 20. A tub A is half -filled with slaked lime ; a regu-
lated current of water passes through the pipe d, the tub A,.
1 Heuze, " Dingl. Polyt. Journ."
SOAP-MAKERS' WASTE. 243
and the outlet, carrying lime into the vat B. The water
from which the soap is to be removed enters at the same
time in a continuous stream and leaves at b. It is then only
necessary to run the mud deposited on the bottom of the
vessel into the filtering basket D, placed below, by raising the
plugs c. The lime soap collected in the basket is decomposed
with hydrochloric or sulphuric acid and steam, the cooled
mass again brought into the filter basket, washed, and freed
from water by draining and pressing. The fatty mass
obtained is still by no means pure enough for the fat press.
In the case of waters from a public laundry, it contains
FIG. 20.
40-50 per cent of foreign matter sand, pieces of wood, and
cellulose so that the production of fat therefrom is not a
remunerative operation, apart from the cost of the apparatus.
It is more economical to recover the fat by extraction with
carbon bisulphide, a method already much in use. An
apparatus very suitable for this purpose is shown in Fig. 21.
It consists of the water-bath A and the boiler B, contained in
A, for the reception of the fat. The impure fat is placed in
C, D is the condenser, and E the storage vessel for the carbon
bisulphide. After the cylinder C has been filled through a
with fat, which lies on a perforated bottom between the open-
ing k and I, carbon bisulphide is admitted homE through the
244
THE UTILIZATION OF WASTE PKODUCTS.
tap i. It dissolves the fat contained in the impure mass and
carries it through c into the boiler J5, in which the carbon
bisulphide evaporates. The vapour rises through the pipe b
into the condenser D, where it is condensed, the liquid then
passing to C, whence it again carries fat to B. When all the
FIG. 21.
fat has been removed in this manner, the taps, c,/, g, and h
are opened, whilst at the same time e, d, and i are closed.
Steam then passes from A through g into C, expels through
7^ the carbon bisulphide, which collects in E, together with
that evaporated in B ; k and I are openings for emptying the
cylinder C. By this arrangement of the apparatus, not only
SOAP-MAKEES' WASTE. 245
is all the fat recovered, but also the loss of carbon bisul-
phide is reduced to a minimum, assuming that the necessary
quantity of cold water is supplied to the vessel D through m.
The fat remaining in B still requires refining, which is
accomplished in the usual manner.
Utilization of Liquids Containing Fatty Acids. In all the
textile industries there is formed a number of waste liquors
containing fatty acids, the quantity of which is so consider-
able that its recovery is at times a source of not inconsiderable
profit. In regard to the composition of these liquors, there
are in general three different kinds to be distinguished :
(1) The waste liquors obtained in removing the perspiration
and grease from wool and woollen fabrics, to which are to be
added the waste soapy waters of houses and large laundries ;
(2) the used soap liquors obtained in boiling silk to remove
the " gum " ; (3) the waste liquors of Turkey-red dyeing,
which contain oil. In all the liquids mentioned the fatty
acid compounds are mainly united to alkalies ; accordingly their
separation by a strong mineral acid appears to be suitable,
and this method is almost always used when these liquids are
treated. The method is, however, attended with so many in-
conveniences that many industrial establishments are a verse to
the utilization of these waste products. In the first place the
liquids, in addition to the alkali compounds, always contain
lime soaps produced by the lime in the water. When the oils
and fats are separated by sulphuric acid, or by crude hydro-
chloric acid, which always contains sulphuric acid, the lime is
always separated as sulphate, which forms a pasty mass with
the oil. This mass is not readily separated from the water,
so that its application in making soap or illuminating gas is
not easy. Also, the storage of the fluid oil in barrels is
laborious and subject to considerable loss. Thus the desira-
bility of separation of the fatty acids in the form of a solid
compound of fairly constant composition appears to be in-
dicated. Vohl has previously shown 1 that, when lime or
a lime salt is added to these liquids, all the fatty matter is
1 " Muster-Zeitung," 1873.
246 THE UTILIZATION OF WASTE PRODUCTS.
separated as a solid lime soap, from which the liquid can
readily be drawn off, and which can be stored in the dry
state. This lime soap is a substance which can readily be
transported and sold to works occupied with the separation of
oil and fat from such material. It is, of course, not the case
that each establishment carries out the complete utilization of
its own soap waste, but simply that it removes the fat from
its waste soap-suds with lime, and then sells the lime soaps,
which contain about 40 per cent of acids, to the proper works.
The apparatus required for this precipitation of lime soaps is
of an extremely simple nature, and easily obtained. Since
lime soaps give rise to the formation of gypsum when treated
with crude hydrochloric acid, which always contains sulphuric
acid, and the gypsum makes the separation of the oil from
the aqueous liquid very difficult, Vohl experimented with a
magnesium salt, by which the fatty acids are as completely
precipitated. The magnesium soaps occupy a much smaller
volume, contain about 60 per cent of fat, and produce no
gypsum when decomposed by sulphuric acid, or hydrochloric
acid containing sulphuric acid. The lime and magnesia soaps
may also be directly employed for the manufacture of
illuminating gas ; the tar, which is simultaneously produced,
may be used like pure oil in gas-making. The gas obtained
from the lime and magnesia soaps is of very high illuminat-
ing power, and the yield is very considerable.
The Residues of Oil-manufacturing are recommended by
G. F. Reisenbichler to be used in soap-making. 1 After they
have been subjected to the strongest pressure, oil seeds retain
5-10 per cent of oil, which can only be extracted by chemical
means. These residues may be used with great advantage in
soap-making in the case of very cheap soaps ; a small quantity
is added, not exceeding 20 per cent. The residues from ex-
pressed nuts of all kinds are especially suitable ; less suitable,
or not at all, are expressed linseed and rape seed, since they
contain too many hard particles. When these fatty residues
are to be added to soaps, they must be fresh, and previously be
1 "Neue Seifensieder-Zeitung."
SOAP-MAKEKS' WASTE. 247
finely ground. They are then mixed directly with the lye,
which is then boiled, and later the principal fat added to the
resulting thick liquor. The saponification is much accelerated
by the addition of this powdered material to the lye, and the
consequent thick condition of the latter. Eeisenbichler recom-
mends in particular for this purpose the residuals obtained in
expressing olive oil from the olive. The cake, which contains
fairly fine skins and is very oily, readily dissolves in the lye
to form a tolerably uniform paste. 1 " Oil foots " are also used
in soap-making.
