What industry owes to chemical science

*THE ENGINEER" SERIES

WHAT INDUSTRY OWES
TO CHEMICAL SCIENCE

RICHARD B.PILCHER

AND

FRANK BUTLER-JONES

WITH AN INTRODUCTION BY
SIR GEORGE BEILBY

" THE ENGINEER " SERIES.

WHAT INDUSTRY OWES
TO CHEMICAL SCIENCE.

By

RICHARD B. PILCHER,

Registrar and Secretary of the Institute of
Chemistry of Great Britain and Ireland;

AND

FRANK BUTLER-JONES, B.A. (Cantab.), A.I.C.,

Assistant, Laboratory of the Department of
Explosives Supplies, Ministry of Munitions.

With an Introduction by
Sir GEORGE BEILBY, LL.D., F.R.S.,

Past President of the Inttitute of Chemistry
and of the Society of Cktmieal Industry.

New York :

D. VAN NOSTRAND COMPANY,
25, Park Place.

1918.

PRINTED IN GREAT BRITAIN.

CONTENTS.

INTRODUCTION vii

PREFACE xiii

Chap. I. MINERALS AND METALS 1

II. HEAVY CHEMICALS AND ALKALI 22

III. COAL AND COAL GAS 34

IV. DYES, EXPLOSIVES, AND CELLULOSE ... 41
V. OILS, FATS, AND WAXES 53

VI. LEATHER 59

VII. RUBBER 63

VIII. MORTAR AND CEMENT 65

IX. REFRACTORY MATERIALS 68

X. GLASS AND ENAMELS 70

XI. POTTERY AND PORCELAIN 77

XII. CHEMICAL PRODUCTS' 80

XIII. PHOTOGRAPHY 90

XIV. AGRICULTURE AND FOOD 95

XV. BREWING 104

XVI. ALCOHOL, WINES AND SPIRITS 109

XVII. TOBACCO, INKS, PENCILS, ETC. ... ... 115

XVIII. GASES 122

XIX. GOVERNMENT CHEMISTRY 133

CONCLUSION 138

BIBLIOGRAPHY 141

INDEX 144

387485

INTRODUCTION.

AMIDST the flood of opinions and advice on the
relations of science to education and industrial
prosperity with which we have been deluged
during the past two or three years, we may turn
with welcome relief to the unembellished records
of work done and of ends accomplished which the
authors have here presented for our enlightenment
and encouragement. The majority among us
stood much in need of enlightenment on this
subject, and many of us will feel grateful for the
encouragement which is to he derived from these
records of past achievement. These records supply
a complete answer to a question with which most
chemists have had to deal at one time or another
during their career : what is the place of the
chemist in practical life, and what part has he
taken in industrial and social development ?

The engineer ministers to the comfort and
convenience of the community in ways which
can hardly escape the notice even of the man in
the street. The Forth Bridge, the ocean grey-
hound, the motor car and the aeroplane are at
once recognised as the fruits of his skill and energy,

viii WHAT INDUSTRY OWES

but for the most part, the work of the chemist is
inobvious, and is little, if at all, understood. But
the chemist and his half-brother, the metallurgist,
have all the time been hard at work in the back-
ground, helping to provide the engineer with
metals and other ^materials of new and improved
qualities, without which he could not have produced
the machines and structures which represent the
triumphs of his art.

In many other directions chemistry has been
the handmaid of arts and crafts, which make
their appeal to the public on far other grounds
than those of the chemical and other scientific
help they have laid under contribution.

But chemistry also has its own triumphs, and
those who will take the trouble to study this work
will be rewarded with visions of achievement in
this field which they had not hitherto dreamt of.

These records ought to prove stimulating and
suggestive to those whose sons and daughters
have not yet selected a calling or profession. The
place of chemistry in the national life has been
far more important than the majority of educated
people have imagined, and this place bids fair to
become of vastly increased importance in the near
future. The special message for parents and
teachers is, therefore, that trained chemists will,
in the near future, be in increased demand for
industrial and official positions.

TO CHEMICAL SCIENCE ix

For the responsible teachers of chemistry there
are other messages also, if they care to seek for
them ; for from these records of achievement
much may be learned as to the actual needs of
industry on its scientific side, and as to the types
of workers who will have to be trained if these
needs are to be properly met.

The great body of teachers of science on the one
hand, and the still greater body of manufacturers
on the other hand, have been equally at sea as to
how (a) the results of scientific discovery, and
(6) the young graduates in science who are prepared
at our universities and colleges, can best be utilised
in industry. Speaking broadly, the teachers of
science do not know the needs of industry, either
in regard to the nature of the problems which
await solution, or to the kinds of trained experts
who will be required to take part in the more
highly organised industries of the future. Again,
speaking broadly, manufacturers and leaders of
industry are equally at a loss as to the means
whereby scientific discovery, scientific methods and
scientifically trained men can be used most
effectively in the development of the industries
for which they are responsible.

Fortunately, there are already lines of communi-
cation open between these two important bodies,
and the hope for the future is that these lines may
be broadened out into a common ground on which

WHAT INDUSTRY OWES

mutual understanding will be reached and where
practical schemes of development will be developed.
Much can, undoubtedly, be done to improve
the training of chemists for practical life. It is in
the laboratory that the foundations of this training
must be well and truly laid by sound training and
ample practice in manipulation and methods. Not
only manipulative skill, but resourcefulness and the
power of organising routine work ought to be
acquired in the laboratory, if the training is on the
right lines. On the foundations thus laid, a super-
structure of knowledge of physical, mechanical, and
chemical laws can be securely built. But a
scientific equipment, however sound, is not in
itself sufficient ; it is of equal importance that the
young chemist throughout his training should be
thoroughly imbued with the spirit and aims of the
successful leaders of industry. Nothing will so
surely awaken in the student an appreciation of
practical aims as a wisely directed study of the
achievements of science in industry. The present
work will supply teachers of chemistry with
abundant material for the purposes of this study.
This study ought not, however, to displace the
parallel study of the steps by which chemical
theory has been evolved by the deep insight and
the patient observation and experiment of the
great leaders in chemical science. It ought to be
made clear to the student that, though in one sense

TO CHEMICAL SCIENCE

the two aims, the attainment of knowledge for its
own sake, and its attainment as a means to practical
ends, are at opposite poles, yet that there is no
real antagonism between them, each is com-
plementary to the other. There are intellectual
triumphs to be won in the application of science
as well as in its pursuit for its own sake.

The deeper and more prolonged search into the
phenomena and laws of Nature must, of necessity,
be left to those who by natural endowment and by
opportunity can pursue this search apart from
the distractions of the work-a-day world. The
workers on the applications of science may well
realise their debt to these seekers after knowledge,
for the seeds of achievement on the practical side
must, in many cases, be planted and watered under
their fostering care.

During the past three years the scientific
developments of modern warfare have been the
means of bringing the workers in pure and in
applied science into touch to an extent which
would have appeared almost impossible in pre-war
times. There are encouraging evidences that this
new co-operation has been appreciated on both
sides, and that a return to the former condition of
isolation would be regarded as most unfortunate.

The authors have wisely disclaimed any attempt
in this work to present the extraordinary wealth of
material at their disposal in anything like its true

xii WHAT INDUSTRY OWES

proportions and perspective. The precious stones
in the necklace have been strung together rather
with an eye to their collective preservation than
to their artistic effect as a whole. Apart from the
reasons for this, which the authors themselves
have given, I am inclined to think that for the
serious purpose they had in view, the method has
much to commend it. The central object was not
to present a pleasing and finished literary work
which would gently stimulate the imagination of
the general reader, but to set forth in their bare
simplicity the broad facts of achievement, leaving
each case to make its own appeal.

In conclusion, I would express the hope that
this work will not only be widely read by the
general public, but that it will be cordially welcomed
by those who are most deeply concerned in the
future of British industry.

GEORGE BEILBY.

TO CHEMICAL SCIENCE xiii

PREFACE.

IN recent times, and especially during the war,
a great deal has been written and said on the
benefits derived from the applications of science
to industry ; the subject has been discussed in the
technical and daily Press, and in monographs
devoted to particular industries ; but, for the most
part, it has been dealt with in the abstract or with
very limited reference to the actual results achieved.

The contents of this volume appeared as a
series of articles published in The Engineer during
the seven months December, 1916, to July, 1917,
inclusive, under the title of " What Industry Owes
to Science." The articles were not intended to
embrace subjects of common knowledge to the
engineer, in which the influence of physical and
mechanical science would have claimed greater
attention, but dealt mainly with chemical science.
For that reason the title of the work has been
modified ; the text, however, remains piactically
the same.

The object was to take each industry in turn,
and to show by examples how science had
advanced the methods and processes of production

xiv WHAT INDUSTRY OWES

and had laid the foundation for the establishment
of new manufactures.

The work covers a survey of many important
industries, presented in such a manner that the
substance is not altogether out of the depth nor
beyond the interest of the educated public. We
hope that it may be especially useful to students of
chemistry and engineering, as affording them an
indication of the vast field open to them in their
professional careers, work in which it may be
anticipated that there will be increasing activity
and boundless scope in the near future ; and that
it will find a place in the offices of men of business
in many branches of commerce, and of public
companies concerned with productive industries,
as well as in the libraries of Chambers of Commerce
and Trade Associations.

A bibliography is provided, including many
useful books referred to during the preparation
of the work.

The authors desire to express their deep indebted-
ness to Sir George Beilby for his kindness in
contributing an introduction, which they feel has
very greatly enhanced the value of the volume.

R. B.P.
F. B.-J.
London, 1917.

TO CHEMICAL

WHAT INDUSTRY OWES TO
CHEMICAL SCIENCE.

CHAPTER I.
MINERALS AND METALS.

WE have heard a good deal lately of our neglect
of science, particularly of applied science — and we
are prepared to admit that this country has been
behind other countries in realising the importance of
scientific principles in industry. The fact remains,
however, that though we have been so remiss, we can-
not have ignored science entirely, or surely the
position of our industries — those that are left to us —
to-day would not be what it is. Instead of pursuing
the subject in the abstract, we propose in a few brief
chapters to deal with accomplished facts ; to show by
illustrative examples the extraordinary developments
directly attributable to scientific thought and method
and the benefits derived therefrom by the community.
The whole art of engineering is based on physical
and mechanical science, and the materials employed
in this art are dependent in some degree on the
science of chemistry. This country has never lacked
engineers of the first order, and, therefore, if we may
judge by their works, we must conclude that their
science has been as truly founded as their structures,
and their materials must likewise have been suitable
for their purpose. Clearly, then, we have not been
lacking the aid of physicists, mathematicians, and
chemists in the art of engineering and all that the
term denotes. The materials of construction cannot
be used intelligently unless the engineer has a proper

'WHAT INDUSTRY OWES

knowledge of their physical powers of withstanding
stress and strain, as well as of their chemical proper-
ties, including their internal structure and power of
resistance to air, fire, water, and other agencies.

The subject is so vast and its ramifications so diverse
that it is difficult to deal with it without being drawn
into the production of a text-book, but we will
endeavour to keep to the principal aim of showing the
influence of science in industrial progress.

Our methods of utilising science may be wrong,
and there may be room for great improvement,
but the impression is gaining ground that in the
habit of decrying ourselves and our doings we have
overshot the mark. We have used science more
than we realise, but have not talked about it as much
as some other people. We know, for instance,
several Sheffield steel firms who employ thirty to forty
chemists and are in constant touch with the most
experienced men of science interested in this branch
of industry. We know also that both in the direc-
torate and in the control of the actual processes
of manufacture in the works the industry is coming
more and more under the personal supervision of
scientific men, that new laboratories are being
equipped, and that science in the steel industry is
now very much to the fore.

STEEL.

German delegates to the meeting of the Iron and
Steel Institute held at Sheffield in 1905, freely
admitted that Germany had much to learn from that
centre and no doubt derived benefit from the hos-
pitality then extended to them. The reputation of
Sheffield in steel production dates from 1740,
when Huntsman discovered the process of casting
completely fused rnetal from crucibles. Sixty
years ago steel was obtained by decarburising pig
iron to malleable iron in a puddling furnace and
subsequently introducing the requisite amount of
carbon by the cementation process. These operations
were protracted, required exhausting labour, and
involved the use of large and expensive furnaces

TO CHEMICAL SCIENCE 3

subjected to considerable wear and tear and consuming
large quantities of fuel.

In 1856, Bessemer — a scientific man — as the result
of experiments deliberately directed to a definite
object, introduced his process for *' The Preparation
of Steel without Fuel." He found that by forcing
a blast of atmospheric air through molten cast iron,
contained in a suitable vessel lined with ganister,
a siliceous material, the oxidisable impurities in the
iron could be removed without the external applica-
tion of heat, since the heat produced by oxidation
was sufficient to keep the mass in a molten state.
Manual or mechanical stirring was unnecessary. The
pig was melted in a cupola, and transferred to a mixer
of up to 600 tons capacity. From the mixer a charge
was conveyed by a ladle to the converter, the latter
being swung into position after the " blow " had been
started. In twenty minutes the operation was
completed ; the blast was stopped for a few seconds
while a workman threw in from a shovel sufficient
spiegel or ferro-manganese to introduce the proper
proportions of carbon ; the blast was started again
for a short time to mix the metal and the charge was
immediately poured into moulds.

Contrast the rapidity and simplicity of this method
with the time and labour expended in the other.
Cementation alone required seven to ten days ; the
equivalent effect, after Bessemerisation, occupies only
the time required to add the spiegel and re -mix the
charge. The fuel expended is only that used in the
cupolas, and even that is obviated in some cases where
the constancy of grade of pig from the blast-furnaces
can be relied on, when the pig is taken direct from the
blast-furnace to the converter.

The original or acid Bessemer process had, however,
two disadvantages: — (1) phosphorus and sulphur
could not be removed owing to the reduction of their
oxides by iron and, therefore, only special " Bessemer
pigs," free from phosphorus and very low in sulphur,
could be used ; (2) the ingots produced contained
blow-holes. Science overcame the first of these
disadvantages. In 1879 Thomas and Gilchrist found

B

WHAT INDUSTRY OWES

that by lining a converter with burnt dolomite or
magnesite, instead of ganister, and by adding a
quantity of lime to the charge, the whole of the
phosphorus and some of the sulphur could be removed.
This was the result not only of scientific methods
of research but of the direct application of a scientific
principle, viz., that of using a basic lining and adding
lime, a basic material, to retain the acidic substances
produced by the oxidation of phosphorus and sulphur.
The second problem, however, was solved by the
empirical discovery that the addition of a very small
quantity — 5 to 8 oz. per ton — of aluminium to the
molten metal minimised the formation of blow -holes.
The only important rival to the Bessemer method is
the open-hearth process, perfected about twelve years
later by Sir William Siemens and his brother — both
scientific men. After great initial difficulties, they
succeeded in decarburising iron without contact with
solid fuel. In this process an exceedingly high
temperature is produced in an oxidising atmosphere
by the combustion of a mixture of producer gas and
air fed into the furnace. Changes take place of the
same character as in the Bessemer process. Both
acid and basic hearths are used, and the principle of
regenerative heating is utilised.

To Dr. Sorby, of Sheffield, we owe the introduction
of metallography, and in this connection the names
of Osmond, Martens, Stead, Roberts-Austen, Sauveur,
and Le Chatelier, all men of science, must be remem-
bered. Up to the present day, and for some years past,
the miscroscopic examination of the etched surfaces of
metal has been common practice in steel works labora-
tories. Researches on the cause of recalescence, com-
bined with the intimate knowledge of the structure of
steels afforded by miscroscopic examination, have
placed in the clear light the equilibrium relations of
iron and carbon, and have thus changed rule-of -thumb
experience into sound scientific principle. Our views
on the physical and chemical nature of these equili-
brium relations have been changed by the progress of
research. Explanation by means of the solution theory
has replaced that based on the theory of the allotropy

TO CHEMICAL SCIENCE

of iron, and our knowledge of the subject is thus be-
coming more definitely established. To be able to ex-
plain a phenomenon is second only to knowing that
the phenomenon will occur. Whereas rule -of -thumb
or empirical discoveries may occasionally give us good
results, science, organised knowledge, enables us to
proceed on definite lines.

The discovery of rarer metals has led to the manu-
facture of many varieties of steel, including alloys of
special hardness. The properties of special steels
and their behaviour under varying conditions, the
bearing of the character of their internal structure
and similar questions have formed the basis of
numerous researches which have rendered the in-
dustry in an increasing degree more exact and
scientific. The researches of Sir Robert Hadfield
have resulted in supplying us with special steels
differing from ordinary steels, through the addition
of various elements other than those commonly
present, whereby they acquire properties of enhanced
hardness, toughness, elasticity, &c.

Thus, by adding 7 to 20 per cent, of manganese we
ensure great strength and toughness, the well-known
Hadfield steel ordinarily containing about 13' per cent,
of manganese and 1 per cent, of carbon ; the addition
of about 3 per cent, of nickel and 0.2 per cent, carbon
gives us a steel of tensile strength and elasticity suit-
able for the manufacture of gun barrels ; and the
addition of 2 to 3 per cent, of chromium with about
1 per cent, of combined carbon gives a remarkable
steel which, when hardened and tempered, is employed
in the manufacture of locomotive tires and springs,
armour plates, armour-piercing projectiles, and certain
qualities of files. Similarly, the introduction of
titanium, molybdenum, tungsten, aluminium, vana-
dium, and boron gives varying effects now easily
obtainable by the scientific steel maker.

These examples serve to illustrate clearly the
advantages gained by the application of scientific
knowledge in the production of one of our chief
materials ; but the function of the chemists in a steel
works or any works is not confined to devising pro-

B 2

6 WHAT INDUSTRY OWES

cesses or producing varieties of the products. They
are concerned with problems of many kinds, and
among these the question of fuel and fuel economy
both in raising power and in smelting operations are
of primary importance. Science determines the
suitability and value of the coal employed. Tests are
made to determine the calorific power and to estimate
the sulphur, ash, and the volatile matter, including
moisture, all important factors from the point of view
of economy. The manufacturer who ignores these
questions must suffer through the employment of coal
containing sulphur which attacks his fire-boxes, and
the purchase of water and useless mineral matter.
Next, the treatment of boiler-feed water where the
supply is not naturally soft must not be neglected, or
the accumulation of scale will result in waste of heat,
inefficient working, and other deplorable conditions.
The method of water softening, by the addition of
lime, was established by Dr. Thomas Clark, Professor
of Chemistry at Aberdeen University, from 1833-39,
and its importance in every industry involving the use
of boilers, or requiring the use of soft water, must
have been and still is inestimable.

NON-FERROUS METALS.

Mining and metallurgical industries are essentially
scientific, calling for the services of chemists (1) on
the mines, to examine ores, to advise on their concen-
tration and generally to specify the methods to be
adopted for the extraction of metals, and (2) in the
actual working of the metal.

The production of non-ferrous metals, such as
copper, lead, zinc and aluminium, needs the help of
trained technologists whose labours are constantly
directed to the discovery of improved processes and of
new varieties of alloys adapted to special purposes,
particularly those demanded by the trend of engineer-
ing development.

In surveying the history of non-ferrous metallurgy,
the most striking feature is the extent of comparatively
recent scientific advancement. In many cases the
methods of treating ores to obtain crude metal

TO CHEMICAL SCIENCE

remain fundamentally the same as when they were
originally discovered — for the most part empirically ;
but they have been explained, modified, and improved
by science ; while in other cases, new and better
methods, due solely to science, have been substituted
for old ones.

The Separation of Minerals. — The ores of heavy
metals are frequently of such low grade that the
metal cannot be won economically. Thousands
of tons of valuable minerals would still remain
unworked except for the scientific methods of con-
centration now employed. An ore containing only
one per cent, of tin will repay treatment.
It cannot be smelted, but a complex process
of table washing, roasting, and washing again con-
centrates it to 60 to 70 per cent, ready for the
smelter. Low grade sulphide ores and graphite
ores are concentrated by one or other of various
methods of oil separation and flotation which afford
interesting examples of discovery originated in
empiricism, developed by chance discovery and
mechanical ingenuity and further improved by the
direct application of scientific thought, whereby their
utility has become widely extended so as to effect
invaluable economies in the mineral industries.
Although various theories have been advanced to
explain the phenomena of flotation, the true mechan-
ism remains as yet obscure. It is instructive to
follow the stages of the advances made in this direc-
tion, and to indicate the present views on the subject.

In 1886 Carrie J. Everson found that sulphide
mineral particles could be separated from the gangue
in ores by kneading the finely crushed ore with a paste
formed by the action of sulphuric acid on certain
oils, e.g., linseed or cotton seed. The oil adhered to
the particles of sulphide mineral and bound the whole
into a coherent mass. The gangue was then washed
away by water. The process was very little used, its
application being limited to rich pyritic gold ores,
the treatment of which was profitable.

The next development, patented by Elmore in 1898,
was an oil separation process wherein the finely

8 WHAT INDUSTRY OWES

crushed sulphide ore made into a pulp with water
was well mixed with 3 to 6 per cent, of its weight
of residuum oil. The oil floated to the top and
formed a layer carrying the sulphides, leaving behind
the gangue. The top layer was separated by means
of a spitzkasten and the oil run into a centifrugal
machine containing warm water, where some of the
oil was separated to be used over again. The partially
de -oiled concentrates were further treated in a smaller
centifrugal to effect a further separation of oil, and
were then ready for the smelter. In 1901 Elmore
patented the use of sulphuric acid in the process, as
an aid to the production of cleaner concentrates.
The process was not generally adopted because the
losses of oil due to entanglement in the gangue pulp
were very high.

The Elmore vacuum method was an outcome of
the above. This is an oil flotation process, as distinct
from an oil separation process. The pulp of ore and
water, mixed with a very small quantity of oil and
enough sulphuric acid to make the mixture slightly
acid, is exposed to a partial vacuum ; the air
dissolved in the water rises up through it in the form
of bubbles, floating the oiled sulphides to the top,
whence they are drawn off. From a 2 to 3 per cent,
copper ore, concentrates of up to 20 per cent, can
be produced.

In 1901 C. V. Potter, working on Broken Hill ore,
heated the crushed ore in an acid water pulp. The
action of the acid upon carbonates in the ore generated
carbonic acid gas, which, rising to the top, carried
sulphide mineral with it. In 1902, in connection with
this process, G. D. Delprat used salt cake instead of
sulphuric acid.

In 1903 Cattermole, by adding 4 to 6 per cent,
of oleic acid to the ore -water pulp and applying slow
agitation, caused the sulphide particles to aggregate
into large granules with the oil. The gangue which
remained in the pulp was then separated by means
of an up -cast. The principle of the method was good,
but the expense in oil was large. It was in connection
with the work on this process, however, that the froth

TO CHEMICAL SCIENCE 9

flotation process was discovered. By using small quan-
tities of oil — up to 0. 1 per cent, calculated on the ore,
though less generally — and churning up the pulp with
air by rapid agitation with a special paddle, the oiled
sulphide particles are caused to rise to the top as a
strong froth which is floated off by a spitzkasten. This
process especially has been developed by scientific re-
search, and the efficiency and the economy of ore con-
centration have been thereby greatly improved. Sul-
phide ores of zinc, copper, lead, iron, antimony,
molybdenum, and of other metals are very efficiently
treated. Tin -stone -pyrites table concentrates are
separated, the pyrites being floated off ; and graphite
is easily concentrated to an exceedingly clean product.
The grade of the concentrates is high and the recovery
excellent. The use of acid is sometimes necessary
to produce clean concentrates, enough being added
to ensure an acid reaction in the pulp. Curves can be
plotted showing the variations hi grade of concen-
trates and recovery with variation in the amounts of
oil and acid used. The testing of ores is scientifically
carried out in special apparatus. The experimenter
not only finds the best method for treating the ore,
but also observes and records any peculiarities ex-
hibited that may be of use in furthering the aims of
the process or may serve to throw light on the
ultimate causes of the principles underlying the
method. Wood's modification of the above process
renders it possible to concentrate certain ores without
the use of oil.

These concentration processes are of comparatively
recent invention, and are increasingly applied to the
treatment of low grade sulphide ores and the tailings
from table concentrations.

Experiments on the flotation of other minerals,
such as native copper, gold, and Scheelite, an ore of
tungsten, have met with success, and will probably
be greatly developed during the next few years. The
flotation of carbonate and other oxidised ores has
been attempted with positive results, but this exten-
sion also is as yet in the experimental stage. The
general opinion of men of science at the present day

10 WHAT INDUSTRY OWES

is that flotation, is an effect of surface tension, though
some favour the view that the mineral particles must
also carry an electric charge. The ultimate causes
can only be established by further research.

In dealing with the separation of minerals we should
mention also the important work of electrical and
mechanical engineers, to whom much credit is due for
the invention of magnetic separators. Many ores
containing magnetic minerals are now efficiently
treated by these machines, involving both wet and dry
methods. As instances may be taken the magnetic
concentration of magnetite ores, and the separation
of this mineral from pyrites. Magnetic separation
has also been applied in the treatment of monazite
sands for the concentration of thorium, to which we
will refer later.

Copper. — Scientific knowledge has come to the aid
of the copper smelter and refiner in various ways. The
introduction of water -jacketed blast furnaces — such
as are used in lead smelting — in the fusion for regulus,
has reduced wear and tear to the minimum. These
furnaces are made of iron and are double walled, with
water circulating through the space between the
walls, producing a cooling effect inside the furnace in
the immediate vicinity of the wall. The result is
that some of the molten slag solidifies on the wall,
forming a protective coating which is not further
attacked, since the liquid does not corrode it, and
thus the iron walls of the furnace scarcely come into
contact with the liquid.

A method of smelting pyritic copper, silver, or gold
ores by the heat of oxidation of the pyrites, without
the aid of any other fuel was introduced as recently
as 1905 ; in actual practice, however, up to 5 per cent,
of carbonaceous fuel is now added. Water-jacketed
blast furnaces are used, and air — pre-heated in some
cases — is liberally supplied through a large number
of tuyeres.

Copper intended for use as an electrical conductor
must be of high quality, the presence of very small
quantities of certain other bodies causing a marked
diminution in its efficiency. The necessary degree of

TO CHEMICAL SCIENCE 11

purity can now easily be obtained by the methods of
electrolytic refining. A thin sheet of electrolytic
copper forms the cathode, a slab of blister copper
the anode, and the electrolyte is an acidified solution
of copper sulphate.

Pure copper is deposited on the cathode, the anode
being gradually dissolved. Impurities in the copper,
such as iron, zinc, nickel, &c., of which the sulphates
are soluble, are allowed to accumulate in the solution
until their quantity renders the liquor inconvenient
to deal with. At this stage the copper in the liquor
is precipitated with metallic iron and fresh solution
substituted. Other metals present, such as platinum,
gold, silver, lead, and arsenic, form a fine mud in the
bath, and this mud is afterwards treated for recovery
of the precious metals. Thus, by this scientific
method, not only is copper obtained in a very pure
state, but the gold, silver, and platinum also can be
extracted profitably.

Lead. — A remarkable instance of the application of
pure science to the solution of a technical problem is
provided in the methods employed in the desilverisa-
tion of lead by the Pattinson and the Parkes methods.
Before 1833 the only available process was cupellation,
and this could only be effected economically if the lead
contained 8 oz. per ton or more of silver. Therefore
much silver remained in the lead, of which, in the
aggregate, large quantities contained less than this
amount. The method patented by Hugh Lee
Pattinson in 1833 depended on the fact that when
a solution is partially frozen some of the solvent
separates in the solid form, leaving a solution richer
in the dissolved substance. For instance, when salt
water is frozen, pure ice separates and the remaining
solution Is stronger in salt. Molten lead containing
silver may be regarded as a solution of silver in lead,
and if this solution is allowed to solidify partially,
almost pure lead separates out in crystals. Two
methods are adopted, that of thirds and that of
eighths. Usually, sixteen kettles, lined with lime to
prevent attack by litharge and holding about 12 tons
each, are employed. For lead comparatively rich in

12 WHAT INDUSTRY OWES

silver, two-thirds of the contents of each pot are
removed as lead crystals ; and for lead which is
poorer in silver, seven-eighths of the contents is
removed from each pot. In the latter case fewer
pots are required. By these means, respectively,
starting from a lead containing up to 3 oz. of silver
per ton, a silvery lead containing 700 oz. per ton,
and a " pure " lead containing only £ oz. to £ oz. of
silver per ton can be obtained. The process in each
case is stopped when the silver reaches about 700 oz.
per ton, as this is approaching the eutectic.* A
modification of the method nas been introduced
whereby the lead is cooled more quickly by blowing
in steam and spraying the top of the lead with cold
water, the rich silvery lead being poured off from the
crystals instead of the latter being baled out.

The silvery lead obtained by either process is
cupelled on a hearth made partially of bone ash,
which absorbs most of the lead oxide. Some of the
litharge produced is blown over the side of the cupel
by the blast of air, and is used in the manufacture of
paint.

The Parkes process depends upon the fact that
silver is much more soluble in zinc than it is in lead,
whilst lead and zinc are mutually soluble only to a
small extent. A saturated solution of zinc in lead
contains only about 1 per cent, of zinc whilst a
saturated solution of lead in zinc contains 2 to 3 per
cent, of lead. If, therefore, molten argentiferous lead
is stirred up with molten zinc the latter extracts most
of the silver from the lead and when the stirring is
discontinued rises to the top, forming a separate layer.
An exactly parallel operation frequently used in the
laboratory is the method of extraction by ether.
On shaking ether and water together each dissolves a
little of the other. When the shaking is stopped the
liquids separate into two layers, the ether being the
uppermost. Suppose we are dealing with the aqueous
solution of a substance that is more soluble in ether
than in water, and that the solution in water is
inconvenient to work with, the substance can be

* See note on p. 21.

TO CHEMICAL SCIENCE 13

almost completely removed as a solution in ether by
shaking the solution repeatedly with small quantities
of ether, which can then be removed by distillation.

In practice, the work lead is purified by remelting,
to effect the removal of copper, arsenic, antimony, &c.
The lead, so far purified, is then melted in a pot
and heated to about 500 deg. C., lumps of zinc are
added and the liquid is well stirred with iron paddles.
The quantity of zinc added depends on the richness
of the lead in silver, but in any case is very small and
rarely exceeds 2 per cent, of the weight of the lead.
When the agitation is stopped, the liquid is allowed to
cool and a crust of zinc containing the silver solidifies
on top of the still molten lead, is removed by ladles
and liquated to separate some of the zinc. The
remainder of the zinc -silver mixture is then transferred
to graphite retorts and the zinc is distilled off. It is
found to be advantageous in extraction by zinc — as in
the case of ether — to add the zinc in three instalments,
and not all at once. When the lead contains gold,
about one-tenth of the zinc is put in at first, when the
scum of zinc separated contains all the gold. The
silver is then extracted by continuing the process.
The remaining lead contains about 1 per cent, of
zinc, which is removed by blowing air and steam
through the molten metal, the zinc being blown away
as oxide, leaving the lead in a very pure state. The
Parkes process, now used extensively, has been
rendered more efficient by the recent discovery that
graphite retorts can be used for the distillation of the
zinc.

These processes for desilverisation not only yield
valuable quantities of silver but also produce lead
in a high state of purity. In fact, lead as now pro-
duced is one of the purest of the commercial metals.
It would probably not be so if no precious metal
could be extracted from it, because in order to win
the silver all other impurities must also be removed.
Whereas work lead is hard, pure lead is soft and can
be easily manipulated, purity being, moreover, very
important in the starting material for the manufac-
ture of white lead for making paint.

