Man And The Chemical Elements

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MAN AND THE
CHEMICAL ELEMENTS

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[Frontispiece

Man's most notable achievement in the investigation of the elements

The trial explosion in New Mexico of the first atomic bomb may well prove
to be one of the most significant events in Man's history. The photographs
were .taken respectively O016 second and 8 seconds after the initiation of

the explosion. (See page 320.)
Reproduced by permission of the Directorate of Atomic Energy, Ministry of Supply

PREFACE

Some ten years ago I wrote a series of articles on "The
Historical and Industrial Discovery of the Elements'*.
They were published in Chemistry and Industry and the
many kind letters I received encouraged me to write a
comprehensive book on the subject incorporating
most of the original material, augmenting it with much
information of equal academic importance and of no
less general interest, and including accounts of recent
developments.

There can be little doubt that one of the best
approaches to a science is through its history, and no
doubt at all that the story of man and the chemical
elements is of great fascination. That the first of j^hese
is widely recognised is adequately demonstrated by the
frequent appearance of historical questions in academic
and professional examination papers; and the second I
have tried to show in these pages.

My information has been culled from many and
various sources; I believe that all the important ones are
acknowledged in the text. My sincere thanks are due to
the Society of Chemical Industry for permission to make
full use of my earlier articles, and to the publishers who
have done all in their power to facilitate the work,

J. NEWTON FRIEND
July 1951

CONTENTS

Chapter Page

1 PREAMBLE ...... 1

What is an element? The atomic number Relative abundance
of the elements The ages of man The stone ages The age
of metals Elements known to the ancients Problems The
alchemists Transmutation The sulphur-mercury theory
The miner The growth of minerals

2 THE PERMANENT GASES .... 20
Oxygen The theory of phlogiston Lavoisier's theory of com-
bustion Isotopes Applications of oxygen Ozone Nitro-
gen Active nitrogen Uses of nitrogen The atomic clock
Hydrogen Spin isomerism Balloons Deuterium Tritium

General uses of hydrogen and deuterium The hydrogen bomb

3 THE INERT GASES ..... 41
Argon Helium Neon Krypton Xenon Applications

4 THE HALOGENS ^ 46

Chlorine Iodine Bromine Fluorine Alabamine

5 CARBON 53

Charcoal Graphite Diamond Some famous diamonds

6 THE METALLOIDS BORON AND SILICON. . 68

7 THE SULPHUR GROUP. .... 71
Sulphur Selenium Tellurium

8 THE PHOSPHORUS GROUP .... 76

Phosphorus The match industry Arsenic Antimony
Bismuth

9 THE COINAGE METALS .... 80

Occurrence of native copper Primitive metallurgy of copper
Copper and the Egyptians Copper in Holy Writ Copper and
the Romans Copper in Britain Copper and the alchemists
Brass Uses of copper Miscellaneous alloys Bell metal
Silver Some famous silver mines Silver and the Egyptians

Silver in Holy Writ Silver and the Romans Silver and the
alchemists Uses of silver Sheffield plate Silver coins
Gold Some gold mines of interest Gold in Holy Writ Man's
cupidity Gold in Egypt Gold and the Romans The gold
of the Incas Gold -and the alchemists Uses of gold Gold
coins Gold leaf

vii

CONTENTS
Chapter Page

10 THE ALKALI METALS .... 142

Potassium Sodium Lithium Rubidium Caesium

11 MAGNESIUM AND THE ALKALINE EARTH METALS 149
Magnesium Calcium Strontium Barium

12 THE ZINC GROUP 154

Beryllium Zinc Cadmium

13 THE ALUMINIUM GROUP .... 160

Aluminium Indium Thallium

14 MENDELEEFF'S PREDICTEES i

Doebereiner triads Law of octaves Periodic classification
Scandium Gallium Germanium

15 THE RARE EARTH OR LANTHANIDE SERIES . 175
Relative abundance Electronic configurations The yttrium

group The cerium group Position in the periodic table

16 JHE HEAVY METALS LEAD, TIN, AND MERCURY 186

Lead Primitive metallurgy of lead Lead in Holy Writ
Lead and Egypt Lead and the Mediterranean Lead and the
Romans Silver in lead Lead in Britain Lead in Derbyshire
^- The fuel problem Lead and the alchemists Uses of lead
Lead shot Type metals Tin Tin in Britain Tin and the
alchemists Tin plague The tin-plate industry Tin foil

Pewter Solder Sources of tin Mercury or quicksilver

Mercury and the ancients Mercury and the Romans
Mercury and the alchemists The story of vermilion Uses
of mercury The thermometer The fixed thermometric points

Various thermometers

17 THE TITANIUM GROUP .... 228
Titanium Zirconium Hafnium Thorium The gasmantle
industry

18 THE VANADIUM GROUP .... 237

Vanadium Niobium and tantalum

19 THE CHROMIUM GROUP .... 242

Chromium Molybdenum Tungsten

20 THE MANGANESE GROUP .... 248
Manganese Elements 43 and 75 Rhenium Does element

43 exist in nature?

viii

CONTENTS

Page

21 THE IRON GROUP 253

Iron Meteorites The lodestone Iron and primitive man
Iron in Egypt Iron in Holy Writ Iron in India Iron in the
Far East Iron and the Greeks Iron and the Romans Iron
in pre-Roman Britain The Mabinogion Iron in Roman
Britain Iron and post- Roman Britain Iron for swords fast
iron The fuel problem Uses of iron Ships Bridges
Nails and horseshoes Alloys of iron Iron for adornment
Cobalt Nickel Nickel coins Miscellaneous alloys Nickel
plating Occurrence

3 THE PLATINUM METALS .... 300

Platinum Palladium and rhodium Indium and osmium
Ruthenium Uses of the platinum metals Standards of length
and mass

\ THE RADIOELEMENTS AND THE ACTINIDE

SERIES 311

Uranium Radium Atomic energy Isotopy of uranium
The uranium bomb The atomic pile Thorium Actinium
Atomic weight of lead Radon Transuranium elements

NAME INDEX ...... 329

SUBJECT INDEX 339

PLATES

Facing page
The New Mexico atomic bomb

1 The Imgig relief 92

2 The Delhi pillar 264

3 A Roman ferrule and a nineteenth century steel brooch 274

CHAPTER 1

PREAMBLE

What is an element ?

At the outset let us be mutually agreed as to the meaning we propose
to assign to the word "element".

The term is usually taken to indicate something fundamental,
something simple, with the aid of which more complex systems or
bodies can be produced. Thus the child goes to school to learn his
ABC the elements or the rudiments of his mother-tongue. To
the chemist, however, the word "element" has a special significance,
He has long realised that the matter by which he is surrounded
is often extremely complex; it is built up in some mysterious way
from simpler bodies, just as words may be built up from letters 9
These simpler bodies came to be known as the chemist's LMN's.
Pronounce these letters quickly and it is not difficult to arrive at
our word "element".

The so-called Aristotelean elements, Fire, Air, Earth, and
Water, were postulated by Empedocles (490 to 430 B.C.) at least
half a century before Aristotle (384 to 322 B.C.) saw the light.
They were regarded as simple, material bodies; but in later years,
largely as the result of Aristotelean philosophy, the terms were
used in an abstract sense to denote essences or qualities of
bodies. Thus hot substances and combustible materials were rich
in the element Fire, whilst liquids owed their fluid properties to
Water.

A nearer approach to the present conception of an element was
that of Anaxagoras (500 to 427 B.C.) who assumed as many elements
as there were "simple" substances. Thus sand and salt were
simple substances, since the latter could be extracted from a
mixture by dissolution in water and recovered by evaporation.
But the number of these "simple" substances was inordinately
large.

The word element was first used in its more modern sense by

THE CHEMICAL ELEMENTS

Boyle about 1662, and was clearly defined by Lavoisier in 1789
as implying

A substance that cannot be split up by any known means into some-
thing simpler

or, an element is

Matter in its simplest form.

For over a century this definition sufficed. It was, nevertheless,
unsatisfactory, being neither more nor less than a, confession of
ignorance and impotence. Thus it demanded that caustic potash
should be regarded as an element until Davy succeeded in decom-
posing it by electrolysis in 1807. Similarly lime was regarded as
an element and when Charles Tennant chlorinated slaked lime in
1799, the product was perforce called chloride of lime, a name
that clings to it even to-day.

Lavoisier's definition is now no longer true. With the aid of
fast-moving projectiles, such as a-particles, protons, deuterons
and neutrons, under the influence of high potential differences, or
in some cases ejected from radio-active matter, it is possible to
effect the artificial transmutation of what are regarded as true
elements into new ones of higher or lower atomic weight. Thus
in 1919 the late Lord Rutherford bombarded nitrogen with
a-particles from Radium C and obtained evidence of the libera-
tion of protons or hydrogen nuclei as the result of "head on"
collisions between nitrogen atoms and the a-particles. Similarly,
in 1932 Cockcroft and Walton effected the disintegration of several
elements by using, as projectiles, protons and deuterons, moving
under potential differences up to one quarter of a million volts. In
1934 Curie and Joliot obtained radio-elements of even higher
atomic weight than the parent by exposing the latter to bombard-
ment with a-particles from polonium. Thus boron (at. wt. 10)
yielded radionitrogen (13)) whilst aluminium (27) was converted
into radiophosphorus (30).

More recently still, it has been found possible, not only to
synthesise elements of atomic weight higher even than that of
uranium, but to break down these elements or effect their "fission",
is it is now termed, into elements of only about half their own
itomic weights (p. 3 1 8). It has now been found possible to convert
mercury into gold but the gold is radioactive, and the process is

PREAMBLE

costly (p. 2 2 1). Thus the dream of the early alchemists has come true,
but not quite in the way they had hoped.

The atomic number

Many years ago, therefore, it became evident that Lavoisier's
definition would have to be replaced by a new one more in harmony
with the known facts of the case. Fortunately chelhiists had not
far to turn. In 1895 R^ntgen, professor of physics in the University
of Wtirzburg in Bavaria, discovered that when matter is bombarded
with cathode rays it emits new rays of extraordinary penetrating
power. These rays, often now called R6ntgen rays, were termed
X-rays as their nature was then unknown, just as iodine was referred
to as substance X at the time of its discovery (p. 48) before it was
recognised to be an element.

X-rays are invisible but their presence may be shown by the
fluorescence produced on, for example, a screen of barium platino-
cyanide when placed in their path. They also travel in straight
lines, they ionise gases so that their presence can readily be de-
tected electroscopically; indeed the electroscope can be used to
measure their intensity. They are regarded as pulsations in the
ether of space, similar to light waves, but of very much shorter wave-
length. X-rays cannot be examined with an ordinary * prism or
diffraction grating, such as may be used for an optical spectrum,
because their wavelengths are too small. But the orderly arrangement
of the atoms in a crystal enables the latter to function as a grating
and to produce an X-ray spectrum. For this purpose Iceland spar
is largely used.

In 1913 Moseley made a remarkable observation. He was a
young scientist of unusually brilliant promise working at Man-
chester University under the guidance of the late Lord Rutherford.
Unfortunately for science he felt it imperative to obey the call of
his Country during the first World War, and perished at the
Dardanelles in 1915. Moseley discovered that the X-rays, emitted
by an element when bombarded with cathode rays, yield on
analysis with a crystal grating a characteristic spectrum consisting
of groups of lines. The three principal groups belong to what are
known as the K, L and M series. These spectra are fortunately
very simple. Thus, in the K-series the spectrum of an element
consists of but two well-marked lines, and what is more remarkable
still is Moseley's observation that the wave-numbers of these
lines shift in stepwise manner with great regularity from one

3

THE CHEMICAL ELEMENTS

adjoining member in the Periodic Table to another. Mathem-,
atically expressed

W OC (Z ) 2

w being the wave number, z the positive charge on the nucleus
of the atom, and b a constant. If ^/w is plotted against z the
relationship is'linear, and measurement of w enables us to calculate
z. Each element yields only one value for z, so that if we arrange
the elements in the serial order of their z charges, beginning with
hydrogen as unity, we can give to each a serial number known as
the Moseley number or the atomic number. Isotopes of any one
element all have the same atomic number.