Recovery of Glycerine as % a By-product. Glycerine is
obtained by saponification of fats and as a by-product in the
preparation of fajbty acids. In soap-making small quantities
of glycerine were formerly obtained ; according to Schwanert 2
the liquid below the supernatant soap the so-called under-
lye which contains glycerine, alkaline hydroxides, sodium
and potassium chlorides, was < exactly neutralized with
hydrochloric or sulphuric acid, evaporated to dryness on
the water-bath, the residue extracted with 90 per cent
alcohol, and the glycerine obtained as a yellow syrup on
evaporation of the extract in a still. According to Rey-
nolds, the under-lye was concentrated by evaporation,
the salt deposited on the bottom of the pan was removed
from time to time and brought into a drainer, from which
the liquid could flow back into the pan. When the liquid
had reached such a concentration that it boiled at 109 C.,
it was heated in a still until its boiling point rose to 193
C., when high-pressure or superheated steam was driven
through the upper layers of the liquid and the glycerine dis-
tilled over in the steam. It was necessary to regulate the
temperature carefully, so that the glycerine should not be
decomposed at too high a temperature, and that the distilla-
tion should not be stopped by too low a temperature. After
the distillation, the distillate was evaporated at a moderate
1 Eisner regards these additions as not permissible, and soap made in this
manner as adulterated.
2 Muspratt's " Chemie ".
248 THE UTILIZATION OF WASTE PRODUCTS.
heat, when the glycerine remained behind. When this
method of manufacture is considered, it can readily be under-
stood that glycerine can now be made very cheaply and on a
very large scale from the under-lyes of the soap-maker, also
it can be regained, readily and cheaply, from the crude
glycerine obtained in the manufacture of stearin candles.
But although small soap-works may not be able to work up
the under-lyes for glycerine in this manner, experiments in
other directions must not be omitted. Linke first drew at-
tention to the large quantity of glycerine lost in these lyes,
which he estimated at 8,500,000 kilos (8500 tons) per annum
in Germany alone, of a value of 3,000,000-3,600,000 marks
(150,000-180,000). These figures explain the attempts
which have been made to find a method by which glycerine
can be recovered from this liquid, and Schwanert made a step
in the right direction when he drew attention to the crystal-
lizability of glycerine, by means of which property it may
perhaps be recovered more profitably from soap-lyes. In
1867, Sarg had already obtained crystalline glycerine at
several degrees below zero, but Kraut, of Hanover, was the
first, in 1870, to discover a method of crystallizing glycerine
in any required quantity and quality. The method was
transferred to Sarg, Son and Co., of Liesing, near Vienna,
with all right of priority. This firm obtained patents in
Austria, England, and Kussia, and worked the process on the
large scale. The crystallization is conducted in sheet-iron
vessels from which the crystals can readily be loosened ; they
are then freed from the adherent mother liquor by treatment
for fifteen minutes in a centrifugal running at 1200 revolutions
per minute, and after they have dried are melted. Crude
glycerine must be once recrystallized. As Schwanert states
in these communications, the temperature has a consider-
able influence on the yield ; at temperatures higher than
2 C. the mother liquor amounts to more than 30 per cent of
the glycerine used. In mild winters the crystallization is not
profitable. In addition to the application of a temperature
several degrees below zero, a certain amount of movement
SOAP-MAKEKS' WASTE. 249
appears to be one of the conditions under which the glycerine
becomes solid and crystalline. Experiments with a view to
crystallizing glycerine in a simple manner, applicable to larger
quantities, would certainly be very profitable, since the most
complete purification is .obtained in this manner, all the im-
purities remaining in the mother liquor. The under-lyes of
soap-works might by this means be utilized in a most pro-
ductive manner.
A process for the recovery of glycerine from waste soap-lyes,
due to H. van Euymbecke, consists in new means for evap-
orating, distilling, and concentrating these lyes. The ap-
paratus is constituted of cylindrical cast-iron evaporators
with the usual accessories steam-pipes, man-holes, valves,
etc. to which are connected two cylinders, and finally the
condenser. The process is as follows: The soap lye is
brought into the evaporator, mixed with green vitriol or an-
other suitable metallic salt. Then a low vacuum, about 26
inches, is produced, and steam passed into the cylinder inside
the evaporator ; a concentration of 28 B. at the outflow, or
30 B. at 15 C., is then obtained. The evaporation causes
the salts to crystallize out, they collect at the bottom, and
may be removed, dried, and purified. At the density given
above the liquid contains about 50 per cent of glycerine,
while most of the salts have crystallized out. The liquid
now passes into a second evaporator, where it is concentrated
down to 34 B. at 15 C. Salts again separate, and are re-
moved and dried. The evaporation is effected in two stages,
because the salt impregnated with strong crude glycerine
would be difficult to dry and free from the mother liquor ;
from the second evaporator the liquid passes into the distil-
ling apparatus, which works under a vacuum, and in which it
is heated almost to boiling by means of steam. Euymbecke
uses again expanded steam, which, injected into the vacuum
of about 28 ins., induces rapid distillation. The least
volatile distillate collects in the first cylinder, and is very
pure glycerine ; the greater part of the glycerine is found in
the second cylinder ; the most volatile distillate, which con-
250 THE UTILIZATION OF WASTE PRODUCTS.
tains much water, passes into the condenser. If the product
is not sufficiently pure it is distilled again.
The method given by H. Flemming, of Kalk, for the
recovery of pure glycerine from soap-lyes, depends on the
application of dialysis (German patent, 12,209). Glycerine
is a substance which, when in aqueous solution, does not
readily pass through parchment paper, whilst the salts con-
tained in the under-lyes can readily penetrate. In order to
separate the glycerine from the salts, Flemming employs an
apparatus very similar in construction to the diffuser used in
sugar-works. The lyes, previously evaporated until much
salt separates, flow through vessels, one side of which is
made of parchment paper; water flows on the other side
of the parchment paper. The process which occurs is an
ordinary osmosis ; the salts in the glycerine solution pass
through the permeable division the parchment paper and
dissolve in the water, a corresponding quantity of which
passes through to the glycerine and dilutes it.