14 WHAT INDUSTRY OWES

Nickel was discovered by Cronstedt in 1750-
During recent years it has assumed an important
position in the civilised world. It is malleable,
ductile, hard, takes a high polish, and is very
resistant to atmospheric oxidation. To these
valuable properties nickel owes its use in the electro-
plating of small iron and steel articles to prevent
rusting, in the manufacture of rifle bullets, which are
covered with a layer of nickel to give a hard clean
surface that will not foul the barrel, and also in the
preparation of nickel steels and of certain alloys
with copper and zinc, such as nickel silver, which
are used in the manufacture of forks and spools,
ornamental articles, wire, medals, and coins. Nickel
is also used in the finely divided state as a catalyst,
in the hydrogenation of certain oils and fats. By the
action of hydrogen in the presence of finely divided
nickel, liquid oils such as fish oil, linseed oil, olive oil,
can be " hardened " into solid fats suitable for the
starting materials in the manufacture of foodstuffs,
candles, and soap. For these purposes the nickel
used must be very pure. The older methods of pro-
duction were difficult and expensive, but in 1895
Ludwig Mond introduced a method by which the
pure metal can be obtained at a comparatively low
cost from the matte produced by the first smelting
operation. Mond discovered that metallic nickel
combines with carbon monoxide when heated to
80 deg. C. in an atmosphere of that gas, yielding
a volatile compound, nickel carbonyl. The matte is
roasted and then reduced at 400 deg. C. by
producer gas. The reduced metal is then exposed
at 80 deg. C. in a " volatiliser " to the action of
carbon monoxide. The gas issuing from the volatiliser
containing the nickel carbonyl is passed through
vessels heated to 180 deg. C., where the nickel is
deposited in the pure state. The carbon monoxide
is obtained from flue gases by passing first through
boiling potassium carbonate solution and then over
hot coke. The carbon monoxide obtained by the
decomposition of the nickel carbonyl at 180 deg. C.
is also used over again. This brief survey shows how

TO CHEMICAL SCIENCE 15

Mond's scientific discovery and its exploitation has
had its effect on very diverse industries.

Sodium. — Metallic sodium was first obtained by Sir
Humphry Davy, in 1807, by the electrolysis of caustic
soda, but no attempt was then made to manufacture
sodium on the large scale by that process. Up to 1891
it was produced by carbon reduction methods. The
method of Brunner, improved by Deville, consisted in
igniting a mixture of sodium carbonate and charcoal ;
but this process was very wasteful and expensive,
and the price of sodium was consequently high.
In 1886 Castner employed caustic soda instead of
sodium carbonate, and this improvement, the outcome
of scientific research, effected substantial decrease in
the cost of production. In 1891 the old process was
entirely abandoned and replaced by Castner's electro-
lytic method, founded on Davy's discovery and
developed in the laboratory, by which fused caustic
soda was electrolysed in an iron vessel under special
precautions for even heating and the maintenance of
a constant temperature. The method was cleaner
and more efficient, and as a result sodium became really
a commercial product, thousands of tons being ren-
dered available annually for the preparation of sodium
cyanide for gold extraction, under the MacArthur-
Forrest process for dealing with low grade ores and
sand and slime tailings.

Aluminium — so much valued for its lightness,
strength, and unalterability in air — has a history
resembling that of sodium. It was first isolated in the
pure state in 1827 by Wohler by fusing the chloride
of the metal with potassium in a closed crucible, and
again by the same chemist by passing the vapour of
aluminium chloride over potassium. In 1854 Bunsen
used the method of electrolysis of the fused chloride,
and Deville applied the method of Wohler in attempts
to manufacture the metal on a large scale using
sodium instead of potassium. Samples of Deville's pro-
ducts were shown in ingots at the Paris Exhibition of
1855, where they occupied a prominent position, care-
fully guarded by gendarmes, only a few visitors being
allowed to handle the exhibit, which was regarded as

16 WHAT INDUSTRY OWES

a great curiosity. This was an incentive to further
research, with the result that a short time later the
large scale manufacture was established at Alais on
the Loire. The use of sodium, then itself a costly
metal, was only one item in the heavy expense
involved. The method held its own for some years,
but in 1887 Bernard Freres, of Paris, reverting
to the method of Bunsen, founded their electro-
lytic process, using a mixture of cryolite and
common salt as the electrolyte. Before 1887
aluminum was sold at £3 per pound. Now it can be made
at very low cost, where power is cheap, to be sold at
little more than a shilling per pound. The method
whereby a solution of oxide of aluminium in fused
cryolite is kept in the molten state, and decomposed,
by an electric current, yields a metal of over 99 per
cent, purity compared with the' 97 to 98 per cent,
metal from the older process. The expenditure of
electrical energy is high, and in the light of our
present knowledge it appears futile to endea-
vour to reduce it. When aluminium is used in
the thermite process, an enormous quantity of energy
is evolved in the form of heat, producing a very high
temperature, the aluminium being converted into the
oxide. To win back the metal from the oxide an
equal amount of energy has to be put back, thus
accounting for the quantity of energy absorbed in
the preparation of the metal.

Magnesium was first isolated by Davy. Ib owes its
method of preparation and present-day uses solely to
scientific investigation. It is manufactured by a pro-
cess similar to that used for aluminium, by the electro-
lysis of fused anhydrous carnallite, a double chloride of
magnesium and potassium. The " magnalium "
alloys of aluminium and magnesium are lighter than
the former metal, give very good castings, and are
as strong as brass and bronze. The use of magnesium
in flashlight photography is well known.

Molybdenum and Tungsten, like aluminium and
magnesium, are children of science. Both are used
for making special steels, and tungsten is also formed

TO CHEMICAL SCIENCE 17

into filaments for incandescent electric lamps, its
efficiency in this role being very great.

Chromium, which was discovered by Vauquelin in
1797, and is much used in the manufacture of special
steels, has a very high melting point, and on that
account cannot be prepared in a fused state by
ordinary methods. The metal was isolated by
Deville by heating chromium oxide and sugar char-
coal in a lime crucible ; and by Wohler by heating
the chloride with metallic zinc under a layer of
sodium chloride, and subsequently removing the
zinc by treatment with nitric acid, the chromium
being thereby obtained in the form of a grey powder ;
but these and similar methods could not be adopted
economically on a commercial scale. In 1893
Moissan published the method whereby a mixture
of chromium oxide and carbon is heated to the high
temperature of the electric furnace, giving a product
containing large quantities of carbon from which it
can be freed only by difficult and expensive processes.
Ferrochrome, however, an alloy of iron containing 60
to 70 per cent, of chromium, is manufactured on a
large scale by the thermite process. Chromite, an
ore of chromium and iron, is finely crushed and well
mixed with aluminium dust. The mixture is ignited
with the aid of burning magnesium. The aluminium
reduces the oxides of iron and chromium with evolu-
tion of great heat, and consequent production of a
temperature sufficiently high to fuse the ferrochrome,
the alloy being thus produced in a compact and
homogeneous condition. Chromium metal of over
99 . 5 per cent, purity can be obtained by the thermite
process, the principal impurities being small quanti-
ties of iron and silicon. The thermite process is used
when freedom from carbon is desired, that of Moissan
being applicable when the presence of a certain
quantity of carbon is not objectionable.

Thorium, discovered by Berzelius in 1828, is
interesting scientifically by reason of its radioactivity.
It has found no useful application as a metal, but its
oxide, thoria, has proved invaluable to the gas
industry, being used for the manufacture of incan-

18 WHAT INDUSTRY OWES

descent mantles, of which the world's production is
estimated at over 400,000,000 annually. Thoria,
when heated directly in a flame, possesses the property
of converting heat energy into light. Research was
therefore directed to the utilisation of this property,
the evolution of the modern gas mantle being the
result of purely scientific investigations, requiring
great skill and patience. Not the least difficult pro-
blem to be solved was the production of thoria in
the necessary state of purity. In the early history
of the manufacture of the mantles, the known sources
of thoria were not numerous, although the available
ores were rich, and presented little difficulty in treat-
ment, but the discovery of large deposits of monazite
sand in South America stimulated the industry by
considerably diminishing the cost of the materials
employed. For a time, while the value of the sand
remained unrecognised by the States wherein it was
found, the sand was shipped to Europe as ballast — an
illustration of the advantages to be gained from
scientific investigation into natural resources. How-
ever, that is another story ! Monazite is a complex
mineral consisting of the phosphates of thorium and
the metals of the rare earths, occurring mixed with
other minerals as a sand. To obtain pure thoria
from this ore a protracted treatment . is necessary,
involving concentration by tables and by magnetic
separation, followed by fractional precipitation of
the oxides from solution. The thoria appears on the
market as nitrate. In the manufacture of mantles
a cotton framework, supported on an asbestos collar,
is soaked with a solution of the nitrate and dried ; the
cotton is burned away, and the resultant oxide is
hardened by further heating, and stiffened by dipping
into collodion, which in turn is removed by burning
when the mantle is placed in position ready for use.
It was found that the presence of about one per cent, of
cerium oxide in the mantle increased to a maximum
the transformation of heat energy into light, whereas
a marked diminution of luminosity was observed
when the quantity of cerium oxide was increased or
diminished. For this reason the equivalent of one

TO CHEMICAL SCIENCE 19

per cent, of cerium oxide is added to the solution of
thorium nitrate. The credit for practically the whole
of the scientific work underlying the industry is due
to Auer von Welsbach.

Vanadium, discovered in 1830 by Sefstrom, in the
refinery slag of the iron ore of Taberg, in Sweden, is
of increasing service to the maker of special steels.
In effect 0 . 2 per cent, is equivalent to 3 to 4 per cent,
of nickel, and experience tends to show that it imparts
to steel the power of resisting changes caused by
vibration, a most valuable property from the engi-
neer's point of view. It is mainly used as an alloy,
ferrovanadium, prepared by the thermite process.
It is worthy of note, as affording an instance of the
utilisation of " waste," that the mixture of metals
obtained by reducing the rare earth oxides forming
the residue of monazite after the extraction of thoria
is employed, in the place of aluminium, to produce
pure vanadium by a method resembling the thermite
process.

THE NOBLE METALS.

Gold. — In the recovery of gold large quantities
of metal were previously thrown away in tailings,
owing to the fact that amalgamation left a certain
amount unextracted from the ore. The Plattner
chlorine method and the Mac Arthur -Forrest cyanide
process have now rendered the tailing metal
available. The Plattner method, which is also used
in the treatment of auriferous pyrites, depends on the
action of chlorine gas on the roasted ore, the chloride
produced being subsequently leached out with water.
The gold is then precipitated by treating the solution
with some suitable material, such as ferrous sulphate,
charcoal, sulphuretted hydrogen, sulphide of iron, or
sulphide of copper. The MacArthur-Forrest pro-
cess, also founded on the study of the chemical
properties of gold, consists in the treatment of the
sand or slime tailings from the amalgamation
process, or, in some cases, a very low grade ore,
with a dilute solution, not more than 0.3 per cent.,
of potassium or sodium cyanide, and the subsequent

20 WHAT INDUSTRY OWES

precipitation of the dissolved gold by means of zinc
shavings. The zinc is removed by distillation from
graphite retorts, or sometimes by dissolution in
sulphuric acid, the latter method yielding a somewhat
richer bullion. In a method introduced by Tavener,
the zinc -gold precipitate is mixed with litharge, saw-
dust and assay slags, and melted in a reverberatory,
the resultant lead bullion being subsequently cupelled
for recovery of the gold. In another method,
devised by Siemens and Halske, the gold is precipi-
tated from the cyanide solution by electrolysis, using
iron anodes and lead cathodes and recovering the
gold by cupelling the cathodes.

In the separation of gold from silver, nitric acid
was at one time universally employed, but in 1802
D'Arcet utilised the fact, discovered in 1753 by
Scheele, that concentrated sulphuric acid was equally
suitable for the purpose. This constituted an improve-
ment of considerable value, effecting a saving both of
cost and time, and it must be remembered that in this
connection " time is money," for gold brings interest.
The Platinum Group. — The metals of the plati-
num group are among the most valuable acqui-
sitions of civilised man, and their availability is
entirely due to chemists, among whom may be
mentioned Achard, Janetty, Knight, Wollaston,
Deville, and the firm of Johnson, Matthey and Co.
Platinum itself is easily worked by the oxy -hydrogen
flame method of Hare, modified and improved by
Deville and Debray, and is useful for many purposes
in which special resistant properties are essential,
such as for vessels employed in analytical chemistry,
for stills for the concentration of chamber acid,
for standard weights and measures, for electrical
leads fused into glass, as a catalyst in the contact
process for making sulphuric acid, as a photographic
medium, and for mounting jewellery.

Other members of the group are iridium, discovered
by Tennant in 1804, used in combination with plati-
num in the construction of pyrometers, and as pure
metal for tipping gold pens ; osmium, discovered by
Descotils in 1803, and by Tennant in 1804, used in the

TO CHEMICAL SCIENCE 21

preparation of metallic filaments of electric lamps,
and combined with iridium for tipping gold pens and
for the bearings of the mariner's compass ; palladium
discovered by Wollaston in 1803, employed by
dentists and jewellers ; and rhodium, discovered by
Wollaston in 1804, used in the manufacture of certain
forms of chemical apparatus.

NOTE (p. 12). — An alloy is termed eutectic when it is the
most fusible of the alloys of two metals, the melting
point being lower than that of either of the two
metals of which it is composed. On cooling from the
molten state it deposits a solid having the same com-
position as that of the molten mixture. For example,
the melting points of lead and tin are 328 and 232 deg.
Cent, respectively, but an alloy of these metals containing
31 per cent, of lead melts at 180 deg. Cent., any variation
from this composition entailing a rise in the melting point.
If an alloy richer in either constituent be slowly cooled, the
metal present in excess of the above composition separates
in the solid state as cooling progresses, until the composi-
tion of the remaining fluid is that of the eutectic, which
then separates in the solid state. In the case of alloys of
gold and silver there is no eutectic, the melting points
rising regularly from that of silver to that of gold.

c 2

22 WHAT INDUSTRY OWES

CHAPTER II.
HEAVY CHEMICALS AND ALKALI.

IN reviewing the progress made in chemical
industries proper, we are met with such a condition
of interdependence that it is impossible to avoid over-
lapping of the subjects to be treated. Moreover,
the steps made in the improvement and development
of processes, and in the evolution of new products,
are so numerous that space will not allow of a com-
prehensive scheme. Indeed, the library of the Patent-
office, one of the best for technological literature,
cannot contain all that is due to chemists, nor disclose
to which chemists the credit should be given for many
important advances. We must, perforce, recognise,
however, that science is the basis of all substantial
development in the industrial arts, and that the rule
of thumb is dead.

It has often been said that the prosperity of a
country might be gauged by its output of sul-
phuric acid ; yet it is remarkable how little
the man in the street realises the importance of
this substance. He has a vague idea that it is
the same thing as, or in some way akin to, vitriol,
which he knows is destructive to clothing, and is
associated with charges of criminal assault wherein
some evil-minded wretch has employed it as the
agency for disfiguring the features of a fellow-being.
If he were told that, even in normal times, the world's
output exceeded 5,000,000 tons he would marvel
how it is that he never sees, and probably never
has seen, the substance. The reason for this is,
that the consumer of large quantities of the acid
generally finds it convenient and economical to make
it himself. Thus, although large quantities are
produced and consumed there is only a comparatively

TO CHEMICAL SCIENCE 23

small quantity on the market. When we come
to consider its technical applications we find there
is scarcely an industry that does not depend directly
or indirectly on its use. It is employed in the
manufacture of superphosphate fertiliser, as a solvent
for metals — for example, in the parting of gold
and silver — as a constituent of dipping baths for
cleansing brass and bronze castings, and is used
in the electrolytic refining of copper. Ammonia
from the coal -tar and shale oil industries is absorbed
in sulphuric acid, the resultant sulphate being exten-
sively employed as a fertiliser. (The world's
production of ammonium sulphate probably exceeds
1,500,000 tons.) The refining of oils, fats, and waxes,
and of tar and petroleum products is also carried out
with the aid of sulphuric acid, and it is extensively
used in the manufacture and sulphonation of dyestuffs.
Nitric acid, guncotton — and therefore, cordite, collo-
dion and celluloid — nitroglycerine for dynamite,
phenol, picric acid, T.N.T., ether, saccharine, many
drugs, liquid glue, alum, persulphates, and a host
of other useful substances are produced by processes
in which sulphuric acid is an essential factor. It
must be remembered, moreover, that many such
substances are but the starting materials for the
manufacture of other products ; so that regarded
as a mediaeval ancestor, sulphuric acid can boast
a genealogical tree of no mean order with many
a noble family and innumerable progeny. Nor
must we forget that not the least important of its uses
is in the laboratory, where also many of its relations
are to be found among the reagents required by
the chemist. Discovered in the fifteenth century
by the alchemists, it was made until about 1770
by two methods : (i. ) by the distillation of crystallised
sulphate of iron prepared by roasting iron pyrites ;
and (ii.) by the combustion of sulphur in a bell jar
over water. Of these methods, the first survived
until recently, being the only method available
for making fuming acid, the second being the fore-
runner of the modern lead chamber process. Both
are attributed to Basil Valentine (15th century),

24 WHAT INDUSTRY OWES

who next discovered that by the addition of antimony
sulphide and nitre, the yield could be substantially
increased. Up to about the middle of the eighteenth
century the principal workers at the problem had
been alchemists — monks and others — the pioneers
of modern science ; and the only process that could
be called a manufacture was that with sulphate of
iron as starting material. At about that time,
however, two French chemists, Lefevre and Lemery,
produced a method, used on a small manufacturing
scale, wherein a mixture of sulphur and nitre, without
antimony sulphide, was burned under a bell-jar
over water. About 1770 Dr. Roebuck, of Birmingham,
first employed lead chambers containing water,
instead of glass bell- jars, thus considerably enlarging
the scale of operations. The procedure was the same
as in the bell-jar method. The floor of the lead
chamber was covered with a few inches of water, and
a kind of stand in the middle of the floor carried the
charge of sulphur and nitre. The charge was ignited
aid the door was immediately closed and luted
securely. The operations of charging, burning, and
discharging were repeated until the acid attained
the maximum strength compatible with the safety
of the lead, when the liquid was drawn off and concen-
trated. This was a discontinuous process, but in
principle it was the modern continuous method
in a primitive state. The transition from the one
to the other was gradual, the outcome of much
thought and research. A step towards continuity
of working was obtained by burning the sulphur
in a separate vessel, and leading into the lead chamber
the products of combustion, mixed with excess of
air, and the fumes evolved on treating nitre with
sulphuric acid. • Complete continuity and greater
speed of working was obtained when Kestner intro-
duced the injection of steam into the chamber.
The rationale of the process was explained by chemists
by the aid of various theories, but a fact of great
importance was clearly recognised, viz., that the
nitric acid was merely a carrier of the atmospheric
oxygen, and needed to be used only in small quantity.

TO CHEMICAL SCIENCE 25

Next it was found that the spent gas issuing from
the chamber gave rise, in contact with atmospheric
air, to oxidised nitrogen compounds that could be
used again in the chamber. Nitre being the most
expensive raw material, many efforts were directed
towards the recovery of these gases and their return
to the circuit. The most successful of these and
the one universally adopted was due to the great
French chemist, Gay-Lussac, the friendly rival
in many fields of work of our own Sir Humphry
Davy. The gases issuing from the chamber were
conducted up a tower of lead or stone, packed with
coke, down which a slow stream of strong sulphuric
acid was caused to trickle. The acid issuing from
the foot of the tower contained all the oxides of
nitrogen present in the chamber gas. This acid
was then conveyed to the top of another tower,
invented by Glover, and in penetrating the length
of the tower was met by the hot gases from the sulphur
burners and deprived of its nitrogen oxides which
were returned to the chamber with the ingoing gases,
to play again their part in the transformation. The
acid drawn from the chamber was concentrated
in glass retorts, platinum being afterwards substituted
for glass. Although the initial outlay on platinum
was very considerable, the loss by breakage was
avoided.

This short history of sulphuric acid manufacture
should serve to illustrate how science has been the
primary factor in its evolution. The subject of the
use of iron pyrites as a source of sulphur will be
deferred until we consider the alkali industry.

We must digress for a moment to refer to another
industry in order to indicate the origin of the contact
process. About thirty-six years ago, various methods
were discovered for the preparation of artificial
indigo, and endeavours were made to apply the best
of these on a commercial scale to compete with
the natural product. The starting material in the
most successful processes was naphthalene, at one
time regarded by the tar distiller as a nuisance
but now recognised as a valuable product. In the

26 WHAT INDUSTRY OWES

first stage of the synthesis of indigo, naphthalene
is converted by oxidation into phthalic acid. This
was originally effected by chlorination and subsequent
oxidation with nitric acid ; but the process was too
expensive for successful application on the large
scale. Next the discovery was made that the direct
oxidation of naphthalene could easily be effected
by fuming sulphuric acid in the presence of mercuric
sulphate. At that time, however, the only method
of preparing the fuming acid was the Nordhausen
process, by heating sulphate of iron, and the product
was too highly priced for the prospective indigo
manufacturer. Cheap fuming acid was, therefore,
a necessity. It had been known to chemists for
a half a century or more that sulphuric acid anhydride
could be made from sulphur dioxide and oxygen
by passing the mixed gases over heated finely divided
platinum, and it was found that by absorbing the
anhydride in concentrated sulphuric acid the product
was the fuming acid. In the laboratory, where
the materials employed were comparatively pure,
the method left nothing to be desired, but on the
works where, for reasons of economy, materials of
a crude nature, such as pyrites, had to be used,
further obstacles were encountered. The process
would go briskly for a time and then it would slow
up and finally stop altogether. The platinum had
lost its efficiency and the chemists were confronted
with another difficulty. They are accustomed to
this sort of thing and enjoy it. Indeed, some are
almost disappointed when results come too easily
and there is a lull in the chase. They found that
the platinum had been " poisoned " by arsenic,
antimony and mercury from the pyrites ; they there-
fore devised the means for washing these oxides
out of the sulphur dioxide, and with this purified
material their labours were crowned with success.
The manufacture of fuming acid and ordinary con-
centrated sulphuric acid by the " contact process "
is a fast growing industry, and will doubtless in
time largely replace the lead chamber process by
reason of its efficiency and cleanliness, and the

TO CHEMICAL SCIENCE 27

compactness of the plant required. Moreover, it
is convenient and economical to be able to produce
acid of any strength without the expense involved
in the concentration necessary in the older process.
On account of the diversity of its uses sulphuric
acid is required in varying conditions of purity and
concentration, from the chamber acid and B.O.V.
of commerce to the redistilled acid required in
analytical operations. Researches have been con-
ducted with a view to the elimination of impurities,
and especially of arsenic. The contact process
satisfies this requirement, but acid from the chamber
process may contain this impurity in considerable
quantity. The use of sulphur instead of pyrites
results in the production of arsenic free acid,
but chamber acid already containing arsenic can
be freed from this impurity by precipitating it as
sulphide with sulphuretted hydrogen before con-
centrating the acid. Another method has been
suggested whereby dry hydrogen chloride is passed
through strong sulphuric acid heated above 150 deg.
Cent., when the arsenic is entirely removed as
trichloride, but this has not received extensive
application. Both these methods are founded on
everyday laboratory experience.

One hundred and thirty years ago, as a result
of the French revolutionary wars, France was cut
off from the supply of alkali and an appeal was
made to chemists *' to render vain the efforts
and hatred of despots," and, incidentally, to win
a prize by producing a process for making alkali.
This offer resulted, in 1794, in the submission to the
Convention of more than a dozen processes, some of
which had already been in operation, including that
of the apothecary Leblanc, which was accepted. In
1814 it was introduced into England, and in 1823 the
first works of importance were established near Liver-
pool by James Muspratt. In the Leblanc ^process
sulphuric acid is employed for the decomposition of
common salt. The resulting sulphate is heated with
chalk and small coal in a reverberatory furnace ; the
mass is lixiviated with cold or tepid water; the

28 WHAT INDUSTRY OWES

solution is evaporated to dryness and the product
is calcined with sawdust in a suitable furnace. The
soda-ash or crude sodium carbonate thus obtained
is dissolved in hot water, treated with lime, to obtain
caustic soda, to be used by the soap and candlemakers,
or the solution of the carbonate in water is filtered
and crystallised to give washing soda. We have
indicated that the substances required for the
process were salt, coal, chalk, and sulphuric acid.
The first three were to be found in abundance in
Nature, but up to that time sulphuric acid was
comparatively expensive, and the demand for it
was not such as to warrant its extensive manufacture.
It was to meet the requirements of the Leblanc
process that the output of the acid was enormously
increased, and although the process has now been
superseded by that of Solvay, as far as carbonate is
concerned, and is being replaced by electrolytic
methods for making caustic soda, it must not be over-
looked that we owe to Leblanc, indirectly, our cheap
sulphuric acid, and therefore a thousand and one
other cheap commodities.

To return to the sodium carbonate, we may well
ask how many good citizens and washerwomen
who use it have any idea that a chemist has anything
to do with its production ? Possibly they think
it exists naturally in the condition supplied ; more
probably still, they think nothing at all about it
so long as it serves its purpose.

If the crystals are re -dissolved in water, filtered
and re -crystallised, we have the pure sodium carbonate
used in pharmacy. By passing carbonic acid gas
into a cold solution of the carbonate, and by placing
the crystals in an atmosphere of the gas, we obtain
the bi-carbonate which is also employed in pharmacy,
and as an ingredient of baking powders.

The aim of the technologist is to avoid waste
of any kind, either of matter or energy, the cost
of a product to the consumer being in a great degree
dependent on the efficient utilisation both of raw
material and of by-products. The alkali industry
furnishes many examples. In the Leblanc process,

TO CHEMICAL SCIENCE 29

among the main products are soda ash, which we have
shown is purified to obtain soda crystals, and " alkali
waste," of which about 30 per cent, is calcium sulphide
containing the sulphur from the original sulphuric
acid. The waste was long regarded as useless, but is
now treated for the recovery of the sulphur. Many
attempts have been made to recover this sulphur in
a useful form, but it was only comparatively recently
that the Chance-Glaus method was introduced,
whereby the alkali waste is made into a paste with
water, and acted on by carbonic acid gas — lime -kiln
gas and furnace gas being used for the purpose.
The sulphur of the calcium sulphide is converted
thereby into sulphuretted hydrogen, which is mixed
with a carefully regulated supply of air and burned
in contact with hot ferric oxide in Claus kilns. The
hydrogen burns off and the sulphur is deposited
in a practically pure state — a very valuable product.
When, in 1839, an export embargo was placed
on Sicilian sulphur, the alkali manufacturers, having
to look elsewhere for their supply, found it in iron
pyrites. The residue of oxide of iron from the pyrites
burners was not used as a source of iron, as it retained
enough sulphur to render it unfit for this purpose.
The pyrites used also contained a certain amount
of copper, averaging 3 per cent., as well as small
quantities of gold and silver. Until 1865 these
residues were dumped as useless, but in that year
Henderson introduced a method whereby the whole
of the copper could be recovered by roasting the
residues with common salt, lixiviating the mass
with water, and precipitating the copper from the
resultant solution by means of scrap iron. In 1870,
a method was devised by Claudet to recover the gold
and silver occurring in the residues. The copper
solution formed on lixiviation in Henderson's process
contains the gold and silver as chlorides dissolved
in the excess of common salt. By Claudet' s method
the gold and silver are precipitated by the addition
of zinc iodide to this solution, the precipitated
iodides being subsequently reduced with metallic
zinc in the presence of hydrochloric acid.

30 WHAT INDUSTRY OWES

Thus by the application of science the revenue
of the sulphuric acid and alkali maker increased,
the price of his products is lowered, and valuable
materials are rescued from the dump. More
than 500,000 tons of pyrites are burned annually
in England for the sake of the sulphur. The residue
from this yields on extraction about 15,000 tons of
copper, 400,000 ounces of silver, and 2000 ounces
of gold, the final residue being transformed into a
valuable source of iron.

In connection with this subject can be related one
of the most interesting episodes in indurstrial history.
For some time after the inception of the Leblanc
process, the hydrochloric acid produced was allowed
to escape into the air, as no use had been found for
it. Metal ware was corroded, and vegetable growth
destroyed for miles around the works and the nuisance
gave rise to much litigation. The obvious remedy
was to absorb the noxious gas, and to effect this
many of the larger works adopted in 1836 a method
devised by Gossage. It was not until 1863, however,
that the Alkali Act was passed, enacting that not
less than 95 per cent, of the hydrochloric acid gas
produced should be absorbed, a regulation rendered
more stringent by subsequent legislation. Some idea
of the quantity concerned may be gathered from the
fact that at that time about 3000 tons of the gas
were produced annually in England. To hark
back to the earlier days when the makers first laid
out capital to provide means for the absorption
of the gas, they naturally wondered what return
they could get for it. This was forthcoming in the
increased demand for chlorine to make bleaching
powder to be used for bleaching raw cotton and
materials for paper making. Chlorine, set free from
the hydrochloric acid by the action of manganese
dioxide, was led over slaked lime, and the product
was bleaching powder. The same gas passed into
cold solutions of caustic soda and potash formed
useful bleaching solutions, while if boiling potash was
used the product was chlorate of potash, a valuable
substance in pyrotechny, in the manufacture of

TO CHEMICAL SCIENCE 31

certain explosives, and in medicine. The manganese
dioxide employed to liberate the chlorine was
converted into a useless product, which was a loss
to the manufacturer. Science again came to his
aid in the discovery of Weldon, that the action of
lime and air on the manganese waste resulted in
the regeneration of an oxygenated body which might
be used in exactly the same way as the original
dioxide. Thus, by this process the dioxide acts
merely as an agent in liberating the chlorine, and
can be used over and over again, atmospheric oxygen
being the real factor concerned in the change.

The Deacon process for the manufacture of chlorine
from hydrochloric acid is a scientific method, whereby
hydrochloric acid gas and air are passed over hot
brick-work impregnated with copper salts. The
products are chlorine gas and water, the copper
salts acting merely as carriers of oxygen. The only
losses are that of the hydrogen of the hydrochloric
acid and the oxygen of the air.

The two processes last considered, together with
the lead chamber sulphuric acid process, being among
the earliest of this type to be employed, serve to
show how the chemist is teaching the manufacturer
to use catalytic* and contact agents to effect certain
chemical changes — more especially those involving
oxidation. Such processes are numerous and success-
ful at the present day, effecting wonderful economies,
needing only simple and compact plant, and bringing
about the required changes in the cleanest and least
wasteful manner.

The Ammonia-Soda or Solvay Process. — In this
process sodium bicarbonate is produced by the action
of carbon dioxide on an ammoniacal solution of
common salt. The bicarbonate crystallises out,
leaving ammonium chloride in solution, the ammonia
being recovered by heating the solution with lime,
and used over again. The lime employed is burnt at
the works, the lime-kiln gas being the source of some
of the carbon dioxide, while the gas expelled from
the bicarbonate by calcination to make normal
carbonate provides the remainder. The salt solution

32 WHAT INDUSTRY OWES

used — brine pumped up from brine pits — is subjected
to preliminary purification. Magnesium salts are
precipitated by the addition of lime, the lime salts
being afterwards removed by adding the necessary
quantity of sodium carbonate or ammonia liquor
containing ammonium carbonate. After settling the
solution is drawn off and is then ready for use.

This process, which was patented by Dyer and
Hemming in 1838, though simple from the chemists'
point of view, presented considerable mechanical
difficulties. The first attempt to utilise the reaction
on the large scale was made by Schloessing and
Holland in 1855, at a works near Paris. At the end
of two years, however, the difficulties remained
unsolved and the project was abandoned. In 1863,
Solvay, who had taken out a patent two years earlier,
erected an experimental factory near Brussels ; as the
result of perseverance, he secured the success of the
process, and in 1872 established a far larger works
near Nancy. Two years later the process was intro-
duced into this country, under the Solvay patents, by
Mond, continued by Brunner, Mond and Co., Limited,
at Northwich, where for the first time natural brine
was employed and other improvements were adopted.
In 1895 the production by the Solvay process exceeded
that by the Leblanc process, over which it has several
incontestable advantages. The use of brine from the
pits effected a great economy that could not be
shared by the older process. The Solvay process is
cleaner and the product purer. There is, of course,
no sulphur to be recovered, but the chlorine from the
salt is frequently wasted as calcium chloride. As an
improvement in the process, magnesia is now used in
some cases to liberate the ammonia from the mother
liquor, the resulting magnesium chloride being
subsequently decomposed by heat into magnesia (to
be used over again) and hydrochloric acid.