As in general z rises with the atomic weight, the above arrange-
ment of the elements is almost identical with MendelefFs periodic
scheme; indeed it is the modern interpretation of the Periodic
Law, and yields the Ideal Periodic Table, for there are no excep-
tions to it. Thus argon and potassium, nickel and cobalt, iodine
and tellurium, now fall into line with the periodic scheme although
consideration of their atomic weights, as in Mendel^eff's scheme,
throws them out of gear.

We m^y therefore define an element as

A substante possessing one atomic number and one only. I ]

Thus ammonium, NH 4 , would, if it could be tested, yield two
atomic numbers, namely those of hydrogen and nitrogen. Despite
its resemblance in combination to an alkali metal, it is not an element.
Radium, on the other hand, yields only one atomic number, despite
the fact that upon disintegration other elements are obtained from
it; it is an element, therefore, and not a compound.

Moseley's researches have given us a method of ascertaining
the maximum number of elements that can possibly exist in serial
order between any two known elements. Thus between barium
(atomic number 56) and hafnium (72) exactly 15 elements are
possible; all of these are known and all occur in Nature with the
exception possibly of No, 61. They are the rare-earth elements
and resemble one another very closely; Mendel^eff's system gave
no indication as to their number. In early days, therefore, con-
siderable confusion existed, some of the elements being known
under two or more names and regarded as separate entities; on
the other hand mixtures of two or more elements were frequently
regarded as single elements, as for example didymium, which

PREAMBLE

ta

fcS

3S

TH

CO

3 ll

O

8a

i

s

ail

c?

8fi

o

o

l^

**

r-

vO

G

I s

I 8

| 3

W O

us

Based on the Report of the Commission of Atomic Weights of the International
Union of Chemistry at its meeting in Amsterdam in September 1949. Values in

THE CHEMICAL ELEMENTS

Welsbach showed in 1885 to consist of two elements which he
named neodymium and praseodymium.

Between hydrogen and uranium a maximum number of 90
elements is indicated and all of these are known to occur in Nature
with the exception, possibly, of elements 61, 85 and 87. The
search for an element of higher atomic number than uranium for
long proved abortive; indeed theoretical reasons were adduced to
show that such an element would be too unstable to exist more than
momentarily. But elements 93 (neptunium) and 94 (plutonium)
are now known to occur in Nature ; they have also been synthesised
together with 95 (americium) and 96 (curium)*.

Relative abundance of the elements

Numerous estimates have been made of the relative amounts
of the various elements that occur in the Earth's crust. They vary
considerably, as is to be expected when we * bear in mind the
limitations of our experience; apart from the atmosphere and ocean
a limited portion only of a thin shell of solid on the surface of the
Earth constitutes all that we can examine. For the atmosphere
and ocean our information is fairly good, though still subject to
minor corrections. For the solid crust we must select some
arbitrary depth and that of 10 miles is usually chosen as this
clears the lower depths of the oceans. The average composition of
the lithosphere (Greek Kthos y stone) must approximate closely to
that of the igneous rocks alone, some of which were the earliest
to be formed; the sedimentary rocks represent altered igneous
material from which some of the soluble salts have been leached
into the oceans and to which oxygen, carbon dioxide and water
have been supplied, mainly from the atmosphere. The thin film of
organic matter on the Earth's surface can be neglected; even coal
beds are negligible; the ocean itself comprises about 6*8 per cent
of the Earth's lomile crust.

The estimated figures are as follows

10 12 tons

Total weight of the Earth 6,000,000,000

Solid iom\\e crust 17,418,000

Oceans 1,276,000

Atmosphere , . . 5,260

*To these have recently (1950) been added berkelium (97) and californium (98).

PREAMBLE

In the following table* are given the approximate percentages
of the more abundant elements in the Earth's romile crust,
including the air and the ocean.

Per Cent Per Cent

Oxygen . . . . 50-0 Fluorine . . . . o-io

Silicon . . . . 26-0 Barium . . . . 0*08

Aluminium . . 7-30 Manganese . . 0-08
Iron .. .. 4-18 Nitrogen.. .. 0^03
Calcium . . . . 3*22 Copper . . . . 0-02
Sodium . . . . 2-36 Strontium . . 0*02

Potassium .. 2-28 Nickel .. .. 0-016

Magnesium . . 2-08 Cerium . . . . 0-009

Hydrogen . . 0-37 Tin . . . . 0-008

Titanium . . 0*37 Lead . . . . 0-003

Chlorine . . . . 0-20 Silver . . 2 X icr 5

Carbon .. .. 0-18 Gold .. 2 X icr 7

Sulphur .. .. o-ii Radium .. 1-4 X icr 12
Phosphorus . . o-n All other elements 0-874
It will be noted that oxygen and silicon are overwhelmingly
abundant; amongst the metals, aluminium, iron and calcium are
the most plentiful. It may be a surprise to note that ledd is less
common than tin, despite the much higher price of the latter in
the metal market; the so-called rare-earth metal cerium is more
plentiful than either. Silver is 100 times as plentiful as gold and
the latter at 2488. per oz, troy would appear to be much under-
valued with silver standing round 58. Although nitrogen is more
than three times as abundant in the atmosphere as oxygen, there
are only 6 parts of nitrogen to 10,000 of oxygen in the Earth's crust,

The ages of man

It is often convenient to divide the history of man's progress into
epochs or ages, according to the nature of the materials he commonly
used in his daily life. Thus in the various stone ages his weapons
were mainly of flint, in the bronze age of bronze, and so on. These
ages represent stages of civilisation rather than time intervals and
were not necessarily co-eval for different races. Thus the ancient
Philistines, mentioned in the Old Testament, were in their iron
age whilst the Hebrews were still in their bronze age.

*Thislistis essentially that given by F. W. CLARKE, "Data of Geochemistry"
(Washington, 1916) p. 34, down to strontium. The remaining data are culled from
various sources.

THE CHEMICAL ELEMENTS

The stone ages

At first man's weapons would be of the simplest and crudest
types; oft-times ordinary stones, branches of trees, horns of
animals would be used for hunting down his quarry. But as stones
suitable in shape and size might not always be at hand at the
critical moment it would occur to him to collect them beforehand
and improve them by fracture, chipping or rubbing. In this way
shapes would be evolved that were particularly suitable for special
purposes, such as axes, arrow and spear heads, knives, Scrapers and
so on. The rude flaking of the earliest periods would gradually be
improved upon until implements were ultimately produced ex-
hibiting the most beautiful workmanship. Some of the finest
specimens were produced in Egypt just prior to the First Dynasty,
some 3,500 B.C.

At an early date man became acquainted with fire and learned
how to produce it at will. This was an event of stupendous im-
portance. His camp fire added both to his comfort and to his safety
at night, keeping the wild beasts at a distance; it guided his friends
to camp after dark; it enabled him to harden clay into pottery and
eventually to reduce metals from their ores.

Virtually co-eval with the knowledge of fire would be the
recognition of charcoal, so that this form of carbon was one of the
very earliest elements to be known.

A second epoch-making event was the invention of the bow and
arrow. When this took place we do not know; possibly some
50,000 B.C. This gave man an immense superiority over the
animal ; it was no longer necessary to go close up to wild beasts to
spear them; birds could be caught on the wing at much greater
distances than with a stone, skilful though primitive man must have
been in the art of stone throwing. Man thus became more secure
in his home, and his food supply was more certain than ever before.
He now had time on his hands; what should he do? He began to
adorn his cave-dwelling with pictures or frescoes such as those
found in 1875 * n *he fe mous rock-shelter "La Madelaine", in 1879
at Altamira in Spain, and in the Dordogne in 1895. As pigments
he used various earths such as chalk for a background, oxides of
iron for red and brown colours, and charcoal produced in his fires
for sharp outlines.

Meanwhile he certainly became acquainted with metals; he was
familiar with gold, and prized it because of its intrinsic beauty and
freedom from tarnish. He also knew copper, silver, and any other

PREAMBLE

metals that perchance occurred native. This does not mean, how-
ever, that he was in any sense a metallurgist; that was to come
later. He would regard a metal merely as a stone, though a very
useful one withal, because it could be hammered into shape,
rubbed to a sharp edge, or made into pretty ornaments for his

women-folk.

The age of metals

It is generally held that the metallurgical discovery of metals,
as products of ores, was brought about in a commonplace and
humble manner, namely, in the domestic hearths of stone-age man
(P'9) This was another of the real epoch-making events of human
history. The possession of metal weapons gave men decisive advan-
tage in battle and the chase over those who relied upon stone alone.
A courage, born of security or a sense of superiority, coupled with
a desire to find new sources of the metal, was one of the factors
leading to the exploration of new lands.

The discovery that bronze is not obtained from a single pure ore,
but from a mixture of at least two ores, followed in due course; by
this time man had acquired a very substantial degree of metal-
lurgical skill and knowledge. At the zenith of the bronze .age some
of the workers appear even to have regulated the percentages of tin
in their alloys to suit particular purposes.

As time progressed, bronze gradually gave way to iron. For many
years the two metals were used side by side; in certain prehistoric
remains, such as those at Hallstadt in the Austrian Tyrol, im-
plements of bronze and iron have been discovered lying together,
indicative of contemporary use.

Elements known to the ancients

Seven metallic and two non-metallic elements were known to
man before the Christian Era. The metals include those popularly
called the "coinage metals, gold, silver and copper, together with
lead, tin and iron ; to these quicksilver or mercury was added about
the fourth century B.C. The two non-metals were carbon in its
various forms as diamond, graphite and charcoal, and brimstone
or sulphur. Six of the metals are mentioned by name in the Old
Testament, together with the diamond and brimstone. As will be
explained later, the "tin" of Holy Writ was not the pure metal as
we know it to-day, but a rich tin-copper alloy. It is uncertain if the
"diamond" was our stone (p. 55); the Biblical "brass" was usually

THE CHEMICAL ELEMENTS

a bronze, for zinc was unknown to the ancients, and only occasion-
ally would brass be produced as a "natural alloy". According to
the Old Testament, gold, iron and "brass" were known before the
"Flood", that is prior to about 4000 B.C. Silver, lead and "tin" are
not mentioned until after the Flood. Homer, writing circa 880 B.C.
knew of the ,six metals ; he was, of course, familiar with charcoal
and was moreover aware of the disinfectant properties of brimstone.

There is an old Canaanitish legend, to which reference is made
in the book of Genesis iv, 22, in which the humanised god, Tubal
Cain, son of Zillah, is described as "an instructor of every artificer
in brass and iron". The word Tubal is believed to be Babylonian
and connected with Gibril, the god of Solar Fire. The suffix Cain
is missing from the Greek version and means artificer. It was per-
haps added to Tubal to explain why the hero was regarded as the
father or instructor of smiths. Possibly in the earliest form of the
Hebrew legend Tubal was the instructor of men in the art of
making fire, probably by rubbing two pieces of wood together, for
this is an old Arabian method and appears in later times in connec-
tion with ritual. Enoch* recalls the general tradition that the first
metal worker was supernatural, the fallen angel Azazel being a
teacher of the art. Azazel was the leader of the evil angels who are
stated in Genesis vi. 2, 4, to have formed unions with the daughters
of men and taught them various arts. Their offspring were the giants
who filled the earth with unrighteousness.

In later years the Egyptians became wonderfully skilful in the
working of metals, so much so that when the Greeks conquered
Egypt in the fourth century B.C. they were greatly impressed. Egypt
is watered by the longest river of the old world. Every autumn the
Nile rises in flood, bringing down with it a fine mud which fertilises
the soil. The black appearance of the land after flooding caused the
country to be known as Khem or Black Land. In referring, therefore,
to the skill of the natives in working metals, the Greeks spoke of
the Art of Khem. This word descended to us through the Arabic
as Alchemy. Later the prefix #/, which is merely the Arabic definite
article, was dropped and to-day we speak of Chemistry. In its
original meaning, therefore, chemistry was more akin to metal-
lurgy; but the world has moved on since then so has science,
and chemistry with it.

It is customary to divide the elements into three groups, namely
non-metals, metals and metalloids, the. last named being inter-
*See "The Book of Enoch'* written circa 105 to 64 B.C.