In working with under-lyes, which are strongly alkaline,
it is advisable to neutralize with sulphuric acid before
dialysing, since the sulphate diffuses more rapidly than the
compounds of alkaline reaction. When the under-lye is sub-
jected to the osmotic action for a sufficient length of time,
the glycerine solution is obtained very pure, when it can be
converted into pure glycerine by concentration, at first in
open pans, then by distillation in a vacuum apparatus. The
low cost of providing an apparatus suitable to the dialysis of
under-lyes, which would consist essentially of a vessel con-
taining frames stretched over with parchment paper, makes
Flemming's process available even for small works, which can
then utilize very well the under-lyes which would otherwise
be wasted, and dispose of the dialysed solutions to glycerine
works for further treatment.
See also " Soaps," by G. H. Hurst ; and " The Handbook
of Soap Manufacture," by Simmons and Appleton (Scott,
Greenwood & Son).
CHAPTEE XLIL
ALKALI WASTE AND THE RECOVERY OF SODA.
Utilization of Alkali Waste. Since almost all Leblanc soda-
works make sulphur from alkali waste, there remains a residue
consisting chiefly of carbonate, sulphate, and sulphide of lime.
According to M. Schaffner l this residue, from which railway
embankments can be made, is especially suitable for the upper
layers, where it is used instead of, or together with, river sand.
The sleepers lie dry, since the desulphurized residues are
porous ; the latter also appear to have a considerable pre-
servative action on the sleepers.
Schott proposed to use alkali waste in glass-making, since
the sodium sulphide would serve as a reducing agent in place
of coal, and lime would also be introduced into the mixture.
On this point, however, Lunge remarks: 2 "Alkali waste
always contains, in addition to calcium sulphide, excess of
lime both as carbonate and caustic lime, and excess of coal,
and would thus be the more suitable for the use proposed by
Schott if it did not contain, with these useful constituents,
certain harmful substances alumina, ferric oxide, gypsum,
etc." These constituents prevent the use of alkali waste
except for the lowest qualities of glass ; and, in fact, Lunge
himself disposed of alkali waste to makers of beer bottles.
The desulphurized residue, treated by the process of Schaffner
or Mond, which is never free from undecomposed sodium
sulphide, is suitable for the same purpose.
Eecovering Sulphur from Alkali Waste. The Chance pro-
cess of recovering sulphur from alkali waste is one of the
finest examples of the application of technical knowledge in
1 " Dingler's Journ.," 199, p. 243. 2 Ibid., 216, 375.
(251)
252 THE UTILIZATION OF WASTE PEODUCTS.
existence. The waste, which has accumulated for years in
enormous quantities in the vicinity of chemical works, is
treated with water in a series of closed cylinders through
which is pumped carbonic acid under pressure. The carbonic
acid is generated in a lime kiln from lime or magnesite which
are both used in the works. The sulphuretted hydrogen
liberated from the cylinders is taken to a Glaus kiln where it
is burnt in a limited supply of air which combines only with
the hydrogen, the liberated sulphur passing on into a chamber
where part of it is deposited in the form of flowers, the re-
mainder fusing in the bottom of the chamber and being
tapped out from time to time into cylindrical moulds in the
form of roll sulphur or brimstone. The operations are con-
tinuous ; as one cylinder becomes free of sulphuretted hydro-
gen it is disconnected from the series, emptied, and filled
again with the mixture of waste and water.
Utilization of the Eesidue of the Caustic Alkali Manu-
facture. The caustic soda liquor (and caustic potash
similarly) is made from 10 parts of calcined soda, 100 parts
of water, and 20 parts of fresh-slaked lime, by dissolving the
soda by boiling, and then gradually adding the powdered
and sieved lime. The boiling is continued until there is no
more sodium carbonate in the solution, the carbonic acid
having united with the lime to form carbonate of lime, whilst
caustic soda remains in solution. After cooling, the clear
liquor is carefully drawn off and brought into closed bottles
or carboys, so that it may not absorb carbonic acid from the
air. The paste remaining in the boiler is then brought on to
linen strainers, previously moistioned with water, where the
caustic liquor drains off, leaving behind the carbonate of
lime. As a rule, the residue in the strainer is washed with
warm water, when a somewhat weak caustic liquor is ob-
tained, which is added in a fresh operation, i.e. when fresh
caustic liquor is boiled. The washed paste is then brought
into wooden boxes, which are perforated at the bottom with
very fine holes, over which coarse linen is laid. Here more
liquor drains away. The stiff mass is pressed in moulds
ALKALI WASTE AND THE EECOVEEY OF SODA. 253
similar to those used in brickmaking. The bricks are dried
on boards in the air ; the dried bricks are then very finely
ground and sieved in order to remove all impurities. The
fine powder may then be used in various manufactures. 1
In the preparation of an artificial chalk, for which some
binding medium is requisite, the mass is made plastic with
an addition of water-glass as binding agent, then pressed and
slowly dried. The mass thus becomes as hard and firm as
natural chalk; it can easily be cut up for use as writing
chalk.
For the manufacture of a fertilizer for grass : the dried
residue always contains a few per cent of alkali, which can-
not readily be removed by washing. In combination with
other fertilizers this is very useful, especially when it is
mixed with sieved wood ashes, bone meal, ground excrement,
or dried blood in certain proportions. The following are
very good proportions :
Fifty parts of the ground alkali residue, 25 parts sieved
wood ashes, 20 parts bone meal, 20 parts excrement, 10
parts dried blood.
Another composition : 50 parts ground alkali residue, 50
parts bone meal, 30 parts ground excrement, 30 parts sieved
wood ashes.
And another : 60 parts ground alkali residue, 60 parts
sieved wood ashes, 30 parts ground kainite, 40 parts ground
excrement.
These are all well mixed, sieved, and packed into casks,
which must be well closed.
Utilization of the alkali residue in making polishing
powder and paste. The following recipes are given :
Polishing powder : Finely powdered residue (containing
soda) , 50 parts ; finely powdered rouge, 20 parts ; finely
powdered magnesia, 10 parts ; finely powdered glass, 20
'parts. These substances are very thoroughly ground to-
gether and the mixture sieved.