Before leaving the subject of alkali we must note
that electrolytic methods of manufacture form an
increasingly important branch of the industry.
Solutions of common salt are electrolysed in a special
vessel, of which the Castner rocking cell is a type,

TO CHEMICAL SCIENCE 33

and caustic soda and chlorine, both marketable
products, are obtained in separate compartments.
When the process is modified so that the chlorine
is allowed to come into contact with the soda solution,
chlorate or hypochlorite may be produced by
employing hot or cold solutions respectively. The
value of chlorates has already been indicated ;
sodium hypochlorite is used as a bleaching agent and
as an ingredient in one step of the manufacture
of indigo.

34 WHAT INDUSTRY OWES

CHAPTER III.
COAL AND COAL GAS.

WE live in an age of coal and iron. The great war
is waged very much with coal — or rather, what we
get from it — and iron ; on the manipulation of these
substances by engineers and chemists the produc-
tion of munitions of war largely depends. Some of
the coal we use to smelt the iron ore and to fashion
the metal into convenient form for our use. When
we have won the iron we can use it, scrap it, and use
it again many times, but the coal once used is
destroyed for all time. The world's annual production
of this valuable mineral probably exceeds 1 ,335,000,000
short tons, and it is utilised (1) as a domestic fuel,
with which we are all familiar ; (2) as a source of
mechanical and electrical power through the agency
of steam ; . (3) as a reducing agent in certain chemical
and metallurgical operations ; (4) for the production
of coke in ovens ; (5) as a source of gas for illumi-
nating and heating purposes and of many other
valuable products.

The influence of scientific thought on the second of
these uses is well known, though perhaps its extent
is not always clearly recognised. For more than
half-a-century, steam engines were designed to meet
the requirements of coal as a fuel. It was the bed-
rock of the art of engineering. The abundance of
coal gave impetus to invention and the modern steam
engine is the result of the co-operation of physicists,
chemists and mathematicians, with the practical engi-
neer. As a reducing agent in applied chemistry and
metallurgy coal itself is less used than coke. The
ironmaster is a great consumer of coke-oven coke as
a reducing agent, and it has found an important use
in the manufacture of water gas and producer gas.

TO CHEMICAL SCIENCE 35

The first, a mixture rich in hydrogen and carbon
monoxide, is obtained by passing steam through red
hot coke ; the second, a mixture of carbon monoxide
and atmospheric nitrogen is formed by the similar
treatment of carbon dioxide produced by the com-
bustion of coke. Although water gas has a much
greater calorific power than producer gas, it is not
economical to make it alone, because the reaction
between the coke and the steam is endothermic and
the coke chamber must be heated externally to main-
tain the requisite temperature. Dowson gas and
Mond gas are mixtures intermediate between water
gas and producer gas, made by combining the two
processes and passing a mixture of steam and air over
the red hot coke. When the coke cools during the
operation the temperature is raised again by cutting
off the steam and allowing air alone to pass through.
The use of these gases for heating purposes is very
economical and finds extensive application.

As one of the most striking examples of the influence
of science in industry, coal gas manufacture demands
consideration in somewhat fuller detail, treating of
the distillation of a highly complex body from which
the chemist has obtained a vast variety of useful
substances. The history is interesting also as an
illustration of a development of philosophical experi-
ment. In the seventeenth century the pursuit of
science was the hobby of many men of learning and
particularly of the clergy. The Rev. Dr. Clayton,
rector of Crofton, distilled gas from coal and collected
it in a bladder ; the fact being communicated, in
1688, to the Royal Society by Boyle. In 1750, Dr.
Watson, Bishop of Llandaff, not only distilled gas
but conveyed it in pipes from one place to another.
The credit, however, is given to an engineer, William
Murdock, for the first suggestion that coal gas should
be generally employed for lighting purposes. In
1792 he conveyed it from iron retorts through tinned
iron and copper pipes, tapped at intervals, a distance
of 70ft., lighting his house and offices. His early
experiments were carried out at Redruth, and six
years later he lighted the Soho foundry of Boulton and

36 WHAT INDUSTRY OWES

Watt, at Birmingham. In 1799, Le Bon commenced
similar experiments in France. In 1807, after one
side of Pall Mall had been lighted by Winsor, a Bill
was promoted in Parliament to authorise a company
for the supply of gas in London ; in 1810 an Act was
passed for this purpose, and two years later a charter of
incorporation was granted to the Gas Light and Coke
Company, still by far the largest gas undertaking in
the world. Westminster Bridge and the Houses of
Parliament were lighted in 1813, and from that time
the practice of gas lighting spread rapidly in all
civilised countries.

The gas industry is essentially chemical, though it
was formerly entirely controlled by engineers. There
was a time when gas engineers were disinclined to
show much appreciation of the chemical aspects of
the industry. In some works the chemists, if any
were employed, were exclusively relegated to the
laboratory for routine testing without any opportunity
of acquiring experience in large scale operations. The
remuneration and prospects of such chemists were so
poor that few worthy of the name could be induced
to remain long in such employment. In many
important works, however, chemists acquired the
essential knowledge of the engineering side of the
industry, led the way in the introduction of improved
methods and effected developments of a far-reaching
character, especially in the profitable utilisation of
material hitherto regarded as waste and the manu-
facture of new products.

Enormous quantities of coal are subjected to
destructive distillation to obtain its numerous and
valuable decomposition products, of which gas, tar,
ammonia and its salts, coke, and gas carbon are made
on a huge scale and all consumed. The gas provides
light and heat, whilst the tar, useful in many ways in
the crude state, gives, when distilled, benzene, toluene,
solvent naphtha, carbolic acids, naphathalene, anthra-
cene, and many other substances, which in their turn
yield, in the hands of the technologist, a host of further
useful bodies, including explosives, dyes, disinfectants,
and drugs. Pitch, the residue of tar distillation, is

TO CHEMICAL SCIENCE 37

used largely in the manufacture of patent fuel and
provides excellent material in road making. Ammo-
nia is employed in medicine, in the laboratory, and in
cleaning cloth, and there are many uses for its salts,
especially the sulphate, a valuable fertiliser. Gas
carbon, a hard, compact substance, is used by electrical
engineers in the operation of arc lamps and fur-
naces, and as a fuel in making producer gas.

The purified coal-gas of commerce roughly consists
of — hydrogen about 50 per cent, by volume, and
marsh gas or carburetted hydrogen about 35 per cent.,
carbon monoxide 5 per cent., heavy hydrocarbons
5 per cent., and nitrogen 5 per cent. As it issues
from the hydraulic mains, which receive the vapour
from the ascension pipes from the retorts, it is not
at once ready for delivery to the consumer. Besides
its essential constituents, it contains substances
such as condensable hydrocarbons, ammonia, carbon
dioxide, carbon bisulphide, sulphuretted hydrogen,
cyanogen, and cyanides, some of which are of sufficient
value to pay for their extraction, all being undesirable
impurities on account of their reducing the heating
power of the gas or of the objectionable character
of the products of their combustion. These bodies
are therefore removed by condensation by cooling,
" scrubbing " with water, and by passing the gas
over suitable materials. The operation of scrubbing
with water or with aqueous liquors from the hydraulic
mains removes the ammonia and part of the carbon
dioxide. The gas then passes into a chamber
containing moist slaked lime, where cyanogen com-
pounds and the remainder of the carbon dioxide
are removed, the former in a state from which they
cannot be recovered. Their recovery from the gas,
however, can be effected, when desired, by a pre-
liminary treatment with oxide of iron before the
gas passes through the lime chambers.

After the lime treatment the gas is led over moist
oxide of iron, or Weldon mud, for absorption of
the sulphuretted hydrogen, the material when
spent being revivified by action of the air. The
gas next passes over sulphided lime — the substance

D 2

38 WHAT INDUSTRY OWES

formed by the action of sulphuretted hydrogen on
slaked lime — to eliminate carbon bisulphide, and,
finally, undergoes an extra check treatment with
oxide of iron, or Weldon mud, to remove any traces
of sulphuretted hydrogen taken up from the sulphided
lime. Subject to passing the prescribed tests for
illuminating and heating power, the gas now passes
to the holder — in ordinary parlance the gasometer —
and is ready for the public supply.

It is obvious that science is responsible for such
a process of purification. There is scope for chemistry,
physics, and mechanics in every step.

We have stated that the pipes from the retorts
convey the vapour to the hydraulic main, where it
is partially condensed, and the liquid thus condensing
forms two layers, coal tar and aqueous liquor. The
latter is uppermost, and contains ammonia and other
soluble bodies. The tar was for long the bugbear
of gas manufacture, its disposal being a difficult
problem, but now it is of such value that the industry
of tar distillation has grown to be of great importance.
It is distilled in large iron stills, the vapours evolved
from which are condensed, the distillate being
separated into fractions as follows : — First runnings
up to 105 deg. Cent. ; light oil from 105 to 210 deg.
Cent. ; carbolic oil from 210 to 240 deg. Cent. ; creosote
oil from 240 to 270 deg. Cent. ; anthracene oil from
270 up to the pitching point, this last temperature
being determined by the quality of pitch desired.
The first runnings form two layers in the receiver,
consisting of ammoniacal liquor and crude naphtha.
These are separated, the former being added to the
bulk of ammoniacal liquor, the latter being reserved
for subsequent treatment. The second or light oil
fraction, consisting mainly of hydrocarbons of the
benzene series, is first re-distilled, yielding first
runnings, which are added to the crude naphtha
from the original tar first runnings, and last runnings
which are worked up with the carbolic oil.

The crude naphtha is washed with caustic soda
solution to remove phenols in an easily recoverable
fonn ; then with strong sulphuric acid, which dis-

TO CHEMICAL SCIENCE 39

solves bases and unsaturated bodies, and carbonises
other impurities, forming substances of a heavy,
tarry nature, and finally another soda washing is
given to remove the residual sulphuric acid. The
spent sulphuric acid Is used in the ammonia plant
for the production of sulphate of ammonia. The
naphtha so far purified is next redistilled from an
iron still. Two fractions are collected — crude benzol
up to 140 deg. Cent., and solvent naphtha from 140
to 170 deg. Cent., the residue in the still being reserved
for addition to the carbolic oil. From the crude
benzol are obtained by further acid and alkali washing
and careful fractionation, forerunnings of benzol,
containing benzene, toluene, carbon bisulphide and
thiophenes, commercial and pure benzol and toluol,
and solvent naphtha. Benzols and toluols are used
by the dye manufacturers, and at the present day in
enormous quantities in the manufacture of explosives,
benzene being the starting point in one process
for making picric acid, toluene being the material
from which T.N.T. is made. Solvent naphtha is
used as a solvent for india-rubber, the higher boiling
portions containing naphthalene, forming a fuel for
naphtha lamps.

The carbolic oil is treated by cooling to separate
naphthalene, and subsequently washing with a
solution of caustic soda, which dissolves the carbolic
and cresylic acids. These acids are recovered by
neutralising the solution with sulphuric acid, when
crude carbolic acid and sodium sulphate are formed,
the former being subsequently worked up for pure
carbolic acid and cresylic acid, both used in the
manufacture of dyes, disinfectants, and explosives.
A modification of the above method is that known as
the West-Knight and Gall process, whereby the
oil is treated with a mixture of sodium sulphate
solution and lime for the production of sodium
" carbolate " and sulphate of lime. The solution
is worked up as before, the sodium sulphate being
utilised again for mixing with more lime. The
insoluble oil is either mixed with the light oil or is
worked up for naphthalene.

40 WHAT INDUSTRY OWES

Creosote oil is of value as a source of naphthalene,
and for preserving wood from the action of the
weather and destructive insects. Naphthalene, once
a waste product, is now used largely in the manufac-
ture of dyes, being the parent substance of artificial
indigo, as an insecticide, and in other minor roles.
Anthracene oil is the source of anthracene, a condensed
hydrocarbon of the benzene series, from which the
alizarin dyes are made.

TO CHEMICAL SCIENCE 41

CHAPTER IV.
DYES, EXPLOSIVES AND CELLULOSE.

THE invention of dyeing has been attributed to the
Phoenicians, probably because it is chronicled that
Solomon sent to Hiram of Tyre for " a man cunning
to work " inter alia " in purple and crimson and blue."
The Tyrian purple was derived from the throats of a
species of murex, a molluscous animal, a single drop
from each. Other dyes from animal substances
include sepia derived from the black secretion of the
cuttlefish, and cochineal which consists of dried female
cochineal insects, discovered by the Spaniards in
1518.

The importance of the dye industry is not so much
in the value of the dyes as in the vast interests of the
textile industry with which it is so intimately
associated. At a high estimate this country does not
use annually dyes to the value of £2,000,000, or, say,
less than Is. per head, presuming the use to be
confined to the British Isles ; but the various industries
affected exceed in annual value a sum of £200,000,000,
and the labour involved in dyeing and printing
processes is not far short of 2,000,000. Clearly then
we cannot afford to be dependent on other countries
for supplies of materials of this kind so long as we have
the power to produce them ourselves. It is well
known that the Government has now given active sup-
port to the industry ; and we may rejoice that British
Dyes, Limited, and other British dye concerns are
making good progress towards its firmer establishment.
Even before the outbreak of war, progress had been
made in certain directions towards successful com-
petition with the Germans, and since the war, by the
aid of science, discoveries have been made which, in
the view of the enemy producers, were calculated to

42 WHAT INDUSTRY OWES

defy our chemists for at least ten years. Compared
with the period occupied by the Germans in dis-
covering artificial indigo — about thirty-five years and
an expenditure of over £1,000,000 — the taunt may be
taken as a compliment ; but in two years from the
discovery of artificial indigo 426,100 out of 755,900
acres of plantations went out of cultivation. It was
first sold in 1897 and in the course of a few years drove
the natural dyestuff out of the markets of the world,
being only about one-third of the price, and the busi-
ness passed from India to Germany.

The history of the subject covering the consideration
of all the dyes known would fill volumes exceeding in
bulk the " Encyclopaedia Britannica." The number of
dyes revealed by science and the substances which
science can foretell with certainty would form dyes,
and the myriad derivatives of known colouring
matters, would run into many thousands, though
800 to 1000 should be more than sufficient for all
practical purposes.

The artificial dyes have several advantages over
natural products. The range of shade for any colour
can be extended and graded by the employment of
suitable materials in a manner that cannot be attained
by using the natural dyes ; the purity of artificial
dyes is much greater, and the total cost of production is
considerably less. On account of this superiority of
synthetic dyes, the cultivation of indigo and madder,
and the trade in cochineal have been almost completely
overshadowed. Both indigo and madder have been
investigated by scientific men, and the composition
and nature of the dyestuffs determined. Further
researches have led to the discovery of methods of
synthesis of these substances, not only interesting
from an academic point of view, but capable of holding
their own and beating their natural prototypes in
commercial competition. The use of cochineal has
been largely replaced by the discovery and utilisation
of azo-red dyes which imitate the colour very closely,
such, for example, as Bieberich scarlet. The most
important material used in the economical manu-
facture of indigo is naphthalene obtained from the

TO CHEMICAL SCIENCE 43

creosote oil fraction of the tar distiller by cooling,
washing the crystals produced with alkali and with
acid, and distilling or subliming the product. Other
ingredients are chloracetic acid and sodium hypo-
chlorite, the preparation of which provides one of the
numerous outlets for the elementary chlorine of the
alkali manufacturer. A short sketch of the method
of Heumann will not be out of place.

Naphthalene is converted into phthalic anhydride
by heating with sulphuric acid and mercuric sulphate.
The phthalic anhydride in turn is transformed into
phthalimide by heating under pressure with ammonia.
By the action of sodium hypochlorite on phthalimide,
anthranilic acid is produced and this substance, when
treated with chloracetic acid, yields phenyl glycine-
carboxylic acid, which by fusing with alkali, dissolving
the melt in water and passing a stream of air through
the solution, yields indigo blue. This complex series of
operations has met with complete commercial success.

Alizarin, the dyestuff contained in madder, is made
from anthracene, another coal tar product, by the
action of sodium bichromate and sulphuric acid to
form anthraquinone ; this is transformed by the action
of sulphuric acid into anthraquinone sulphonic acid,
the sodium salt of which when fused with soda and
a little potassium chlorate yields a compound of
alizarin containing sodium, from which alizarin itself
is made by the action of acid.

Bieberich scarlet, one of the naphthol azo dyes,
a very important group, is, like indigo, prepared from
naphthalene as starting material.

These three examples serve to show how the
laboratory and the factory have replaced the cultiva-
tion field. There are also thousands of new dyes
prepared from benzene, toluene, and carbolic acid, as
well as many others from naphthalene. The name
" coal tar dyes," however, is rather misleading to the
uninitiated, for it seems to imply that the dyes exist as
such in the tar and only need extraction. What is
meant, is that the raw materials are found in the tar
and need to be transformed before anything of the
nature of a dye can be produced.

44 WHAT INDUSTRY OWES

The recovery and utilisation of these tar products
in the manner indicated is a great achievement. The
first known coal tar colour mauveine was made from
aniline by Perkin in 1856, aniline having been
discovered by Unverdorben, thirty years earlier, by
distilling indigo.

Dyeing. — The processes of dyeing and calico
printing are definitely chemical and depend entirely
on scientific control. Dyes are transparent and the
effects they produce vary according to the light
reflected by the fibres of materials before they are
dyed. Obviously, therefore, black cannot be dyed,
and such colours as red, blue, and yellow can only
be dyed in the same hues, unless the material, as is
possible in the case of velvets and velveteens, be
previously bleached. White reflects all rays and
is essential as the basis for bright dyes. There must
be chemical combination between the colouring
matter and the cloth, and the dye must be dissolved
in a solution having a weaker affinity for the colour
than the cloth, while for economical working there
must be accurate adjustment between these relations.
Wool has a stronger affinity for dyes than silk, cotton,
or linen. The solutions used must be varied as
occasion requires. The choice of dyes for a given
material involves the consideration of fastness to
washing, and the action of light. Certain dyes will
fix themselves directly to certain fibres but not to
others without the use of mordants. The mordants
commonly employed, such as tannin, and the oxides of
iron and aluminium, were discovered empirically,
but science has explained their action, while research
has contributed to the discovery of many new kinds
of colouring matter. In the art of dyeing the neglect
of science is mainly responsible for the loss incurred
by spoiled and impoverished material.

EXPLOSIVES.

From a brief review of one of the most interesting
arts of peace we will pass to one of the principal
industries of war. The methods of production of
explosives are so closely allied to those of the coal

TO CHEMICAL SCIENCE 45

tar dyes that without much modification of plant
the dye maker can turn his attention to the war
industry. We will not go so far as to suggest that
the development of the dye industry of the Germans
was part of their plan of preparations for war,
but they have undoubtedly been able to take
advantage of the existence of their great factories
for fine chemicals and dyes in this connection. From
the discovery of pulvis fulminans by Roger Bacon
in the thirteenth century, the invention of gunpowder
and guns by Swartz, the monk of Cologne, in the
fourteenth, and the first use of cannon in ships in
the sixteenth century, there was little development
in the science or industry of explosives until the
nineteenth century; then, of course, the need for
explosives in mining and engineering was far in excess
of that for war. Our present business is not to
moralise, but to indicate with caution what science
has done for an industry, the foundation of which
lies in the realisation, by scientific men, of the causes
of explosion. An explosive compound or mixture
is one that can be converted exothermically and with
great rapidity into gaseous products which at the
high temperature attained would occupy at ordinary
pressure a much greater space than that occupied
by the original compound or mixture. The enormous
pressure generated by sudden expansion constitutes
the explosive force, and the principle involved has
led to the utilisation of the explosive nature of a
number of substances possessing this property which
might otherwise have been overlooked. For instance,
it is not at all easy to bring about the explosion of
trinitrotoluene, or T.N.T. It is a relatively stable
substance ; but a study of its nature and comparison
with picric acid, a similarly constituted body of
known explosive properties, would lead one to suppose
that it could be detonated by percussion.

In 1832, Braconnot demonstrated the formation
of an explosive substance by the action of nitric
acid on wood fibre, and in 1845 Schonbein obtained
gun-cotton by treating cotton with a mixture of
sulphuric and nitric acids. Its manufacture, however,

46 WHAT INDUSTRY OWES

though started in several foreign countries, was not
successful, the production being unstable and
dangerous, owing to lack of care in the details of
the operations involved. Sir Frederick Abel showed
not only that must the starting material, cotton
waste, be carefully selected, but that thorough water
washing after nitration was an important factor.
The instability of the Schonbein material was due
to the presence of free acids. The introduction of
centrifugal driers and of paper pulping machines for
breaking up the cotton fibre facilitated the wash-
ing process, and reduced the risk of manufac-
ture.

Gun-cotton is used for a variety of military
purposes, such as filling subterranean and submarine
mines and torpedoes, and it possesses the great
advantage that it can be exploded when wet, although
the wet substance is safe for handling, transportation,
and storage. When dry, it is exploded by a primer
of fulminate of mercury ; when wet, a primer of
dry gun-cotton is used. The explosive power of
gun-cotton led to attempts being made to use it as
a propellant, but gun-cotton, as such, is not suitable
for the purpose because its explosion is very rapid,
violent, and uncertain. Attempts to " tame " it by
gelatinisation with certain organic liquids met with
success in the smokeless powders of Walter F. Reid
and Vieille. The most remarkable result in this
direction, however, was achieved by Alfred Nobel,
who produced a homogeneous mixture of gun-cotton
and nitroglycerine by the evaporation of a solution
of those substances in acetone. By the modern
development of this method, gun-cotton, nitro-
glycerine, and a small quantity of mineral jelly are
mixed well with acetone, and the resulting paste
is squeezed through jets to form continuous cords,
which, when dry, have the appearance of catgut.
This is cordite, the propellant explosive used in
firearms of many sorts and sizes.

Nitroglycerine, mentioned above, was discovered
by Sobrero, in 1847, but its explosive properties
were not utilised until its value was recognised by

TO CHEMICAL SCIENCE 47

Nobel. It is a fairly heavy oily liquid, detonating
violently by percussion, when struck a sharp blow,
or suddenly heated. On account of these propensities
the substance, as such, is seldom, if ever, employed
at the present time, but is converted into a safer
form by incorporation with some inert material, as,
for example, magnesia alba, or kieselghur, the
product in the latter case being dynamite. In this
form, although a certain amount of danger still
attends its use, it is much safer than in the free state.
Sometimes nitroglycerine is incorporated with an
explosive diluent, as with collodion cotton, to
produce blasting gelatine, a body with explosive
power exceeding that of nitroglycerine ; while a
mixture of thinly gelatinised nitroglycerine with nitre,
woodmeal, and a trace of soda, gives us gelatine
dynamite, another useful blasting agent. Explosives
of this class, used largely in mining, quarrying, and
civil engineering operations, have been specially
developed by Nobel's Explosives Company.

When we come to consider the class of substances
used for the bursting charge of shells, it is difficult
to give any individual the credit for their first applica-
tion, or, shall we say, " give the devil his due."
Picric acid, the oldest of these, was discovered in
1799 by Welter, and its nature as a derivative of
phenol was elucidated by Laurent in 1 842. Preparations
of picric acid are used by various countries, as a military
high explosive under such names as lyddite, shimose,
and melinite. Its great disadvantage is that it forma
very sensitive and highly explosive salts when left
in contact with metals for any length of time. This
drawback is not shared by T.N.T., which has come so
much into use during the war. The substitution
of T.N.T. involves a loss of explosive power, but this
is more than counterbalanced by the advantages
gained. It is used both alone and in conjunction
with other substances such as aluminium powder and
ammonium nitrate. Such a mixture is ammonal,
a safe but very powerful explosive employed by the
Austrians. Another very violent explosive is tetra-
nitroaniline, discovered by Fleurscheim. It is not

48 WHAT INDUSTRY OWES

very largely used, as the materials required for its
manufacture are comparatively expensive.

The whole industry is based on science, and should
be controlled by trained men of science in every
department. It has demanded its toll of human life,
in spite of extraordinary precautions ; but without
science that toll would have been far greater, and
certain it is that without the search for knowledge,
the desire to experiment, and the power to apply
the knowledge gained, such an industry could not
exist.

CELLULOSE.

Cellulose. — Cellulose belongs to the class of sub-
stances known chemically as carbohydrates. All
carbohydrates consist of carbon, hydrogen, and
oxygen, the second and last occurring in the same
proportions as in water.

Cellulose is not affected by ordinary solvents, but
is attacked by strong sulphuric acid, yielding a
starch-like body called amyloid, and is dissolved by
ammoniacal solutions of copper salts, from which
it can be precipitated in an amorphous form by the
addition of acids. This property constitutes the basis
of one method of making artificial silk. It may be
mentioned, incidentally, that when heated to 200-
220 deg. Cent, with caustic potash, cellulose is broken
down into oxalic acid, and large quantities of that
acid are made in this way. Sawdust is fused with
potash in iron pans ; the melt when cold is extracted
with water, and the oxalic acid is precipitated as the
insoluble calcium salt from which it is subsequently
liberated by the action of sulphuric acid. This
process, which was discovered by Gay-Lussac in 1829,
and was first employed on the manufacturing scale
by Dale in 1856, is far cheaper than the older method
of oxidising sugar or starch with nitric acid.

The cellulose industry is held to include the manu-
facture of cotton, linen, paper and pasteboard, and
hemp and jute articles. We do not claim much in
the way of debts to science in connection with the

TO CHEMICAL SCIENCE 49

manufacture of cotton and linen, but will choose
paper and pasteboard for our purpose, and then refer
briefly to artificial silk and celluloid.

Paper may be regarded as one of the civili-
sing agents in the existence of man. It is diffi-
cult to imagine what progress the world would
have made without it. The early history of paper
is obscured by conflicting records. It is believed
to have been used in China long before the Greeks
and Romans ceased to use papyrus, but according
to M. Terentius Varro, a voluminous writer contem-
porary with Cicero, the invention was devised at
Alexandria on the conquest of Egypt by Alexander
the Great (B.C. 331). It was in use in Arabia over
1000 years ago, and the Crusaders are said to have
brought the industry to Europe. The earliest MS.
on cotton paper in the Bodleian Collection in the
British Museum is dated 1049, while one on the same
material in the Library of Paris is dated 1050. Paper
made of linen rags was in use here in 1170. The
Moors are credited with having introduced the
industry into Spain, where 12th century specimens
still exist. The first paper mill in this country was
established by Tate, in Hertfordshire, in the reign
of Henry VII., who visited it, and the first important
one was started at Dartford, in Kent, in 1588, or
thereabouts, when Queen Elizabeth granted a
monopoly, for gathering rags and making paper,
to Spielmann, the Court Jeweller.

Until the end of the 18th century paper was made
by tearing and beating rags to pulp in a machine,
dipping a wire sieve into the pulp, transferring the
mass to a felt and pressing it in moulds of various
sizes. About 1800 a Frenchman devised a method
of making it in a continuous web, which he introduced
into England, where it was steadily improved until
about 1860, by which time, for all ordinary purposes,
it had superseded the old hand-made method,
although the latter is still employed for bank notes,
bonds, ledgers, and important documents.

With the introduction of machine-made papers

50 WHAT INDUSTRY OWES

the output has been vastly increased, the cost reduced,
and the variety extended to such a degree that there
are now probably more than 20,000 kinds. In 1820
the machines produced paper at the rate of about
40ft. per minute ; the most modern can now exceed
500ft. per minute. Before 1860, paper consisted
almost entirely of rags, but about that time an
Englishman introduced the use of esparto, Macrochloa
(or Stipa) tenacissima, a grass also employed for making
mats, nets, baskets, &c., of which the consumption in
paper-making is normally about 200,000 tons a year,
at £4 to £4 10s. per ton, almost all of it coming to this
country for the production of fine printing papers.
Over 400 different materials have been tried in the
industry, but rags and esparto are the chief for good
papers. Since the year 1880, chemical wood pulp
has been used as the chief material for middling
kinds, and more recently mechanical wood — made by
crushing wood between rollers or by pressing it
against a grindstone — mixed with varying quantities
of chemical wood pulp, has been employed for the
cheapest newspapers and common printings.

Science has played an important part in the
development of the paper industry. The introduction
of cheap bleaching agents such as chloride of lime
to which, as a by-product of the Leblanc process
we have already referred, has effected considerable
improvements and economies, while the utilisation of
esparto and wood has been made practicable only
by scientific research, the processes evolved from which
we will now outline.

Wood fibre is a lignocellulose, a compound of
cellulose and a complex substance called lignone,
which acts apparently as a binding material. The
forest wood is deprived of its bark and cut across the
grain into small chips, which are cleaned and then
boiled at high temperature, under pressure, in a
solution of caustic soda. From coniferous wood the
yield of cellulose is about one-third of the weight
of the prepared wood treated, the other two-thirds
being taken up by the alkaline solution. The caustic
soda required, amounting to about 20 per cent, of

TO CHEMICAL SCIENCE 51

the weight of the wood, is recovered by evaporating
the spent liquor, incinerating the residue and treating
a solution of the ash with lime. The organic matter
in the residue, on burning, provides a good deal of
the heat necessary for evaporating the solution.
The process, however, has one disadvantage in the
fact that a proportion of the cellulose is destroyed
by the action of the strong alkali. In order to obtain
better yields two modifications have been introduced
comparatively recently. One consists in the sub-
stitution of sodium sulphide for the caustic soda,
the sulphide being prepared on the spot by the reduc-
tion of sulphate of soda with the residue obtained
by evaporating the spent alkali. The cycle of
operations is then completed by making up the
working loss of sodium sulphide by the addition of
sulphate of soda to the residue before incineration.
The other modification consists in the application
of an acid hydrolysing agent instead of the alkali.
The acid substance employed is a solution of calcium
or magnesium bisulphite containing approximately
4 per cent, of sulphur dioxide. This solution is
prepared by passing pyrites gases up a tower filled
with calcite or dolomite down which water is trickling.
The cost of the process is slightly higher, but not out-
of proportion to the increased yield of cellulose.

The cellulose obtained by either of the methods
is mashed to a pulp, washed free from adhering liquor,
and bleached with chloride of lime and sulphuric
acid, before being utilised in the manufacture of
paper. Those who are interested in this subject may
be invited to study the series of articles on " Paper
Making," which appeared in Vol. CXX. of THE
ENGINEER.

" Artificial Silk" — The production from cellulose
of materials resembling silk is the result of many
years of scientific research and costly experiment.
In 1889 the Comte de Chardonnet produced the
first artificial silk by nitrating cellulose and dissolving
the resulting product in a mixture of alcohol and
ether, thereby obtaining a viscous liquid which he
forced through holes of very small diameter into water.

52 WHAT INDUSTRY OWES

The threads thus produced were then subjected to
the reducing action of ammonium sulphide and con-
verted into an amorphous cellulose having the
appearance of silk.

The method now extensively used is that devised
by Cross and Bevan, who have contributed largely
to the existing knowledge of the chemistry and
technology of cellulose. The starting material,
wood pulp, is treated successively with caustic soda
solution and carbon bisulphide, the viscous mass
thus obtained being forced through small apertures,
from which are produced filaments which are spun
into a fine material also closely resembling silk.

Celluloid — a very useful substitute for horn,
tortoiseshell, ivory, &c. — was first made in 1869
by treating nitrocellulose with camphor and alcohol.
Its inflammability, however, has proved to be a
very serious drawback, attempts to overcome which
have met with some success. By the substitution
of acetate of cellulose for cellulose itself in the process,
a non-inflammable product — sicoid or cellon — is
formed which for some purposes is more useful
than celluloid.