10

PREAMBLE

mediary (p. 68). The word metal comes from the Greek metallon,
which is believed to have originated in a verb meaning to seek or
search for. The metallurgist was thus the one who prospected for
ores, mined them when found and worked the ore for metals; he
was at once a prospector, a miner and a metal worker.

Problems

It is often difficult to ascertain, from the study of the literature
alone, what particular metals or alloys were used for specific
purposes in the past. For this there are several reasons.

(1) Although the early workers could usually distinguish
without much difficulty between gold, silver and copper or bronze,
they often confused other base metals and alloys with one another.
Their statements are thus apt to be misleading.

Thus, for example, lead and tin do not appear to have been
distinguished before Roman times, and even in Pliny's day they
seem to have been regarded more as varieties of the same metal
than as entirely different species.

(2) As knowledge grows, words gradually change their mean-
ings. For example, the Mexicans called their own copper or
bronze tepuztli, a West Indian word that is said to have driginally
meant "hatchet". Later the same word was used for iron, with
which metal the Mexicans were already familiar at the time of the
Spanish Conquest. Tepuztli then became a general term for metal,
and in order to distinguish copper from iron the former was
termed red and the latter black tepuztli*.

Similarly the Greek word chalkbs at first referred to copper or
bronze and we use the word chalcolithic to indicate that stage or era
of human culture in which copper was the predominant metal. But
as iron gradually supplanted copper, so chalkos came to mean
iron, and chalkeus, the copper smith, became the "worker in iron"
in Homer's Odyssey. As the smith had worked in copper and bronze
long before he had ever beaten iron on his anvil, he and his smithy
derived their name from these early metals; but chalkeus and
chalkeion continued to designate blacksmith and forge throughout
all classical Greek literature, when iron was the metal that was
workedf.

We moderns have done the same thing. The washerwoman's
"copper", though made of iron, still retains its old designation;

*TYLOR, "Mexico and the Mexicans", 1861, p. 140.

fRiDGEWAY, 'The Early Age of Greece 11 (C.U.P., 1901) Volume 1, p. 295.

11

THE CHEMICAL ELEMENTS

and who is not familiar with fire-"irons" made of brass, "tin"-tacks
of iron and sealing "wax" of shellac?

In the Torres Strait Region an earth oven or hole in the ground
in which food is baked is commonly called a "copper" and many
have erroneously supposed the name to have been borrowed from
the "copper',' cooking vessels of New Zealand whalers. The word
is really, however, a form in pidgin English of the native term
kopa, an earth oven*.

Somewhat similar difficulties have arisen in the interpretation of
the words brimstone (p. 22) and quicksilver (p. 16), owing to their
having been used in a spiritual as well as a material sense.

(3) Finally, it should be mentioned that, in the past, the
antiquary has not always possessed the requisite chemical or metal-
lurgical knowledge, with the result that relics have not infrequently
been most incorrectly described. Copper objects have been classed as
bronzes and vice versa, whilst, to the present author's own knowledge,
haematite arrow-heads have been described as made of iron of such
excellent quality that it had resisted corrosion throughout the ages!

The alchemists

From the earliest times gold has been regarded as the perfect
metal; the medieval alchemists denoted it symbolically by a circle,
the hall mark of mathematical perfection. It was also identified
with the sun in accordance with the practice of associating metals
with celestial bodies. How this practice originated we do not know,
but it may have been connected with the holy number seven.
There were seven metals or alloys known to the ancients and there
were also seven dominating celestial bodies, these latter including
the sun, moon and five planets, namely Mercury, Venus, Mars,
Jupiter and Saturn, revolving, as was then believed, round the
Earth. Man is slow to realise his own insignificance. Aristarchus
some 250 B.C. had already explained, though much in advance of
his time, that the Earth must be travelling round the Sun. But for
almost another two millenia man preferred to believe that his world
was the hub of the universe. Uranus was not known to the ancients,
being discovered by Sir William Herschel in 1781; this was a
great achievement for, counting the Earth as one, there were now
seven planets known. The discovery of Neptune in 1846 upset
this holy number and matters were made even worse when Pluto
was observed in 1930.

*SMYTHE PALMER, "The Folk and their Word-lore" (Routledge, 1904), p. 15.
12

PREAMBLE

For the ancients there was thus one metal for each heavenly
body. Gold was naturally associated with the sun in virtue of its
bright yellow colour and dominant position among the metals.
Indeed some alchemists spoke of gold as "condensed sunbeams",
much in the same way as quartz or rock crystal was regarded by
Albertus Magnus, round A.D. 1250, as a form of iceso hardened
by Alpine frosts that it refused to melt. Silver, the less perfect
metal, was allowed only half a circle, its symbol thus resembling
the crescent moon ; this, coupled with its pale colour, clinched the
connection with that luminary.

Symbols of the alchemists

Gold O Sun Lead . . ^ Saturn

Silver )) Moon Iron . . <J Mars

Copper $ Venus Quicksilver Mercury

Tin 2J. Jupiter !

Iron, the warrior's metal par excellence, came under the aegis of
Mars, the god of war ; it was appropriately symbolised by a shield and
spear. The symbols of the remaining elements bore a cross signifying
the close connection between alchemy and religion. Tin and lead
were given somewhat similar symbols because they were soAietimes
regarded as mere variants of one and the same metal. In either case
they were debased forms of silver, hence the curved portions. The
lead symbol suggests a sickle or scythe. As lead was heavy, dense
and dull it came under the influence of Saturn, the farthest known
planet from the Earth, and apparently therefore moving the most
sluggishly. From this originated the "scythe of Saturn" and the
idea of spiritual density or moroseness associated with the word
saturnine.

Some authorities see in the symbol for tin the Zeta of Zeus or
Jupiter; others the arabic 4 or arbah $, indicating the fourth
planet again Jupiter. Copper with its orange colour more closely
resembles gold than the other metals and was awarded a disc plus
the inevitable cross. The symbol thus bore a fanciful resemblance
to a hand mirror and was hence called the looking-glass of Venus.
The Egyptian symbol ankh, $, the "handled cross", denoting the
sun's gift of life to the world, is closely similar.

Quicksilver, as its name implies, is alive and active corresponding
to Mercury the nimble messenger of the gods. Its symbol, regarded
as the caduceus or wand of Mercury, embodied the sign of the
cross, surmounted by the circle of perfection and the crescent of

13

THE CHEMICAL ELEMENTS

silver which latter metal it so closely resembles in colour and bright-
ness. As the supposed constituent of all metals (p. 15) and by
virtue of its incorrodibility, quicksilver had earned the circle of
perfection.

In early days apothecaries were wont to have with them bottles
containing coloured liquids and labelled with appropriate signs, as
badges of office, so to speak. These included yellow solutions,
indicative of gold, marked with a circle; red solutions signifying
iron and marked with the shield and spear of Mars; and so on. As
the years rolled by and the profits increased it was appropriate that the
size of the bottles should also increase until they reached the dimen-
sions now familiar to us in the shops of our wealthy pharmacists.

It is of interest to recall that the seven days of our week are
associated through the celestial bodies with the seven metals known
to the ancients. Thus the sun and moon are clearly perpetuated in
Sunday and Monday, the gold and silver days. Tuesday is the day
of Tiw, the Anglo-Saxon equivalent of Mars. Woden, the Saxon
counterpart of the Scandinavian Odin, gives us Wednesday; the
Romans early identified Wodin with Mercury; the French use the
word mercredi, that is mercurii dies. Thursday is Thorns day, Thor
being equivalent to Jupiter, whence the French jeudi or Jovis dies.
Frigg was the wife of Woden and corresponds to Venus, the goddess
of love; whence Friday and the French vendredi, the veneris dies.
Saturday is clearly Saturn's day. The French name for Sunday,
dimanche, departs from this scheme : it is a corruption of domini dies,
the Lord's Day.

In this connection it may be noted that the order of the days of
the week is not random, as at first sight it appears to be. In times
when astrology was an important branch of science, day and night
were each divided into twelve planetary or unequal hours (unequal
because day and night vary in length throughout the year). The
hour of one planet succeeded that of another in the order of dim-
inishing planetary distance from the earth according to the
Ptolemaic* system of astronomy

Saturn Jupiter Mars Sun Venus Mercury Moon

s 2j <? o g -g

*The geocentric Ptolemaic system was superseded by the heliocentric system
of Copernicus (1473-1543) principally owing to the work of Galileo, Kepler, and
Newton in the seventeenth century. The planets are now known to revolve
about the sun in elliptical orbits of small eccentricity at the following mean
distances (in millions of miles) Mercury, 36;. Venus, 67*2; Earth, 92*9; Mars,
141-5; Jupiter, 483-3; Saturn, 886-1; Uranus, 1783; Neptune, 2793; Pluto, 3666.

14

PREAMBLE

The day took its name from the hour with which it began. "Under-
stonde wel", says Chaucer*, "that these houres inequales ben clepid
[called] houres of planetes . . . The firste houre mequal of every
Saturday is to Saturne, and the seconde to lupiter, the thirde to
Mars, the fourthe to the sonne, the fifte to Venus, the sixte to
Mercurius, the seventhe to the mone. And then ageyn the 8 is to
Saturne, the 9 to lupiter . . ." Continuing in this way, the twenty-
fifth hour (or the first hour of the next day) is found to be "the
houre of the forseide sonne". So the day after Saturday is Sunday
and so on through the week.

Transmutation

The idea that the metals could undergo transmutation under
natural conditions with the lapse of time was widespread for many
centuries. Plato (427 to 344 B.C.) believed this. The ancient
Chinese philosophers believed that arsenic, in the course of 200
years in the ground became converted into tin (p. 19). Even as late
as the eighteenth century miners believed that lead was gradually
converted to silver and that bismuth was lead half-way on the road
thither (p. 87). The alchemists believed it might be possible to
hurry up or catalyse this transmutation in the laboratory, and if so,
why not make it profitable by converting a base metal direct into
gold? At first blush this might appear but a foolish dream; it was
however a logical conclusion from the then current ideas of the
constitution of matter.

The sulphur-mercury theory

Geberf, the famous Arabian chemist, regarded the six metals
gold, silver, copper, lead, tin, and iron, as compounds of quicksilver
with sulphur in different proportions. Gold was composed of the
purest mercury and sulphur. The base metals contained the same
essential ingredients as gold, but were contaminated with various
impurities. If, therefore, these latter could be removed pure gold
must result; the base metals would thus be transmuted to gold.
The name Geber is the Westernised form of Jabir, the full name
of this famous chemist being Abu Musa Jabir ibn Hayyan. He
was born at Tus, near Meshed, A.D. 721 or 722, the son ofa

*"A Treatise on the Astrolabe 11 . The quotation is from "The Works of
Chaucer", Globe edition (Macmillan, 1910).

f'The Works of Geber". Translated by R. Russell, 1678. Introduction by
Holmyard (Dent, 1928).

15

THE CHEMICAL ELEMENTS

druggist. Losing his father at an early age* he was sent to Arabia
to study the Koran and ultimately became persona grata at the court
of Harun al-Rashid, at Baghdad; this Harun was the Caliph of the
"Arabian Nights". Later he retired to Kufa in Iraq, which had
been his father's home, and remained there in seclusion until the
time of his death early in the ninth century. Some 200 years later
a street in Kufa, known as Damascus Gate, was rebuilt and in the
course of necessary demolitions Geber's laboratory was uncovered.
In it were found a mortar and a large lump of gold which, says the
chronicler, "the King's Chamberlain took possession of. It was
assumed of course, that the gold was the product of transmutation.