Polishing paste : Finely powdered residue (containing
1 Neueste Erfindungen und Erfahrungen," 1896.
254 THE UTILIZATION OF WASTE PEODUCTS.
soda), 60 parts ; kieselguhr, well sieved, 40 parts ; rouge, 20
parts ; glass, finely powdered, 20 parts ; magnesia, 10 parts.
These substances are well mixed, and then well ground with
olei'ne to a paste in a paint mill.
Recovery of Soda in Cellulose Works. In regard to the
recovery of soda in cellulose works, M. Faudel remarks in a
long paper, 1 in the first place, that, generally speaking, in the
best works the recovered soda amounts to little more than 70
per cent of the quantity used. Although the lime mud obtained
in causticizing the soda be repeatedly washed with fresh water
and the dilute liquors obtained be used in preparing strong
liquors, and although the most rational apparatus be used for
washing the boiled wood, yet there is lost in the lime mud
about 5 per cent, and in the wood about an equal quantity, by
leakages and in the evaporating furnaces about 20 per cent ;
thus, on the whole, about 30 per cent, and in some works,
no doubt, much more is lost.
Faudel ascribes a portion of this loss to be due to the
evaporating furnaces, which, in some works, are long, low
flues with a powerful and wasteful fireplace at one end,
from which the fire gases pass over the lyes. The liquors
are evaporated in these furnaces only to a certain concen-
tration ; they are then removed in the form of a toler-
ably solid but tarry mass, and further heated and melted on
separate hearths or on iron plates in the open. The soda
is thus obtained in the form of large hard lumps, which
frequently have to be broken and ground, at no inconsider-
able cost, before they can again be used in the preparation
of the lye. Quite apart from the complexity of the process,
an enormous amount of heat is lost, owing to the formation
of a solid crust over the surface of the lye in the furnace,
which, unless broken up at the proper time, hinders the
further evaporation of the liquor beneath.
According to Faudel, Porion's evaporating furnace is
more rational than the one just described; the soda pro-
duced is porous, and it may be used in the preparation of fresh
1 " Dingler's Journ.," 219, p. 432.
ALKALI WASTE AND THE EECOVEEY OF SODA. 255
caustic lye without pulverizing. A furnace as used in South
Germany permits the liquor to flow down a series of pans
arranged in steps, so that it meets the fire gases on its way.
This furnace, which is said to require frequent repairs, pro-
duces the soda in as convenient a condition as that first
described, and probably, therefore, offers little advantage
over it.
A fourth furnace, which appears to the author worthy
of notice, is that patented by the Belgian Werotte, and
known under the name of Fernau.
M. Montagnon, a Paris chemist, has proposed a method
for the recovery of soda in the wet way 1 which simply
consists in removing from the black liquors (of cellulose
works) the gummy, albuminous and mineral matters derived
from the plants. This can only be done when they are pre-
cipitated as compounds insoluble in a combination of the
liberated soda with the precipitant. The compound of soda
and the precipitant remaining in solution must then be treated
with a base which expels the acids combined with the soda,
liberating the soda which is left dissolved in the water used
at the first solution. These conditions are fulfilled by certain
common and cheap materials pyrites and lime, or powdered
iron ore (ferric oxide) and sulphuric acid. The cost of re-
covery of 1 ton of soda is given below for two methods of
procedure, in which either (1) pyrites and lime, or (2) ferric
oxide and sulphuric acid are used.
The cost of the recovery of soda in the wet way should not
be charged entirely to its recovery, since certain by-products
in great demand are also produced. These by-products may
be used with advantage for bleaching paper-pulp, or may be
converted into the original materials which may be again used.
In using pyrites and lime to recover the 1 ton of soda
contained in 15,400 gals, of black liquor, 2 tons of calcium
sulphite are formed, from which the sulphurous acid may be
obtained by treatment with sulphuric acid and this can be
used for bleaching paper-pulp.
1 " Journ. des Fabricants de Papier."
256 THE UTILIZATION OF WASTE PEODUCTS.
When ferric oxide and sulphuric acid are used to recover
1 ton of soda, 2-J tons of ferric sulphate are produced, which
can either be sold as such or decomposed in reverberatory
furnaces into ferric oxide and sulphuric acid, which may again
be used in the recovery of soda.
In both cases there results about six tons of the ex-
tracted gummy, albuminous, and mineral matters, the
mixture of which is sold as a fertilizer at a value of ten
shillings per ton.
The following calculations of the costs make clear the
relative advantages of the two processes of recovery :
1. BECOVERY IN THE DRY WAY (PORION'S PROCESS).
s. d.
3 '7 tons of coal at 22s. 6d M for the evaporation of 70 tons
of water . 82 3
1 ton of lime for causticizing 20
Loss of soda, 20 per cent from 1 ton, i.e. 4 cwt., at 28s. 112
Depreciation and interest for the furnace, i.e. 15 per cent
on 1600, for a daily recovery of 1 ton for 360 days
per annum 13 4
Total 227 7
2. RECOVERY IN THE WET WAY (MONTAGNON'S FIRST PROCESS).
1-25 ton of pyrites at 24s 30
1 ton of lime 20
Wages and general expenses 40
4 cwt. coal at 24s. . 4 10
Loss of soda, at a high estimate, 20 per cent from 1000
kilos, i.e. 4 cwt., at 28s 112 1)
Depreciation and interest, 15 per cent of the cost of the
installation, 200, i.e. per day . . . . . 18
Total 218 6
Value of by-products to be deducted s. d.
6 tons fertilizer at 10s 60
2 tons calcium sulphite at 32s. . . . . 64
124
Cost of recovery per ton .... 94 6
ALKALI WASTE AND THE RECOVEEY OF SODA. 257
(MONTAGKON'S SECOND PROCESS )
S. d.
1-13 ton of ferric oxide at 20s. per ton ' . . . 22 7
1*58 ton of sulphuric acid at 4s. per cwt. .... 126 5
Wages and general expenses 40
Loss of soda, at a high estimate 112
Depreciation and interest 18
Total 302 8
Value of by-products to be deducted s. d.
6 tons of fertilizer at 10s. ' 60
2-5 tons of ferric sulphate at 56s 140
Cost of recovery per ton
The economy resulting from Montagnon's processes over
the recovery in the dry way is, therefore, for one ton of re-
covered soda :
First process '.* . 227s. 7d. - 94s. 6d. = 183s. Id.