TO CHEMICAL SCIENCE 53

CHAPTER V.
OILS, FATS AND WAXES.

OILS may be divided into : (a) animal, including
whale and fish oils, stearin, which is mainly obtained
from beef and mutton suet, and neats-foot oil from
the feet of cattle ; (ft) vegetable, such as olive, linseed,
cotton seed, maize, palm, rape, castor, and turpentine,
and essential oils ; and (c) mineral oils, so-called, such
as petroleum, ozokerite, and shale. It is difficult to
make a sharp division, however, for the reason that
some are obtained from more than one of these sources ;
for instance, stearin exists in the vegetable kingdom,
and petroleum is certainly derived from the products
of long submerged fish life. The tar oils we have
already noticed in dealing with coal and coal gas.
Among the most useful substances at our disposal
oils are employed as fuel, illuminants and lubricants,
and provide us with material for food and medicine,
as well as for the manufacture of paints and varnishes,
polishes and perfumes.

Oil has been defined as a neutral fatty substance,
liquid at ordinary temperatures ; but although we are
not satisfied with the definition, we will not attempt
to improve upon it, preferring rather to proceed with
our task of indicating th° influence of science in the
vast field of industry involved. That influence has
been more marked in the direction of improvement
and adaptation rather than of new and striking dis-
covery. In some cases, however, scientific principles
have been applied to the fundamental processes of
oil production, with the result that substances at one
time ignored as valueless have become the source of
products now regarded as indispensable, while the
science of geology has rendered inestimable service in
locating and surveying sources of mineral oil ; indeed,

E 2

I

54 WHAT INDUSTRY OWES

a knowledge of economic geology is essential to all
mining engineers.

The world's output of petroleum before the war was
probably not far short of 350,000,000 barrels of 42
gallons, of which about two-thirds were produced in
the United States. Dame Nature seems anxious to
get rid of it as if it were the offensive exudation of a
deep-seated abscess. If nothing could be profitably
extracted from it we might well wish it to remain in
the bowels of the earth, counting it nothing but a
nuisance when it came to the surface. Science can
at least claim to have made it useful, seeing that by
the process of fractional distillation this disagreeable
natural substance can be made to yield in enormous
quantities such valuable products as illuminating gas,
motor spirit, cleaning spirit, kerosene or lamp oil,
paraffin wax, vaseline, and a viscid residue used as
fuel. The crude petroleum itself would be useless for
any of the purposes to which its derivatives are
applied, mainly on account of its highly volatile
constituents, which are a source of danger in transport
and storage, owing to the inflammable nature of the
vapour arising from it. The crude oil is conveyed by
pipe lines, in some cases over a distance of several
hundred miles, to the refinery, where it is distilled into
temperature fractions. The lighter fractions are
purified by washing with sulphuric acid, alkali and
water ; while sulphur, when it occurs in objectionable
quantity, must be removed by means of copper oxide.
Among the higher fractions lubricating oil is purified
by nitration through animal charcoal.

The lightest fraction, cymogene, which requires
special cooling and pressure for its condensation, is
used in ice-making machines. Other fractions
obtained are rhigolene, the illuminant used in the pen-
tane standard lamp, and as a local anaesthetic in surgery;
gasolene, employed for the carburation of water gas
for illuminating purposes, for making " air gas," and
as a solvent ; ligroin, also a solvent ; benzine or petrol,
which supplies us with motor spirit ; and kerosene or
lamp oil. Among other products may be mentioned
paraffin wax, which, with an admixture of stearic

TO CHEMICAL SCIENCE 55

acid, is used for the manufacture of candles, solar oils,
various grades of lubricants, and vaseline. The
quantity of lighter fractions can be increased if
desired by the " cracking " of the more complex
bodies.

Astatki, the residue from the distillation of Russian
petroleum, yields, on distillation, an excellent illumi-
nating gas, besides quantities of benzol, toluol,
naphthalene, anthracene, and pitch.

The shale oil industry, founded by James Young,
of Kelly, in 1851, which produces valuable quantities
of niuminating and lubricating oils, ammonia, and
paraffin wax, depends in a similar manner on scientific
operations.

We claim less for science in the extraction of
animal and vegetable oils, which has been
practised since time immemorial, but must place to
the credit side of the account the responsibility for the
differentiation and classification of such oils, the
selection of then* most useful applications, with
methods of purification and of analysis and valuation.

Vegetable oils, such as linseed oil — a so-called
drying oil — and turpentine are used as vehicles in the
manufacture of paints and oil varnishes. The paint
industry has derived great benefit from science in the
discovery and application of new pigments, and in the
improvement of the older methods of making pig-
ments. Turpentine is the starting material for the
manufacture of artificial camphor, a synthesis that is
a credit to organic chemistry, and although the
artificial product cannot as yet be made to compete
with the natural substance, it renders good service
in keeping down the price of natural camphor, of which
the production is practically monopolised by the
Japanese. Other vegetable oils, such as olive oil,
rape oil, maize oil, and castor oil, are employed as
lubricants, whilst some are good illuminating oils.

The essential oils, of which oil of turpentine is an
example, are vegetable oils used in many cases as
perfumes. There are three methods of winning the
essential oils : (1) by distillation with steam ; (2) by
pressure of the plant substance and (3) by extraction

56 WHAT INDUSTRY OWES

with suitable solvents. Science has entered largely
into the essential oil industry by finding the con-
stitution of many of the odoriferous principles, which
have afterwards been successfully made in the labora-
tory from simple materials. In some cases, where the
actual substances have not been made, very close
imitations have successfully competed with the
natural products. Examples of the first are terpiriol,
which is the important constituent of Lily of the Valley,
and coumarin, New Mown Hay and Jockey Club ;
whilst in the second class we have such substances as
ionone and nitrobenzene substitutes for essence of
violets and oil of bitter almonds respectively.

SOAP AND CANDLES.

The soap and candle industries must now be
regarded as offshoots of the oil industries. Their origin
is remote, but it was not until 1813, when Chevreul
published his remarkable researches on the composi-
tion of oils and fats, that anything was known of the
true nature of the processes involved in their manu-
facture. Nowadays the chemist should be in para-
mount control of their production. The recovery of
glycerine, which at one time flowed into our rivers
and streams as a waste product, was a scientific
achievement of far-reaching importance, as we have
indicated in our remarks on explosives, while its use
in medicine is considerable. Incidentally we may
mention also that glycerine, mixed with water,
prevents evaporation and freezing, and this property
finds application in the mechanism of gas meters.

Both animal and vegetable oils are used in the
manufacture of soap and candles. When fats and oils
— such as tallow, palm oil, olive oil — are boiled in large
cast iron pans with caustic alkali, they become decom-'
posed and yield an alkaline salt of the fatty acid — soap
and glycerine. The excess of alkali and the glycerine
are separated by the addition of a solution of common
salt ; the soap, being insoluble in the brine, rises to the
top, and is ladled out as a granular curdy mass, run
off into frames — boxes — to cool and solidify. Hard
soaps, such as curd and yellow soap, are compounds

TO CHEMICAL SCIENCE 57

with soda, consisting of about 26 per cent, of water,
7 per cent, of soda, and 66 per cent, of fatty acids,
with, in the case of yellow soap, a small percentage
of resin. Soft soaps are compounds with potash, or
potash and soda, with fatty acids derived from drying
oils, such as whale and seal oils, linseed, &c. With
regard to the water content of hard soap it has been
rumoured that, since soaps containing as much as
90 per cent, of water have been encountered, it
appears to be the aim of some soap makers to cause
water to stand upright.

CANDLES.

The old tallow dips, prepared by dipping a wick
repeatedly into melted tallow, gave rise, on burning,
to a pungent substance called acrolein, produced by
the decomposition of the glycerine combined in the
tallow. Modern candles are without this disadvan-
tage, as they contain no glycerine, the free fatty acids
from which they are made being liberated from the
fat either by the hydrolytic action of sulphuric acid,
or by precipitation of the lime salt and its subsequent
decomposition with sulphuric acid. The fatty acid —
e.g., stearic or palmitic acid — so prepared is melted and
cast round about wicks in moulds of pewter or tin, or
sometimes of glass, supported in a wooden frame, the
upper part forming a trough. The wicks are arranged
taut, the wax is poured in, cooled with water to solidi-
fication, and removed as candles. All sorts of waste
fats, such as those from wool washing and glue making,
are used for making candles, the free acid being
extracted by treating the fat with sulphuric acid.

These industries furnish examples of the utilisation
of waste products. The soap used for cleansing
purposes in yarn mills is recovered by precipitating
the soap from waste liquids with lime, and pressing
the precipitate into briquettes, from which sufficient
gas can be obtained by distillation to light the mills.
Efforts are at the present time being made to recover
fat from sewage, mainly for the sake of the glycerine
content.

58 WHAT INDUSTRY OWES

EDIBLE FATS.

The invention of butter substitutes, now popularised
by prevailing conditions and the need for the exercise
of economy, is due to the chemist. These substances
are commonly made by mixing intimately a solid
animal fat, such as stearin, with some vegetable oil,
such as cotton seed or cocoanut oil, and milk. The
use of solid animal oil for this purpose absorbs some
of the raw material formerly available to the soap
maker, but the deficiency has been made good by the
conversion of the plentiful supply of vegetable oils,
such as olive oil, into solid fats by hydrogenation in
the presence of finely divided nickel, to which we
referred in dealing with that metal.

TO CHEMICAL SCIENCE 59

CHAPTEB VI.
LEATHER,

UP to the close of the eighteenth century the
progress of industry was slow but sure, much of it
based undoubtedly 011 the workings of great minds
and patient inventive genius, and much again on
chance discovery ; but the nineteenth century
marked an epoch of development, definitely hastened
by the advance made simultaneously in mechanical,
physical, chemical, and biological science. Yet when
we consider all that was done in ancient times, for
example, in the winning of metals, in the dyeing of
fabrics, in agriculture and the domestic arts, we
are forced to marvel at the vast amount of knowledge
and experience, commonly referred to as empiricism,
accumulated for centuries before the advent of
modern science. We are also convinced that there
is no finality in the matter, and that what appears
to be ideal to-day will be improved upon to-morrow
or the day after.

An ancient industry is the manufacture of leather,
which had seemingly reached the highest degree
of efficiency centuries ago if one may judge by exist-
ing specimens. To the modern chemist, however, the
subject is open to further investigation, involving
problems directed to the speeding up of production
and decrease of cost without diminishing the quality —
aims not easily attained, as many have learned from
personal experience. In fact, one of our leading
authorities has recently expressed the opinion that
the science of this important industry is but in its
infamy. We are reassured, however, by the statement
that the work of Professor H. R. Procter and the
Leather Department of the University of Leeds, was
largely the factor which rendered it possible for the

60 WHAT INDUSTRY OWES

nation to supply the enormously increased demand
for the military equipment of the Allied Armies,
including boots, belts, leggings, saddlery, traces,
dressed sheep skins, and numerous minor require-
ments, besides the driving belts of the munition
factories. With such a demand to meet, the price
for the time being of leather for furniture, port-
manteaux, gloves, book-binding, and parchment is
naturally high.

The processes whereby raw hides are converted
into useful and durable material by treatment with
various solutions of substances of animal, vegetable
and sometimes mineral origin, are distinctly chemical
and biological. They are investigated and explained
by research, and modified and superseded by better
processes, so far as the increase of knowledge admits,
while accidental impurities of a harmful nature in
the liquors employed can be traced and their presence
avoided.

The hydrochloric acid washing given to hides
that have been unhaired by lime, to free them from
that substance, is clearly an operation of a scientific
nature, and is also the chemical investigation of the
water supply, the quality of the water being important.
The science of bacteriology has rendered invaluable
assistance in furthering our knowledge of puering —
the process of softening hides prior to tanning.
The changes involved in the old process of treating
the unhaired and washed hides with an infusion of
dog -dung have been investigated very thoroughly by
scientific methods, and have been shown to be the
result of bacterial action. Patents, founded on this
knowledge, have been taken out for the use of
artificial cultures of bacteria instead of the obnoxious
infusion referred to. Some of these methods give
excellent results, and would doubtless be more gener-
ally adopted were it not for the conservatism of the
workman and his dislike of the trouble necessitated
by a change of procedure.

The oldest method of treating skin and hide for
the purpose of preservation in a flexible state, which
consisted in kneading with fatty substances, is of

TO CHEMICAL SCIENCE 61

historic interest only, though chamois leather is
still prepared with oil. Next in chronological order
conies vegetable tanning, still very extensively used,
the tanning liquor being an infusion of some bark.
e.g., of oak or willow. Up to the end of the eighteenth
century the prepared hides were simply soaked in a
strong infusion of the tan, but about that time Seguin,
a Frenchman, introduced a method for soaking the
hides successively in tan liquor, or ooze, of increasing
strength, the untanned hide going first into the
weakest, the completely tanned material being taken
from the strongest liquor. By this means thorough
permeation by the tan liquor was ensured, and the
quality of leather considerably improved. This
method was patented in England by William Desmond
in 1795.

Sir Humphry Davy investigated the process of
tanning with useful results, indicating the nature
of the action between the hide and the tanning
material, but only recently has science obtained a
hearing in the industry. The reason for this is not
far to seek ; the changes involved in tanning are
exceedingly complex in character, and depend to a
large extent upon the properties of substances in a
colloidal condition. Examples of this state are to
be found in solutions of gelatine and starch having
properties different from ordinary solutions, such
as that of setting with the formation of a jelly.
The scientific study of the colloidal state is now being
more vigorously pursued, and as our knowledge
of it increases we may expect further advances in
the leather industry.

Mineral tannages, of which alum was the first
known, are also of interest. The " tawing " solution
contains alum and common salt, the latter serving to
counteract the swelling of the hide produced by the
free acid in the alum solution. Salts of the metals
iron and chromium, chemically similar to aluminium,
have been used for tanning, and although iron salts
have no application as tannages at the present time,
chrome tanning is a very important industry, founded
and reared upon scientific knowledge. Many patents

62 WHAT INDUSTRY OWES

have been taken out, inchiding those by Knapp in
1858, by J. W.— later Sir J. W. — Swan, by Hein-
zerling in 1879 (the first commercially successful
process introduced into England) and that by
Augustus Schultz, a New York dye works chemist, in
1884. Valuable scientific work has also been done in
this branch by Eitner and by Procter. A soft and
durable leather can be produced which will fix an acid
dye without a mordant.

Leather cloth substitutes for leather, used for
covering furniture, for bookbinding, stationery cases,
pocket books, and many other useful articles, are
also produced under scientific supervision. This
industry, however, with that of linoleum and similar
material, might have been dealt with as branches of
the oil industry had we attempted to deal more
comprehensively with that subject.

Apart from skins and hides there are other products
of the slaughter-house, such as horn, blood, hair and
bristles, waste wool and the like, from which valuable
chemicals such as cyanide are produced. Glue, too,
is made from the chippings of hides, horns and hoofs,
which are washed in lime-water, boiled, skimmed,
strained, evaporated, cooled in moulds, cut into
convenient pieces and dried on nets. The processes
are nowadays supervised by trained chemists.

TO CHEMICAL SCIENCE 63

CHAPTER VII.
RUBBER.

RUBBER, formerly commonly called caoutchouc,
was originally imported from French Guiana. It
was obtained from the Siphonia elastica, and
from Brazil, from the Siphonia or Hevea Brazilien-
sis, lutea and brevifolia, through the port of Para,
and later from the ficus elastica, or india-rubber
tree. It was first brought to Europe in the early
part of the eighteenth century, but it was many
years before its usefulness was realissd. Priestley,
the discoverer of oxygen, suggested its use for re-
moving pencil marks and, in 1791, Samuel Piat
obtained a patent for making waterproof fabrics by
dissolving caoutchouc in spirits of turpentine.
Hancock, in 1823, and Macintosh followed on similar
lines, but the invention of the vulcanising process by
Charles Goodyear, whereby the addition of sulphur
gave it the consistency of horn, marked the starting
point of still greater developments.

The rubber industry has recognised the importance
of scientific control, by botanists and chemists, in
planting, cultivation and tapping, with consequent
increased yields. Chemists examine the latex, and
supervise its drying and preparation for use. The
variability of tensile strength is largely dependent on
the size of the globules in the latex, which is valued
accordingly. No standards of purity have been
established, but fine Para is generally considered
superior to other varieties.

For nearly sixty years chemists of all countries
have devoted much time and labour to its synthetic
production in the laboratory. In 1860 Greville
Williams isolated a compound, which he called
isoprene, from the products of the distillation o£

64 WHAT INDUSTRY OWES

natural rubber. Nineteen years later, Bouchardat
showed that a substance very closely resembling
rubber could be reproduced from isoprene by the
action of strong hydrochloric acid, and that by the
action of heat alone isoprene yielded turpentine.
The work of the French chemist was confirmed, in
1884, by Professor — now Sir—William Tilden, who
suggested a formula for isoprene, which subsequently
proved to be correct, and also obtained isoprene from
turpentine. Later, these researches formed the basis
on which the synthetic rubber industry was founded,
though German chemists, who have also done good
work in this field of investigation, lay claim to having
established principles the credit for which was clearly
not due to them. Among other British chemists who
have contributed to the investigations on the subject
may be mentioned Professor W. H. Perkin, Dr.
Strange, and Dr. F. E. Matthews. Two chemically
different rubbers are produced : isoprene -caoutchouc
and butadiene -caoutchouc. The raw materials,
isoprene and butadiene, are obtained from a variety
of substances, including turpentine, isopentane (from
the rhigolene fraction of American petroleum), coal
tar (the material from this source being para-cresol,
one of the homologues of carbolic acid), starch and
cellulose. The raw material is converted into
caoutchouc by methods, involving (i.) polymerisation,
by heating under pressure with a suitable substance
such as acetic acid, and (ii.) polymerisation, by the
action of sodium. The latter method, discovered
almost simultaneously by F. E. Matthews in England
and Harries in Germany, is the more convenient
and gives the greater yield, although the resulting
product does not vulcanise so well as that from the
former method. All this is progress. As in the case
of indigo, science, if successful, will help one form of
industry to the detriment of another ; the scientific
work on the plantations tends constantly to increased
yields and economical working, and the artificial
rubber has not as yet displaced the natural either in
its properties or in cost of production.

TO CHEMICAL SCIENCE 65

CHAPTER VIII.
MORTAR AND CEMENT.

THE simplest and most ancient cementitious
material is mud, which is still used, reinforced by
sticks and grass, by African natives in the construc-
tion of their huts. Ordinary mortar is made of
water, lime, and sand intimately mixed together.
Science has shown that there is no chemical union
between the lime and sand ; that the sand acts
simply as a diluent, preventing undue shrinkage,
which occurs when lime is used alone ; that the setting
is due to loss of water, and that the hardening is
caused by the gradual formation of interlacing
crystals of calcium carbonate, which effectively bind
the material into a coherent mass.

Long before these facts had been established,
experience had proved that a pure or " fat " lime
produced a better mortar than an impure lime. In
the case of hydraulic mortars and cements, however,
the knowledge of their structure and action was
indefinite until 1887, when the researches of Le
Chatelier were published, though a fairly systematic
investigation of the nature of hydraulic mortar or
rather of the hydraulic limestones employed in its
manufacture, was made about the year 1756 by
Smeaton, whilst searching for the most suitable
binding material for the foundations of the Eddystone
Lighthouse, which he had been commissioned to
rebuild. He consulted his friend Cookworthy, a
chemist, who instructed him in the analysis of lime-
stones, and he found that clay was an essential
constituent of a hydraulic limestone, the poor lime
obtained on burning it being far superior to fat lime
for making mortar intended to withstand exposure
to water.

66 WHAT INDUSTRY OWES

Cements are made by heating in a furnace an
intimate mixture of limestone or chalk and clay to a
temperature at which clinkering takes place. The
product is broken up, finely ground, and put upon the
market as cement. " Roman " cement was first made
by James Parker in 1796, by heating argillaceous lime-
stone containing, already mixed, the two necessary
ingredients. The manufacture of Portland cement
was founded on attempts to imitate Roman cement,
using a mixture of lime and clay instead of the
argillaceous limestone. Nothing was understood
of the why and the wherefore of the process, and
often the best part of the product was rejected in
the unslakeable portions. Chemical action in the
furnace was unthought of, and even when it was
evident to scientific men and duly published, con-
siderable time elapsed before the manufacturers
took advantage of the efforts of science towards the
furtherance of their industry. It is now known
that chemical action between the lime and the clay
in the furnace effects the formation of silicate and
aluminate of calcium. When the cement is treated
with water, these compounds are decomposed with
the production of slaked lime, and the acids derived
from silica and alumina. These substances again
interact, with the formation of the hydrated silicates
and aluminates as interlacing crystals, giving tenacity
to the preparation, with the result that first setting
and subsequently hardening take place, these
phenomena being merely stages in one process.
Thus the researches of chemists have established
facts which have been most serviceable to the cement
maker in increasing the efficiency of his product
through the choice and treatment of the best
materials.

We owe more than this, however, to the study
of the chemistry of cement. It remained for chemists
to show the dangerous effect of certain impurities,
such as magnesia, in excess, and sulphates, on the
resistance of cement to the attack of water. Such
substances must be carefully excluded within well-
defined limits. When cement is used to make

TO CHEMICAL SCIENCE 67

concrete foundations exposed to sea, water, the mass
must be either very compact and impervious, or
be covered with an impenetrable stone facing, for
the reason that sea water contains sulphates and
salts of magnesium in plenty, and, consequently,
if penetration by the water takes place, the cement
decomposes and the life of the structure is corres-
pondingly shortened.

It is obvious that for such a substance, on which
the stability of costly buildings and structures so
largely depends, the provision of a definite standard
specification became a necessity. The British
Standard Specification was formulated in 1904 by a
sub -committee, appointed by the Engineering
Standards Committee, including engineers and con-
tractors, chemists, architects, manufacturers, and
representatives of official bodies using large quan-
tities of Portland cement for public works. The
specification provided for both chemical and mechani-
cal tests, and, although subsequently modified in
the direction of improving the quality of the cement
supplied under the specification, remains essentially
the same to-day — a definitely scientific safeguard
accepted alike by producers and users.

We have indicated how the explanation of scientific
phenomena tends to improvement in manufacture,
and it is interesting to note that a reason has been
advanced for the use of straw in the making of bricks
by the Israelites. It is not a suitable binding material,
but Acheson has shown that clay is rendered more
plastic by the addition of tannin, and that an extract
obtained by soaking straw in water produces the
same effect. The Israelites complained, therefore,
of the hardship of working with less suitable materials,
while they had to produce the same tale of bricks.
Possibly the use of grass assists in the same way the
African natives in making their mud huts.

68 WHAT INDUSTRY OWES

CHAPTER IX.
REFRACTORY MATERIALS.

A MATERIAL ia termed refractory when it resists
the ordinary treatment to which materials of its
class are subjected ; it may be a mineral which does
not yield readily to the hammer, or an ore not easily
reduced. In recent times, however, the term has
become specially associated with substances that will
resist economically the temperature of a furnace, and
the corrosive action of other substances with which
they come into contact. Refractoriness may, there-
fore, be a vice or a virtue, according to circumstances,
and a given material may be refractory in one process,
but break down easily if employed in another.

The increased demand for refractory materials during
the war, particularly in the manufacture of steel and
glass, has shown the need for further scientific investi-
gation. Experiment on the large scale is costly,
especially if carried out in an unscientific manner.
The help of chemists is therefore essential in deter-
mining the composition and the chemical and physical
properties of such substances, having in view the
purposes to which they are to be applied. The
work is not confined to the investigation of known
refractories, but is extended to the discovery and
utilisation of new refractories to cope with the con-
ditions created by their employment in high tempera-
ture furnaces.

Having selected a suitable material, from the
chemical point of view, it is necessary to ascertain
whether it will withstand, without shrinkage, fusion
or softening — and consequent deformation — the
temperature required for the desired reaction. The
refractory that will last for ever has yet to be found,
but that with the longest life is the most economical,

TO CHEMICAL SCIENCE 69

provided the saving effected by the increased length
of life — renewals being less frequently required —
plus the saving of time and labour, in more continuous
running of the furnace, is proportionate to any
additional cost. The subject has long been treated
more or less scientifically, the older refractories
being classified into acid, basic, and neutral materials^
As examples of the acid class we have fire-clays, such
as ganister, the highly siliceous material used for
lining acid Bessemer converters ; in the basic class,
such substances as lime, magnesia, and calcined
dolomite ; while among the neutral refractories we
may include gas carbon and graphite. These mate-
rials have proved eminently suitable for some pur-
poses, but with the use of the electric furnace we
require substances still more refractory, and in recent
years science has provided a number of them.

Carborundum, the extremely hard and refractory
carbide of silicon, was first made in 1891 by Acheson,
who obtained it by heating graphite with sand in the
electric furnace, and it is now employed as a refractory
lining for such furnaces, besides being useful as an
abrasive. It has also been incorporated with cement
to give grip to surfaces, as on staircases subjected to
considerable wear. Other modern refractories are
alundum — fused aluminium oxide — silicon, fused
silica, zirconia, and artificially made graphite. Cru-
cibles of graphite, intimately mixed with sufficient
clay to give the mixture coherence, are far preferable
for many purposes, and much more durable than those
made of clay alone.

F 2

70 WHAT INDUSTRY OWES

CHAPTEB X.
GLASS AND ENAMELS.

THE manufacture of glass dates from the first
period of Egyptian history. Egypt, the instructor
of the world in so many arts, possessed in very early
times craftsmen skilled in making, blowing, colour-
ing and cutting this most remarkable and useful
material. The industry survived through the vicis-
situdes of the country until the time of Tiberius
(A.D. 14-41), who brought Egyptian glass workers to
Rome, where the art nourished until the decline of the
empire, during which the principal centre of manu-
facture was transferred to Byzantium. The value
attached to glass by the ancients is indicated by the
circumstance that the industry was always supported
and encouraged by the most powerful and influential
rulers, migrating with their power from one country
to another. However, at the time of the fall of
Constantinople it had become established in various
centres, of which the chief was Venice, where it soon
attained such proportions as to give occupation to
over 8000 persons.

In the Middle Ages the industry was developed in
Germany and Bohemia, especially in the latter country ,
which, owing to the native supply of pure quartz,
ultimately superseded Venice as the source of the finest
glass. Inl870 glass making gave employment to 30,000
workers in Bohemia. The invention of glass mirrors
has been attributed to the Germans, the original
method being to back the glass with polished metal.
Glass was first used for windows in England about
the end of the eleventh century, and was made here
in the fifteenth, but with little success until about
1557, when French artisans were employed in London.
In 1670 Venetian workers were brought over to make

TO CHEMICAL SCIENCE 71

the heavier and finer kinds, and in 1771 the industry
became more firmly established by the formation of
the British Plate Glass Company, whose successors
are still in existence at St. Helens.

The scientific study of glass was first made on the
physical side, its transparency, permanence, and the
absence of crystalline structure with consequent
birefringence, combining to render it an almost ideal
material for the construction of the essential parts of
optical instruments. In fact, the science of optics,
with its manifold applications to spectacles, micro-
scopes, telescopes and spectroscopes, owes its exist-
ence to our possession of glass. The first investiga-
tions in the chemistry of the subject were made with
a view to the improvement and better adaptation of
glass to optical purposes. Up to 1829 the only
varieties of optical glass were soda-lime or crown
glass, potash-lime or Bohemian glass, and potash-lead
or flint glass, also known as crystal or strass, these
being made from mixtures of the silicates of the
metals indicated. Before that year Fraunhofer and
Guinand had made experiments modifying the com-
position of crown and flint glasses, and had produced
compound lenses with a fair approach to achro-
matism. In 1829, however, Dobereiner produced
glasses containing barium and strontium, metals
closely allied to calcium, the metal contained in lime,
and in 1834 Harcourt, in England, commenced a long
series of researches on the production of new glasses,
which — although the positive results obtained were
of small value — established principles subsequently
turned to good account in the manufacture of special
kinds for thermometers, laboratory apparatus, lamp
chimneys, optical instruments, and many other
important articles. The next advance, an epoch-
making one, was begun about 1880, when Schott, a
trained chemist, the son of a Westphalian glass maker,
was encouraged by Abbe to search for new and
better optical glass. His knowledge of mineralogy
served him well, for instead of proceeding laboriously
along the lines of methodical research, he took almost
a direct road to the desired goal, producing glass con-

72 WHAT INDUSTRY OWES

taining boric and phosphoric oxides with alumina and
baryta. Microscopes designed for these new glasses
proved perfectly achromatic, and in every way
superior to the older kinds ; and this striking advance
has doubtless contributed enormously to the useful-
ness of the microscope, and of the microscope to
industry generally.

Schott next turned his attention to the solution of
the problems of thermal expansion and volume tem-
perature hysteresis of glass. Owing to its low thermal
conductivity it is important that glass intended to
withstand sudden changes of temperature should
have a thermal expansion as slight as possible, in
order to hold against the strain set up by unequal
temperature changes, and so that the risk of cracking
may be minimised within reasonable limits ; the
range of temperature change varying inversely as the
thermal expansion. Pursuing his investigations,
Schott produced borosilicate glasses with exceed-
ingly low coefficients of expansion, and capable of
resisting a sudden temperature change of over 190
deg. Cent., whereas the ordinary Bohemian glass
would scarcely withstand a change of much over 90
deg. The borosilicate glasses have therefore been of
service for the construction of incandescence gas
chimneys, and also of apparatus for laboratory use ;
their slight solubility in chemical reagents constitut-
ing an additional advantage.

When a thermometer made of ordinary glass is heated
to a temperature much above that of the air the glass
bulb, on cooling, does not return immediately to its
original volume, and may take months or even years
to do so. Consequently if the bulb, before it has re-
gained its original volume, is surrounded by melting
ice, the thermometer will not register the true melting
point, but a point, varying with the thermometer, from
0.5 to 1 deg. Cent, below the correct temperature ;
and lower temperatures in general will not be regis-
tered correctly until the bulb has regained its original
volume. This defect was largely overcome by the
results obtained by Schott, whose Jena normal glass
16111 and Jena borosilicate glass 59111, when used for

TO CHEMICAL SCIENCE 73

thermometers, show a zero depression of only about
0. 05 deg. Cent, after heating to 100 deg. Cent. Owing
to their infusibility, glasses of this type can also be
used for nitrogen-filled thermometers, registering up
to about 575 deg. Cent.

The list of new and useful scientific products might
be much further extended if we were to deal with the
subject more thoroughly, but it would be regarded as
an oversight if we omitted to mention fused silica
glass, a comparatively recent invention. From pure
quartz worked in the oxy-hydrogen flame excellent
glass is produced, having the property of withstanding
a sudden change of temperature of over 1000 deg.
Cent. Being highly resistant to chemical action, it
useful in the laboratory for many purposes for
which platinum was formerly employed.

Until the outbreak of war the production of glass-
ware for use in chemical investigations was almost
exclusively in the hands of Germany and Austria.
Stocks were becoming speedily exhausted and the
position would have become serious for many impor-
tant industries if British chemists had not promptly
taken the matter in hand. They had not merely to
imitate glasses previously imported, but to find
substitutes for certain ingredients of batch mixtures,
notably potash, for which also we had hitherto been
dependent on Germany and of which supplies were
running low. The work of Professor Herbert Jackson*,
in conjunction with the Glass Research Committee of
the Institute of Chemistry, was especially successful,
and, with the co-operation of a number of well-known
firms, laboratory vessels, such as beakers and flasks,
and all ordinary forms of apparatus are now produced
in this country, having qualities in some respects
superior to those of enemy origin. In some cases,
perhaps, the products have not quite the same finish
as those of the experienced German workers, but we
are convinced that the defects are not radical, and
that given time, the British makers will not only equal,
but excel the German in both quality and technique.

* Now Sir Herbert Jackson, K.B.E.