The word "gibberish" is derived from Geber and refers to the
unintelligible jargon used by alchemists of whom Geber was
regarded as the typical representative. Sylvester, writing in 1621,
says of the builders of the tower of Babel: "som howl, som halloo,
sum do stut and strain. Each hath his gibberish." We are reminded
of Isaiah's reference to a people who speak with "a stammering
tongue, that thou canst not understand" (Isaiah xxxiii. 19). Al-
chemists were sometimes nicknamed "Geber's cooks" and Camden,
writing in 1637, referred to alchemy as "Geber's cookery". ~

It is evident that Geber's quicksilver and sulphur were not the
material elements known by those names, for he mentions that on
heating the material elements together "the red stone known to
men of science as cinnabar" was produced. The constituents of
gold were thus hypothetical or idealised substances to which
material quicksilver and sulphur were the nearest known approach
(p. 71). The European alchemist, Albertus Magnus, who became
Bishop of Ratisbon in 1259, is believed to have subscribed to the
quicksilver-sulphur theory, although the authenticity of the
alchemistic works attributed to him has been queried. It was he
who introduced the word "affinity" to indicate the reason why
sulphur united with quicksilver a term that is widely used and
appreciated by chemists to-day. -^

Sir Isaac Newton appears to have believed in the possibility of
transmuting base metals into gold and to have kept furnaces going
for many weeks with this end in view, sitting up at nights to attend
to them. But after his appointment 'as Master of the Mint in 1699
it would hardly have been wise for him to allow his name to be
associated with alchemy. The less said the better. At his death in

*He was a druggist and was beheaded by the Caliph for political intrigue.
16

PREAMBLE

1727 the catalogue of his library contained many works on alchemy.

Numerous stories were current in alchemistic days of base metals
being transmuted to gold. All were told by "reputable witnesses"
and were "undeniably true".

Jean Jacques Manget who, from 1669 unt ^ h* s decease in 1742,
was "first physician" to the Elector of Brandenburg relates one
such story in his "Bibliotheca Chemica Curiosa", He says that in
1650 a young cleric who spoke fluent Italian was asked to show an
Italian visitor to Geneva the "sights" of that beautiful city. After
a couple of weeks the stranger ran short of money and asked his
guide to introduce him to a goldsmith who would be willing to
lend him some crucibles and allow him the use of a furnace. This
being duly arranged, the stranger melted some tin in a crucible
and to it added mercury that had been heated in a second crucible
together with a red powder in a wax capsule. The mixture became
greatly agitated and evolved copious fumes. When these had cleared
away the stranger poured the still molten contents of the crucible
into moulds and obtained thereby six bars of pure gold. One of
these he gave as recompense to the goldsmith and the others he
sold to the Master of the Mint, who thereby guaranteed the
genuineness of the metal. Being now in funds the stranger paid
his hotel bill, handed the cleric 20 gold coins as honorarium for his
services and to these added a further 1 5 for joint entertainment
with the goldsmith during the next few days. He then left, promis-
ing to return and have supper with them that evening. But he
failed to return and was not heard of again another mysterious
disappearance.

Most of the stories end like that just as they are becoming
interesting.

Many alchemists, like Paracelsus (1490 to 1535) and Basil
Valentine (p. 84), published recipes for making the Philosopher's
Stone, the magic wand, with the aid of which base metals may be
converted to gold. But why such generosityP/We look askance jt
these recipes, remembering the words of Alfred C, Lewis ~~

It's not the man who knows the most
That has the most to say;
It's not the man who has the most
That gives the most away.

In general this is true, and human nature has not altered much
with the lapse of centuries.

17

THE CHEMICAL ELEMENTS

It is perhaps worth noting that alchemy has several times
received the serious attention of legislature in this country. In 1404,
during the reign of Henry iv, the making of gold and silver was
forbidden by Act of Parliament; to transmute metals was to com-
pound a felony. The authorities feared that a successful alchemist
might becon^e a menace to the state. On the other hand the feeble-
minded Henry vi (1422 to 1461) granted several patents to people
who imagined they had discovered the philosopher's stone and
could thus transmute metals.

The miner

Miners have been proverbially superstitious. Working under-
ground, deprived of the stimulating rays of the sun, they were apt
to cherish a belief in the supernatural that most of us who labour
above ground hesitate to share.

The Welsh mines were believed to house "knockers", little
fellows about 18 inches in height, good-natured and willing to
assist the miner by drawing his attention to the richest veins of
ore. These knockers were not generally to be seen, but guided by
knocks the miners who followed in the direction of the sounds.
Other inhabitants of mines have not always been quite so friendly,
Christopher Merret*, writing in 1677 of the Cornish tin mines,
stated that the miners were wont to tell stories of sprites or "small
people" as they called them, who terrified them by causing horrid
knockings and fearful hammerings. Many German mines were
similarly peopled by sprites or goblins known as "kobalds". These
pestilential gnomes placed poisonous ores in the path of the miners
and on the sabbath it was customary to pray for deliverance from
their machinations when attending church. This belief is per-
petuated in the name cobalt (p. 291).

The growth of minerals

Miners have long cherished the idea that metals and minerals,
like plants and animals, can grow and breed. Pliny, writing at the
beginning of the Christian Eraf, refers to certain lead mines

*C. MERRET, Phil. Trans., 1677, 12, No. 138, p. 949.

fPLiNY, "Natural History", translated by Bostock and Riley (Bohn, 1857),
Book 34, Chap. 49. Pliny was probably born at Novum Comum, A.D. 23, on the
south shore of Lake Larius in N. Italy. He died at the age of 56 in A.D. 79 when
Herculaneum and Pompeii were overwhelmed by the eruption of Vesuvius. Pliny
is famous for his enormous literary production -"Historia Naturalis", the only
one of his works that has survived to our times. It was completed A.D. 77.

18

PREAMBLE

which "when they have been abandoned for some time, become
replenished and are more prolific than before." Even to-day the
Tibetan miners will collect and export gold dust; they refuse,
however, to touch the nuggets as these are believed to breed the
dust. In effect the nuggets are the geese that lay the golden eggs.

Many circumstances contributed to these beliefs. Take, for
example, the bog iron ore which "grows" in the Swedish lakes. It
consists essentially of hydrated ferric oxide, probably oxidised from
dissolved ferrous salts and thrown out of solution by lowly organisms.
The ore once removed from the lake bed is gradually replenished.
In Cumberland and in Lancashire there are places where lime-
stone has been replaced molecule by molecule with ferrous
carbonate from percolating waters charged with ferrous salts in
solution. Oxidation and heat have converted the ferrous carbonate
to haematite; the rocks thus possess the appearance of having
"grown together" as the miners say, the haematite gradually
passing into the limestone and possessing similar stratifications
and dip. Casts of mollusca and other fossils characteristic of
carboniferous limestone have been found in the haematite as well
as crystals of haematite pseudomorphic with calcite.

In the Middle Ages mines were frequently closed in order that
the supply of metals might be renewed.

Merret* mentions that a "white sparr" found along with tin-
stone in Cornish mines was locally regarded as the "mother" of the
ore. Even as late as the middle of the nineteenth century the country
folk in Berkshire believed that the stones in the fields grew. "They
could prove to you" wrote John M. Baconf "that stones grew
from year to year, even as cabbages grow, though of course much
more slowly; since did they not pick the 'big-uns' off the field
every season for road mending, yet their number never dimin-
ished, showing beyond doubt that the 'little uns had growed'."

Early Chinese philosophers believed that arsenic would regenerate
itself after 200 years and after a like period would be transmuted
to tin (p. 15).

*MERRET, loc. tit., p. 951.

fGERTRUDE BACON, "The Record of an Aeronaut" (London, 1907), p. 52.

19

CHAPTER 2

THE PERMANENT GASES

THE permanent gases included in this chapter comprise oxygen,
nitrogen, hydrogen, deuterium and tritium.

The ancients recognised only two forms of matter, to which we
give the names solid and liquid. The rustling of the leaves of the
trees in the woods was due to nymphs dancing from bough to bough;
the waves of the sea during a tempest were lashed into fury by
Neptune's god-like wrath. But gradually it was realised that these
conceptions created many insoluble problem*; it was better to
assume that matter was not destroyed when wood burned and
water evaporated, but was converted into an invisible spirit-like
substance which was still in existence even if it could not be seen.
We owe the word "gas" to that erratic genius van Helmont
(1577 to 1644) w h probably derived it from the Dutch Geest,
ghost or spirit, in view of its elusive nature*.

Faraday, who resumed his earlier work on the liquefaction of
gases in 1845 found himself utterly unable to liquefy hydrogen,
nitrogen, oxygen, nitric oxide and carbon monoxide, no matter
what pressure he applied, and concluded that they were un-
liquefiable; they came to be known, therefore, as permanent gases.
We now know the reason for this. For every gas there is a tempera-
ture, known as the critical temperature, above which a gas cannot
be liquefied no matter how great the pressure. Above its critical
temperature any gas is permanent ; below it the gas is a vapour. The
critical temperatures of the above-mentioned gases lie well below
the ordinary temperature of the atmosphere ; that was why Faraday
was unable to liquefy them; they have all since been liquefied;
liquid air and oxygen are now commercial commodities.

We shall now proceed to discuss the following gases oxygen,
ozone, nitrogen, hydrogen with its isotopes, and, in the next chapter,
the inert gases. Although fluorine and chlorine are also permanent
gases, it is convenient to consider them later along with the other
halogens.

*An alternative derivation from the Greek chaos, space, accepted by many
authorities appears to the present Author to be less probable.

20

THE PERMANENT CASES

Oxygen

So much has been written from time to time about the early
history of this element that the barest outline will now suffice.
Oxygen is the most abundant element in the earth's crust of which
it constitutes some 50 per cent if we include the ocean and the
atmosphere. The last named alone holds approximately 1218
billion tons of the gas. Leonardo da Vinci (1452 to 1519), the
famous artist whose painting of "The Last Supper", in Milan, is
world famous, appears to have been fhe first European to state
that air is not completely consumed during respiration or combus-
tion. Boyle showed in 1660 that air was necessary for life, and in
1670 an Italian naturalist wrote that if the air holes of an insect
were covered with oil or syrup, the insect would die in convulsions
while one might say a Paternoster a monkish method of measur-
ing time.

Although Harvey discovered the circulation of the blood in 1619,
he believed the object of the air in entering the lungs was merely
to cool the heart. Hooke, in 1665, knew that nitre contained a
constituent similar to the active principle of the air, and in 1728
Stephen Hales, Vicar of Teddington, actually heated nitre,
collected the oxygen and measured its volume. But he did not
examine the gas. A great discovery was thus narrowly missed.

In the early seventies of the eighteenth century the Swedish
chemist Scheele and Presbyterian minister Joseph Priestley* dis-
covered oxygen independently. Both investigators obtained it,
probably as early as 1773, in several ways, including the heating
of mercuric oxide. The Priestley statue in Birmingham represents
Priestley heating the oxide iri a tube with the sun's heat concen-
trated by a lens held between his thumb and second finger. Poetic
licence! The actual lens was twelve inches across! Legend hath it
that Priestley discovered the gas on 1st August 1774; this is
apparently due to a misreading of his laboratory notes. He prepared
the gas on that day, but not for the first time. He had been familiar
with it for at least a year. His first public announcement was at
the Royal Society on 23rd March 1775, and in most cases that
would now be taken as the date of the discovery.

Scheele embodied an account of his researches in a book entitled
"Air and Fire", the manuscript of which was completed in 1775;
but publication was delayed by the printer until 1777, much to

*See his "Memoirs" edited by his son in 1805.

21

THE CHEMICAL ELEMENTS

the chagrin of Scheele, for, in the meantime, Priestley had announced
his discovery of oxygen. Scheele called the gas empyreal or fire air y
the^term "air" being synonymous with the present use of our word
gas. These names reflected the ease with which substances burned
in the gas. So did Priestley's term dephlogisticated air, but to
appreciate thjs and the importance of the discovery of oxygen it is
necessary to appreciate also the then current views on combustion.
It is safe to say that neither Scheele not Priestley realised the
important part played in combustion processes by the gas they had
discovered.

The theory of phlogiston*

Why do substances burn? This is a problem that exercised the
curiosity of man from the earliest times. Colour, shape, hardness,
opacity none of these properties appeared to have anything to
do with it. Surely the explanation must be that substances burn
because they possess the essence of combustibility; in 1697
Stahl, professor of Chemistry and Medicine at Halle University,
coined the name "phlogiston" for this essence, deriving it from the
Greek phlox, flame, or phlogistein, to set on fire. Substances burning
in air gave up phlogiston to the air which was regarded as not yet
saturated with it; as soon as it became saturated no further com-
bustion could occur, for phlogiston could not escape from matter
unless it had somewhere to go. The idea was much like that of a
sponge which until it is saturated can absorb water; but once it is
saturated it no longer functions.