Second process .-." , V 227s. 7d. - 102s. 8d. = 124s. lid.
Thus for every cwt. of straw treated there is a saving of
eight shillings, or two shillings on one cwt. of white paper-
pulp.
Kecently K. Schneider has constructed an evaporating and
calcining furnace for the recovery of soda in cellulose works,
which appears worthy of special mention. The waste liquors
of cellulose works are evaporated and the residue calcined
without the production of noxious odours, by the application
of highly heated air. In 1875 Siemens described a regenera-
tive hot-air apparatus, consisting of two chambers, built of
fireproof bricks, with the requisite openings for air to enter
and leave, and filled with fireproof bricks after the manner
of the well-known Siemens' regenerators. In Schneider's
apparatus two of these chambers are connected with the
calcining and evaporating furnaces. The larger stands in
front of the furnace, which is somewhat smaller, about 17
metres (56 ft.) long, at a distance of about one-third of the
length of the furnace from the principal apparatus. The gas
obtained from lignite in the producer a simple vertical fur-
nace passes through flues provided with dampers into the
17
258 THE UTILIZATION OF WASTE PRODUCTS.
hot-air apparatus, where it burns, the resulting products of
combustion being then conducted, not to the calcining
furnace but by flues direct to the chimney. By the proper
change in the dampers a current of highly heated air from
the larger apparatus enters the furnace at the end, and a
second current from the second hot-air apparatus enters, in
a direction at right angles to the first, the calcining space
just in front of the fire-bridge. The gases pass under
the wrought-iron evaporating pan, then between this
and a second evaporating pan, and finally under a pre-
liminary heater, from which they pass to the chimney, 35
metres (115 ft.) high. The liquor collected in the preliminary
heater passes in the opposite direction through a pipe into
one evaporating pan, thence to the second, and finally to the
calcining furnace. The calcining space has a capacity of
about 2* 7 cub. metres (95 cub. ft.) of liquor, one evaporating
pan a capacity of 7'5 cub. metres (265 cub. ft.), the other
17 cub. metres (600 cub. ft.), and the preliminary heater 29
cub. metres (1023 cub. ft.).
If we assume that the hot-air apparatus is in the pre-
scribed condition and is supplying a continuous current of
highly heated air to the calcining space, then the process is
conducted as follows : The evaporating pans and preliminary
heater being full, the valves are opened, the calcining space
slowly filled, and the two evaporating pans again filled accord-
ing to the indications of the gauge glasses. According to the
consistency of the liquor, this process is repeated two or three
times within three to five hours, during which time heating
gases enter from the larger apparatus, in consequence of which
the temperature in the calcining space rises considerably, de-
spite the strong evaporation. When the evaporation has pro-
ceeded to a certain extent, after about three hours the current
of gas is cut off, and there now enters into the larger apparatus,
as during the whole period already from the smaller hot-air
apparatus, only atmospheric air at a high temperature (about
1000 C.). This air is thus present in the required quantity
from the commencement of the calcination and is completely
ALKALI WASTE AND THE RECOVERY OF SODA. 259
diffused through the whole of the calcining space. It would
therefore appear to be impossible for any gas of organic origin
to leave the calcining space undecomposed.
When the mass in the calcining furnace is completely burnt,
it is drawn out through doors, and, after removing the iron
plates, brought into the cooling-room. The gases which are
still produced here during the slow cooling enter the calcining
space through openings provided for the purpose, and burn
there completely in the hot current of air coming from the
larger hot-air apparatus.
CHAPTEE XLIII.
KECOVERY OF POTASH SALTS.
IN the patent granted to 0. Delion, Cassel (Ger. Pat. 284,936),
claim is made for the recovery of potash from the waste salt
(" Abrauin") from potash mining by treating with a solution
of common salt, which extracts potassium chloride and
hardens the other components of the mass, forming a pro-
duct of the nature of magnesia cement.
In the past a considerable quantity of potash was ob-
tained by the incineration of waste molasses, but these are
now too valuable to be treated in this way. The residual
beetroot has also been employed for the purpose, but this
was found to be a mistake, since it should be fed to cattle
and thus returned to the land in the form of manure.
In Kussia, sunflowers are cultivated on account of their
seeds, which are employed both for food purposes and for the
extraction of oil. The residual stalks, etc., are then burnt
to an ash which is extracted^ with water. On evaporation
of the solution impure carbonate of potash is obtained. This
can be converted into pearl-ash by treating with water, filter-
ing, and re-evaporation. In Southern Eussia this has now
become a flourishing industry, there being 24 factories which
in 1907 turned out 14,500 tons of potash.
Potash can also be obtained from "kelp," i.e. the ash
obtained by burning seaweeds in heaps. Iodine and bromine
are also obtained from the same material. The disadvantage
with this material is its high content of water, i.e. about 85
per cent. It may, however, first be dried by spreading out
on the sands above high water-mark. Seaweeds yield, ac-
cording to Balch, 1 500 Ib. of potash and 3 Ib. of iodine.
A valuable source of potash is the " suint " or sweat from
1 C. G. Cresswell, " Journ. Soc. Chem. Indt.," 1915, 387.
(260)
BECOVEKY OF POTASH SALTS. 261
the wool of the sheep. In the ordinary method of washing
this is carried into the drains and finally into the nearest
stream or river, but at Field Head Mills, Bradford, the dirty,
raw wool, containing 40-50 per cent of dirt, and about 4
per cent of potash, is washed with soap and water. The
suds are treated by the Smith-Leach process, which separ-
ates the emulsified wool grease by centrifugal action. The
liquids are then evaporated and the potash extracted from
the residue. According to Professor Gardner, 100 Ib. of raw
wool yield 18-20 Ib. of grease, and would also yield 5-6 Ib.
of potash if this were extracted. At one time several works
successfully treated this material for recovery of potash, but
owing to changes in conditions of trade it does not now pay.
According to Bott, 1000 Ib. of wool will yield 90 Ib. of potas-
sium carbonate and 5-6 Ib. of other potassium compounds.
In one district in France the amount of wool washed in a
year amounted, according to Bott, to 30,000,000 kilos ; from
this could be obtained 1,200,000 kilos of potash, of the value
of 85,000. The total French production in 1890 was
4,000,000 kilos, the production showing a distinct decline.
Fertilizer from the Waste Liquor from Potash Works.