74 WHAT INDUSTRY OWES

In addition to the needs of the laboratory, many other
kinds of glass were required, and the work was
extended to the investigation of over forty varieties
for which formulas have been supplied to approved
firms. With shortage of labour and other economic
difficulties, firms have undertaken with remarkable
energy new branches of work which it is hoped they
will be able to retain, in the future, in the face of
competition from our quondam enemies.

Yet another problem has been successfully tackled
by Professor Jackson for the Ministry of Munitions,
viz., the treatment of clay used for making vessels
employed in glass production.

For the production of optical glass essential to the
services, we, fortunately, had well-established manu-
facturers, by whose praiseworthy endeavours the
output has been sufficient to cope with the greatly
increased demand. Professor Jackson has supplied
formulas for batch mixtures for several important
varieties not hitherto made in this country. The
difficulty of securing supplies of suitable sand had
also to be faced, and our mineralogists and chemists
devoted attention to this question, with satisfactory
results, the report of Dr. Boswell, of the Imperial
College of Science and Technology, indicates that we
possess natural resources which can be utilised by our
manufacturers to their advantage. Research work
on refractories and electric furnace methods is also
in progress at the National Physical Laboratory.

In the course of time an enterprising firm, with the
aid of chemists and from indigenous sources, produced
supplies of potash of high quality in sufficient bulk
for the imperative requirements of glass makers, and
this factor was of no small consequence, since it is
admitted that for certain glasses potash is practically
indispensable.

From the foregoing, it is evident that in spite of
the antiquity of the industry, and the fact that good
glasses for ordinary and ornamental purposes were
produced independently of modern science, many
special glasses owe their origin entirely to scientific
investigation. It is not too much to say that on the

TO CHEMICAL SCIENCE 75

possession of such glasses in time of war may depend
the fate of many a good ship and many a good man.
Who can say, then, how great is the debt of the
industry to science and of the country to both ?

ENAMELS.

The art of enamelling is of remote origin. We
have already referred to its application to pottery by
the Chinese. It was practised also by the Egyptians
and Etruscans, passing in the course of time to the
Greeks and Romans ; but we propose to deal more
particularly with the enamelling of metals, which
appears to have been invented in Western Asia
and to have traversed Europe in the early centuries
of the Christian era. The history of the subject is
of absorbing interest to those who regard it as an art,
and much may be gleaned from BushelFs work on
" Chinese Art," published by the Board of Education.
The Chinese give the credit for its discovery to
Constantinople ; the similarity between the methods
of the Chinese and the Byzantine enamellers is held
to support this opinion. We are concerned here, how-
ever, with the utilitarian rather than the artistic
applications of enamels. We use them in the manu-
facture of badges, watch and clock faces, and on
surfaces exposed to weather (advertisements), on th«
blades of exhaust fans, on baths and domestic utensils,
and on vessels employed in chemical industry.

An ordinary enamel may be prepared from common
glass fused with lead oxide, and rendered opaque by the
addition of oxide of tin. Colours may be produced
by the addition of other metallic oxides. Thus, from
copper we obtain green ; from iron or gold, red, and
from cobalt, blue. Small quantities of manganese
dioxide give us a fine violet colour and larger quantities
black. For the production of good colours, the
purity of the raw materials is of the first importance,
and the enamel maker looks, therefore, to the help
of the chemist to ensure satisfactory results. If an
enamel is to be pigmented with copper, the presence
of this metal in the raw material will not be objection-
able if its degree of oxidation is the same as that of the

76 WHAT INDUSTRY OWES

pigment used. If the enamel is to be coloured green
with cupric oxide and that substance is present in the
lead oxide used, the impurity is of small consequence ;
but if the enamel is to be coloured yellow with anti-
mony oxide, the green produced by the copper
impurity will spoil the effect. The presence of small
quantities of ferric oxide in the lime will modify the
green produced by copper oxide, and is undesirable
unless it be required to tone the green colour, when
it can be added to materials originally free from this
substance. In any case, the quantity of impurity
should be estimated and due allowance made for
its effect. Much may depend on the method of
preparation of the pigment. For instance, cupric
oxide may be prepared by roasting copper filings in
air, but the product will not yield nearly such good
colours as the oxide chemically prepared from pure
copper ; and again, the blue colour produced from
commercial cobalt compounds is greatly inferior to
that obtained from chemically prepared cobaltous
silicate.

Of the methods of preparing chemical and heat resist-
ing enamel for industrial plant little is common know-
ledge. In some cases the coating consists of two
layers, the first being devised to bind with the metal
and act as intermediary between the metal and the
finishing enamel. Having in view the uses to which
such vessels are put, there is plenty of room for
further investigation, particularly on the coefficients
of expansion of various metals and alloys and the
relation of such physical considerations to the
composition of the enamels employed. The surface
remains good until a craze appears, but once liquid
gets to the metal the vessel begins to lose its coating.
It is reassuring to know that chemical firms of long
standing find British enamel ware, such as evaporating
pans, at least as satisfactory as that from Germany,
though our manufacturers, as is often the case with
other commodities, have been less inclined to put
themselves about to supply special requirements, for
instance, with regard to the shapes and sizes of the
vessels required.

TO CHEMICAL SCIENCE 77

CHAPTER XI.
POTTERY AND PORCELAIN.

THE manufacture of pottery is yet another industry
which has been handed down from veiy early times.
Pliny attributed the craft, in which the Greeks and
Etruscans excelled, to Coraebus, an Athenian, but
obviously it was of far greater antiquity, the potter
being frequently referred to in ancient Egyptian
records to symbolise the Creator of man. The
earthenware of the Greeks and Romans was unglazed
and porous, but they rendered their vessels impervious
by covering them with wax, tallow and bitumen.
The invention of porcelain is generally credited to
the Chinese. It is mentioned in books of the Han
dynasty, the earliest date suggested being about
185 B.C. Its origin has been attributed to attempts
made to imitate glass imported from Syria and
Egypt, and by some it is supposed to have been
discovered accidentally by alchemists in their
search for the philosopher's stone. The industry
was started in Japan before 27 B.C., and found
its way from the Far East to Persia, where it is
known as chini, coming to us, in the course of time,
through Arabia, Spain, Italy and Holland, the
potteries of Lambeth being founded by men from
Holland about 1 640. Porcelain was made in France, at
St. Cloud, towards the end of the seventeenth
century, and in nearly all European countries in
the eighteenth century.

We can only marvel that such porcelain as, say,
that of the Ming Dynasty (1368-1643), with all
the technique involved in the selection of materials
and its treatment, the craftsmanship, colouring and
glazing, was produced before science, as we now use
the term, had any voice in such matters. The

78 WHAT INDUSTRY OWES

Chinese hard paste porcelain consisted of kaolin
in a pure and very finely divided state, and petuntzo
(finely ground felspathic stone) ; and the glaze was
made from selected petuntze mixed with specially-
prepared lime.

One of the first European makers of fine porcelain
of whom we have records was Botticher, a Saxon
chemist who was placed in charge of the Meissen
factory, established in 1710, the methods employed
being kept secret. Pott, a Prussian chemist, en-
deavoured to compete with him, and although his
efforts were not successful, his researches on materials
likely to be useful in porcelain manufacture gained
for the industry some helpful knowledge. About
the middle of the eighteenth century 700 men were
employed at Meissen, but in the meantime Stolzel,
who escaped from the factory about 1720, founded
the Austrian industry at Vienna, where 500 men
were employed in 1785. Mention should also be
made of the circumstance that William Cookworthy,
chemist of Plymouth, to whom we have already
referred in connection with cement, found kaolin
at Tregonning, near Helston, and took out a patent
in 1768, which he worked at Plymouth for two or
three years before establishing a factory at Bristol.
We must admit that the claims of science so far were
slender, and we do not propose to pursue the history
of the subject further ; but science required for her
own purposes porcelain resistant to chemical action,
heat, and variations of temperature. The production
of Royal Berlin basins and crucibles for the laboratory
could only be secured by careful selection and
utilisation of the most suitable materials and much
painstaking experiment. Science examined the pro-
cesses employed and explained the changes involved,
while one notable achievement, viz., the discovery
of means for measuring high temperatures, found
direct application in the industry. The temperature
of kilns is a factor of no little importance, and is
usually determined by cones made of oxides of iron,
aluminium, and silicon. The softening points of
the cones are known with reasonable accuracy — a

TO CHEMICAL SCIENCE

series of thirty-six allowing for the observation of
sufficient range of temperature in porcelain burning.
As the temperatures exceed 1000 deg. Cent, ordinary
thermometric methods are not applicable. The
series of cones could only be constructed and stan-
dardised with the aid of physical science, which has
provided Le Chatelier's thermo-electric pyrometer,
Callendar's platinum resistance thermometer and the
Fery radiation pyrometer. Their use in the stan-
dardisation of the cones, however, is, of course,
insignificant compared with their use in metal-
lurgical operations.

For supplies of porcelain for laboratory pur-
poses this country has hitherto been mainly de-
pendent, as in the case of glass, on Germany. Our
chemists have taken the matter in hand, however,
and remarkable progress has been made by several
British manufacturers. Research on the subject of
hard porcelain is progressing, and there is good ground
for hoping that this branch of the industry will be
retained here in the future.

The danger to workers of lead oxide as a constituent
of glazes for earthenware has also provided a problem
for chemists. The employment of lead silicates
instead of oxide, as suggested by Thorpe and Sim-
monds, is less harmful ; and the lead glazes have
been largely superseded in recent years by mixtures
containing silica, alumina, potash, and soda, with
about 10 per cent, of boric acid to increase the
fusibility. Where lead is an essential constituent
it is applied in the form of silicate.

80 WHAT INDUSTRY OWES

CHAPTEB XII.
CHEMICAL PRODUCTS.

IN our second chapter we have dealt with the
heavy chemicals and alkalies, and we will proceed
now to consider the production of other chemical
substances of value in industry, or useful for
domestic, medicinal, scientific, or other purposes.
The importance of this branch is so wide and
fundamental that it is not too much to say that
industry as a whole is largely dependent on an
adequate supply of chemical products. The field
is so great that we cannot attempt to indicate all
or nearly all the substances coming under this head,
but we will choose a few examples of different types,
all rendered available by scientific methods.

Acids. — Certain acids, such as tartaric, citric,
lactic, oxalic, formic, salicylic, benzoic, acetic,
hydrofluoric, boric, and arsenic acids are not prepared
on a scale comparable with that of sulphuric, hydro-
chloric, and nitric, but their value in technical
operations and for other purposes warrants their
industrial production in a condition more or less
pure, according to circumstances. Tartaric and
citric acids, from vegetable sources, and lactic acid
of animal origin, are used in calico printing. The
first is an ingredient of baking powders and effer-
vescing medicines, such as seidlitz powders, and
the second is used in the production of summer
beverages. Oxalic acid, -which is prepared by heating
sawdust with a mixture of caustic potash and soda
in the presence of air, is also used in calico printing,
and its acid salts are valuable as detergents, under
the name of salts of sorrel or salts of lemon. Formic
acid is useful in dyeing and tanning, and it is interest-
ing to note that it was formerly obtained by distilling

TO CHEMICAL SCIENCE 81

red ants, but is now made by heating caustic soda
with carbon monoxide under pressure. Salicylic
acid, which is prepared from phenol, is used in the
production of various drugs, of which aspirin is an
example, and is employed as an antiseptic. Benzoic
acid, from toluene, finds application in the manu-
facture of dyes and as a preservative ; acetic acid
in bleaching, dyeing, and calico printing, and in
the manufacture of artificial vinegar. Hydrofluoric
acid, which is obtained by the action of sulphuric
acid on fluorspar, comes on the market as an aqueous
solution in gutta-percha bottles, and is used for
etching glass as well as for antiseptic purposes.
Boric acid, from mineral sources, is valuable as a
constituent of various kinds of glass, and is used as
an antiseptic and a food preservative. Arsenic
acid is employed in dyeing and in the preparation
of certain aniline colours.

Bases. — Among the common bases we have caustic
potash, caustic soda — with which we have already
dealt — strontium hydroxide, and magnesia, — alkaline
metallic oxides capable of neutralising acids with the
production, by double decomposition, of salts and
water, the metals replacing the hydrogen in the
acids. Caustic potash is prepared either by electro-
lysis of the chloride or by the action of lime on a-
solution of potassium carbonate, that salt being
obtained from the chloride by a modification of the
Leblanc process or by a method identical in principle
with the ammonia-soda process, in which trimethyl-
amine — of which something will be said later —
takes the place of ammonia. For some purposes
the cheaper base, caustic soda, is equal in efficiency
to the more expensive but more powerful potash ;
but for others the latter is more economical — for
instance, in the production of oxalic acid from saw-
dust on the large scale. When caustic soda alone
is used, the yield of acid is not more than a third of
that obtained by the use of caustic potash or of a
mixture of potash and soda. On the other hand,
in the analysis of flue gases, a valuable check on
fuel economy, a soda solution of pyrogallic acid is

82 WHAT INDUSTRY OWES

a very much more rapid and efficient absorbing
reagent for oxygen than a potash solution of the
same. Caustic potash decomposes most metallic
salts, and at a high temperature acts with energy
on many substances. It is employed in numerous
industrial operations, and is ordinarily used for the
manufacture of soft soap, in which it is combined
with the fatty acids derived from the drying oils,
such as linseed, whale, and seal oils.

Strontium hydroxide, prepared mainly from the
mineral sulphate, is largely used in the extraction
of the uncrystallisable sugar from molasses. The
native carbonate requires a higher temperature for
calcination to oxide than does calcium carbonate to
lime. However, in certain sugar works, where fuel,
including exhausted cane, is cheap, this process is
used for the production of the material.

The use of magnesia in the ammonia-soda process,
and also as a refractory material, has already been
mentioned. Considerable quantities are consumed
in medicine as an anti-acid.

Salts. — The salts of technical importance are very
numerous. Those of sodium, on account of their
cheapness, easy solubility in water, and comparative
harmlessness, are in constant use in many in-
dustries, and are often interchangeable with
potassium salts ; but in some cases the special
properties of the latter yield better products for
manufacturing purposes. Potassium permanga-
nate and chlorate can be crystallised better
than the corresponding sodium salts, and are
therefore obtainable in a higher state of purity.
Potassium nitrate is used in the manufacture of
ordinary gunpowder, whereas the use of sodium
nitrate would be impracticable on account of its
ready absorption of atmospheric moisture. Potassium
sulphate, a constituent of ordinary alum, occurs as
the mineral kainite, and is valuable as a fertiliser.
Potassium f errocyanide and bichromate are ingredients
in the production of certain pigments, and the latter
finds employment in tanning and photography, as
well as in the cells of bichromate electric batteries.

TO CHEMICAL SCIENCE 83

Both these salts are now largely replaced by the
cheaper sodium compounds, owing to the stoppage
of supplies from Germany. A mixture of sodium
and potassium cyanides obtained by heating potassium
ferrocyanide with metallic sodium is used in the
Mac Arthur -Forrest gold extraction process. Sodium
nitrite and hypochlorite are largely used in the pro-
duction of dyestuffs, and, indeed, the fact that the
former was hitherto obtained almost exclusively
from Germany formed no small obstacle to the
manufacture of certain important dyes in this country.
Sodium thiosulphate — hypo — is used in bleaching
as an antichlor and in photography as a solvent for
silver halides. Sodium silicate — water glass — is used
for preserving eggs and also for protecting carbonate
stone buildings from the action of weathering.

Ammonium sulphate we have already mentioned
as an artificial manure. The chloride is used in
soldering, and its solution forms the electrolyte in
Leclanche cells. The nitrate is the source of ** laugh-
ing gas," and the commercial carbonate is commonly
the principal constituent of " smelling salts."

Mention must also be made of certain peroxy
compounds, some of which have attained considerable
technical importance in comparatively recent times.
Sodium peroxide is obtained by the action of hot air on
sodium contained in aluminium trays. The per-
carbonates and persulphates of sodium, potassium,
and ammonium are prepared by methods of electro-
lysis. Barium peroxide is made by heating the
oxide to a dull redness in dry air, free from carbon-
dioxide, and is used in the manufacture of hydrogen
peroxide, which, as are other peroxy compounds, is
largely applied as a bleaching agent for cellulose
materials.

The salts of barium and strontium are very useful
in pyrotechny, the former for producing green and
the latter red light. Magnesium sulphate is Epsom
salts. Mercury salts, including calomel, are also em-
ployed in medicine. Mercuric chloride or corrosive
sublimate is an excellent antiseptic, and the fulminate
is a useful explosive. Zinc chloride is used for the

Q

84 WHAT INDUSTRY OWES

destruction of insects and parasites, and other zinc
compounds are of medicinal value. Gold, silver,
and platinum salts are extensively used in photo-
graphy, and copper, tin, and antimony salts in
dyeing and calico printing. Copper salts are also
important in the Deacon chlorine process, in electro -
typing, in the manufacture of pigments, and the
protection of wheat from smut. Lead carbonate,
or white lead, is used in large quantities in paint
manufacture, and the azide is an explosive body,
which may be employed in percussion caps. Bismuth
and iron salts find good use in medicine, the sulphate
of iron being also useful in gold extraction.

Solvents. — Water, the commonest and most useful
solvent, cannot be discussed here for the obvious
reason that under ordinary conditions it is not a
chemical product from our point of view. Water
purified by distillation, however, is a commercial
article, and might perhaps be included. Among
inorganic solvents, mention must be made of ammo-
niacal copper solution for cellulose, and sulphur
chloride, which is prepared by the direct union of
the elements and is a valuable solvent for sulphur,
being largely employed in vulcanising rubber. The
common acids, such as nitric, sulphuric, and hydro-
chloric, are excellent solvents for metals and oxides,
but the solutions so obtained are not simple, the
original metal or oxide not being recoverable by
merely evaporating the solvent. Alcohol, or spirits
of wine, prepared by the rectification of fermented
liquor, is a valuable solvent in many ways, such as,
for instance, the purification of certain organic pro-
ducts by crystallisation from alcoholic solution.

In manufacturing processes, substances, such as
fatty oils, rubber, and sulphur, which are insoluble
in water, are frequently required in the form
of a solution, and it rests with the chemist to
discover the best solvents for such substances and
the methods of preparing and applying them.
Carbon disulphide, a volatile, poisonous, highly
refracting liquid, heavier than water, was discovered
in 1796 by Lampadius, who obtained it by distilling

TO CHEMICAL SCIENCE 85

iron pyrites with carbon. As ordinarily met with
it has a most obnoxious smell, but when pure the
odour is ethereal and not unpleasant. It occurs
in the products of the destructive distillation of coal,
but is manufactured mainly by the direct union of
charcoal or coke with sulphur in retorts or in the
electric furnace. Its uses are many ; it dissolves
sulphur, gums, rubber, phosphorus, resins, essential
oils, iodine, and alkaloids. It is used sometimes for
the extraction of fatty oils remaining in the residue
after crushing seeds, being subsequently removed by
distillation and used again. A solution of sulphur
in carbon disulphide is used for the vulcanisa-
tion of rubber. Its poisonous action has been
utilised for destroying blight in grain without ill
effects — except to the blight ; and potassium thio-
carbonate — a compound of carbon bisulphide and
potassium sulphide — is destructive to insects which
infest vines. On account of its high index of refrac'
tion, hollow glass prisms filled with carbon disulphide
are employed in spectroscopy. A solution of iodine
in carbon disulphide is of use in certain physical
experiments, for the reason that such a solution is
opaque to rays of light, while it transmits heat rays
freely. Lastly, we may mention that from carbon
disulphide and chlorine is obtained carbon tetra-
chloride, a solvent for fats, which is also employed
in the production of certain dyes, and being non-
inflammable, serves a useful purpose in fire -extinguish-
ing apparatus.

Among the organic solvents are several that are also
anaesthetics. Chloroform was discovered simultane-
ously by Guthrie, an American, and Souberain, a
Frenchman, in 1831, and was first employed as an anae-
sthetic by Lawrence in London, and Simpson in Edin-
burgh, in 1847. Itis prepared on the large scale by the
action of chloride of lime on alcohol or acetone, the
product being a valuable solvent for fatty oils, india-
rubber, alkaloids, resins, and other substances.
Prepared by the above process, however, it contains
highly poisonous impurities, which are gravely
detrimental to its use as an anaesthetic, for which

G 2

86 WHAT INDUSTRY OWES

purpose it is obtained by distilling chloral — resulting
from the action of chlorine on alcohol — or its hydrate
with caustic soda, the final product being sufficiently
pure.

Ether, another solvent, also an anaesthetic, was
known in the sixteenth century, and described by
Valerius Cordus, a German physician. It was
prepared by the action of sulphuric acid on alcohol,
and in the early part of the eighteenth century was
employed as a mixture with alcohol, under the
name of Hoffmann's Anodyne, to allay pain. Its
use as an anaesthetic was discovered by Charles
Jackson, of Boston, in 1842. The most economical
method of manufacture is the continuous process,
devised by Boullay.

Acetone, a valuable solvent for oils, and employed
largely in the manufacture of explosives, is found
in the free state in the products of the destructive
distillation of wood, and is obtained by the dry
distillation of acetate of lime, which substance is
also produced from pyroligneous acid.

Fine Chemicals. — The many substances we have
mentioned under the heading of chemical products,
represent only a very small proportion of those in
common use, and do not include all that are employed
in the laboratory, or those at present of purely
scientific interest, which are very numerous. We say
" at present " purposely, for no one can tell how soon
they may find practical application. The value of
" research for its own sake " has already been shown
in the many examples we have cited of the discovery
of elements and compounds, at first merely regarded
a,s scientific curiosities, but sooner or later proved to
be of incalculable importance to industry and to the
world. So much depends on the accuracy of
analytical results, that an adequate supply of
chemicals in a sufficiently pure state to be used as
reagents is an essential requirement in all laboratories.
The statement should be too obvious to mention, but
it must be remembered that we buy and sell on
analytical data ; we check and control vast technical
operations on such data, and must be able to rely on

TO CHEMICAL SCIENCE 37

sound reagents in most chemical investigations.
German fine chemicals have enjoyed a reputation for
purity, but of chemicals generally, apart from dye-
stuffs, we produce the bulk of our own requirements ;
our export trade has been greater than that of our
continental competitors, and there is no doubt that,
with increased scientific control and care, we can
manufacture products of equally high standard.

A number of concerns of established repute are now
energetically developing the fine chemical industry.
The processes of manufacture and purification call
for the services of highly trained chemists, of whom
the supply will certainly be forthcoming as the demand
for them increases.

A pamphlet prepared by a special committee
appointed by the Councils of the Institute of
Chemistry and of the Society of Public Analysts, was
issued early in 1915, giving details of the tests for
purity of a number of important analytical reagents.
This provides a standard for the manufacturers who
will still continue to make products of other grades
for various uses, while producing the fine chemicals
up to the specification standard at a higher cost,
which the consumer is always willing to pay. For
one example out of many, sulphuric acid for many
technical purposes is highly impure. In some cases
the impurities are substances which do not affect the
behaviour of the acid and its suitability for the purposes
for which it is required. A purer acid is made for
general laboratory use ; but for good analytical work
the acid must be free from lead, calcium and other
metals, from arsenic, selenium, nitrogen and halogen
•ompounds, and from reducing substances, and should
leave no solid residue on evaporation to dryness.
Tests are prescribed whereby such impurities may
be detected, but it is most advantageous to be able
to secure reliable supplies without the necessity of
applying them, and possibly being obliged to purify
the substances in the laboratory before using them.
The purification of sulphuric acid on the small scale
is an expensive, difficult, and tedious operation. It
is a hopeful sign therefore that a number of our well-

88 WHAT INDUSTRY OWES

known manufacturers are now producing guaranteed
analytical reagents of recognised standard degrees
of purity.

Drugs. — After all the references we have made to
the work of the chemist in industry, we do not need
to labour the distinction between the man who
practises chemistry and the man who practises
pharmacy. The latter has to depend on the former
for many of the materials he employs in dispensing,
or the physician may prescribe with very uncertain
results, and the patient perish, or, in any case, pay to
no purpose. The subject of drugs and pharma-
ceuticals, with all its ramifications into the substances
compounded into medicines of all kinds, pills, powders,
ointments, lotions, tinctures, and so forth, is too
extensive for us to treat adequately, and we can only
deal with the subject by indicating a few develop-
ments in this important branch of industry.

Many of the drugs used in medicine are of vegetable
origin. Quinine, for instance — discovered in 1820 by
Pelletier and Caventou — is extracted from the bark
of trees of the Cinchona species. Strychnine is
obtained from the seeds of various plants such as
Strychnos mix vomica. Atropine is prepared from
deadly nightshade juice, which contains two alkaloids,
hyoscyamine and hyoscine. The juice is treated with
caustic potash, the hyoscyamine being thereby con-
verted into atropine. The mixture is shaken with
chloroform and the solvent evaporated, the atropine
being extracted with dilute sulphuric acid, precipi-
tated by potassium carbonate, and re-crystallised from
alcohol. A solution of the alkaloid has the property,
when placed in the eye, of dilating the pupil, a most
useful aid to the ophthalmic surgeon.

An increasing number of useful organic drugs,
including alkaloids, is now made synthetically from
other chemical substances. Many of these are
unknown in Nature, their production and utilisation
being solely due to science. Salicylic acid and its
derivatives, including aspirin, are made from phenol,
and used extensively in the treatment of rheumatic
and nervous disorders. On account of certain objec-

TO CHEMICAL SCIENCE 89

tionable physiological properties, attempts have been,
and are being, made to obtain other derivatives that
have no such disadvantages, and good results have
been obtained with acetylsahcylic anhydride and
cinnamoylsalicylic anhydride. The antipyretics,
phenacetin and antifebrin, are made from phenol;
antipyrene, which is put to similar uses, being the
product obtained by methylating the pyrazolon
derivative formed by the condensation of acetoacetic
ester with phenylhydrazine. Derivatives of antipyrene
include salipyrene and tolypyrene. Veronal is
another synthetic drug.

The use of metallic compounds, as bactericidal
agents, has long been known. Compounds of mercury
have long been used in the treatment of certain dis-
eases. Recently the researches of Ehrlich on the
organic compounds of arsenic have done much to
alleviate suffering, such complex bodies being much
less poisonous to human beings than are the simpler
compounds of arsenic. Salvarsan and neosalvarsan
have met with success. One of the simplest of such
derivatives, atoxyl, has been used in the treatment of
sleeping sickness.

Local anaesthetics, administered hypodermically,
include cocaine, novacaine, and stoveine, the first
being extracted from the coca plant by alcohol acidi-
fied with a small quantity of sulphuric acid, and the
two latter being synthetic products.

Among antiseptics we must again mention phenol
(now being manufactured from benzene in large quan-
tities for making explosives), cresols, formaldehyde,
mercuric chloride — corrosive sublimate — and boric
acid ; while as disinfectants and insecticides, bleaching
powder, carbolic acid, potassium permanganate,
naphthalene, and zinc chloride — all chemical products
— are now largely used.

90 WHAT INDUSTRY OWES

CHAPTER XIII.
PHOTOGRAPHY.

THIS beautiful and now almost essential art is
dependent upon the action of light on various
chemical compounds, principally the salts of silver.
It was first observed by Boyle about the middle of
the seventeenth century, that luna cornea — silver
chloride — darkens on exposure to light, and this
phenomenon was further investigated by the Swedish
chemist, Scheele, in 1784. No attempt, however,
was made to utilise this property for the production
of pictures until 1802, when Thomas Wedgwood
obtained prints of leaves and other flat bodies on
sensitive surfaces prepared by moistening white
leather or paper with silver nitrate solution. Similar
experiments were carried out by Sir Humphry Davy,
but the pictures produced lacked one important
advantage ; they were not permanent in daylight, and
therefore had to be kept in the dark and examined
only in weak, artificial light. The next workers of
note were Niepce and Daguerre, a great advance
being made by the latter, when, in 1839, he introduced
a new departure, well-known as the daguerrotyp©
process. This was long ago superseded by other and
better methods, but it served the purpose of indicating
the right road to success. A plate of polished silver
was exposed to the action of iodine vapour, being
thereby covered with a film of silver iodide. On
exposure in a camera no apparent change took place
until development, as is the case with modern
photographic plates. The method of development
of the Daguerre plates was an accidental discovery.
Daguerre, while experimenting, was called away just
after he had removed a plate from his camera. For
safety, he put the plate in the first dark place that

TO CHEMICAL SCIENCE 91

caught his eye — a box containing odd pieces of
apparatus — and when he returned to continue the
work, he was surprised to find that during his absence
the image on the plate had developed. Investiga-
tion of the contents of the box led to the final con-
clusion that the agent was some metallic mercury
loose in the bottom of the box. This provided the
means of development, the plates after exposure to
light being acted upon by the vapour of mercury.
The image was made permanent by dissolving the
unaltered silver iodide in the parts less affected by
light with a hot solution of common salt, an improve-
ment being almost immediately effected by the
suggestion of Herschel, that sodium thiosulphate —
" hypo " — was a more suitable fixing agent.

Meanwhile, other investigators had not been idle.
In the Calotype or Talbotype process, elaborated by
Fox Talbot, and introduced in 1841, we find the
principle of modern photography showing signs of
active germination. The method depended entirely
on the use of papers sensitised with chloride and
iodide of silver. In his earlier researches, a piece of
paper was covered with silver chloride by immersion,
successively in solutions of common salt and silver
nitrate. Prolonged exposure in the camera resulted
in the production of a negative image, which could be
fixed by common salt solution. This method wa»
soon afterwards greatly modified in the following way.
The image formed by the camera lens was received
on a sheet of paper covered with silver iodide, and was
subsequently developed by a mixture of silver nitrate,
acetic acid, and gallie acid. When the resulting
negative was made transparent by means of wax,
positive prints could be obtained by allowing sunlight
to pass through the negative on to a piece of the sensi-
tive silver cKloride paper. The first use of glass
plates was made by Archer in 1851, the glass being
covered with a film of collodion in which cadmium
or zinc bromide or iodide had been dissolved. The
plate was sensitised by dipping into a solution of
silver nitrate and it was exposed in the wet state in the
camera, the image being developed by washing with

92 WHAT INDUSTRY OWES

some reducing agent, such as ferrous sulphate. The
image being fixed by a solution of sodium thiosulphate
or potassium cyanide provided, when dried, a negative
from which any number of positive prints could be
taken. By this means the detail of the pictures was
better than that given by the older processes, and other
advantages were obtained, including the shortened
time of exposure of the more sensitive collodion film.
By this time very many workers had entered the
field, and the art made rapid strides. A further
improvement was the introduction of dry plates, the
sensitive surface being composed of gelatine impreg-
nated with silver bromide ; but to give a detailed
history of the development of modern photography
would be beyond the scope of this article.

The modern dry plates consist of sheets of glasa
cut to standard size and covered with a gelatine
emulsion of silver bromide. The emulsion is prepared
by the inter-action of ammoniacal silver nitrate with
excess of potassium bromide containing a little iodide
in hot gelatine solution, the emulsion, formed being
kept at a temperature of 45 deg. Cent, for some time —
an operation which increases the sensitiveness. The
emulsion is then washed free from soluble salts, run
in an even coating on to the plates, and dried. After
exposure, the plates are developed by the reducing
action of certain compounds, such as pyrogallic acid,
hydroquinone, metol, ferrous oxalate, and others, with
various substances added to modify favourably the
course of development. The developed plates are
fixed by means of a solution of sodium thiosulphate,
well washed and dried. The introduction of celluloid
films has lessened the inconvenience attached to the
bulkiness and rigidity of plates, films being invariably
used when compactness and lightness of outfit are
required.