The new gas of Scheele and Priestley allowed unusually vigorous
combustion to occur. It was a really 'dry "sponge"; it could mop
up the phlogiston in which it was perhaps entirely deficient.
Hence Priestley's name for it dephlogisticated air.

The substance we are familiar with under the Latin name of
"sulphur" was for a long time known as "brimstone" or burning
stone, the stone that burned completely away and, unlike wood,
left no* ash. Brimstone thus became the personification of combust-
ibility, and the words brimstone and sulphur developed a double
meaning, spiritual and material. This has naturally led to some
confusion of thought. In Holy Wrtf we read, for example, in
Rev. xxi. 8, that the wicked "shall have their part in the lake which
burneth with fire and brimstone". From statements like this the

*This theory has been exhaustively studied by PARTINGTON and McKis,
Annals of Science. 1937, 2, 361; I93&, 3, i, 337; I 939. 4, 113.

22

THE PERMANENT GASES

conception of hell, which continued down to recent times, was that
of a place where the wicked were exposed eternally to intense heat
aggravated by fumes of burning sulphur; in other words hell jvas
a heated poison-gas chamber. Such, however, was by no means
the original idea, for material sulphur was not in the mind of the
writer. The expression meant "fire and the essence of fire" a
typical eastern duplication so common in languages that have no
comparatives, to indicate great intensity, like our expressions,
"out and out" or "through and through". The wicked were thus
to be exposed to intense fire. But even this is not quite the rea!
meaning. The early Hebrew tongue had relatively few words and
practically none to represent abstract moral ideas. Thus when %
man was angry he was said to be "hot", and the lesson the sacred
writer wished to convey was that hell is a place or state where th<
wicked are exposed to the intense wrath of God after all, a verj
modern conception.

In 1 640 Albaro Barba wrote a book entitled "The Art of Metals'
in which occurs one of the earliest known references to Americar
Petroleum. It runs*

"La Naphte is a sulphurous liquor, sometimes white, and some-
times black also, and is that which is called Oyl of Peter, oi
admirable vertue to cure old pains, proceeding from cold causes
It will draw fire to it (as the loadstone does iron) ..."

Clearly there was no suggestion of material sulphur here. We need
not laugh at our ancestors for giving material and spiritual mean-
ings to the same words. We do the same to-day. When we are told
that a man is full of good spirits we do not infer that he has just
polished off a bottle of whisky. There is no confusion in our minds;
neither was there in the minds of our forefathers. With the intro-
duction of the conception of phlogiston many came to regard the
spiritual sulphur and phlogiston as the same essence.

When metals are calcined in air, oxides are usually produced.
This was explained by Stahl on the supposition that the metal, on
being heated, parted with its phlogiston leaving a residue of calx.
In the light or this idea the calx was of simpler composition than
the metal itself. Thus

metal = calx -f phlogiston
A substance such as charcoal was regarded as being rich in

*This quotation is from the English translation of 1669 by the EARL OF
SANDWICH.

23

THE CHEMICAL ELEMENTS

phlogiston and could reverse the above process by restoring the
phlogiston to the calx when heated with it and so reproduce the
metpl. Thus

calx -f charcoal = metal + charcoal ash

Paracelsus (p. 85) at the beginning of the sixteenth century, had
already described metals that had undergone oxidation as dead.
Thus a calx was a dead metal; verdigris was dead copper. He
mentioned that metals could be brought to life again or "reduced
to the metallic state" by heating with charcoal; he was the first to
use the word reduce in this sense.

The theory of phlogiston was during the eighteenth century
very popular amongst chemists despite the fact that it was full of
anomalies. For example, if phlogiston were a material body, it is
evident from the equation given above that a metal must weigh
more than its calx. If phlogiston were merely an immaterial
essence, the two would weigh the same just as a hot body weighs
the same as when it is cold within the error of experiment. Now
Jean Rey had already in 1630 shown that lead and tin actually
increase in weight when calcined; but trifles of this kind were not
allowed to interfere with so convenient a theory!
In 1766 Cavendish identified hydrogen and distinguished it from
carbon monoxide, marsh gas, and other inflammable gases.
Priestley, on hearing of this, immediately identified hydrogen with
phlogiston and, as hydrogen was so much lighter than air, he
round here an explanation for the gain in weight of a metal when
converted to calx. Evidently a gross confusion of thought.

Lavoisier's theory of combustion

In 1774 Priestley was in Paris and met Lavoisier, already at the
age of 31 the foremost chemist in France. Unfortunately his
brilliant career was doomed to end with his execution in 1794, a
victim to the blood-lust of the French Revolution. Of him Legrange
said "It required but a moment to strike off his head and probably
100 years will not suffice to reproduce such another."

Priestley gave an account of his experiments to Lavoisier who
then realised that the theory of phlogiston could not be true. He
explained combustion as due to union of the combustible material
with this new gas, which evidently now required a new name. At
first he called it "eminently pure air"; later he changed the name
to oxygen or acid producer (Greek oxus, sharp or acid ; gennao> I

24

THE PERMANENT GASES

produce) in his belief that the element was an essential constituent
of all acids. The German name Sauerstoff embodies the same idea.
This is one of the few instances in which the name given to *an
element by its discoverer has not been retained. Nitrogen and
hydrogen, the two next elements to be considered, are further
examples, as are also chlorine, iodine, tellurium and beryllium.

Isotopes

In 1929 spectroscopic examination of the absorption bands of
oxygen led Giauque and Johnston to conclude that it is not a simple
gas but contains three isotopes of atomic weights (16), (17) and
(i 8). The two latter are present in only small amount, nevertheless
their existence has been confirmed by the mass spectrograph.
Atmospheric oxygen contains these isotopes in the proportions of
99-76 of isotope (16), 0-04 of (17) and 0-20 of (18).

This discovery of the complexity of ordinary oxygen was one of
great importance. Since 1906 the atomic weight of ordinary
oxygen gas has been standardised at 16*000, all other atomic
weights being expressed relatively thereto. This mean value of
16-000 is really 1-000275 times as great as that of the single
isotope (16). When, therefore, atomic weights are determined by
the mass spectrograph relatively to the physical isotope (16), the
values are relatively too high for the chemical standard and must
be divided by i 000275, termed the conversion factor ', in order to
render them comparable with purely chemical data. As will be seen
shortly, this was the source of the clue to the discovery of deuterium

(p. 36).

Applications of oxygen

An important modern use to which oxygen is put is to enrich
the air supplied to aeronauts at high altitudes and to certain invalids,
and to resuscitate persons who have been suffocated or are suffering
from carbon monoxide poisoning, etc. The "iron lung" has become
quite a feature in modern medical practice. In conjunction with
hydrogen and acetylene the gas is used to attain high temperatures
for metal cutting and welding. Oxygen is used in bleaching, in the
oxidation and thickening of oils, etc, and in the preparation of
ozone.

The isotopy of oxygen has proved valuable in certain academic
studies. For example using water containing the O (18) isotope,

25

THE CHEMICAL ELEMENTS

namely H 2 18 O, it has been shown that, in the hydrolysis of esters '
with caustic soda, fission occurs at the C atom. Thus

X.OEt /O-fEt

RC and not RC

V)

Ozone

Ozone is a "condensed" form of oxygen containing three atoms
in the molecule. In 1785 van Marum drew attention to the fact
that the air in the neighbourhood of an electrical machine in action
possesses a peculiar odour. This "electrified air" was used shortly
afterwards by Cavallo as a remedy for foetid ulcers, its power of
removing unpleasant smells being thus early recognised. Sch6n-
bein*, in 1 840, concluded that the odour was caused by the presence
of a new gas which he called ozone from the Greek ozo, I smell.

It was at first thought that ozone was a compound of oxygen
and hydrogen, but this was negatived when Marignac obtained
it from dry oxygen. In 1845 Marignac and de la Rivef suggested,
therefore, that ozone was a peculiar or allotropic form of oxygen.
In 1848 Hunt suggested that it was an oxide of oxygen, of formula
O.O 2 , analogous to SO 2 and SeO 2 . This was supported in 1860
by the observation of Andrews and Tait^: that, when ozone was
formed from oxygen, a contraction occurred, so that the new gas
possessed a higher density. Odling in 1861 suggested that the
reaction involved might be most easily represented by the equa-
tion

3 2 - 2 3

and the correctness of this was experimentally proved by Soret in
1866 and confirmed by Brodie in 1872. The reaction may be
pictured as follows. Three molecules of oxygen approach as in-
dicated by (i) in the scheme shown (Fig. i). When they are
sufficiently close the attraction of the two central atoms for each
other in the unstable complex (ii) counterbalances that of the two
external pairs. Circumstances will decide whether the complex
shall dissociate to oxygen again or to ozone.

On account of its powerful oxidising properties ozone exerts a
marked bactericidal effect. It is frequently employed therefore in

*SCHONBEIN, Pogg Annalen, 1840, 50, 616; 1843, 59, 240; 1844, 63, 520.
t MARIGNAC and DE LA RIVE, Compt. rend., 1845, 20, 1291.
{ANDREWS and TAIT, Phil. Trans. , 1860, 160, 113. /. Chem. Soc., 1860, 13, 344.
ODLING, "Manual of Chemistry", 1861, p. 94.

26

THE PERMANENT GASES

improving the atmosphere of buildings that are likely to be
crowded, such as underground passages, and the stations and tunnels
of electric tube railways ; care must of course be taken that ihe
concentration of the gas shall always be well under the danger limit.
Another extensive application is in the sterilisation of water. As
early as 1886 experiments were carried out on the ozonisation of
water to effect the removal of organic matter and bacteria. Eight
years previously Pasteur had introduced his germ theory of disease
and the danger of transmitting diseases such as typhoid and cholera
by vitiated waters was beginning to be realised. In 1885 Percy
Frankland had shown that almost all the bacterial content of water

'o CM |'o\

I | i ) ' I
lo J I o i

/

o o * i o i o

o;

(i) (ii) (iii)

Fig. 1 Formation of ozone from oxygen

could be removed by sand filtration. By the use of ozone after
filtration it was hoped that complete removal might be achieved.
It was not until the development of more efficient types of large
ozonisers had been effected that the process could become one of
industrial importance. Many such systems were eventually installed,
mostly on the Continent; but the advantages of the use of chlorine
for this purpose are so obvious that, at any rate in this country,
sterilisation by chlorination is now largely adopted.

Small ozone sterilisation plants are made for sterilising water,
etc, used in the manufacture of beverages and foods generally.

Ozone is used as an oxidiser in bleaching such substances as
starch, flour, oils, wax, delicate fabrics, etc. It has also been used to
aid the "ageing" or maturing of wines, spirits and tobacco. The
action of ozone on unsaturated organic substances provides a
convenient general method for the preparation of aldehydes and
ketones; it has been applied to the production of vanillin for
flavouring purposes and heliotropin for perfumery. An ozoniser
of the silent discharge type is used and air is treated to emerge from
the apparatus with an ozone content approximating to 2 or 3 grams
per cubic metre. The "ozone water" of commerce contains no
ozone; its activity is due to such substances as hypochlorites, etc.

27

THE CHEMICAL ELEMENTS

Nitrogen

The discovery of nitrogen in 1772 is usually credited to Daniel
Rutherford, pupil of Joseph Black who held the Chair of Chemistry
at Edinburgh University*; he happened also to be uncle to Sir
Walter Scott. As has been mentioned, it was already known to
Leonardo da, Vinci that air was a mixture; at the suggestion of
Black, Rutherford investigated the gas left after the oxygen of the
air had been used up either chemically or by animal respiration,
the carbon dioxide in the latter case being removed with alkali. As
the residual gas would not support combustion, it was regarded as
saturated with phlogiston, whence its name phlogisticated air.
Priestley was the first to show quantitatively in 1772 that one-fifth
of the air disappeared when charcoal was burnt in a closed vessel
and the residual gas shaken with milk of lime. Scheele independently
discovered it and called it foul air. Lavoisier in 1776 definitely
recognised this residue as a simple gas and called it azote from the
Greek a, not, and zoos, living. This name is still used by the French
and is retained in our "azo" and "diazo".