The Kaliwerke Grossherzog von Sachsen, A. G. Dietlas and
K. Hepke, Dorndorf, have obtained a patent (Ger. Pat.
292,209, Jan. 29, 1915) for the utilization of the waste liquors
of potash works. These liquors contain principally magnes-
ium chloride, which on passing in gaseous ammonia is con-
verted into ammonium chloride and magnesia, the former
being suitable for use as a fertilizer, while the latter may be
again converted into chloride by addition of hydrochloric
acid.
CHAPTEE XLIV.
SULPHUR.
Recovery of Sulphur from Sodium Sulphide. At Stolberg,
near Aix, the sulphur dioxide obtained by roasting zinc
blende, etc., is cooled, and then absorbed by sodium sulphide,
under the action of steam, when sodium thiosulphate and
sulphur are formed, which are removed in barrels, whilst the
furnace gases, freed from sulphur dioxide, pass up the chim-
ney. From the mixture of sodium thiosulphate and sulphur
the latter is distilled off, the soluble matter sodium sulphide
and sulphate extracted from the residue, the Glauber's salt
separated by crystallization from the sodium sulphide, and
the former again converted by ignition with coal into sodium
sulphide, which may again be used to absorb sulphur dioxide.
Sulphur from Goal Gas. In purifying coal gas by means
of Laming's mixture, there is obtained a product containing
as much as 40 per cent of free sulphur, from which sulphur
can be obtained by distillation over an open fire, or with
superheated steam, or by extraction with heavy tar oils or
carbon bisulphide.
Sulphur from Gypsum, Barytes, Alkaline Sulphates, and
Barium Sulphide. The author of the article " Sulphur " in
Muspratt's " Chemistry " remarks that these methods, in spite
of the cheap raw materials, have not yet attained to economic
results, on account of the difficulty of separating the sulphur.
Sulphuric acid has also become so cheap since its production
on the large scale in smelting works, that it is used with ad-
vantage in making artificial gypsum for paper-works. (Also
compare the process of Schaffner and Helbig, under " Ke-
covery of Sulphur from Alkali Waste," p. 254.)
(262)
SULPHITE. 263
Sulphur Obtained in the Manufacture of Iodine from Sea-
weed. In making iodine in Scotland, France, and the Orkney
Islands, from kelp, the so-called vegetable sulphur separates
from the mother liquors in large quantities, owing to the de-
compositions which take place.
Sulphur from Calcium or Potassium Sulphide is obtained
as a precipitate (milk of sulphur) on decomposition by an
acid (hydrochloric).
According to an English patent, J. Hollway, of London,
obtains sulphur from pyrites, by passing steam over the
pyrites at a dark red heat. About half the sulphur then
distils over uncombined ; the remainder is evolved as sul-
phuretted hydrogen, leaving a residue of ferric oxide.
Recovery of Sulphur from Alkali Waste. Among the
numerous methods for the recovery of sulphur, the majority
of which can have no long existence since they have not
succeeded in practice, the process of M. Schaffner and W.
Helbig, of Aussig, which has been found practically suc-
cessful, is to be regarded as especially good. These two
chemists have succeeded in solving a long-attacked problem,
by again making useful the plague of soda-works alkali
waste from black ash. Whilst by the processes hitherto used,
which depend on the oxidation of the calcium sulphide, only
half the sulphur has been regained, while all the lime, together
with the other half of the sulphur, has remained as a second
waste product, Schaffner and Helbig recover all the lime
and all the sulphur in a usable form. Their process, as
patented in Germany, for the preparation of sulphur from
soda residues, gypsum, barytes, and sulphuric acid, with the
simultaneous recovery, as carbonates, of the earths united
with the sulphur, is based, in the first place, on the use of
magnesium chloride to decompose the calcium sulphide, a
reaction not hitherto applied on the large scale. The
reaction is
CaS + MgCl 2 + H,0 = CaCl 2 + MgO + H 2 S.
The calcium carbonate is not attacked by the magnesium
chloride.
264 THE UTILIZATION OF WASTE PRODUCTS.
The magnesium chloride employed is obtained by sub-
jecting to the action of carbon dioxide the residue, consisting
of magnesia, calcium chloride, and the remaining unattacked
constituents of the waste black ash, which remains from the
action of magnesium chloride on calcium sulphide after the
sulphuretted hydrogen has been driven off. Calcium car-
bonate and magnesium chloride are obtained according to
the equation
MgO + CaCl 2 + C0 2 = MgCl 2 + CaC0 3 .
Instead of magnesium chloride alone, hydrochloric acid,
to replace a portion, may be run in simultaneously or alter-
nately. The acid at once dissolves the separated magnesia,
when it can again exert its action. The sulphuretted
hydrogen is converted into sulphur by means of sulphur
dioxide, according to the equation
2H 2 S + 1S0 2 = 2H 2 + 3S.
However, not only sulphur and water are formed here,
but also other compounds, such as tetrathionic acid the in-
ventors say pentathionic acid, which, according to the re-
searches of Spring, 1 does not exist ; this reaction would not
be applicable on the large scale if the inventors had not found
a means of preventing the formation of tetrathionic acid,
etc., or of precipitating the sulphur from it if formed. This
means consists in the use of a solution of calcium or mag-
nesium chloride, in which the sulphuretted hydrogen and
sulphur dioxide decompose one another. The theoretical
quantity of sulphur is separated. If an excess of one gas or
another be present, it is without influence on the decom-
position, and is found unaltered in the solution. The function
of these chlorides in the reaction is not yet ascertained ; it
has, however, been found that about one equivalent of calcium
or magnesium chloride is required to the total sulphur
present. Schaffner and Helbighave later discovered that the
calcium and magnesium chlorides used in the main patent to
prevent the formation of pentathionic acid, etc., in the con-
version of sulphuretted hydrogen into sulphur by means of
1 Post's " Zeits. f. d. chem. Grossgew."
SULPHUR. 265
sulphur dioxide, may be replaced with equal success by hydro-
chloric acid, sodium sulphate, magnesium sulphate, barium
chloride, and sodium chloride. About one equivalent of
either of these salts is used to the total sulphur present.
The alkali waste is decomposed hot by magnesium
chloride in large closed iron tanks provided with stirrers.