Many kinds of printing paper are available at
the present time. Silver chloride papers, both
in gelatine and collodion, are used for daylight
printing, ordinary P.O. P. being toned with a solution
containing gold chloride before fixing with hypo.
Self-toning papers require washing and fixing only,

TO CHEMICAL SCIENCE 93

the paper already containing the necessary gold, but
modifications of tone may be obtained by washing
the prints in a solution of common salt before fixing.
Silver bromide and silver iodide are the sensitive
bodies in bromide and gaslight papers, of which many
varieties are on the market, these papers requiring
development, as in the case of plates. Beautiful
tones may be obtained by platinotype papers.

Other methods of printing include the carbon
process, depending upon the fact that when a gelatine
solution of potassium bichromate is exposed to light,
the gelatine becomes insoluble in water. Brilliant
black and white prints may be obtained by the
adhesion, after washing, of finely divided carbon to
the insoluble gelatine surface. The paper for the
blue prints familiar to engineers is prepared by immer-
sion in a solution containing potassium ferrocyanide
and ferrous ammonium citrate, the prints merely
requiring to be washed in water and dried. Other
methods have been devised to obtain engineers'
prints in various colours on a white ground, but for
most purposes the blue print method is adequate.

Colour photography, which has attracted much
attention during the last few years, has been developed
with some success. Many processes have been
devised, one of the most striking being the mirror
method of Lippmann, which depends upon the
interference of direct and reflected rays at different
depths in the film, the ultimate deposition of metallic
silver produced by development occurring at a distance
from the reflecting surface fixed by the wave length
of the impinging light. On viewing the developed
and fixed plate similar interference phenomena take
place with the consequent natural colouring of the
image. With the aid of orthochromatic and of pan-
chromatic plates, prepared by the use of various
dyes, combined with screens or colour filters, excellent
coloured photographs may be obtained. Three -
plate and single-plate processes are available, the
latter type being more convenient. The Lumiere
process is a single-plate process, in which the screen
consists of a mixture of starch grains, dyed red,

WHAT INDUSTRY OWES

green, and blue, incorporated in a single layer in the
plate. All these colour photography processes,
however, are still somewhat expensive.

Mention could be made of many debts to photo-
graphy, including the discovery of radioactivity,
which was directly due to the sensitiveness of the
photographic plate, the discovery of stars too faint
to be observed by the most powerful telescopes, the
invention of photo -mechanical processes employed in
illustrating books and journals, photomicrography and
its numerous applications, and the cinematograph,
Apart from its everyday uses in peace and war.

Photographic Materials. — The manufacture of
photographic materials is essentially a branch of the
fine chemical industry, since the production of good
results depends as much on the purity of the materials
employed as on the manner of employing them.
Developers, such as pyrogallic acid, metol, and hydro -
quinone, toning solutions containing gold chloride,
and the materials for making and sensitising plates,
films, and printing papers must necessarily be pure.
In fact, the whole art of photography depends, from
start to finish, on a high order of scientific work, both
chemical and physical.

TO CHEMICAL SCIENCE 95

.CHAPTER XIV.
AGRICULTURE AND FOOD.

AGRICULTURE.

AGRICULTURE, though primarily concerned with the
cultivation of the soil — tillage, pasturage, and
gardening — may be regarded as the industry to
which we look, not only for food — animal and
vegetable — but, directly or indirectly, for clothing
and textiles, timber, drugs, leather, rubber, and a host
of other necessaries and comforts. Little reflection
is required to show that agriculture is dependent on
science, and, although many practical farmers
still scout such ideas, the various branches of the
industry owe much to geology, biology — botany and
zoology — chemistry, physics and meteorology, as well
as to the art of engineering. We propose to refer,
briefly, to the work of the chemist, especially in
connection with the subject of fertilisers.

The fear has been expressed from time to time that,
even making allowance for the effects of war, the pro-
duction of food will fall behind the needs of the
increasing population of the earth, unless science can
devise measures for coping with the problem. We
have shown how, through science, fields devoted to
the cultivation of indigo and madder have made way
for cereals, and we may confidently expect further
changes of the same kind, or even find, in the labora-
tory, means for obtaining food independently of the
processes of Nature by reproducing something akin
to the vital processes of vegetable and animal life.

Fertilisers. — Mother Earth readily repays the kindly
attentions of man and offers an illimitable field to
science in the development of food supplies for man
and beast. The chemist examines the soil, decides
the means to be adopted for the restoration of its

96 WHAT INDUSTRY OWES

fertility, and barren land is thereby reclaimed.
Natural manures, through the agency of which the
soil regains its creative energy, are supplemented by
artificial fertilisers, and the yield of foodstuffs is
increased. Thus, sodium nitrate, found in enormous
deposits in certain parts of Western South America, is
very largely used as a nitrogenous manure, the crude
material being purified by crystallisation. Potassium
sulphate, in the form of the mineral kierserite,
enriches the soil deficient in potash. Ammonium
sulphate, from the distillation of coal and shale, is
another valuable nitrogenous manure, and super-
phosphate of lime, prepared by the action of sulphuric
acid on mineral phosphates, provides a fertiliser
containing a large proportion of soluble phosphate.
The manufacture of this substance, moreover, has
been largely instrumental in keeping alive the lead
chamber process — chamber acid, as such, being suit-
able for the purpose.

The calculation of Vergara that the South American
sodium nitrate beds would be exhausted by the
year 1923 has been proved to be erroneous. Surveys
of the known beds show that the supply from them
will be sufficient to meet the increasing demand for
the next fifty years or more, while the general character
of the country leads to the reasonable supposition
that other beds of vast extent exist and will be
capable of supplying the needs of the world for a
further 200 years. However, the end must come
sooner or later, and in view of the importance of this
substance, both as a fertiliser and as a starting
material in the manufacture of potassium nitrate,
nitric acid, and other nitrogen compounds, the
prospective shortage has given an impetus to research
with the object of utilising the nitrogen in the air.
One of the methods employed aims at the preparation
of nitrates by heating air in a specially constructed
electric furnace in which, by a suitable arrangement
of electro -magnets, the arc is caused to assume a
discous shape. The oxide of nitrogen produced is
led away to an oxidising chamber, where it is converted
by atmospheric oxygen into a higher oxide, which is

TO CHEMICAL SCIENCE 97

absorbed by bases such as lime, soda, potash, or
ammonia. The process, primarily discovered by Sir
William Crookes, was adapted by McDougall and
Howies, in America, and later by Birkeland and Eyde,
in Norway, where electric power is cheap, and bases,
manufactured in Germany, were sent to Norway and
returned as nitrates.

The cyanamide process, which forms a great
German industry, consists in heating calcium carbide
with nitrogen in the electric furnace. The nitrogen
is obtained from liquid air by boiling off the oxygen,
or as residue from water gas or producer gas, which
has been used in the manufacture of hydrogen. The
cyanamide is applied directly as a manure, and on
exposure to water at ordinary temperature slowly
evolves ammonia, which, under the action of nitrifying
bacteria, is converted into compounds of nitrogen
readily absorbed by the plant. It may be noted also
that ammonia is easily formed by heating calcium
cyanamide with water under pressure. If barium
carbide is used instead of the calcium compound, the
main yield is barium cyanide, a convenient starting
material for the manufacture of other cyanides.

Nitrides, such as those of magnesium, boron, and
silicon, are prepared in the electric furnace, and find
application as manures rich in nitrogen and as sources
of ammonia, though their cost of production is rather
high. Many other processes have been patented and
used for the fixation of nitrogen, and British chemists
have not been idle, in spite of the difficulty of com-
peting against the lower cost of power in other
countries. Water power, abundant in Norway, is
readily converted into electricity, and is, therefore,
a most valuable possession in this connection ; but
we are assured that an earnest endeavour is being
made to produce nitrates in this country at the present
time. Incidentally, we would remark that the
fixation of nitrogen is of such importance that it is
practically certain that if Germany had not solved
the problem before the war, she could not have
maintained for so long the supply of munitions to her
army.

98 WHAT INDUSTRY OWES

Basic slag — the phosphatic slag from the Thomas
and Gilchrist basic Bessemer process — when finely
ground is a useful manure for certain purposes, grass
land especially deriving benefit from its application.
Its employment in other directions has not, so far,
been extensive, possibly owing to the existence of a
somewhat arbitrary standard of valuation. It is
desirable that careful experiment should be made
with various crops to ascertain if this standard is
reasonable for all purposes. In the result it is not
unlikely that great dumps of slag, hitherto regarded
as waste, both from the basic Bessemer and from the
open-hearth processes, may be available for agri-
cultural purposes.

The quality of artificial fertilisers is to some extent
safeguarded by the provisions of the Fertilisers and
Feeding Stuffs Act, under which the seller of any
artificially prepared or imported fertiliser, and any
artificially prepared feeding stuff, is required to give a
warranty to the purchaser as to the constituents of
value in these articles, and an undertaking that the per-
centages found in these articles do not differ from those
stated in the invoice, beyond certa.in prescribed limits
of error. Official agricultural analysts and samplers
are appointed to assist in the administration of the
Act, and the Board of Agriculture is empowered to
make regulations for the purpose of carrying the Act
into execution. It is generally agreed, however, that,
with few exceptions, the county and borough authori-
ties concerned have practically ignored it, and beyond
appointing officials as required by the Act have given
them little or nothing to do, so that offending traders
are rarely brought to justice.

Feeding Stuffs. — Among the principal artificially
prepared feeding stuffs for cattle and sheep may be
mentioned cotton cake and meal, which are very rich
in albuminoids, as are also cake and meal from the
ground nut and Chinese soya bean, and linseed and rape
cake, prepared from the marc or refuse from crushing
for oil. Other industries provide food material, such
as brewers' grains, malt dust and yeast, and beet
sugar fibrous wastes.

TO CHEMICAL SCIENCE 99

FOOD.

While, as we have indicated above, the measures
taken to assure the quality of food for cattle are, to
a large extent, ineffective, those taken in respect of
our own food are certainly more satisfactory, although
the Sale of Food and Drugs Acts might, with advan-
tage, be more thoroughly administered in some parts
of the country. The term " food " includes every
article used for food or drink by man, other than
drugs or water, and any article which ordinarily
enters into, or is used in, the composition or prepara-
tion of human food, and also flavouring matters and
condiments ; the term " drug " includes medicines
for internal or external use. Public analysts are
appointed to examine samples — chiefly milk and
dairy products — taken under the Act, and proceedings
frequently follow both in the interests of health and of
the prevention of fraud. Some may protest that the
work of the public analyst is not in the interests of
industry, but it must be admitted that the honest
vendor is directly protected by the prosecution of the
fraudulent, and it should be noted also that many
prepared foods, such as biscuits, cocoa, margarine,
preserved meat, fish, fruits and vegetables, jams and
confectionery, and beverages are produced under
scientific supervision.

The methods of preservation of perishable food
products are due to the application of science. The
sterilisation by boiling of meat and of fish, followed
by immediate hermetic sealing in cans, is the result
of a knowledge of the nature of bacterial life, as also
is the practice of preserving by the application of
cold, the meat or fish being either actually frozen, or
maintained at a temperature near the freezing point
without actual congelation. We will refer again to
the subject of cold storage later.

The law governing the sale of milk in this
country enacts that the content of fat (cream)
shall be not less than 3 per cent. The various
preservatives available for use are either prohi-
bited, or are restricted as to the quantity that

H

100 WHAT INDUSTRY OWES

may be added. This is a necessary precaution, as
most of the preservatives, such as formalin and boric
acid, are not desirable from the point of view of
health, especially in the case of milk, which is so
important to infants and invalids. The sterilisation
of milk by pasteurisation, which consists in prolonged
heating at a moderate temperature, is a useful means
of safeguarding the public health, the taste, and
therefore the palatability, of the milk being very little
affected by the treatment.

Science provides the means of distinguishing
between genuine butter and the various substitutes
now in common use, such distinction being necessary
for the detection of fraud.

Careful investigation by botanical workers, com-
bined with the proper application of manures, has
greatly increased the yield of cereals, and the cultiva-
tion of many other foodstuffs, such as roots, fruits,
tea and coffee, comes more and more under scientific
control, with beneficial results. We propose now to
consider, as an example, an important foodstuff, in
the production of which chemical, botanical and
mechanical sciences have played no mean part.

SUGAR.

Sugar is contained in the sap of many trees, such as
the date, palm, and the maple, and in nearly all fruits.
The main sources, however, are the sugar-cane and the
beet. The extraction of sugar from cane is said to
have been practised in Bengal and in China about
800 B.C., and existing records indicate that the Egyp-
tians, Arabs, and Persians were acquainted with cane
sugar over 1100 years ago. The cane is now culti-
vated in the West and East Indies, in the Southern
States,'and in South America.

In the old method of manipulation the cane, which
contains up to 18 per cent, of its weight in sugar, was
crushed between rollers, the expressed juice treated
with milk of lime to neutralise acidity, filtered and
evaporated to obtain the crystals. The solid was
separated by drainage in perforated casks, and the
mother liquor — which contains various substances

TO CHEMICAL /^eiESSf

which prevent complete crystallisation — appeared on
the market as treacle or molasses, or was fermented to
make rum. With modern mechanical and chemical
developments the industry has been brought to a
state of great efficiency. The introduction of evapo-
rating pans and similar plant has effected marked
ecofcomy in fuel ; the crystals are separated by
centrifuges, resulting in great saving of time, and a
leaf has been taken from the book of the beet sugar
manufacturers by the employment of a diffusion
process to replace the crushing. The cane is shredded
and soaked in water, the sugar diffusing through the
cell walls of the cane into the water, and the yield
is enormously increased.

The process of refining crude sugar generally
consists in dissolving it in hot water — blood being
added to very crude sugars to carry down impurities
in coagulating — filtering, decolourising by the action
of animal charcoal, and evaporating to crystallisation.
The products are separated into various grades
according to purity. As an instance of the value
of scientific control in sugar-refining processes, we
may mention that one concern has for many years
past effected a saving of between £75,000 and £100,000
a year as a return for an expenditure of £20,000 a
yea,r on it» laboratories and staffs of chemists.

Sugar was discovered in beetroot by Marggraf, a
German chemist, in 1747, but it was not until 1801
that a factory was established for its extraction,
the first being erected in Silesia by Achard. In
the light of present-day events it is interesting to
observe that the German industry received consider-
able impetus in its early years through the land
blockade of Prussia, enforced by Buonaparte, which
made the home production of sugar a necessity.
Buonaparte also gave encouragement to the estab-
lishment of the industry in France, and it is now
carried on in Russia, Holland, and other European
countries. The juice of the common beet contains
only a low percentage of sugar, but by careful
scientific cultivation the yield has been steadily
increased, so that some varieties give over 15 Ib.

H 2

102 WHAT INDUSTRY OWES

of sugar per 100 Ib. of beet, instead of about 6 Ib. or
less. The yield of beetroot from the land has been
increased by about 15 per cent., and the coal con-
sumption in the process of extraction has been
reduced by about 80 per cent. The exhausted sub-
stance is utilised for making feeding stuffs for cattle.
In the early method of extraction the roots were
cleaned and shredded, the shreds placed in woollen
bags, and the juice squeezed out by hydraulic
pressure. This practice still prevails in some places,
but has been replaced in others by the cleaner and
more efficient diffusion process. The roots are
cut into thin strips which are exposed to the action
of water ; the sugar diffuses out into the water,
leaving colloidal substances in the cells, the walls
of which are impervious to colloids. The treatment
of the juice is similar to that employed in the case
of cane sugar, the yield of crystallised sugar being
about 70 per cent, of the sugar in the root, the other
30 per cent, remaining in solution as molasses or
treacle, to be sold as such or used to make rum.

Increased yields of sugar in the crystallised state,
from both cane and beet, are largely attributable
to the Osmose process, based on Graham's work
on dialysis, and the Elution processes elaborated by
Steffen and by Scheibler. In the first process the
sugar is allowed to diffuse through a parchment
membrane into pure water, the substances which
prevent crystallisation being unable to pass through
the membrane. The solution obtained is then worked
up for sugar and for potassium nitrate which accom-
panies it, while the remaining liquor goes to the
distillery for the manufacture of by-products.

The Elution processes depend on the formation of
the sparingly soluble calcium or strontium salts
formed by sugar — calcium and strontium saccharates.
These salts, obtained by various methods in pure
condition from the sugar in molasses, are suspended
in water and decomposed into sugar and calcium or
strontium carbonate, as the case may be, by the action
of carbonic acid gas.

Other such processes have boen devised, but that

TO CHEMICAL SCIENCE 103

involving the use of strontium hydroxide is most
largely employed.

COLD STORAGE.

A valuable by-product of the beet sugar industry
is trimethylamine, which is obtained by distillation
from the final residue or vinasses of the Osmose
process, and also in large quantities from herring-brine
by distillation with lime. It is a gas at ordinary
temperatures condensing in the cold to a liquid
which boils at 3.5 deg. Cent., and is used, as we have
noticed before, in the place of ammonia, in the
manufacture of potassium bicarbonate by a method
analogous to the ammonia soda process. By heating
its hydrochloride with hydrochloric acid, methyl
chloride, an easily condensable gas, is obtained, and
used for making certain dyes, and also as a freezing
agent in the technical production of ice.

The preservation of food by cold storage is of
great importance, and depends for its usefulness
upon the availability of a large and cheap supply of
ice. In the preparation of ice, advantage is taken
of the heat absorption of boiling liquids. A gas
that can easily be liquefied by pressure can be used
as a freezing agent, provided that its other properties
are not objectionable. The gas is liquefied by
mechanical pressure, and is then allowed to evaporate
under low pressure, the only heat available for its
vaporisation being that contained by the water it
is desired to freeze. The freezing agent is, of course,
not destroyed, but can be recondensed and used
over again. Gases in common use as freezing agents
are methyl chloride, which liquefies t at ordinary
temperature under two or three atmospheres pressure,
and boils under ordinary pressure at 24 Centigrade
degrees below zero, ammonia gas, which liquefies
under about six or seven atmospheres and boils under
ordinary pressure at 33.5 Centigrade degrees below zero,
carbonic acid gas, and cymogene (referred to in
Chapter V.).

104 WHAT INDUSTRY OWES

CHAPTER XV.
BREWING.

THE production of malted liquors was one of the
first industries to recognise the value of scientific
investigation in the elucidation of technological pro-
blems ; but the industry has not alone profited — the
field of work has proved so rich in discovery that an
important domain of chemical science, the chemistry
of fermentation, with its applications to the leather,
tobacco, food and other industries, as well as to physio-
logical science, has been opened up, primarily through
the study of the principles underlying the practice
of brewing.

Alcoholic liquors were brewed from grain stuffs in
Egypt as early as the 4th Dynasty (B.C. 3000 to
4000), the beverages taking the place of wine in
countries where the climatic conditions were un-
favourable to the cultivation of the vine. Although
the Egyptians had vineyards in the Nile Valley, it is
probable that this restriction of area gave rise to the
brewing of grain liquors in other less favoured parts.
The earliest fermented liquor known in Britain was
mead, made from honey ; the production of beer
from barley, and of cider from apples followed in the
order indicated. All three beverages were in use in
the South of England at the time of the invasion by
the Romans, who are said to have considerably
improved the manufacture of beer, which subse-
quently became the national drink of the country.
In the Middle Ages rents were sometimes paid in malt
or beer, and it is not without interest to note that one
of the municipal appointments in the time of Queen
Elizabeth was that of the ale -taster, a post held
by the father of William Shakespeare at Stratford-
on-Avon. Ale-tasters were required to examine

TO CHEMICAL SCIENCE 105

beer and ale to see that they were good and whole-
some, and sold at proper prices. Public analysts
may now be considered to carry on these duties,
the custom of appointing ale -tasters having been
discontinued in most places since beer and ale
became excisable commodities.

In normal times about 35 million barrels of 36 gallons
are brewed per year in the United Kingdom, involving
the consumption of 50 million bushels of malt, over
60 million pounds weight of hops, more than a million
hundredweights of specially prepared rice and
maize, and about three million hundredweights of
sugar.

The question of water supply is of great importance
to the brewer, the nature of the impurities in the
water used in mashing greatly influencing the quality
of the product. The excellence of the pale ales pro-
duced at Burton has been traced to the existence in
solution of large quantities of calcium and magnesium
sulphates in the Burton well water. Stout and porter
are better brewed with the softer water of London or
Dublin, which does not contain the sulphates above
mentioned. Sometimes the water in a locality can be
so modified, by the addition of the requisite substances,
as to be suitable for the brewing of different classes
of beer ; but the industry has been largely established
in districts where the natural supply needs no special
treatment.

The production of beer from barley involves three
main operations : the conversion of the grain into
malt ; the preparation of an infusion of the malt
called wort ; and the fermentation of the wort by
means of yeast. Malt is obtained by keeping barley
in a moist atmosphere until the induced germination
has proceeded to the requisite extent determined by
examination of the grain. The product is then
heated to a temperature above 50 deg. Cent, to stop
germination. The infusion known as wort is made by
mashing the finely ground malt with water, and
keeping it for some time at about 67 deg. Cent. The
resulting liquor, after straining through spent wort,
is sterilised by boiling, when hops are added to impart

106 WHAT INDUSTRY OWES

a bitter flavour, and to yield to the liquor certain
preservative substances. The liquor is then cleared
by settling, drawn off, cooled by " coolers " and
refrigerators, and fermented by yeast.

The chief change taking place in malting barley is
the production of an active body called diastase, which
has the power to convert starch into sugar. During
malting albuminoid substances are broken down into
simpler bodies, and the starch undergoes modifica-
tions, assuming a form more easily attacked by the
diastase. During the mashing operation the starch
is converted by the diastase into a sugar, which is fer-
mentable by yeast, thereby yielding alcohol. As the
finished malt contains much more diastase than is
necessary to convert all the starch present into sugar,
starch, in the form of flaked rice or flaked maize, is
sometimes added to the malt before mashing, the
final result being an increased production of alcohol.
When desirable the quantity of sugar in the wort can
be increased by. the direct addition of invert sugar
or of glucose. Invert sugar, which contains nearly
equal quantities of two fermentable sugars — dextrose
and laevulose — is produced in large quantities for the
use of brewers b^ boiling cane sugar with dilute
mineral acids, whilst glucose, containing two sugars —
dextrose and maltose — is made by the hydrolytic
action of dilute mineral acids on starch, an inter-
mediate product being dextrin (British gum). If
the action of the acid were further prolonged dextrose
alone would be the main product. Brewers'
glucose contains 60—70 per cent, of fermentable
sugars.

By boiling, the wort is sterilised and concentrated,
certain complex protein bodies are eliminated by
precipitation, diastatic action is stopped, and the
flavouring and preservative materials are extracted
from the hops which are added at this stage. Hops
contain a yellow granular powder called lupulin,
which is the most valuable constituent from the
brewers' point of view. The lupulin in new hops may
amount to 15 per cent, or more, and contains resins
and bitter principles, which give a flavouring and

TO CHEMICAL ^SCIENCE 107

exert a preservative action on the beer ; and
certain volatile essential oils which also improve the
flavour.

By fermentation with yeast the sugars in the wort
are transformed into alcohol and carbonic acid gas.
The growth of yeast, when supplied with suitable
foods, and its remarkable action on certain sugars,
have held the attention of scientific men for years.
Liebig, in 1839, advanced the theory that yeast, an
unstable nitrogenous compound, possessed the pro-
perty of communicating this instability to sugars,
causing them to decompose, but the living nature of
yeast was not then recognised. About thirty years
later Liebig' s views were overthrown by Pasteur after
a long controversy, and Liebig was compelled to make
certain modifications in his theory. As the result of
a series of epoch-making experiments, Pasteur came
to the conclusion that yeast was an organism capable,
under certain conditions, of maintaining its life with-
out the aid of atmospheric oxygen, that element being
derived from sugars, the presence of which fulfilled
the conditions. The maximum fermentative power
of yeast was therefore attained in the absence of
atmospheric oxygen. This theory held the field until
1892, when the researches of Adrian J. Brown showed
it to be untenable. In 1897 Buchner demonstrated
that the living yeast cell is not necessary for fermen-
tation, but that the clear liquid extracted from the
yeast by heavy pressure served the purpose. He
proved conclusively that the cause of the fermentation
is an enzyme, which he called zymase. Further light
has been thrown on the problem by Arthur Harden,
who separated the active liquid into two inactive
constituents — the enzyme and the co -enzyme — which,
when remixed, became once more active. Harden
has also shown the importance of phosphates in
accelerating the change. To summarise: the living
yeast contains and reproduces an active non-living
body which is capable of converting sugars into
alcohol and carbonic acid gas. The yeast grows
at the expense of certain foods present in the
wort.

108 WHAT INDUSTRY OWES

Utilisation of Waste Products. — Dried yeast is used
as a cattle food, and as the source of an excellent
substitute for meat extract. Carbonic acid gas is
compressed and used for the aeration of beer and
mineral waters.

TO CHEMICAL SCIENCE 109

CHAPTEB XVI.
ALCOHOL, WINES AND SPIRITS.

ALCOHOL is one of the most important chemical
products. We have already referred to it as a
solvent, in which capacity it is of great service to the
chemist in the laboratory as well as in industrial
operations involved in the manufacture of transparent
soap, varnishes, French polish, collodion, and celluloid.
It is not only as a solvent, however, that it figures
extensively in the arts and manufactures. It is used
in the technical preparation of chloroform, iodoform,
fulminates, ether, acetic acid, and many other bodies.
For certain purposes — such as the production of some
kinds of whiskey and brandy, and of liqueurs, and in
the manufacture of scents, fine chemicals and drugs —
only alcohol of a considerable degree of purity can
be used, and the expense is correspondingly high.

Alcohol is made from the cheapest starchy materials
available, such as potatoes, maize, turnips, molasses.
The raw material is mashed with about 5 per cent,
of malt, and fermented in the usual way. After
distillation in a Coffey still, the spirit is diluted with
water, filtered through wood charcoal to remove
fusel oil and redistilled through a fractionating
column. The products are separated into three
grades : first runnings, and first and second quality
spirits. The first runnings, containing about 95 per
cent, of alcohol with a small quantity of aldehyde,
may be used for burning and in manufactures where
the impurities give rise to no deleterious effects.
The first and second qualities, which are 96 to 97 per
cent, in strength and contain only traces of aldehyde —
the second quality also containing a small quantity
of fusel oil — are known as silent spirit, because they
afford no evidence of their source. These qualities

110 WHAT INDUSTRY OWES

are used for drinking purposes — liqueurs and factitious
brandy and whiskey — and for pharmaceutical pre-
parations.

Absolute alcohol, containing 99 per cent, or more of
alcohol, is obtained by dehydrating the finer spirits
by redistilling with about half their weight of quick-
lime, whilst 100 per cent, alcohol may be prepared by
the addition of a small quantity of metallic sodium
to absolute alcohol and further redistillation.

The denaturing of industrial spirit — rectified spirit
and first runnings — consists in adding to the alcohol,
to render it undrinkable, some substance or substances
which cannot be profitably separated, and which have
the minimum harmful effect in the | processes
demanding the use of such spirit. Were it not for
the fact that in most countries the Governments per-
mit the sale and use of denatured or undrinkable spirit
free of duty, the high duty on such spirit would
render its use in ordinary manufactures prohibitive
from the point of view of economy, and the absence
of such facilities would prove a great hindrance to
the industries concerned.

Methylated spirit is duty free, and may be used
instead of rectified spirit— spirits of wine — in the
manufacture of chloroform and varnishes, for pre-
serving anatomical specimens and for many other
purposes. It was originally made by adding about
10 per cent, of methyl alcohol — wood spirit — a product
of the destructive distillation of wood, which has a
sharp fiery flavour and contains substances dis-
agreeable both to taste and smell. The presence of
wood spirit, however, has little or no effect on the
industrial uses of alcohol, from which, moreover, it
cannot be profitably removed. The main use of
wood spirit, therefore, is for denaturing purposes ;
but it is also employed as a solvent for resins and in
the manufacture of dyes, its characteristic component
CHS, appearing in this role as a constituent of the
intermediate products methylaniline and dimethyl -
aniline, bases largely used for the production of basic
dyes, such as methyl violet — the colouring matter of
recording, copying, and typewriting inks — malachite

TO CHEMICAL SCIENCE 111

green, and methylene blue. The processes for the
extraction and purification of wood spirit, however,
were in the course of time so far improved, that its
purity eventually unfitted it for use alone as a de-
naturant ; it is still universally used for the purpose,
but with the enforced addition of other more dis-
agreeable substances, such as — in the case of ordinary
methylated spirit — not less than f per cent, of
paraffin of specific gravity 0.800. For some manu-
facturing purposes the paraffin is a disturbing factor,
causing turbidity on mixing with water, and being
unsatisfactory in other respects. To obviate these
disadvantages, various denatured spirits are now
made, containing from 2 to 10 per cent, of wood
spirit with a smaller quantity of other substances of
unpleasant taste, the choice being determined
according to the purpose for which the spirit is to be
employed. Thus, in the manufacture of transparent
soap, a spirit denatured with wood spirit, castor oil
and caustic soda is useful ; in making mercury
fulminate, a mixture of wood spirit with pyridine
bases forms a suitable denaturant ; and in making
celluloid the spirit may be mixed with wood spirit,
camphor, and benzene. Other denaturants include
toluol, xylol, wood vinegar, turpentine, animal oil,
chloroform, iodoform, and ethyl bromide, according
to the needs of the industry for which the spirit is
required.

Wines. — The production of wines by the fermen-
tation of grapes is an industry of great antiquity.
Several words in Hebrew are translated in our Old
Testament as wine, and we find it associated with Noah,
who, when he began to be an husbandman, planted
a vineyard, drank of the wine and was drunken.
Fermented grape juice was a beverage of the ancient
Egyptians five or six thousand years before our time.

Wine is made by allowing the juice of grapes
to ferment spontaneously, the organism inducing
the change occurring plentifully in the air dust of
vine-growing countries, and speedily infecting any
sugary liquor freely exposed to the air. When white
wine is the product desired, all the seeds and husks

112 WHAT INDUSTRY OWES

of the grapes are carefully excluded, because it is
from these that the colouring matter of red wines
is extracted by the alcoholic liquid produced by
fermentation. The seeds and husks also give up
a small quantity of tannin, which acts favourably
as a preservative of the red wines, and prevents
ropiness. Sparkling wines, such as champagne, are
made by dissolving sugar in a still wine and allowing
it to undergo secondary fermentation in the bottle.
Ordinarily, wine consists of a mixture of alcohol
and water, containing from 7 to 17 per cent, of the
former, together with smaller quantities of sugar,
bitartrate of potash, glycerine, and other bodies,
including traces of flavouring matters. If a sugar
solution contains much more than 30 per cent, of its
weight of sugar it cannot be fermented by yeast.
A solution of alcohol of 16-17 per cent, strength
also inhibits the action of yeast, and it follows,
therefore, that fermented liquor cannot contain more
than this percentage. Should a wine of greater
strength be desired, it can be obtained only by the
addition of stronger distilled spirit. Thus the
strongest port wine, as produced by the ordinary
fermentation, contains not more than 16 to 17 per
cent, of alcohol, but it can be " fortified " if necessary
by the addition of absolute alcohol or rectified spirit
in the proper proportion. For this purpose it is
desirable to use the strongest alcohol obtainable,
as if a weaker, e.g., less than 90 per cent., were used,
the water necessarily added with it would dilute
the other ingredients of the wine to an abnormal
extent, and modify unfavourably its original
characteristics.

Spirits may be divided roughly into two classes, ( 1 )
pot-still spirits, including brandy and whiskey ; and (2)
gin spirits, made by the suitable treatment of plain
rectified spirit or alcohol. The manufacture of
spirits was made possible only by the discovery
of the process of distillation, and is not, therefore,
of such antiquity as the wine and beer industries.
The products differ from fermented liquors from which
they are produced, mainly in the larger content of

TO CHEMICAL SCIENCE 113

alcohol, in the absence of non-volatile matter, and
in the possession of certain distinct flavouring matters,
either occurring naturally or added purposely.
Cognac brandy is made by distilling from a pot
the fermented juice of a small variety of grape,
the alcohol passing over among the first products
of the distillation. The spirit contains about 50 per
cent, of alcohol, and owes its aroma and flavour
to small quantities of capric (cenanthic) ester derived
from the wine. The colour of genuine old brandy
is due to colouring matter extracted from the wood
of the casks in which it is stored, its astringent
flavour being due to tannin from the same source.
New brandy is coloured to resemble the old by the
addition of caramel (sugar — generally starch sugar —
heated to about 190 deg. Cent.), astringency being
sometimes imparted by an infusion of tea.