With the fall of the phlogistic theory, however, the term
"dephlogisticated air" became untenable and Chaptal in 1791
suggested nitrogen, since it is a constituent of nitre.

Active nitrogen

When an electric discharge is passed through nitrogen at low
pressures, circa 2 mm, a yellow glow is seen which persists for some
time after the discharge has ceased. Although this had been known
for some time, it was left for R. J. Struttf, the late Lord Rayleigh,
to examine the physical properties of the after-glow and the chemical
reactions of the active form, which differ widely from those of
ordinary molecular nitrogen.

It was at first thought that the activity was due to triatomic
nitrogen analogous to triatomic oxygen or ozone, but later work
showed that view to be untenable.

The view now held is that active nitrogen contains at least two
distinct species, namely

(i) Metastable, activated molecules, N 2 *, mainly responsible
for the chemical activity and

* PROFESSOR BLACK'S name is well known to chemists for his researches on
"Fixed Air", that is, carbon dioxide. He lived 1728 to 1799.

fSxRUTT, Proc. Roy. Soc., 1911, A85, 219. R. J. Strutt was the fourth Baron
Rayleigh.

28

THE PERMANENT GASES

(ii) A much smaller proportion of nitrogen atoms, responsible
for the glow.

Uses of nitrogen

Nitrogen exists almost exclusively in the atmosphere which holds
some 4041 billion tons of the gas over every ?cre are some
31,000 tons.

About 1913 Langmuir invented the gas-filled electric lamp
bulb, and at first nitrogen was used. This gas has now been super-
seded by certain of the inert gases, such as argon and krypton.
Nitrogen is used in flushing petrol refuelling tubes for aeroplanes
in mid-air to prevent firing, and in various "fixation" processes,
for the production of ammonia, nitric acid, cyanamide, cyanides,
etc. The main industrial use of nitrogen is in the form of its com-
pounds, into which it is converted by natural processes as well as
by artificial.

In 1784 Cavendish showed that nitrogen will combine under
the influence of the electric spark with oxygen to form oxides. This
occurs in nature during thunderstorms and, in temperate climes
it is estimated that in this way 1 1 Ib. of nitrogen are "fixed" per
acre per annum. In the tropics the amount will be much greater.
In 1897 Lord Rayleigh*, describing his experiments in which
argon was isolated from the atmosphere (p. 41), pointed out the
possibilities of utilising the electric arc for the industrial fixation of
nitrogen. The first technical attempt to utilise this reaction was
made in 1902 at Niagara but was not a commercial success. The
following year, however, the Birkeland-Eyde process was started
at Notodden in Norway and proved successful.

Nitrogen may also be fixed as ammonia, by passing the mixed
gases, nitrogen and hydrogen, in the proportion of I to 3 by volume
over a heated catalyst under pressure. The Haber process was the
first to achieve technical success. It was devised by Haber during
World War I to enable the Germans to produce explosives, as our
navy had cut off their Chilean supplies of nitrate. Had Haber not
succeeded, the war would have been over in our favour several
years earlier than it was. Haber was a Jew, and a grateful Fatherland
showed its appreciation of his services many years later by his
expulsion. He died brokenhearted in 1934.

In Serpek's process (1919) atmospheric nitrogen is fixed as

*J. W. STRUTT, third Baron Rayleigh.

29

THE CHEMICAL ELEMENTS

aluminium nitride, A1N, which is subsequently hydrolysed yield-
ing ammonia and pure aluminium hydroxide.

^n 1 784 Scheele observed that, by heating a mixture of potassium
carbonate and carbon in an atmosphere of nitrogen, potassium
cyanide is produced. In 1835 Dawes observed that potassium
cyanide is a p/oduct of the blast furnace, and in 1924 the suggestion
was made by Franchot* that about one per cent of the nitrogen of
the air blast could be recovered as cyanide from the blast furnace.
In the Bucher Process (1917), potassium carbonate is replaced by
the sodium salt ; numerous other modifications have been introduced.
Mention should also be made of the fixation of nitrogen as calcium
cyanide, CaN.NH 2 , the process being patented by Frank and
Caro during the years 1895 to 1898. In 1866 Hellriegel showed
that the bacteria in the roots of leguminous plants can "fix"
atmospheric nitrogen.

The Egyptian national god Amen was known by the Romans
when they conquered Egypt as Ammon, and identified by them
with their god Jupiter. Outside the Egyptian temples the refuse
from the sacrifices, etc, gradually disintegrated and parts were
converted into mineral salts, which became known as "salts of
Ammon". In course of time it was found that these salts were
mixtures, part being volatile. The name Ammon was retained for
these volatile portions which are now termed ammonia or ammon-
ium salts.

The atomic clock

A new use for ammonia, NH 3 , has been foundf. The mean
solar day is not absolutely constant. Owing to variations in the
rate of rotation of the earth on its axis there is a fluctuation of
i second in every 20 to 30 million seconds. In addition to this there
is a slight lengthening of the solar day due to a slowing down of
the earth's rotation, through tidal action mainly, which amounts
to about i second per day every 120,000 years. This has raised the
question as to whether or not it might be possible to check time
intervals by some absolutely constant wave motion on the lines
adopted for measurements of length (p. 308). This problem is in
course of solution by the invention of the "atomic clock", as it is

FRANCHOT, /. Ind. Eng. Ghent., 1924, 16, 235.

fSee Scientific American, 1949, p. 28; 1948, p. 23. Electronics, 1949, 22, 82.
Tech. Bull. Nat. Bureau of Standards, 1949, 33, 17. Radio-Corporation Amer.
Review, 1948, 9, 38.

30

THE PERMANENT GASES

called, the first of which was unveiled in January 1949 at the
National Bureau of Standards, U.S.A. This is based on the
molecule of ammonia which consists of three hydrogen atoms
situated in a plane at the corners of an equilateral triangle with the
nitrogen atom above or below as shown in Fig. 2. The molecule is
capable of absorbing radio-energy at a sharply defined frequency,
the N atom vibrating from position N to N 1 and back. An absorp-
tion line is produced in the spectrum of the incident radiation and

H

*N'

Fig. 2 The ammonia molecule

this is utilised to stabilise the frequency of a microwave oscillator
and thus to check the passage of time. To put the position popularly,
the oscillator corresponds to the pendulum of an ordinary clock.
The ultimate accuracy of such a clock depends upon a variety
of factors. Theoretically it should be possible to obtain a permanent
accuracy of i part in 10 billion (ro 18 ). At present i part in 10
million has been achieved. Such a clock can be used to improve
our astronomical time standards; being entirely constant and
independent of the earth's movement it could be used, for example,
to determine if the sidereal day is more constant than the mean
solar day, as some authorities believe may be the case. Conversely
it may be of great use to the radio-engineer as it could be used to
control more rigidly the frequency of the waves emitted from
various stations and thus make more efficient use of the available
radio spectrum. This is very necessary if overlapping is to be
avoided, because the present crowding has imposed severe limita-
tions both nationally and internationally on the expanding use of
radio for industry and communications.

Hydrogen

Several combustible gases occur in nature and have been observed
by man for ages. At the time of Cavendish they were known as

31

THE CHEMICAL ELEMENTS

inflammable air and were not distinguished from each other.
Cavendish, circa 1766, was the first to examine hydrogen and deter-
mine its physical properties so that it could be recognised again.
He called it inflammable air from metals as he thought it came from
the metals and not from the acids he used.

Cavendish had observed that hydrogen exploded with air, and
Priestley called attention to the dew condensing on the glass walls
of the containing vessel after an explosion. Cavendish investigated
the matter and proved that water was a compound of oxygen and
hydrogen. His paper was published by the Royal Society on
1 5th January 1784. James Watt had almost simultaneously
arrived at the same conclusion. His letter was laid before the Royal
Society on 29th April 1784. He was deeply chagrined to find that
Cavendish had forestalled him.

Both Cavendish and Priestley thought hydrogen was pure
phlogiston. When the phlogistic theory was shown to be untenable
Lavoisier revised the nomenclature and suggested the name
hydrogen (Greek hudor, water), that is, water producer, in place of
inflammable air. The German name Wasserstoff carries the same
idea.

On hearing about Cavendish's experiments Pilatre de Rozier
filled his lungs with hydrogen and set fire to the gas as it escaped
from his mouth. On repeating the experiment with a mixture of
hydrogen and air there was a terrific explosion and de Rozier
thought for a moment that all his teeth had been blown out.

Spin isomerism

The change in specific heat of hydrogen with temperature is
abnormal if the gas consists of only one kind of simple molecule.
The new quantum theory involving wave mechanics led*, in 1927,
to the belief that two different types of diatomic hydrogen molecule
exist, namely 0r//fo-hydrogen, in which the directions of the pro-
tonic spins are the same, and ^tfra-hydrogen, in which they are
Dpposite as shown in Fig. 3. This is not an atomic phenomenon, as
ill the atoms are alike. It is purely molecular and concerns the two
possible ways in which spinning protons can link up. In 1929 the
existence of these two types of molecule was proved experi-
rnentallyf.

*HEISENBERG, Z. Physik, 1927, 41, 239

fBoNHOEFFER and HARTECK, Zeitsch. physikal. Chem., 1929, 134, 113.

VI

THE PERMANENT GASES

Ordinary hydrogen is a mixture of approximately three of ortho
to one of para. The two forms behave alike chemically but differ
very slightly in their physical properties, for the ortho possesses
more energy than the para. Low temperature favours the produc-
tion of para, and the transformation is catalysed by charcoal at low
temperatures enabling pure para-hydrogen to be obtained;
hitherto it has not been found possible to obtain the pure ortho.
The para melts and boils at only 0-03 and O'I3 C respectively
below ordinary hydrogen so that there is little hope of separating
them by purely physical fractionation. Similar spins occur with
molecules other than hydrogen but their effect is negligible except
for deuterium.

Ortho Para

Fig. 3 Ortho- and para -hydrogen
Balloons

One of the earliest uses of hydrogen was for filling balloons, and
Joseph Black*, the well known Edinburgh Professor (p. 28),
appears to have been the first to make this suggestion. Soon after
the appearance of Cavendish's paper in 1766, in which attention
was drawn to the unusually low density of hydrogen, Black invited
a party of his friends to supper informing them that he had some-
thing mysterious to show them. After the party had assembled he
liberated the bladder of a calf filled with hydrogen which
immediately rose to the ceiling. The company fully believed that
the bladder had been attached to a black thread and drawn up to
the ceiling through a minute hole by a confederate operating in the
room above. An equally neat experiment illustrating the buoyancy
of hydrogen was that of Cavallo, a Neapolitan long domiciled in
London, who in 1772 filled soap bubbles with the gas and watched
them rise into the air with boyish enthusiasm. Matthew Boulton
of Birmingham called hydrogen the "goddess of levity".

The first hydrogen-filled balloonf of practical importance was

*W. RAMSAY, "Life and Letters of Joseph Black" (Constable, 1918) p. 78.

fEarlier in the same year a hot-air balloon had been sent aloft by the
Montgolfier Brothers; it was 35 ft. in diameter and reached a height of 1500 ft.
Its cargo included a sheep, a duck and a cock. Paris was thrilled and fire-balloons
became known as montgolneres.

33

THE CHEMICAL ELEMENTS

released in August 1783 from the Champs de Mars in Paris by
M. Charles, the famous engineer known to all students of chemistry
in connection with the fundamental law of the expansion of gases
with rise of temperature (1787). The balloon was 13 ft. in diameter,
rose rapidly to a considerable height and then fell at Gonesse,
1 5 miles from Paris, about an hour later.

The peasants who witnessed its descent were filled with super-
stitious terror at the appearance of so "monstrous and foul a bird",
for the smell of the escaping hydrogen, owing to impurities, was
anything but pleasant. Indeed, the French Government found it
necessary a little later, as interest in ballooning gained ground, to
issue a proclamation throughout the country explaining what a
balloon was and warning people not to be alarmed if they happened
to see one. A century or so later the Russian Government followed
suit.