Either the black-ash waste is gradually introduced into the
total quantity of magnesium chloride required to fill the
tank, or the magnesium chloride solution is run on to the
total quantity of black-ash waste, or finally, the two are
simultaneously and slowly introduced in equivalent quantities.
Loss of sulphuretted hydrogen is avoided by preventing the
accumulation of pressure in the tanks and decomposers,
which is easily effected by flues, fans, or pumps introduced
at suitable points. In the sulphuretted hydrogen decom-
posers there is also always maintained a larger quantity of
sulphurous acid than is equivalent to the sulphuretted
hydrogen coming from the developing tanks.
The siliceous and clayey matters (clinker) present in the
black-ash waste, which, if it remained in the regenerated
lime, would soon accumulate to such an extent as to make it
useless for soda-making, are removed by a process of stirring
with water and allowing to settle, or by passing the decom-
posed residue through a fine sieve. The regeneration of the
magnesium chloride and the lime from the decomposed re-
sidue freed from clinker is effected by the introduction of air
-containing carbon dioxide (flue gases, etc.).
The sulphuretted hydrogen coming from the tanks is
mixed by means of mechanical contrivances in vats or towers
with sulphurous acid and an aqueous solution of magnesium
or calcium chloride. In the case of towers, the arrangement
should be such that the sulphuretted hydrogen is introduced
at the bottom and the sulphurous acid a little higher. The
sulphurous acid required may be made from sulphide ores,
sulphur, or sulphuretted hydrogen, or any furnace gases con-
taining sulphur dioxide are taken and either conveyed direct
to the decomposing apparatus or separately into a condenser,
266 THE UTILIZATION OF WASTE PKODUCTS.
similar to those used for hydrochloric acid, where they pro-
duce a solution of sulphurous acid in water, or in a solution
of calcium or magnesium chloride.
This process may be applied as well to the black-ash waste-
as to gypsum and barytes after their previous reduction to
calcium or barium sulphide. It may also be employed for
utilizing and removing the injurious sulphur dioxide produced
in so many metallurgical processes.
To complete the account of this process, we add a private
communication made by Schaffner to Dr. Post, the editor of
the " Zeitschrift fur das chemische Grossgewerbe," according
to which a little burnt dolomite a double compound of
magnesium and calcium carbonates is added during the
carbonation; this addition also yields magnesium chloride,
which compensates for the unavoidable loss of this com-
pound in working, amounting to 5-6 per cent. The treat-
ment with carbonic acid, which has hitherto taken place in
an apparatus similar to Weldon's manganese mud-oxidation
tower by means of a powerful blowing machine, is now more
economically effected in an ordinary tower with currents of
gas and liquid in opposite directions.
The position of this process in practice is best shown by
an article on the subject in Post's " Zeitschrift fur das chem-
ische Grossgewerbe ". Tn answer to a question, whether the
process of P. W. Hofmann for the regeneration of sulphur
was applied anywhere except by Dieuze, Dr. Griineberg
stated that the precipitation was made by Mond's method and
the fusion after Schaffner's method. Post states that the
sulphur is now precipitated by Mond's method even in the
works at Aussig, since Schaffner's precipitation apparatus,
though working perfectly well, required too much labour and
attention when working on an extensive scale. The oxidation
of the waste is always effected by Schaffner's process, i.e. at
first in heaps in the air, then by blowing in flue gases. (Mond
blows air from a fan through the waste, adds an excess of the
liquor to hydrochloric acid, then neutralizes by hydrochloric
acid, again adds sulphur liquor, and so continues until the:
SULPHUR. 267
vessel is full.) ' K. Kraushaar has described in the " Polyt.
Journ." a process used with great success for many years in
the works at Thann for recovering the sulphur in open
vessels from alkali waste. According to Kraushaar's experi-
ments, there forms in the interior of heaps, as far as possible
protected from the entry of air, calcium hydrosulphide and
hydroxide, water being absorbed. Calcium hyposulphite is not
formed until oxidation occurs through air entering on break-
ing up the heaps, polysulphides being first formed, then
hyposulphite. If now the loosened alkali waste be exposed
to the air for just the proper length of time determined by
the examination of samples that the liquors may contain to-
one molecule of calcium hyposulphite one molecule of calcium
hydrosulphide and two molecules of calcium sulphide, CaS,
then there is no evolution of sulphuretted hydrogen on the
addition of hydrochloric acid, and consequently the decom-
position may be performed in open vessels. At Thann the
process is continuous ; acid liquor in the proper proportions,
enters, near the bottom, a wooden vessel provided with a
stirrer and heated by steam, whilst the decomposed liquor
and the separated sulphur flow away continuously through a
pipe near the upper edge of the tub. Kraushaar states that
the process of forming the hydrosulphide is more rapidly
effected than by stirring the heaps, by treating it with water
and steam at five atmospheres pressure in sheet-iron cylinders ;
90 per cent of the sulphur in the waste can be recovered in
this manner. The remainder is then made available by at-
mospheric oxidation. Kraushaar suggests the use of calcium
hydrosulphide liquor for unhairing hides in tanning.
This process, Post remarks, was not found successful in
small experiments in the works ; 90 per cent of the sulphur
was not obtained. The calcium hydrosulphide appears to de-
compose again at the temperature employed, since on opening
the apparatus streams of sulphuretted hydrogen are evolved.
Since Kraushaar's process is much more costly than that
generally employed, it could only count on adoption if it could
recover considerably more sulphur*than that hitherto obtained.
268 THE UTILIZATION OF WASTE PRODUCTS.
Mactears Utilization of the Yellow Liquor from Alkali
Waste. According to Lunge, 1 Mactear manufactured at Glas-
gow 1500 tons of sulphur per annum from the enormous
heaps of lixiviated black ash, and which had given rise to
great complaint. The essential part of the process is the
treatment of the liquor with an aqueous solution of sulphur-
ous acid, either with or (better) without the addition of lime.
Streams of the yellow liquor, of aqueous sulphurous acid,
and of hydrochloric acid are allowed to run simultaneously
into the precipitating vat, the volumes of the three solu-
tions being so regulated that as little gas and as much sulphur
as possible may be produced, just as Mond has described.
A temperature of 70 C. is the most favourable for the re-
action. The lixiviated black ash can also find a further ap-
plication in being used in place of lime in the preparation of
calcium pentasulphide. If the waste be boiled with sulphur,
the calcium sulphide takes up more sulphur, and a solution is
obtained which contains little hyposulphite.