Whiskey is made from malted barley, or from
a mixture of unmalted and malted grain, the mixture
being dried over a peat fire, from which the whiskey
derives its smoky flavour. By a washing operation
similar to that practised by brewers, a wort is produced
which is cooled quickly by refrigerators and fermented
by purified brewers' yeast, as completely as possible,
at a low temperature. These conditions combine
to ensure the production of a good liquor free from
sourness, and with the minimum of wasteful and
objectionable impurities such as fusel oil and
aldehyde. When the fermentation stops, the liquor
is distilled from a large copper still — up to 12,000
gallons — sometimes with the addition of soap to
prevent undue frothing until all the alcohol has
passed over. The distillate from this operation
known as " low wines " is poor in alcohol and requires
a second distillation. The residue remaining in
the still contains a small quantity of lactic acid,
which is often recovered and used as a substitute
for acetic and tartaric acids in processes where a
weak acid is required, and where the chemical nature
of the acid is not of first importance. The second
distillate is collected in three fractions called " fore-
shoots," " clean spirits," and " feints." The clean

114 WHAT INDUSTRY OWES

spirit is a strong whiskey containing about 60 per
cent, of alcohol. It is generally diluted with water
to about 40 per cent, before being sold to the customer,
the minimum being fixed by Act of Parliament (1879)
at 37 per cent, by weight. The fore-shoots are
highly impure, containing fatty acids and other
substances, while the " feints " consist chiefly of
fusel oil, a mixture of higher boiling alcohols, used
in recent years as a raw material in the production
of synthetic rubber, and also as a solvent. The
" spent lees " remaining in the still is a waste for
which as yet no useful application has been found.

British brandy and whiskey prepared in a similar
way from potato starch need to be freed from a rather
larger percentage of fusel oil than does barley spirit.

Rum, which is made by fermenting treacle or
molasses, and twice distilling the product, owes its
flavour to formic and butyric esters, and is coloured
either by ageing in wood, or artificially by means of
caramel.

The plain spirit, i.e., a mixture containing water
and alcohol only, which is used to make gin and
liqueurs, is produced by fermenting a mixture of
malted and unmalted grain, and distilling the resulting
alcoholic liquor or " wash " through a special fraction-
ating apparatus such as the Coffey still. WThen
distillation takes place from a pot-still little fraction -
ation occurs, and a large proportion of the lower
and higher boiling substances pass over with the
alcohol, necessitating a second distillation ; but by
the use of a contrivance such as the Coffey still,
which is too complicated for description here, the
greater proportion of the impurities can be eliminated
by one distillation.

Gin is made by adding some substance, such as
juniper or liquorice root, to the spirit, and re-dis-
tilling from a pot, when the distillate passing over
carries with it the flavouring matter extracted
from the root. Liqueurs are made by dissolving
large quantities of sugar in the alcohol with various
flavouring and colouring materials.

TO CHEMICAL SCIENCE 115

CHAPTER XVII.

TOBACCO, INKS, PENCILS, &c.

TOBACCO is cultivated in many countries, especially
in Virginia and the Southern States, in Mexico,
Cuba, and the West Indies, in Asia Minor and Persia,
in India, China, and Borneo, and in South Africa,
and affords scope for the botanist, biologist, and
chemist, both in the plantations and in the factories.
In the days of Columbus the natives of the West
Indies smoked the rolled leaf, the Mexicans and
North American Indians used pipes, and the Aztecs
and Hispaniolan Indians applied forked tubes to
the nostrils. Tobacco was introduced into Europe
by Hermandez de Toledo in 1559, into England by
Sir John Hawkins in 1565, and its use speedily
became very general in spite of all forms of opposition.
Smoking was the butt of the wits, denounced by
the clergy, and condemned by rulers and popes,
offenders being subject to severe punishment. In
Turkey it was a capital offence, and in the canton
of Berne was prohibited as an addition to the deca-
logue. In England King James I. issued a " Counter -
blaste to Tobacco," in which smoking was described
as " a custom loathsome to the eye, hateful to the
nose, harmful to the brains, dangerous to the lungs"
. . . as " resembling the horrible smoke of the pit
that is bottomless ; " but although often the subject
of violent diatribes, it remains at the present day
a most popular luxury among, both rich and poor,
and we may contrast the views of the Stuart King
with those of Kingsley indicated in " Westward Ho ! "
" When all things were made none was made better
than Tobacco ; to be a lone man's Companion, a
bachelor's Friend, a hungry man's Food, a sad man's

r

116 WHAT INDUSTRY OWES

Cordial, a wakeful man's Sleep, a chilly man's Fire.
There's no herb like it under the canopy of Heaven."

Tobacco is rarely prescribed in medicine or
employed in pharmacy ; but it is well known that
smoking in moderation acts as a sedative, and is often
beneficial in promoting expectoration in cases of
asthma. Snuff, which is prepared from the ribs
and stems of the tobacco leaf, is occasionally recom-
mended to excite the secretion of mucus from the
nasal membrane. The absorption of very small
quantities of nicotine is stimulating to mind and
body, but in excess the effect is depressing, narcotic,
and injurious to the sight. Much depends upon
the constitution of the smoker, habituation, and other
circumstances. But we have digressed from our
object. The industry is an important one from the
financial standpoint. In normal times we spend
between four and five million pounds on imported
tobacco — more than twice the expenditure on dyes —
and the smoker pays very heavily to the Exchequer for
his luxury. He is protected, however, by the
inspection of imported tobacco by the Government
laboratory. Many thousand samples are examined
annually, in accordance with the legislation for-
bidding adulteration or excess of moisture, offenders
being liable to heavy penalties. Tobacco was formerly
much adulterated with leaves of rhubarb, cabbage,
dock and the like, as well as with sugar, starch,
and gum ; but although sweetening matters such
as sugar, treacle, liquorice, and glycerine are occasion-
ally present in imported tobacco, adulterants are
now comparatively rarely detected.

The chemical composition of tobacco is highly
complex, the determinable constituents numbering
over twenty. The quality of the leaf is attributed
to the nature of the soil where it is grown, though the
finished product must remain largely a matter of taste.
The methods of manufacture depend on the variety
of tobacco and the purpose for which it is intended ;
and the processes are supervised more and more
by men of hcience who can render useful assistance
in many ways, such as the prevention of mouldiness

TO CHEMICAL SCIENCE 117

and the utilisation of waste. The leaves, when
harvested, are allowed to wither to a certain extent,
and then undergo shed-drying or sweating in moderate
heaps covered with matting. The leaf cells transpire
carbohydrates, albuminoid matters become con-
verted into amides, and the heat generated effects
the drying of the leaves, which then undergo fermenta-
tion in bundles arranged in large heaps. Tons of
tobacco are thus allowed to decompose rapidly at
a temperature usually kept below 50 deg. Cent.,
the bundles being turned about so that all are equally
affected. Suchsland is stated to have prepared
cultures of the bacteria of the fermentation, and to
have transferred them from fine West Indian to
German tobacco in the course of fermentation,
with remarkable improvement to the latter.

The leaf as imported to this country is subjected
to secondary fermentation after the addition of
5 to 25 per cent, of water, and is dried or stoved on
heated open trays, or in closed ovens subjected
sometimes to injections of steam, different methods
of treatment affecting the flavour of the product.
The content of nicotine in the leaf varies from 1 to
5, though it is sometimes as high as 8 per cent.; a
single cigar often contains a deadly dose, but it retreats
from the heat as the tobacco burns and accumulates
in the stump or butt. By passing a current of steam
through a mixture of lime and tobacco dust, neutralis-
ing the resulting liquid with sulphuric acid, and adding
caustic potash, nicotine is liberated and may be
dissolved in ether, the solution yielding almost
pure alkaloid, which is employed in the manufacture
of insecticides for horticultural purposes.

We propose now to deal with a few industries under
scientific control which employ chemical products,
and relate to commodities in everyday use.

Inks. — In early times the thoughts and actions of
men were incised on stone, impressed on clay or wax,
or carved on ivory, metal or wood ; but with the
introduction of papyrus, which we have mentioned in

i 2

118 WHAT INDUSTRY OWES

the chapter on cellulose, characters were formed by the
application of coloured fluids by means of a brush or
reed. The word " ink " is associated more closely
with the more ancient methods, being derived from
the Greek encaustos (burnt in), and from the Latin
encaustum (the purple-red ink used by the later
Roman Emperors). The oldest writing material
appears to have been composed of very finely divided
carbon hi a solution of an adhesive substance, which
held the carbon in suspension and fixed it to the
papyrus. Ink of this sort has been found on ancient
Egyptian papyri, and was no doubt also in use in
China at least as early. Carbon inks are permanent
and very resistant to chemical action, but there is a
tendency for the pigment to sink in the liquid unless
it is frequently stirred. Printing inks also consist
mainly of carbon with well-boiled drying oils and soap
or resinous matter. For ordinary writing purposes,
however, carbon inks were superseded centuries ago
by iron-tannin inks, prepared from a decoction of
galls with copperas and gum arabic, formerly home
made, but now produced in common with many other
domestic requirements on an industrial scale. The
action of the tannin — from the decoction of galls — on
the copperas produced a precipitate, which, being
insoluble, formed a deposit, but manufacturers
avoided these conditions by excluding air to prevent
oxidation, and by adding soluble colouring matter.
Good writing ink should remain sweet and fluid when
exposed to air, should be permanent to light under
ordinary atmospheric conditions, and not contain an
excess of free acid which would injure the pen and
paper, though the ink is not always to be blamed for
these contingencies. In the middle of the eighteenth
century logwood was added ; in many cases it replaced
the tannin entirely, and still forms the basis of some
inks. Coloured inks have also been prepared with
cochineal and indigo, and with the introduction of
coal tar dyes a large variety of easily running inks,
specially suitable for stylographic and fountain pens,
have been rendered available, though it should be
remarked that they are not regarded as so permanent

TO CHEMICAL SCIENCE 119

as the iron-gallo-tannates. Many typewriter ribbons
are prepared with coal tar dyes, and are therefore open
to this objection, the ink being fairly easily removed by
chemical means. Inks highly sensitive to tampering
are employed for bankers' cheques, and the detection
of forgeries often depends on the effects produced by
treatment with various chemical reagents. Copying
inks are concentrated writing solutions, usually con-
taining two or three times the amount of colouring
and thickening matter. It is probably no news to
engineers that James Watt invented the copying
press, the patent for which was granted to him in 1780.
He employed an ink prepared from a decoction of
Aleppo galls, green copperas and gum arabic, which
is much the same as the inks now used for the same
purpose, except that they contain soluble dyes,
dextrin or sugar, and in some cases glycerine. Iron
tannin inks, when exposed to the air, become oxidised
and insoluble, so that they cannot be copied.

The juices of various plants have long been utilised
as marking inks, such plants including the ink plant
of New Granada and New Zealand, the cashew nut, the
Indian marking nut and others. Modern marking
inks, which should withstand the action of soap and
alkaline and acid liquids, mainly consist of solutions
of silver nitrate coloured with lampblack and thick-
ened with gum. Salts of gold, platinum, manganese,
and of other metals have been used for the same
purpose.

Pencils. — We have already noted the use of the
brush for applying characters to papyrus. The word
" pencil " is derived from the Latin penicillus, a small
tail. The use of charcoal and similar materials followed
and, at an early date, metallic lead was employed to
mark parchment and papers ; hence, the term
" blacklead " as applied to pencils, denoted the
blacker mark of graphite or plumbago. As a matter
of fact, the graphite used for making pencils consists
almost entirely of carbon and contains no lead.
It has been employed for this purpose since the
seventeenth century, and for a long time was obtained
almost exclusively from the Borrowdale mines in

120 WHAT INDUSTRY OWES

Cumberland, being mined in compact grey-black
masses, cut into thin plates, then into rectangular
sticks and cased in wood. The mine was guarded
by an armed force, and, to maintain the monopoly,
an Act was passed restricting the working to only
six weeks in the year ; for the remainder it was
flooded to prevent theft. The best quality was
exhausted early in the nineteenth century, and the
pencil manufacturers turned their attention to
utilising accumulations of waste from cuttings of
the original masses, which were crushed and mixed
with other materials.

One of the results of such experiments was the
introduction of varying degrees of hardness in which
respect the native graphite was never uniform.
Conte, of Paris, is credited with the method now
generally employed, of making pencils from finely
ground graphite mixed with varying proportions of
clay, allowing for fourteen degrees of hardness and
softness ranging from 6 H to 6 B with HB (hard
and black), and F (firm) as the middle degrees.

Graphite has since been found in many parts of
the world. The crystalline variety occurs in Ceylon,
but is not sufficiently black for pencil-making ;
the massive, which occurs in Bohemia, Bavaria,
and Mexico, is much blacker. It is ground very
fine, mixed with water, and passed through tanks
to allow the heavier particles to fall, the finer particles
passing on to five or six successive tanks, when the
necessary degree of fineness having been obtained,
it is mixed with suitable clay which has been washed
in the same manner. The mixture is submitted
to further grinding, squeezed in bags to remove
superfluous water and forced through tubes to
produce strips of the required shapes and sizes, which,
when dried and baked, are ready for casing in wood.

The wood mostly used for making pencils is that
of red cedar, not the cedar of Lebanon, but the
Juniperus Virginiana which grows in Florida,
Alabama, and Tennessee, and lends itself well to
the purpose on account of its soft character and
straightness of grain. It is usually cut into short thin

TO CHEMICAL SCIENCE 121

slats of the length of a pencil, though sometimes of
several lengths, and sufficiently wide for making
from two to six pencils. The slats are grooved to
receive the lead and, when glued together, can be
cut into the corresponding number of pencils, which
are then smoothed by machinery, polished, stamped
with the letters indicating the degree of hardness,
and the makers' name, tied into bundles, and generally
prepared for sale. Coloured pencils are made from
special clay finely ground with colour, such as Prussian
blue, or vermilion, and mixed with a binding material,
pressed into sticks which are toughened by boiling
in a mixture of special fats and waxes before they are
placed in the slats. For copying-ink and indelible
pencils, an aniline dye is used, the colour being
soluble in water in order that impressions may be
taken on tissue paper. With the demand for pencils
steadily increasing and the supply of suitable cedar
becoming quickly exhausted, manufacturers will be
obliged to use other woods, or users must be content
with mechanical pencils. The industry is restricted
to comparatively few firms, the majority being of
long standing. Details of manufacture are largely
kept secret, but enough has been said to indicate that
the industry owes much to chemical science, in tho
selection, mixing, And general treatment of materials,
and to mechanical science in the invention of labour-
saving machinery for the processes involved.

Other domestic requirements, such as blacklead
(stove polish), and blacking, for leather, are now pro-
duced under scientific control. Black lead for produc-
ing a polished black surface on iron is made from the
massive graphite. Blacking is made of a variety of
materials and consists essentially of some black pig-
ment, such as animal charcoal (bone black), incorporated
with substances capable of taking a polish by friction.
A mixture of bone black, sperm oil, molasses and
vinegar forms a typical blacking, while other kinds
contain starch as ground material with tannate of
iron as colouring agent, and gum arabic as a binding
material.

122 WHAT INDUSTRY OWES

CHAPTEB XVIII.
GASES.

IN the article on coal, we gave a brief description
of the manufacture and purification of one of its
principal decomposition products — coal gas. Before
drawing our work to a conclusion, we propose to say
something of other gases, little known to those who
do not use them, and far simpler in their constitution
than coal gas. Discovered by science, their manu-
facture is the outcome of scientific investigation, and
not the mere retorting of a complex naturally
occurring substance.

The word gas is said to have been introduced by
the Flemish chemist, Van Helmont — sixteenth cen-
tury— being associated with the Dutch geest, a spirit
or ghost, Danish and German, geist, from the same
root as the Anglo-Saxon gaestlic, ghastly. To the
mediaeval mind, the air was a mystery, something
supernatural : it could not be seen or smelled, but
could be felt and heard. Gradually the idea of the
material nature of the air was developed by the
schools, but owing to the vague nature of the entity
concerned and the difficulty of handling it, little
progress was made with experimental investigation
until the middle of the seventeenth century. No
variety was recognised and everything of the nature
of air was classed as air, until the advent of methodical
experiment and logical deduction laid the foundations
of this fundamental department of knowledge.

A gas is physically the simplest form of matter ; the
laws governing its behaviour are less complex than those
regulating the conduct of solids and liquids. To the
recognition of this fact and the application of the
principle of defeating the weakest enemy first, science

TO CHEMICAL SCIENCE 123

owes many of its most wonderful advances, such, for
instance, as we find in the application of the laws of
gases to substances in dilute solution. The extreme
fluid elasticity of gases and vapours and their high
co -efficient of thermal expansion render them
invaluable to the engineer. The nature of explosion,
the problems encountered in aeronautics, in meteoro-
logy, in the study of acoustics, are all closely connected
with the properties, both statical and dynamical, of
substances in the gaseous state.

Until the middle of the seventeenth century, the
philosophers — students of nature — affected to despise
experiment, their opinions being based on observation.
The alchemists — seekers after the universal solvent,
the philosopher's stone and the elixir of life — lovers
as they were of theory and mysticism, extolled the
experimental method by which they hoped to secure
wealth and the extension of life. Modern experi-
mental science may be considered as the outcome of
one of the controversies between two factions of the
former, combined with the overthrow of the methods
of the latter. A discussion arose between the plenists,
or Cartesians, who denied the possibility of a vacuum,
and the Vacuists,who maintained that there was no
reason why a vacuum should not exist. Robert
Boyle, born in 1626, " son of the Earl of Cork, and
the father of modern chemistry," flourished at the
time of the plenist controversy, and the problem
attracted him to physical science, especially the
study of the properties of air. In 1658 he constructed
the pneumatical machine — ah* pump — which was
destined to be of primary importance in many of
his subsequent experiments. His original aim being
to obtain a vacuum, he made with its aid some
significant discoveries. He demonstrated air pressure,
and elucidated the volume pressure relations of gases.
His law — viz., that, at a constant temperature, the
volume of a given quantity of gas varies inversely as
the pressure — was rediscovered independently a few
years later by Marriotte, a Frenchman. Boyle's
speculations on the chemical nature of air, founded on
many observations, including the gain in weight of

124 WHAT INDUSTRY OWES

metals on calcination, contributed to the advance of
knowledge in his time, but the difficulty of pioneer
work on an invisible and almost intangible medium
limited such observations to the phenomena of
combustion and respiration. In 1661 appeared,
anonymously, " The Sceptical Chemist," a book which
criticised the teaching of the alchemists and depre-
cated their method of expression and the ambiguity
of their doctrines. As the author of this production
Boyle did much to sweep away the cobwebs of
mysticism. He was an early member of the
" Invisible College," a body much attacked in its
infancy for encouraging the investigation of Nature —
then regarded by many as rank heresy — which
eventually became our premier learned society, the
Royal Society of London. His researches were
mainly on " air," and there is little doubt that he
prepared the gases now known as hydrogen, carbon
dioxide, and hydrogen chloride ; but he did not
observe their characteristic properties. His work,
however, marked the beginning of a new era in
natural philosophy, his doctrine showing that scientific
advances were made not by theory or practice alone,
but by the application of both.

The discoveries and teachings of a genius have not
infrequently been overshadowed by those of a greater
and better -known contemporary. This was the case
with John Mayow, a medical practitioner of Bath,
who, in his experiments on air and his deductions
therefrom, was ahead of the workers of his time- He
recognised the existence of different kinds of gases in
the air, and prepared a gas — nitric oxide — by the
action of nitric acid on iron. He observed its action
on air, but failed to see the analytical possibilities of
the discovery. Boyle and Newton held the field in
natural philosophy, and Mayow received little
attention. Stephen Hales (1677-1761) prepared a
large number of gases, but regarded them all as
modifications of air, and failed to make use of the
facts he accumulated. When, however, Joseph
Black (1728-1799) discovered carbon dioxide, and
Daniel Rutherford (1749-1819) isolated nitrogen, both

TO CHEMICAL SCIENCE 126

realised that these gases were distinct in their nature
from air.

Then followed the epoch-making discovery of
oxygen by Joseph Priestley and Carl Wilhelm
Scheele, a Swedish chemist, working independently.
Priestley also invented the eudiometer. Henry
Cavendish (1731-1810) made the first analysis of air,
devised the electric spark method of combining
nitrogen and oxygen, thus laying the foundation of
a very modern industry, and determined the com-
position of nitric acid. Cavendish proved the
compound nature of water ; determined its quanti-
titative composition, and also examined thoroughly
the fixed air — carbon dioxide — of Black.

All these eighteenth century investigators expressed
their views on the action of air and combustion in
terms of the phlogistic theory of Becher and Stahl,
and it remained for Antoine-Laurent Lavoisier, the
French savant, who fell a victim to the guillotine in
1794, to free them from this incubus and to develop
the new theory wherein oxygen was assigned its
proper rdle as a constituent of air and a supporter of
combustion.

Thus the composition of air — as a mixture of oxygen
and nitrogen with small quantities of carbon dioxide
and water vapour — and the explanation of the nature
of combustion were gradually established. To these
early workers, and especially to Priestley, Cavendish,
and Lavoisier, chemical science and industry owe an
irredeemable debt. Out of chaos they produced
order, and paved the way for the work of Avogadro,
Clark Maxwell, and Clausius. No new essential
constituents of air were discovered until the last
decade of the nineteenth century, when Rayleigh and
Ramsay, as an outcome of the measurements, by the
former, of the density of nitrogen from various sources,
including atmospheric, discovered five new chemically
inert gases — Argon (without energy), Neon (new),
Helium (Sun), Krypton (hidden), and Xenon
(stranger)— no compounds containing these elements
being as yet known.

Hydrogen. — The discovery of hydrogen is usually

126 WHAT INDUSTRY OWES

attributed to Paracelsus, a Swiss physician and
chemist — fifteenth to sixteenth century. Its ex-
plosive properties were known to Lemery about 1700,
but it was not until seventy or eighty years later
that Cavendish demonstrated the individuality
of the gas, and showed its relation to water. It is
prepared in the laboratory by the action of a metal
such as zinc or iron on dilute sulphuric acid, this being,
in fact, the method by which it was first discovered,
and it is obtained in a much purer state, when neces-
sary, by the electrolysis of barium hydroxide. Traces
of oxygen are removed by passage over hot copper
shavings or platinised asbestos, the issuing gas being
dried by means of calcium chloride, or of phosphorus
pentoxide.

The properties of hydrogen bear no resemblance
to those of any other element. It is colourless,
odourless, tasteless, specifically lighter than any other
known substance, very sparingly soluble in water, and
capable of forming explosive mixtures with air or
oxygen, with chlorine and fluorine. It has also
the property, in the presence of finely-divided
metallic nickel, of combining with certain bodies
that are chemically unsaturated. Its density is
less than one -fourteenth that of air, and its lightness
and buoyancy render it of great value for use in
airships and balloons. Provided that it is sufficiently
pure, the two main advantages over coal gas for this
purpose are superior lifting power and the absence
of deleterious effect on the material of the envelope.

As a constituent of ammonia, hydrogen has in
recent years been largely used in Germany in a process
for the fixation of nitrogen, whereby the combination
of the two gases, under high pressure — up to 200
atmospheres — at a temperature of 500 deg. Gent.,
is effected by the action of certain catalytic agents,
such as osmium, uranium, iron, manganese, or
tungsten. The efficiency of the catalysts is enhanced
by certain compounds of the alkali or alkaline earth
metals ; but catalyst " poisons " also exist, and these
are many and various. The gases must be freed
from these substances, the most obnoxious of which

TO CHEMICAL SCIENCE 127

are compounds of sulphur and the hydrides of arsenic
and phosphorus. The ammonia is separated by
liquefaction, produced by strong cooling, or, in
certain cases, by solution in water. This process
was devised by Haber, is worked by the Badische
Anilin und Soda Fabrik, and promises to become
one of the chief methods of producing nitrogen. It
need not stop at this stage, however, for through the
work of Ostwald a mixture of air and ammonia gas,
under proper conditions, with platinum, as catalyst,
yields nitric acid, and the process may be developed
by proper regulation to yield ammonium nitrate, a
substance of high value as a fertiliser.

The third important use of hydrogen is, as we have
observed in a previous article, in the hardening of
fats, by direct action in the presence of finely-divided
metallic nickel. According to the method of Sabatier
and Senderens certain fine chemicals are now made by
the nickel method of hydrogenation, and this also
is likely to find extended application in industry.

With these developments it has become necessary
to find means of producing hydrogen in large quan-
tities at low cost. Owing to the expense of raw
materials, and the difficulty of securing a convenient
cycle of operations whereby the starting materials
may be recovered, production by the action of metals
on acids is not to much extent carried out on the
works scale, though the method may occasionally
be used for military purposes. Many patents have
been taken out for the manufacture, and we will
refer to some of the more important of them : —
(1) By the action of steam on red hot iron, iron
oxide is formed, and hydrogen is set free. It is
then purified from dust, sulphur compounds, carbon
dioxide, &c., by suitable scrubbing treatment.
The iron oxide is reduced when necessary by replacing
the current of steam by one of water-gas, the residue
from this reaction being a source of nitrogen —
Messerschmitt process. (2) By freeing water-gas
from carbon dioxide, by means of lime or caustic
soda, and subjecting the residue to the extreme cold
produced by boiling liquid air, nitrogen and carbon

128 WHAT INDUSTRY OWES

monoxide are liquefied, leaving the hydrogen in the
gaseous state — Linde-Frank-Caro process. (3) By
the electrolysis of the chloride or hydroxide of an
alkali. (4) The decomposition of acetylene — prepared
from calcium carbide and water — by heating
electrically. Hydrogen is prepared for Zeppelins
by this method, which yields also a valuable by-
product in the form of fine lampblack. (5) The gas
is also produced by a number of other patent methods,
mainly useful for military purposes. Hydrolith is
calcium hydride, prepared by the action of hydrogen
on calcium in the electric furnace, and on contact
with water, yields double the volume of hydrogen
originally expended in preparing it. Hydrogenite
is a mixture of five parts of ferrosilicon, four parts of
slaked lime, and twelve parts of caustic soda. When
heated locally a reaction takes place, and spreads
throughout the mass with evolution of hydrogen.
Both of these processes are due to Jaubert.

Oxygen, discovered by Priestley and Scheele, and
named by Lavoisier, occupies about one-fifth of
the volume of the atmosphere, and its properties as
a supporter of life and combiistion render it one of
the most important of the elements. It is also the
most abundant, representing about half the weight
of the solid crust of the earth, and roughly eight-
ninths of the water. It can be prepared in the labora-
tory by heating chlorate of potash either alone or
with manganese dioxide, by the action of sulphuric
acid on bichromates or permanganates, or by the
electrolysis of dilute sulphuric acid, or of solutions
of alkalies. On a commercial scale, Brin's process of
heating barium monoxide — the analogue of lime —
in dry, purified air to about 700 deg. Cent, under
10 Ib. pressure, for long held the field. The oxide
takes up oxygen, forming barium peroxide ; the
nitrogen is then pumped off, pressure being reduced
to about 2 Ib. Under these conditions the peroxide
gives up its excess of oxygen, which in turn is pumped
off and compressed into cylinders, reforming the
monoxide, which is available again for the same cycle
of changes. The method, however, has now been

TO CHEMICAL SCIENCE 120

largely replaced by the liquid air process, which
depends for its utility on the ease with which air can
bo liquefied by the method of self-intensive cooling
introduced on the Continent by Linde and into
England by Hampson. Advantage is taken of the
fact that a compressed gas cools on expansion. Air
is compressed through a spiral, and allowed to escape
from a jet. On issuing it is cooled, and in turn
cools the air in the spiral by external contact. Thus
the issuing gas becomes increasingly colder, until
finally it issues from the jet in the liquid form. Liquid
oxygen and liquid nitrogen boil at different tempera-
tures, so that if the liquid air is fractionated the two
gases can be obtained in a fair state of purity.

Oxygen finds application in medicine, in the
chemical laboratory, and in the production of high
temperatures, such as are obtained by feeding
acetylene, hydrogen, and coal gas flames with the
gas. Oxy-acetylene cutting and welding, oxy-
hydrogen melting, including platinum working, the
autogenous soldering of lead, and the use of lime-
light, all depend on the production of an intensely hot
oxygen -fed flame.

Ozone is a colourless gas, condensable in liquid air
to a deep blue unstable liquid. Van Marum, in 1785,
and Schonbein, in 1840, observed a peculiar smell
in the neighbourhood of electrical machines in
motion, and the latter found that it was due to a
gas, which he named and found other means of
producing. Andrews, in 1856, showed that the
gas contained oxygen only, and Soret, in 1866, proved
its composition, which is represented by the formula
O3. It is prepared by the action of a silent electric
discharge on air or oxygen, a current of which is
passed through a special apparatus called an ozoniser.
The first of these was devised by Siemens in 1857,
and since that date numerous patents, founded
much on the same principle, have been recorded.

The commercial preparation resembles that on
the small scale. The pure substance is not obtained
in either case ; not more than 25 per cent, of the
oxygen is transformed into ozone under the best

130 WHAT INDUSTRY OWES

conditions. The product is used in the sterilisation
of water and to a less extent of certain foods.

Acetylene was discovered in 1836 by Edmund Davy,
Professor at the Royal Dublin Society, during an
attempt to isolate potassium by heating calcined
tartar with carbon. He obtained a black mass,
which in contact with water gave rise to an inflam-
mable gas, and he suggested that if a cheap method
could be found for preparing it, the gas might well
be used as an illuminant. Its development as an
industrial commodity was not realised until over fifty
years later, but in the meantime several famous
names came into the literature of the subject, includ-
ing Hare, Berthelot, Wohler, Kekule, Vohl, and Sir
James Dewar. Hare unknowingly made calcium
carbide, and from it acetylene, by the action of
water. Berthelot prepared metallic acetylides, and
produced acetylene electrically from methane and
also from carbon and hydrogen. Wohler made
calcium carbide by heating an alloy of zinc and
calcium to a high temperature with carbon. Kekule
prepared acetylene by the electrolysis of the salts of
dibasic unsaturated organic acids. Vohl obtained
the gas by passing oils through red hot tubes, thereby
laying the foundation of our modern oil-cracking
processes. From American petroleum he obtained
a gas containing 20 per cent, of acetylene. Dewar
obtained acetylene by passing hydrogen through
tubes made of retort carbon heated to whiteness by
means of an electric current.

Acetylene is used, as we have already mentioned,
in one of the processes for making hydrogen ; as
an illuminant in isolated dwellings, and in motor
and bicycle lamps. It is invariably prepared by
the action of water on calcium carbide, which comes
on the market in the form of grey lumps, the product
of heating lime with carbon in the electric furnace.
The gas owes its position as an industrial product to
the development of the electric furnace by Siemens,
Bradbury, Oowles, and Moissan ; but the credit
for the realisation of the possibility of producing
calcium carbide on a commercial scale belongs to

TO CHEMICAL SCIENCE 131

Willson, an American. In 1886, Cowles introduced
a furnace lining consisting of a mixture of lime and
carbon, and produced calcium carbide by the acci-
dental overheating of this lining. No attempt was
then made to utilise the discovery ; but, in 1892,
Willson, while working at Spray, with the object
of reducing lime to obtain calcium for the reduction
of alumina, prepared large quantities of the carbide,
and, realising the potentialities of the substance, set
up a works for its production.