No human beings went aloft in Charles's first balloon. The
earliest pioneers to rise above their fellow men in this way were
the Marquis d'Arlandes and the afore-mentioned Pilatre de Rozier
on 2 ist November 1783. The King, Louis xvi, had expressed a
wish that, if human beings were to take part in balloon trips,
criminals should be selected, as their lives were less important to
the state. But de Rozier was indignant "that vile criminals should
have the glory of being the first to rise in the air" and he carried
his point.

The following month M. Charles went aloft with M. Robert.
The trip was so successful that Charles decided to go aloft again,
this time alone; In his excitement he forgot to adjust the ballast
with the result that upon release the balloon shot up with great
rapidity to a height of at least two miles which nearly proved fatal
to the bewildered engineer.

In 1836 Charles Green showed that coal gas could be used in
place of the more expensive hydrogen, but having less buoyancy,
larger balloons were necessary. He passed away at the ripe age of
85 in 1870, having made no fewer than 1400 ascents and earned
for himself the title of "Father of Modern Balloonists".

Unfortunately for the balloonist, both hydrogen and coal gas
ire inflammable and many accidents have resulted from the gases
:atching on fire in mid air. When the properties of helium were
investigated it was realised that this was an ideal gas for the
purpose in view of its chemical inertia. Although twice as dense
is hydrogen, it was still much less dense than air. In 1925 the

THE PERMANENT GASES

U.S.A. prohibited export of the gas as it was needed for home
consumption. As British sources of helium are negligible, we had
perforce to continue using the inflammable gases. This was tjie
indirect cause of the tragic loss of the ill-fated British Airship RIOI,
which was filled with hydrogen obtained by passage of steam over
heated iron. On its way to India it caught fire over Frgince and its
48 occupants were all killed. This happened on 5th October 1930.

At the close of the eighteenth century we British were not on the
best of terms with the French who conceived the idea that balloon-
ing might afford them an opportunity of invading us from the sky,
as our "wooden walls" made any sea attempt too hazardous.
Actually, however, the boot was on the other leg, for the first
balloon to cross the channel left Dover on New Year's Day 1785
to travel in the opposite direction.

The first occasion on which a balloon was used for military
purposes was at the Battle of Fleurus, near Charleroi in Belgium,
in 1794. The balloon was captive and remained up all day, signal-
ling the dispositions of the enemy to Jourdan's army, enabling
them to achieve victory.

In 1798 Napoleon, after taking Cairo, sent up a fire balloon
with the object of impressing the Egyptians, but he was singularly
slow to appreciate the military value of balloons. Had he but used
them as "eyes" at Waterloo in 1815, he would not have mistaken
Blucher for Grouchy, and that page of history might have been
different.

It was early appreciated by scientists that balloons might be
used to obtain invaluable information on meteorological and other
kindred problems. Probably the first chemist to take to the air
with this object in view was Gay-Lussac, whose name is per-
petuated in his Law of Combining Volumes of Gases (1808) and
the Gay-Lussac Tower used in the Chamber Process for the
manufacture of sulphuric acid. On 23rd August 1804, in company
with M. Biot, he ascended from Paris with the object of studying,
amongst other things, the behaviour of the magnetic needle at
high altitudes, and the composition of the atmosphere. At a height
of some 1 1,000 feet they liberated a bird; for a moment it rested
upon the edge of the car, then directed its course in gradually
extended circles towards the earth, thus refuting an old idea that a
bird could not fly in a rarefied atmosphere.

On another occasion, when by himself, Gay-Lussac attained a
height of some 22,000 feet, and wishing to ascend still higher, he

35

THE CHEMICAL ELEMENTS

threw overboard a chair as ballast*. It apparently did not occur tc
him that someone below might be injured; however, a shepherdess
sa^v this wooden chair fall from the skies into some bushes and ran
to tell her friends of the marvel. The simple country folk gathered
round to hear her story and then examined the chair. One thing
puzzled them. If heaven were the beautiful place they were taught
to believe, how was it that the workmanship of the chair was sc
crude?

During the siege of Paris^ in the course of the Franco-Prussian
war of 1870 to 1871, balloons were used by the French to make
contact with the outside world. As many as 64 balloons, averaging
2000 cubic metres of gas, were released from Paris carrying a
personnel of 161 and something like 3 million letters. Of these
balloons 57 fulfilled their purpose, two only being lost at sea
whilst five were captured by the Germans.

Besides freights of letters the majority carried also baskets oi
pigeons and five carried dogs, destined to return with news to the
beleaguered city. As a result no fewer than 50,000 messages were
sent to Paris by pigeon-post. On one voyage a balloon carried two
cases of dynamite, the intention being to drop them on to the
enemy; fortunately for the latter no suitable opportunity presented
itself and Paris capitulated in March 1871.

Deuterium

In 1927 Aston, with his mass spectrograph, compared the masses
of hydrogen and oxygen atoms and obtained the ratio 1-00778 : 16.
This physical value was in excellent agreement with the chemical
one accepted at the time. As already mentioned, however, Giauque
and Johnston two years later showed that ordinary oxygen consists
of three isotopes so that the mean atomic weight is 1-000275
times greater than that of the pure isotope (16) used as standard by
AstonJ. As compared with chemical oxygen, therefore, Aston's
value was 1-000275 times too high. Dividing by this conversion
factor gives the value 1-00753 for the chemical atomic weight of
pure hydrogen, which is too low to be satisfactory. Birge and
Menzel suggested in 1931 that ordinary hydrogen might contain

*This amusing story is told by Miss WEEKS "Discovery of the Elements"
(/. Chemical Education, 1945) Fifth Edition, on the authority of Bugge, "Das
Buch der grossen Chemiker" (Berlin, 1929) Vol. i, pp. 386 seq.

fNature, 1872, 6, 88; 1870, 3, 115* I34 *75-

JThe more recent value for the conversion factor is here used.

BIRGE and MENZEL, Physical Review, 1931, 37, 1669.

36

THE PERMANENT GASES

a heavy isotope, and this was confirmed in December of the same
year by Urey and his co-workers*, who found two faint lines near
the ordinary Balmer lines of a sample of hydrogen taken aa a
residue from the evaporation of a considerable bulk of liquid
hydrogen. The intensity of these lines was increased if fractionation
was continued and the heavier fraction examined. Calculation
showed this "heavy hydrogen" to possess twice the normal mass
of ordinary hydrogen. It was called deuterium, from the Greek
deuteroS) second.

Like hydrogen, deuterium yields ortho and para forms. At room
temperature the ordinary gas comprises 66-6 per cent of ortho.
Low temperature favours the production of para-deuterium, and
the transformation of ortho to para is catalysed by charcoal at low
temperatures exactly as for ordinary hydrogen. For comparative
purposes, some constants may be noted

Hydrogen Deuterium

Atomic weight i oo 8 o 2-0135

Boiling point abs. 20-39 23-5

Molar latent heat in

gm.-calories per mole 183 276

Trouton's Constant, L/T 9-1 1 1 8

Tritium

Another isotope of hydrogen, with an atomic weight 3 was
reported in 1935 as present in natural waters. It occurs only ir
very minute quantities to the tune of I part in lo 17 parts of water:
to this the name tritium was given, with symbol T. It is a short-
lived element, with a half life of about 30 yearsf.

Chemistry is now becoming very complicated. With three
isotopes each of hydrogen and oxygen it is possible for no fewei
than 1 8 different molecules of so simple a substance as water tc
exist. As two natural isotopes of carbon are also known, one
shudders to think of the number of varieties of the starch molecule
that can exist, starch being (C 6 H 10 O 6 ) n , where n is a large number.

General uses of hydrogen and deuterium

Hydrogen is used in the fixation of atmospheric nitrogen as
ammonia by the Haber process ; the manufacture of hydrochloric

*UREY and CO-WORKERS, Physical Review, 1932, 39, 164, 864.

, TAYLOR and BLEAKNEY, /. Amer. Chem. Soc., 1935, 57, 580.

a:

THE CHEMICAL ELEMENTS

acid by direct combustion in chlorine; the hardening of oils;
production of "oil from coal" by hydrogenation of coal; the oxy-
hydrogen flame now largely superseded by the oxy-acetylene,
but still used in making mercury vapour lamps and fusing platinum.
Air-hydrogen mixtures are used in autogeneous soldering of lead
and an atomic hydrogen blowpipe is used in certain welding
processes.

Deuterium has proved extremely useful as a tracer in following
metabolic changes in the animal body. Many experiments have
been carried out on mice. It has been shown, for example, that fat
may be stored in the body even at a time when the body needs it
for conversion into energy. Butyric acid is rapidly consumed to
produce energy, from which it appears that butter may be expected
to relieve exhaustion more rapidly than other fats. Deuterium
oxide, D a O, often called "heavy water" is used as a moderator in
atomic piles to slow down fast moving neutrons to the speed
desired. Most substances either absorb neutrons or are otherwise
unsuitable; neither deuterium nor oxygen absorbs them.

The question as to whether or not small amounts of deuterium
ire essential to the animal organism has not been solved. There
nay be some connection, for it has been found that dilute solutions
:an accelerate the growth of micro-organisms.

The hydrogen bomb

Another use to which hydrogen or deuterium may be put in due
:ourse is in the construction of the H-bomb, the principle of
which is as follows

If, during the course of any reaction, matter is destroyed, it
eappears as energy. The relation between the mass, dm y in grams
destroyed and the energy, dE> in dynes produced is given by
Einstein's Equation (1905)

dE = u*dm = 9 X id**dm

Where u is the velocity of light, namely 3 x lo 10 cm per second.
That is, for every gram of matter destroyed, the energy produced

= 9 X io* dynes
9 x Io2

4-185 X io 7 or2 ' l $ x

18

THE PERMANENT GASES

At the high temperature of the sun, which attains some 20
million C near its centre, hydrogen atoms condense to helium,
some 10,000 helium atoms being produced in every c.c. of the^sun
per second. During this condensation matter is lost and reappears
as energy. This is the source of the sun's heat.

Let us try to gain some idea of its magnitude. For gvery 4 gram-
atoms of hydrogen of atomic weight 1-0080 that condense to
yield I gram-atom of helium (at, wt. 4*003) the amount of matter
lost

= 4 X i -008 4*003 = 0-029 gm

= 0-029 X 2-15 X lo 18 or 6-24 X lo 11 gm-calories.

Big figures like these do not convey much to us. We can perhaps
appreciate them better if we remember that I gram of coke on
combustion to carbon dioxide evolves 8080 gm-calories of heat.

The quantity of heat liberated, therefore, when each gram-atom
of helium is produced from 4 grams of hydrogen is equal to that
obtained by the complete combustion of

* 24 X * or 7-7 x io 7 gm of coke

8080

= 76 tons of coke.

This condensation can only take place, however, at very high
temperatures and it would be necessary to use a uranium or
plutonium bomb as detonator. At the moment of the explosion
there would be a sufficiently high temperature and pressure to
initiate the condensation which could then, under favourable
conditions, become self-supporting, as in the sun.

It might perhaps be found preferable to use deuterium instead
of hydrogen, although the heat liberated per gram-atom of helium
produced would be slightly less, namely

2 X 2-0135 4-0030 = 0-024 gm
= 5-16 X io 11 gm-calories
= 63 tons of coke

Even so it is unlikely that the free gas would be used. Probably a
deuteride would be, such as that of lithium, LiD, or beryllium,
BeD a . In any case it would be necessary to ensure that the deu-
terium was not dissipated by the force of the explosion before
condensation could occur. Unless fairly complete condensation

39

THE CHEMICAL ELEMENTS

were effected, the bomb might not be any more powerful than a
comparable plutonium bomb. Such a bomb, however, would leave
less radio-matter behind. The problem as to whether or not the
H-bomb is worthwhile has yet to be decided. Any work and money
expended in its production are of little value to the world at peace.
Unlike the uranium bomb it offers no promise as a source of
industrial energy or of new products like radio-isotopes of economic
or scientific value.

40

CHAPTER 3

THE INERT GASES

THE inert gases dealt with in this chapter include argon, helium,
neon, krypton and xenon. Radon is discussed later (p. 324).