1( 'Polyt. Journ."
CHAPTEK XLV.
SALT WASTE.
Treatment of the Stassfurt Waste Salts. Whilst referring
to one of the best and most comprehensive publications, 1
we shall follow in general the description of S. Pick a in regard
to the treatment of carnallite, and draw therefrom certain
further conclusions.
Carnallite is treated by a process which involves the
separation of its constituents by crystallization. From the.
crude salt a concentrated solution of potassium chloride is
prepared by the introduction of steam. The solution then
comes into clearing basins, from which it flows to the crystal-
lizing vessels. The residue is again boiled with water, and
the resulting weak solution used in the next operation in
place of water. The extracted residue is calcined, and its
proportion of potassium chloride increased to 15-18 per cent
by the addition of potassium chloride or other waste matters
containing potash, when it is finely ground and brought into
the market as a fertilizer under the name of " prepared
kainite ". The residue is also dissolved and exposed to
the frost, when Glauber's salt is obtained, or it is used in
the preparation of kieserite, by treating with a stream of cold
water, which dissolves the smaller lumps of rock salt, leaving
the larger, and carrying the kieserite away. A channel leads
the water on to a sieve, where only the fine kieserite pene-
trates, whilst the larger pieces of foreign matter remain be-
hind. As soon as the kieserite has collected in the settling
1 " Die Industrie von Stassfurt und Leopoldshall und die dortigen Berg-
werke in chemisch technischer und mineralogischer Hinsicht betrachtet," by
G. Krause (Cothen).
2 "Die Alkalien," 2nd ed., Vienna, Hartleben.
(269)
1270 THE UTILIZATION OF WASTE PBODUCTS.
tanks, it is shovelled out into moulds, in which it soon takes
up water and sets to solid blocks.
The hot, strong solution of carnallite, after settling, is
allowed to cool to 60-70 C. before the real crystallization,
when a large part of the sodium chloride crystallizes out
with a small quantity of potassium chloride. Or the sol-
ution is at once brought into tall crystallizing vessels ; the
potassium chloride, which crystallizes out, still contains
sodium chloride, magnesium chloride, and very small quan-
tities of magnesium sulphate. These impurities are re-
moved by placing the salt in wood or iron vessels with
perforated false bottoms, pouring water over, allowing to
rest for some time, and running off the resulting potassium
chloride solution, which is used to dissolve fresh carnallite.
As a rule, another similar treatment follows, when a salt of
'90 per cent strength is obtained. The potassium chloride is
"then freed from the adherent moisture, either by calcination
in kilns heated by the waste heat from evaporating pans, or
on iron plates heated by steam. The mother liquor left
.after the crystallization of the potassium chloride, which
still contains considerable quantities of that salt, is concen-
trated in evaporating pans. The salt which separates dur-
ing the evaporation is generally calcined and added to the
manurial salts. Formerly the liquor was several times
evaporated to a small extent and left to crystallize after each
evaporation. Now, in consequence of the fall in prices, it is
only evaporated once, but as far as can be done without
much injury to the pan as a rule, to 35 B. From the
clarified liquor artificial carnallite separates on cooling: the
residual mother liquor is either run to waste or worked up
for bromine, or it is evaporated to 40 B. and run into barrels,
in which the magnesium chloride solidifies. The artificial
carnallite serves as a source of very pure potassium chloride.
It is dissolved in hot water to form a solution of 31 B.,
from which coarse potassium chloride crystallizes on cooling.
The crystals are treated in the same manner as the first
crystallization from the crude potash salts, when a very pure
product results.
SALT WASTE. 271
The second and more recent method for treating natural
carnallite is founded on the fact that hot magnesium chloride
solution takes up the total content of the natural impure
carnallite and deposits it again in the crystalline state on
cooling, in a very pure condition, so that on decomposition
with water it produces very pure potassium chloride. The
mother liquor is again applied to the solution of fresh quan-
tities. The mother liquors resulting from the decomposition
of the artificial carnallite are evaporated, when they deposit
small quantities of " stage salt " and give a fresh crop of
carnallite. The process offers great advantages : pure pot-
assium chloride is obtained, and there is less liquor to evap-
orate ; but, on the other hand, it requires complicated
machinery.
The residue obtained in working up the saline deposits
for calcium chloride, amounting to about 30 per cent of the
crude salts, is sold to green glass-works under the name of
"*' glass melt". It is there well dried, finely ground under
edge runners or in a roller mill, and is then best at once
mixed with the other substances used in the charge. The
-air-dried residue contains : potassium chloride, 5*85 per
cent ; sodium chloride, 47'0 per cent ; magnesium chloride,
3'85 per cent ; magnesium sulphate, 29*25 per cent ; in-
soluble matter, 815 per cent ; water, 6'50 per cent.
G. Borsche, of Leopoldshall, near Stassfurt, has patented
a process for the preparation of potassium sulphate from
kieserite and potassium chloride. A mixture of 5-8 equiva-
lents of potassium chloride and 4 equivalents (2 molecules)
of magnesium sulphate is treated in succession with small
quantities of cold or moderately warm water, insufficient
to dissolve the salts completely. For example, 6 equivalents
= 447 grms. of KC1 and 4 equivalents = 920 grins, of
MgS0 4 7H 2 are treated four times in succession, each time
with 300 grms. of water, after each digestion the liquor
being allowed to drain away. The residue is then almost
pure potassium sulphate, and there is in all about 1200
..grams of water to evaporate, leaving an impure magnesium
chloride.
CHAPTEK XLVI.
GOLD AND SILVER WASTE.
Extraction of Gold from Tailings. In the extraction of
gold from its ores either by amalgamation or by chlorina-
tion a considerable quantity of tailings were produced and
accumulated to form great mounds. In the McArthur
Forrest process of gold extraction it was found that these
tailings could be profitably treated for the recovery of even
the small traces of gold which they contained, with the
result that all these heaps have been re-worked and many
companies have earned through this means quite a respect-
able profit. Shortly, this process consists in treating the
pulverized ores or slimes with a weak solution of potassium
cyanide which dissolves out the whole of the gold, the liquid
is caused to percolate through tanks containing boxes filled
with fine scrap zinc, whi 