Nitrogen, which forms about four-fifths of the air,
is produced by the methods we have already indi-
cated,* especially the Linde-Hampson process, and
is used in the synthetic preparation of ammonia, and
of cyanamido and cyanides, from calcium and
barium carbides respectively.

Chlorine, discovered by Scheele in 1774, and pro-
nounced an element by Davy in 1810, is a heavy
yellow poisonous gas of an extremely irritating
odour. It is largely used in the sterilisation of water
and in gold extraction, and has been employed as
poison gas during the war. It is prepared by the
action of manganese dioxide on hydrochloric acid,
the oxide being recovered by the Weldon process.
It may be converted into bleaching powder, through
its absorption by lime, or liquefied by cold and pres-
sure and stored in steel cylinders.

Carbon Dioxide, or carbonic acid gas, a waste
product of the brewery, is used for aerating beer and
mineral waters, and is sometimes employed as a
freezing agent.

Carbonyl Chloride, or phosgene, prepared by the
interaction of chlorine and carbon monoxide in the
presence of animal charcoal, or of antimony penta-
chloride, or by the action of fuming sulphuric acid
on carbon tetrachloride, is used in the manufacture
of dyes, and has also been employed as a poison gas.

Laughing Gas, or nitrous oxide, is made by heating
ammonium nitrate. It was discovered by Priestley
in 1772, and is used as an anaesthetic in dentistry.

* Refer to Agriculture and Hydrogen.

132 WHAT INDUSTRY OWES

We do not need to dilate on the relation between
science and these products which are so obviously
scientific in their conception, elucidation and deve-
lopment

TO CHEMICAL SCIENCE 133

CHAPTER XIX.
GOVERNMENT CHEMISTRY.

IN the article dealing with Agriculture and Food,
we have referred to the official agricultural analysts
and public analysts, who are appointed under statutes
to safeguard the quality of supplies of fertilisers and
feeding stuffs, food and drugs ; and we will now refer
to other official chemists directly or indirectly
concerned with industry.

In 1843 a laboratory was established at Somerset
House, in connection with the Inland Revenue
Department, to check adulteration of tobacco, and
later a second laboratory was established at the
Custom House for the examination of wines, spirits,
and other imported articles liable to duty. In 1894
the control of these laboratories was entrusted to
one Principal, and in 1897 the Excise Branch was
transferred to a new building at Clement's Inn -passage.
In 1911 the Government Laboratory was constituted
an independent department under the Treasury, with
a separate Parliamentary Vote, entitled " Government
Chemist." The Laboratory undertakes investiga-
tions for every other Government Department, the
greater part being carried out at Clement's Inn-
passage, and in the branch laboratory at the Custom
House. The Government Chemist also controls
eighteen stations in different parts of the United
Kingdom, where tests are made for revenue purposes.
From a recent report, we gather that the work for the
Department of Customs and Excise relates, mainly,
to the assessment of duty and drawback, and to regula-
tions and licences, in connect/ion with the manufacture
and sale of dutiable articles, such as beer, spirits,
wine, tobacco, tea, sugar, coffee, cocoa, and prepara-
tions advertised for the cure or relief of human

K 2

134 WHAT INDUSTRY OWES

ailments — commonly called " patent medicines."
The work for the Admiralty includes the examination
of food substances, the analysis of metals and of
contract stores ; that for the Board of Agriculture
and Fisheries refers largely to imported dairy produce
and margarine, and includes — for the Fisheries
Division — samples of river water believed to have
been polluted and to have caused injury to fish, as
well as the determination of the salinities of samples
of sea water for the Permanent International Council
for Exploration of the Sea. Samples of beer and
whiskey are examined for the Central Control Board
(Liquor Traffic) ; and of drugs, pharmaceuticals
and contract supplies for the Ciown Agents for the
Colonies. Fire-clay and limestone from various
districts are examined for the Geological Survey ;
lead glazes and enamels for the Home-office ; drugs
for the India-office, and stamps and inks ior the
Board of Inland Revenue. Investigations on pre-
servatives in food are carried out for the Local
Government Board ; and on paper, pigments, gum,
engineering and general stores for the Post-office ;
ink and typewriter ribbons for the Stationery-office ;
lighthouse stores for the Corporation of Trinity
House ; lime and lemon juice and ship's stores for the
Board of Trade ; food supplies for the Army, drugs
and surgical dressings, for the Army Medical Depart-
ment, for the War-office ; samples of varied character
for the War Trade Department ; samples of water for
the Office of Woods and Forests ; of contractors'
supplies and of water for the Offices of Works —
London and Dublin ; and samples referred by the
magistrates under the Sale of Food and Drugs Acts,
1875 and 1899, and submitted by the Board of
Agriculture, under the Fertilisers and Feeding Stuffs
Act. The total number of samples examined during
the year ended March 31st, 1916, was 383,892. The
work has obviously an important bearing on industry
and commerce, and entails the employment of a
large technical staff, of which many members are
required to be highly trained and competent chemists.
As illustrating the value of their work, we may refer

TO CHEMICAL SCIENCE 135

to the examination of food for the armies in the field
during the war, work essential in the interests both
of the health of the troops and of the Exchequer.
The food must be wholesome ; but the findings of the
chemists will determine the cash value of the supplies :
a deviation of, say, 1 or 2 per cent, of moisture in
flour, biscuits or margarine, may involve a reduction
of hundreds of pounds on a single contract.

Although the Government Laboratory constantly
advises other departments, some possess their own
laboratories for special purposes. The Admiralty has
a staff under the Admiralty Chemist, and einploys
chemists in connection with the examination of
various materials of construction and victualling
stores. The Admiralty has also its duly appointed
Adviser on Petroleum, as well as officers .possessing
special scientific experience, and professors of
chemistry in the Royal Naval Colleges. The War-
office, too, makes good use of chemists, in many
matters arising out of the conditions of modern war-
fare, and instruction in chemistry is given »m the
Royal Ordnance College, the Royal Army Medical
College, the Royal Military Academy, and other
establishments. Under the Ministry of Munitions,
in addition to chemists engaged in an advisory capa-
city, there are considerable numbers in charge of the
production of explosives in Government and con-
trolled factories, and special staffs are appointed
for research and inspection work.

Official analysts are appointed to the Home -office
for toxicological work, as well as in connection with
the Explosives Department and the Factory Depart-
ment. The Local Government Board possesses a
Department for the inspection of food and a staff of
specially qualified inspectors to assist in the adminis-
tration of the Alkali, &c., Works Regulation Act.
The Metropolitan Water Board and the Rivers Boards
in various parts of the country have their chemical
and bacteriological laboratories, and so have the
Sewage Boards and Works. The Scottish Office also
appoints inspectors under the Alkali Act and Rivers
Pollution Prevention Act.

136 WHAT INDUSTRY OWES

The London County Council controls a consider-
able staff for chemical investigations, including gas
testing, and the Board of Trade appoints the Gas
Referees, in accordance with the Metropolis Gas
Acts, to prescribe the apparatus and materials
to be employed for testing the illuminating power,
calorific power, purity and pressure of the gas,
the mode of testing, and, in certain cases, the times
of testing, the current prescriptions being published
in the " Notification of Gas Referees." Other county
and borough authorities make provision for the inspec-
tion of water and gas supplies. Chemists are also
included in the staff of the Patent-office, and Assayers
render responsible service in the Royal Mint and
at the Assay Offices, as well as for the Bank of
England.

The Scientific and Technical Department of the
Imperial Institute conducts investigations for the
Indian and Colonial Government.0, chiefly relating to
the composition and utilisation of raw materials.
The National Physical Laboratory includes a Depart-
ment of Metallurgy and Metallurgical Chemistry.
Laboratories are attached to many public Institu-
tions, such as the Davy-Faraday Research Laboratory
of the Royal Institution, and those of the Lister
Institute and the Royal Dublin Society.

The existence of this extent of official organisation
in chemistry is little known to the general public,
but it is obviously indispensable to the well-being
of the community. The personnel of our chemical
service includes many men of science of high repute
in their professions who deserve well of their country,
and it is essential that the conditions attaching to
this service should be such that it will continue to
attract chemists of the highest competence. We have
endeavoured to make this list fairly comprehensive,
but have not referred to India and the Overseas
Dominions, where many chemists hold appointments
analogous to those we have indicated ; nor have we
referred to the valuable work carried out by analysts
in hospitals and public health laboratories, or the
appointments held in the Universities and Technical

TO CHEMICAL SCIENCE 137

Colleges, to which we look for the continued supply
of lieutenants to meet our requirements in the various
branches of chemical practice.

138 WHAT INDUSTRY OWES

CONCLUSION.

WHILE we have confined our attention mainly to
the debts of industry to chemical science, we do not
suggest that those due to physical and mechanical
science should not be similarly acknowledged.

The art of engineering has been steadily built up
through the ages, but modern developments are,
in the main, directly attributable to the advance
of science. In chemical industries, however, the
processes of manufacture, in many cases, preceded
the discovery of the scientific principles on which they
were based. The ironmaster, the dyer, the soap
and candle maker, the tanner, the potter, and the
glass manufacturer, were in existence centuries
before serious attention was paid to the science under-
lying their work. Conventions die hard, and for
a long time there was little enthusiasm to take advan-
tage of what science had to offer. It is freely admitted
that the state of civilisation attained before the advent
of modern science was far removed from the conditions
of life of primitive man ; but it is claimed that
while science was so little developed, industry had
to look to experience as the only basis to work upon.
Experience, accumulated slowly and at great cost,
had done great things ; but the rate of progress
in industry developed in the past century defies
comparison with all the centuries combined since
time was — so far as we know ! Still, let us admit that
the inheritance was great, and that even the alchemist
preserved much that was good in chemistry, just
as the monks of the Middle Ages preserved much
that was good in classical literature and architecture.
We have endeavoured to indicate the interdependence
of science and industry on one another, and to show
how frequently science — " the nursling of interest
and the daughter of curiosity " — pursued for her

TO CHEMICAL SCIENCE 139

own sake, has sooner or later proved her practical
utility. Incidentally we have shown that though
" Genius is of no country," British men of science,
often in the face of small encouragement, have played
their part in industrial development. There is
no reason to depreciate the value of their work, or to
pay much attention to the Jeremiahs who seem to
delight in bemoaning the industrial and commercial
position of this country but are seldom able to offer
any constructive criticism.

Advancement may be the outcome of the labours of
the consultant, the chemist on the works, the official
chemist, or the professor ; all have contributed their
share to discovery and invention. In any case, it is
certain that our industries have utilised their know-
ledge, skill and experience to a greater extent than
has been generally recognised ; otherwise much that
has been done in the last three years would have been
impossible, and our position would have been far worse
than It is.

We feel that the apathy towards science prevailing
before the war was more imaginary than real and,
such as it was, is being overcome ; that the general
public is beginning to realise something of the
importance of science in the affairs of everyday life,
and that the time is at hand when the services of
the man of science will be better understood and
consequently more substantially rewarded. The
men of science themselves are increasing in number
and influence ; their work lies more and more in the
control of large scale operations, as well as in the
laboratory. The time has passed when men feared
to probe into the truth as if it were sacrilege, or to
imagine things beyond certain knowledge and estab-
lished fact, or to explore into realms of not only the
improbable but the seemingly impossible, whence so
much, with the aid of science, has been and is yet to
be derived.

To-day, the arts and sciences go hand in hand :
the engineer and the chemist, each recognising the
limits of his own domain, though the line dividing them
may often be difficult to define, co-operate with one

140 WHAT INDUSTRY OWES

another and mutually assist in the solution of indus-
trial problems. Now is the time for leaders of indus-
try to see to it that the opportunity is taken of making
good, wherever possible, the connecting link between
science and practice. A thorough overhauling of
n ethods and plant should keep our consulting
chemists and engineers well employed in preparation
for the future. There is no lack of good men, and
soon there will be enough and to spare for permanent
appointments on the works.

If in these articles we have been successful in
indicating some of the triumphs of science in industry,
and if our efforts have in any way conduced to a better
realisation of the value of scientific thought and
method, we may rest satisfied that our labour has not
been in vain.

TO CHEMICAL SCIENCE 141

BIBLIOGRAPHY.

BACON and HAMOR. The American Petroleum Industry.
New York, 1916.

BAKER, J. L. The Brewing Industry. London, 1905.

BLOUNT, B. Cement. Lecture, Institute of Chemistry,
London, 1912.

BLOUNT and BLOXAM. Chemistry for Engineers and
Manufacturers. London, 1910-1911.

BLOXAM, C. L. Chemistry, Inorganic and Organic.
Edited by A. G. Bloxam and S. Judd Lewis. London, 1913.

BORCHERS, W. Electric Smelting and Refining. London,
1904.

BORCHERS, W. Metallurgy. Translated by W. T.
Hall and C. R. Hayward. London and New York, 1911.

BROWN, J. CAMPBELL. History of Chemistry from the
Earliest Times to the Present Day. London, 1913.

BURGESS and LE CHATELIER. The Measurement of
High Temperatures. New York, 1912.

BUTTERFIELD, W. J. A. Chemistry in Gas Works.
Lecfure, Institute of Chemistry. London, 1913.

BYROM and CHRISTOPHER. Modern Coking Practice.
London, 1910.

CAIN and THORPE. The Synthetic Dyestuffs and the
Intermediate Products from which they are derived. London,
1917.

CHAPMAN, A. CH ASTON. Brewing. Cambridge, 1912.

CROSS, C. F. Cellulose. Lecture, Institute of Chemistry.
London, 1912.

CROSS and BEVAN. Researches on Cellulose, 1895/1910.
London, 1901-1912.

A Text-book of Papermaking. London, 1907.

DREAPER, W. P. The Research Chemist in the Works
with Special Reference to the Textile Industry. Lecture,
Institute of Chemistry. London, 1914.

ENGLER and HOFER. Das Erdol. Leipzig, 1909 -f.

FINDLAY, ALEXANDER. Chemistry in the Service of
Man. London, 1917.

HARBORD and HALL. The Metallurgy of Steel. London,
1916.

142 WHAT INDUSTRY OWES

HERRICK, R. F. Denatured or Industrial Alcohol. New
York, 1907.

HILDITCH, T. P. A Concise History of Chemistry.
London, 1911.

HILL, C. A. The Function and Scope of the Chemist in
a Pharmaceutical Works. Lecture, Institute of Chemistry.
London, 1913.

LAFAR, FRANZ. Technical Mycology. London, 1910.

LEEDS and BUTTERFIELD. Acetylene. London, 1910.

LEWKOWITSCH, J. Chemical Technology of Oils, Fats
and Waxes London, 1913-1915.

Loins, HENRY. The Dressing of Minerals. London,
1909.

LUNGE, GEORGE. Coal Tar and Ammonia. London,
1916.

Sulphuric Acid and Alkali. London, 1911.

MACNAB, WILLIAM. Explosives. Lecture, Institute of
Chemistry. London, 1914.

MCMILLAN, W. G. A Treatise on Electro -Metallurgy.
London, 1899.

MARSHALL, ARTHUR. Explosives. London, 1917.

MELLOR, J. W. Treatise on Quantitative Inorganic
Analysis. London, 1913.

MEYER, ERNST VON. A History of Chemistry from
Earliest Times to the Present Day. Translated by George
McGowan. London, 1906.

MIERS, Sir H. A. Mineralogy. London, 1902.

NEWLANDS, B. E. R. Sugar. London, 1913.

PORRITT, B. D. The Chemistry of Rubber. London,
1913.

PRICE, T. SLATER. Per-acids and their Salts. London,
1912.

PROCTER, H. R. The Principles of Leather Manufacture.
London, 1903.

RAMSAY, SIR WILLIAM. The Gases of the Atmosphere,
the History of their Discovery. London, 1915.

REDWOOD, Sir BOVERTON, Bart. Petroleum. London,
1913.

ROBERTS- AUSTEN, Sir W. C. Introduction to the Study of
Metallurgy. London, 1910.

ROSCOE (Sir H. E.) and SCHORLEMMER. Treatise on
Chemistry. London, 1911-1913.

ROSE, Sir T. KIRKE. The Metallurgy of Gold. London,
1915.

STANSFIELD, ALFRED. The Electric Furnace. New
York, 1907.

TO CHEMICAL SCIENCE 143

TERRY, HUBERT L. India-rubber and its Manufacture.
London, 1907.

THORPE, Sir EDWARD. A Dictionary of Applied
Chemistry. London, 1912. •
History of Chemistry. London, 1909-10.

TILDEN, Sir WILLIAM A. Chemical Discovery and
Invention in the, Twentieth Century. London, 1916.

TROTMAN, S. R. Leather Trades Chemistry. London,
1908.

TURNER, T. The Metallurgy of Iron. London, 1915.

WHITE, EDMUND. Thorium. Lecture, Institute of
Chemistry. London, 1912.

WOOD, JOSEPH TURNEY. The Puering, Bating, and
Drenching of Skins. London, 1912.

WRIGHT, S. B. A Practical Handbook on the Distillation
of Alcohol from Farm Products, and De-naturing. New
York, 1907.

144

WHAT INDUSTRY OWES

IN DEX.

ABBE, 71

Abel, 46

Acetic Acid, 81

Acetone, 86

Acetylene, 130

Acetylsalicylic Anhydride, 89

Achard, 20, 101

Acheson, 67, 69

Acids, 80

Agriculture, 95

Alcohol, 84, 109

, Absolute, 110

, Denaturing of, 110

Alizarin, 43

Alkali Act, 30

Manufacture, 27

, Manufacture by Elec-
trolysis, 32

Waste, 29

Alum-tan, 61

Aluminium, 15

Alundum, 69

Ammonal, 47

Ammonia, 37

Gas, 103

Ammonia -soda Process, 31

Ammoniacal Copper Solution.
84

Ammonium Salts, 83

Sulphate, 23

Anaesthetics, 85

, Local, 89

Analytical Re-agents, 87

Andrews, 129

Aniline, 44

Anthracene, 40

Antifebrin, 89

Antimony Salts, 84

Antipyretics, 89
Antiseptics, 89
Archer, 91
Arsenic Acid, 81

, Organic Compounds of,

89

Aspirin, 81, 88
Astatki, 55
Atoxyl, 89
Atropine, 88

BACON, Roger, 45
Bactericidal Agents, 89
Barium, Peroxide, 83

Salts, 83

Bases, 81
Basic Slag, 98
Beer, 104
Benzene, 39
Benzine, 54
Benzoic Acid, 81
Bernard Freres, 16
Berthelot, 130
Berzelius, 17
Bessemer, 3
Bevan, 52

Bieberich Scarlet, 42, 43
Birkeland and Eyde, 97
Bismuth Salts, 84
Black, 124
Blacking, 121
Black Lead, 121
Blast Furnaces, Water-
jacketed, 10
Blasting Gelatine, 47
Bleaching Powder, 30
Blue Prints, 93

TO CHEMICAL SCIENCE

145

Boric Acid, 81

Botticher, 78

Bouchardat, 64

Boullay, 86

Boyle, 35, 90, 123

Braconnot, 45

Bradbury, 130

Brandy, 113

Brewing, 104

Erin's Process, 128 .

Brown, A. J., 107

Brunner, 15

Brunner, Mond and Co., 32

Buchner, 107

Bunsen, 15

Butadiene, 64

Butter Substitutes, 58

CALLENDAR, 79
Calomel, 83
Calotype Process, 91
Camphor, 55
Candles, 57
Caoutchouc, 63
Carbohydrates, 48
Carbolic Acid, 39
Carbon Bisulphide, 84
Carbonic Acid Gas, 103, 108
Carbon Printing Process, 93

Tetrachloride, 85

Carbonyl Chloride, 131
Carborundum, 69
Castner, 15, 32
Catalyst, Poisoning of, 26
Catalytic Agents, 31
Cattermole, 8
Caustic Potash, 81

Soda, 28, 81

Cavendish, 125, 126
Caventou, 88
Cellon, 52
Celluloid, 52
Cellulose, 48
Cement, 65
Cementation, 2, 3

Chamois Leather, 61
Chance-Claus Method, 29
de Chardonnet, 51
Chevreul, 56
Chloral, 86
Chlorates, 33
Chlorate of Potash, 30,
Chlorine, 131

, Recovery of, 30, 32

Chloroform, 85
Chrome-tan, 61
Chromium, 17

Cinnamoylsalicylic Anhy-
dride, 89
Citric Acid, 80
Clark (Water Treatment), 6
Claudet, 29
Claus, 29
Clayton, 35
Cleaning Spirit, 54
Coal, 34
Coal-gas, 35
Coal Tar, 36
Cocaine, 89
Cochineal, 41
Coke, 34

Cold Storage, 103
Colloidal State, 61
Colour Photography, 93
Contact Agents, 31

Process, 26

Conte, 120
Cookworthy, 65, 78
Copper, 10

in Pyrites, 29

, Salts, 84

Cordite, 46

Corrosive Sublimate, 83
Cowles, 130, 131
Cresylic Acid, 39
Cronstedt, 14
Crookes, 97
Cross and Be van, 52
Cyanamide Process, 97
Cyanamides, 83
Cyanides, 62, 83, 97
Cymogene, 54, 103

146

WHAT INDUSTRY OWES

DAGUERRE, 90

Dale, 48

D'Arcet, 20

Davy, Edmund, 130

Davy, H., 15, 16, 25, 81, 90,

131

Deacon, 31
Debray, 20
Delprat, 8
Descotils, 20
Desmond, 61
Deville, 15, 17, 20
Dewar, 130
Diastase, 106

Diffusion Process, 101, 102
Disinfectants, 89
Dobereiner, 71
Dowson Gas, 35
Drugs, 88
Dry Plates, 92
Dye Industry, 41
Dyeing, 44

Dyer and Hemming, 32
Dyes, Artificial ; Advantages

of, 42
Dynamite, 47

EGGS, Preservation of, 83
Ehrlich, 89
Eitner, 62
Elmore, 7, 8
Elution, Process, 102
Enamels, 75
Epsom Salts, 83
Esparto, 50
Essential Oils, 55
Ether, 86

, Extraction by, 12

Everson, 7
Explosives, 44

FATS, 53

Feeding-stuffs, 98
Fermentation, 107
Ferrochrome, 17
Ferromanganese, 3

Ferro vanadium, 19

Fertilisers, 95

Fertilisers and Feeding Stuffs

Act, 98
F&y, 79

Filaments, Electric Lamp, 17
Fine Chemicals, 86
Fire-extinguisher, 85
Fleurscheim, 47
Flotation of Minerals, 7
Food, 95, 99
Formic Acid, 80
Fox Talbot, 91
Fraunhofer, 71
Freezing Agents, 103
Fuel, Economy of, 6
Fusel Oil, 114

CANISTER, 69
Gas Carbon, 37, 69

, Illuminating, 34, 54

Gas Light and Coke Co., 36
Gasolene, 54
Gay-Lussae, 25, 48
Gelatine Dynamite, 47
Glass, 70

, Etching of, 81

, Optical, 71

, Resistant, 72

for Thermometers, 72

Gin, 114
Glover, 25
Glucose, 106
Glue, 62
Glycerine, 56
Gold, 19

in Pyrites, 29

Salts, 84

Goodyear, 63

Gossage, 30

Government Chemistry, 133

Graham, 102

Graphite, 69, 119, 120

Ores, 7

Guinand, 71
Guncotton, 45

TO CHEMICAL SCIENCE

147

Gunpowder, 45
Guthrie, 85

HABER'S Process, 126
Hadfield, 5
Hales, 124
Hampson, 129
Hancock, 63
Harcourt, 71
Harden, 107
Hardening of Oils, 14
Hare, 20, 130
Harries, 64
Heinzerling, 62
Hemming, 32
Henderson, 29
Herschel, 91
Heumann, 43
Hides, Treatment of, 60
Hops, 106
Huntsman, 2
Hydrochloric Acid, 30
Hydroflouric Acid, 81
Hydrogen, 125
Hydrogen Peroxide, 83
Hydrogenite, 128
Hydrolith, 128
Hyoscine, 88
Hyoscyamine, 88
Hypo, 83
Hypochlorites, 33

INDIGO, 42

, Artificial, 25

Inks, 117
Insecticides, 89
Invert Sugar, 106
Iridium, 20
Iron Sulphate, 84
Isoprene, 63

JACKSON, C., 86
Janetty/20 '

Jaubert, 128

Johnson, Matthey and Co., 20

KAINITE, 82
Kekule, 130
Kerosene, 54
Kestner, 24
Knapp, 62
Knight, 20

LACTIC Acid, 80, 113
Lamp Oil, 54
Lampadius, 84
Laughing Gas, 83, 131
Laurent, 47
Lavoisier, 125
Lawrence, 85
Lead Azide, 84

Carbonate, 84

Chamber Process, 24

, Desilverisation of. 11

, Purity of, 13

Leather, 59

Leather Cloth, 62

Leblanc, 27

Le Bon, 36

Le Chatelier, 4, 65, 79

Lefevre, 24

Lemery, 24, 126

Liebig, 107

Lignocellulose, 50

Ligroin, 54

Linde, 129

Linde-Frank-Caro Process,

128

Lipmann, 93
Liqueurs, 114
Liquid Air Process, 129
Lumiere, 93
Lupulin, 106
Lyddite, 47

MAC ARTHUR-FORREST, 19
Macintosh, 63

148

WHAT INDUSTRY OWES

Madder, 42
Magnalium, 16
Magnesia, 82
Magnesium, 16

Sulphate, 83

Magnetic Separation, 10

Malt, 105

Mantles, Gas, 18

Marggraf, 101

Marriotte, 123

Martens, 4

Matthews, 64

Mauveine, 44

Mayow, 124

McDougall and Howies, 97

Melinite, 47

Mercury Fulminate, 83

Messerschmitt Process, 127

Metallography, 4

Methyl Alcohol, 110

Methyl Chloride, 103

Mineral Tannages, 61

Minerals, Separation of, 7

Moissan, 17, 130

Molybdenum, 16

Monazite, 18

Mond. 14, 32

Gas, 35

Mordants, 44
Mortar, 65
Motor Spirit, 54
Murdock, 35
31uspratt, 27

NEOSALVARSAN, 89
Nickel, 14
Nicotine, 116, 117
Niepce, 90
Nitrides, 97
Nitrogen, 131
, Fixation of, 96

Nitroglycerine, 46

Nobel, 46

Nordhausen, 26

Novocaine, 89

OILS, Animal, 55

, Hardening of, 14

, Vegetable, 55

Osmium, 20
Osmond, 4
Osmose Process, 102
Ostwald, 127
Oxalic Acid, 48, 80
Oxygen, 128
Ozone, 129

PALLADIUM, 21

Paper, 49

Paracelsus, 126

Paraffin Wax, 54

Parker, 66

Parkes, 11, 12, 13

Parting of Gold, 20

Pasteur, 107

Pattinson, 11

Pelletier, 88

Pencils, 119

Percarbonates, 83

Perfumes, 56

Perkin, 44, 64

Peroxy Compounds, 83

Persulphates, 83

Petrol, 54

Petroleum, Distillation of, 54

Phenacetin, 89

Phosgene, 131

Photographic Materials, 94

Photography, 90

Piat, 63

Picric Acid, 47

Pitch, 36

Platinum, 20

Salts, 84

Plattner, 19

Plenist Controversy, 123
Plumbago, 119
Poison Gases, 131
Porcelain, 77
Potassium Salts, 81

Thiocarbonate, 85

Pott, 78

TO CHEMICAL SCIENCE

149

Potter, 8

Potter's Cones, 78
Pottery, 77
Priestley, 63, 125, 131
Procter, 59, 62
Puering, 60
Pulvis Fulminans, 45
Pyrometer, 79

QUININE, 88

RAMSAY, 125
Rayleigh, 125
Refractory Materials, 68
Reid, 46
Rhigolene, 54
Rhodium, 21
Roberts -Austin, 4
Roebuck, 24
Rolland, 32
Rubber, 63

, Synthetic, 64

Rum, 114
Rutherford, 124

SABATIEB, 127

Salicylic Acid, 81, 88

Salipyrene, 89

Salts, 82

Salvarsan, 89

Sauveur, 4

Scheele, 20, 90, 125, 131

Scheibler, 102

Schloessing, 32

Schonbein, 45

Schott, 71

Schultz, 62

Sefstrom, 19

Seguin, 61

Senderens, 127

Separation, Magnetic, 10

Sepia, 41

Shale Oil, 55

Shimose, 47

Sicoid, 52

Siemens, 4, 129, 130

and Halske, 20

Silica, Fused, 69, 73
Silicon, 69

Silk, Artificial, 48, 5 1
Silver in Pyrites, 29

Salts, 84

Simmonds, 79
Simpson, 85
Smeaton, 65
Smelling Salts, 83
Soap, 56
Sobrero,.46
Soda Ash, 28
Sodium, 15

— Bicarbonate, 28, 31

Carbonate, 28

Salts, 83

Peroxide, 83

Solar Oils, 55

Solvay, 28, 31, 32

Solvents, 84

Sorby, 4

Soret, 129

Souberain, 85

Spiegel, 3

Spirits, 112

Stead, 4

Steel, 2

Steels, Microscopic Structure

of, 4

, Special, 5

Steffen, 102

Stolzel, 78

Stoveine, 89

Strange, 64

Strontium Hydroxide, 82

Salts, 83

Strychnine, 88

Suchsland, 117

Sugar, Beet, 101

Sugar, Cane, 100

Sulphide Ores, Concentration

of, 7
Sulphur, Recovery of, from

Alkali Waste, 29

— , Chloride, 84

L 2

150

WHAT INDUSTRY OWES

Sulphuric Acid, 22

, Fuming, 26

, Impurities in, 87

, Removal of

Arsenic from, 27
Superphosphate of Lime, 96
Swan, 62
Swartz, 45

TALBOTYPE Process, 91
Tar, Distillation of, 36

Fractions, 38

Tartaric Acid, 80

Tavener, 20

Tawing, 61

Tennant, 20

Tetranitroaniline, 47

Thermite Process, 17, 19

Thomas and Gilchrist, 3

Thorium, 17

Thorpe, 79

Tilden, 64

Tin Ore, Concentration of,

Salts, 84

T.N.T., 45
Tobacco, 115
Toluene, 39
Tolypyrene, 89
Trimethylamine, 81, 103
Trinitrotoluene, 45
Tungsten, 16
Tyrian Purple, 41

UNVERDORBEN, 44

VALENTINE, 23
Van Helmont, 122
VanMarum, 129
Vanadium, 19
Vaseline, 54

Vauquelin, 17
Vegetable Tanning, 61
Vergara, 96
Veronal, 89
Vieille, 46
Vohl, 130
Vulcanising, 63

WASHING Soda, 28
Water, for Brewing, 1 05

Gas, 34

Glass, 83

, Softening of, 6

Watson, 35

Watt, 119

Waxes, 53, 57

Wedgwood, 90

Weldon, 31

Weldon Process, 131

Welsbach, 19

Welter, 47

West-Knight and Gall, 39

Whiskey, 113

Williams, 63

Willson, 131

Wines, 111

Winsor, 36

Wohler, 15, 17, 130

Wollaston, 20

Wood, 9

, Mechanical, 50

Pulp, 51

, Chemical, 50

Spirit, 110

Wort, 105

YOUNG, 55

ZINC Chloride, 83
Zirconia, 69

Printed by GEORGB RKVEIBS, LD., Greystoke Place, Fetter Lane, E.G.

STAMPED BELOW

AN INITIAL FINE OF 25 CENTS

WILL BE ASSESSED FOR FAILURE TO RETURM
THIS BOOK ON THE DATE DUE. THE PENALTY
WILL INCREASE TO SO CENTS ON THE FOURTH
DAY AND TO $1.OO ON THE SEVENTH DA\
OVERDUE.

warm

MAY 17 1937

"

25Apr'58BB

PEC'O ID

APR 1 1 1958

LD 2 1-1 00m- 8

/

/

YB 15476

387485

-T~
UNIVERSITY OF CALIFORNIA LIBRARY