The discovery of the inert gases reads like a romance*. The first
of these gases to be discovered terrestrially was argon. In 1894
Lord Rayleigh observed that the density of atmospheric nitrogen
was greater than that of the chemical gas, and in 1894 asked
chemists to suggest a reason. Sir William Ramsay asked if he
might collaborate. After searching the literature, they found that
Cavendish in 1785 had already noted that, after sparking with
excess oxygen, atmospheric nitrogen yielded an inert residue that
could not be made to combine with oxygen. Was this a new gas?
Rayleigh and Ramsay accordingly, passed atmospheric nitrogen
over magnesium to remove the nitrogen as solid magnesium
nitride, Mg^N 2 , and introduced the residual gas into a Plticker
tube and examined its spectrum. To their joy, although the
characteristic lines of nitrogen were present, there were also new
red and green lines suggesting the presence of a new element. As
this new gas was present in the atmosphere the story goes that the
authors decided to call it aeron, but they received so many letters
asking when Moses would turn up, that they decided in view of
its remarkable chemical inactivity to christen it argon^ a Greek
word meaning inert. Although at the British Association Meeting
in Oxford in 1895 the announcement was received with scepticism,
truth ultimately prevailed.

A word Argon has been known for a long time. Marco Polo
(p. 55), in his travels in the second half of the thirteenth century,
visited the kingdom of a prince named Argon, who would un-
doubtedly have objected to the derivation of the modern word as
applied to himself.

The scene now shifts to India. In 1868 there was a total eclipse
of the sun, visible in that country, and the Danish astronomer

*A detailed history is given by RAMSAY, "The Gases of the Atmosphere"
(Macmillan, 1902). Full references to the original literature are given in FRIEND'S
"Textbook of Inorganic Chemistry" (Griffin, 1914) Vol. I, Pt. 2 by H. V. A.
BRISCOE, and in "Helium" by KEESOM (Amsterdam, 1942).

41

THE CHEMICAL ELEMENTS

Janssen went thither and examined the sun's corona spectro-
scopically for the first time in history. He detected a prominent
yellow line close to, but not identical with, the sodium lines which,
however, did not correspond with any known element. Bunsen
and Kirchhoff in 1860 had concluded that every element has its
own characteristic spectrum and could be detected by it. Frankland
and Lockyer* therefore suggested, in 1868, that this new line was
due to an element present in the sun, but not present terrestrially.
As alkali metals were known to give line spectra it was thought the
new element would be a metal. They therefore suggested it be
called helium from the Greek helios, sun. The same line, designated
as D 8 , was later detected in the spectra of certain stars, and in 1882
Palmieri found it in Vesuvian gases.

In the latter part of 1894, when searching for new sources of
the newly discovered argon, Ramsay received a letter from Miers,
the eminent mineralogist, at that time connected with the British
Museum, suggesting that it might be worth while examining
pitchblendes. Ramsay gratefully took the hint and obtained a
specimen of cleveite, a variety of uraninite, essentially UO 2 .2UO 3 ,
for which it is said he paid 33. 6d. a small sum for so vast a
return. He treated the powdered mineral with dilute sulphuric
acid, sparked the resulting gas with oxygen over soda, removed
excess oxygen with alkaline pyrogallol, washed, dried and trans-
ferred to a vacuum tube. The light given by the passage of
electricity through this tube was examined visually in a spectro-
scope alongside that from a Plticker tube containing argon, for
comparison. It so happened that this second tube, owing to im-
purities in the electrodes, gave the spectra of hydrogen and nitrogen
as well as of argon. It was at once evident that the cleveite gas
contained both argon and hydrogen, but it also gave a brilliant
line in the yellow, nearly but not quite coincident with the yellow
sodium* lines. The wavelength of this line was measured by
Crookesf and proved to be the solar D 3 line. It thus became
known that helium could now be regarded as a terrestrial element.
About the same time Cleve also independently found helium.

In 1889, Hildebrand^ had noticed that uraninite, when dissolved
in acid, evolved a gas which he believed to be nitrogen. He noticed

*A full account was given by SIR NORMAN LOCKYER in Nature, 1896, 53, 319,
342, also FRANKLAND and LOCKYER, Proc. Roy. Soc., 1868, 17, 91.
fCROOKES, Proc. Roy. Soc., 1895, 58, 69.
JHiLDEBRAND, Bull. U.S. Geol. Survey, 1889, No. 78, 43.

42

THE INERT GASES

that the spectrum contained lines not usually attributable to nitrogen ;
he knew however that gaseous spectra are profoundly affected by
changes in pressure and although he and his assistant jocularly
suggested that they might be dealing with a new element, the
matter was allowed to drop. Many a true word is spoken in jest; a
great discovery was narrowly missed.

Before long both the elementary nature of helium and its
identity with the solar element were called into question; but
these doubts were soon set at rest. The homogeneity of the gas
was confirmed by Ramsay and Travers* who showed that spectral
anomalies were due to contamination with argon. The identity of
the celestial and terrestrial spectra was confirmed by Hugginsf and
Hale*.

In 1903 Ramsay and Soddy made a sensational discovery,
namely that helium is a disintegration product of radium.

After many fruitless attempts had been made by Dewar and
others to liquefy helium, that difficult task was achieved by Onnes
in 1908 in his famous cryogenic laboratory at Leyden University.
It was not until 1926, however, that the gas was solidified by
Keesom, the pupil and worthy successor of Onnes, Solid helium
melts at 271*5 Cor 1*5 abs.

The two elements argon and helium suggested the need for a
new vertical group in the periodic table. If so, elements were
required to precede sodium, rubidium and caesium. Ramsay and
Travers searched for these. They examined many possible
sources, but were most successful with liquid air residues, and in
1898 they discovered successively three more gases which they
christened krypton (Greek kryptos\ the hidden one; neon (Greek
neo$), the new one; and xenon (Greek xeno$\ the stranger. The last
member of the series, radon, was not discovered spectroscopically.
It is a radio-element first detected by Dorn in 1900, and is dis-
cussed later.

Helium ought logically to be called helion. This was suggested
by the author to the Chemical Society in 1926, but the Publication
Committee was not in favour of the change.

*RAMSAY and TRAVERS, Proc. Roy. Soc., 1897, 60, 206; 1898, 62, 316. TRAVERS,
ibid., 1897, 60, 449-

fHuGGiNs, Chem. News, 1895, 72, 27.

JHALE, Astrortom. Nachrichten, 1895, 138, 227.

RAMSAY and TRAVERS, Proc. Roy. Soc., 1898, 62, 316; 1898, 63, 405, 437;
Phil. Trans., 1901, 197, 47. See MOORE, Chem. News, ign, 103, 242.

43

THE CHEMICAL ELEMENTS

Applications of helium

Helium is used for air-ships, blimps, etc, its non-inflammability
ren4ering it particularly suitable tor these purposes although its
lifting power is only half that of pure hydrogen. To a limited extent
helium is employed in thermometry and in lamps for yielding the
D 3 line in optical work. When inhaled with oxygen, helium is
used as a cure for asthma and other ailments, such as croup and
diphtheria, in which the windpipe is obstructed.

Helium is of great assistance to the diver and in caisson work.
After prolonged exposure at great depths much time is absorbed
in bringing the diver to the surface; every 33 feet of depth gives
an extra atmosphere of pressure. Helium is also used in the manufac-
ture of zirconium by Kroll's process.*

The average man carries about 1000 c.c. of nitrogen gas dis-
solved in his body under ordinary atmospheric conditions. If the
pressure is increased the volume of dissolved nitrogen increases
proportionately, though it takes several hours for equilibrium to
be reached. If, therefore, the diver is decompressed too rapidly by
being brought swiftly to the surface, nitrogen is released from
solution and bubbles collect in the blood stream; the diver becomes
black in the face due to oxygen shortage for the heart cannot drive
the bubbles through the blood vessels owing to their enormous
resistance. The remedy is to lower again when the bubbles redis-
solve. As helium is much less soluble in the body there is less danger
of bubble formation and decompression may be effected in a mixture
of oxygen and helium (usually i to 4 by volume) in one-twenty-
third of the time required with air. This may be of supreme
importance in cases of accident or of attack by, say, sharks.
Hydrogen appears to be equally effective.

J. B. S. Haldane used a mixture of 9 volumes of hydrogen to I
of air, which is not explosive and may be safely stored in cylinders
under pressure. It contains only 2 per cent of oxygen by volume,
but under a pressure of 10 atmospheres it has as much oxygen per
c.c. as ordinary air. Argon behaves similarly to nitrogen. Neon
may be intermediate.

By way of contrast it may be mentioned that xenon is more
soluble in the body even than nitrogen, and causes dizziness and
numbness. It has been suggested that xenon may be the cause of
air-sickness at high altitudes.

*G. L. MILLER, Industrial Chemist. 1950, 26, 435.
44

THE INERT GASES

Argon is used in gas-filled incandescent electric lamps, being
more efficient than nitrogen. Efficiency increases with the molecular
weight of the gas, and before World War II krypton and xenon
were being used for the purpose. Special plants had been erected
at Ajka in Hungary and at Boulogne in France to separate these
gases from the atmosphere to render them available in sufficient
quantities to meet the needs of the lamp industry.

Neon is used extensively for various types of lighting such as
shop signs, street lighting and illumination of airfields.

45

CH/fPTER 4

THE HALOGENS

THE halogens (Greek hah salt, gennab I beget) constitute a group
of four or possibly five closely allied elements, namely fluorine,
chlorine, bromine and iodine with possibly alabamine or astatine.
Their name was coined by Berzelius (i 779 to 1 848), since the various
members known in his day were to be found as salts in seawater
resembling sea salt or halite. Before fluorine was isolated, the three
remaining elements formed a typical example of the "Doebereiner
triads". In 1829 Doebereiner pointed out that a determination of
the atomic weight of bromine by Berzelius effected the previous year,
supported his prediction that it would probably be the arithmetic
mean of the atomic weights of chlorine and iodine.

Chlorine

The first halogen to be discovered was chlorine, by that in-
defatigable Swedish pharmacist Scheele who also discovered
oxygen. In 1774 he studied the action of muriatic acid (Latin
muria, brine), the name given to an aqueous solution of "marine
acid air", our hydrogen chloride, on pyrolusite and observed that,
upon warming, the mixture smelled like aqua regia, a greenish-
yellow, choking gas being evolved,

Scheele had been brought up on the phlogistic theory already
outlined in connection with oxygen and in consequence regarded
the new gas as marine acid air deprived of its phlogiston by the
pyrolusite. He accordingly baptised it in the name of dephlogisticated
marine acid air. This cumbersome name obviously could not be
retained and with the passing of the phlogistic theory a more
suitable name had to be found*.

For many years chlorine was regarded as a compound of oxygenf.
Its method of preparation appeared to suggest this, the gas being
obtained by the oxidation of muriatic acid. Lavoisier therefore
called it oxymuriatic acid; under such a name it fitted into Lavoisier's

*For full discussion of discovery of chlorine and proof of elementary character
see CHATTAWAY, Chem. News, 1910, 101, 25, 37, 50, 73.

fBERTHOLLET suggested this in 1785, Mem. Acad. Sci. t Paris, 1785, p. 276.

46

THE HALOGENS

scheme, according to which all acids, even muriatic acid itself,
contained oxygen, the "acid producer". Oxymuriatic acid thus
bore the same relation to muriatic acid as sulphuric to sulphurqus.
It was Davy* who, in 1810, showed conclusively that chlorine is
an element. He passed hydrogen chloride over metallic potassium
and found that only the metal chloride and pure hydrogen were
produced. He therefore suggested the name chlorine (Greek
MoroSy greenish yellow) in allusion to its colour. Thus arose
another example in which the name given to an element by its
discoverer came to be changed (p. 25).

Chlorine is used for various purposes on an enormous scale by
civilised communities. In 1910 it was used at Reading during an
epidemic to sterilise the water, and since then this has become a
usual practice; the process received great impetus during the 1914
1918 war, when water supplies for the troops were chlorinated, and
again in 1 940 when the authorities urged the adoption of chlorina-
tion by all of the larger water undertakings in view of the war risks.
Chlorine is used in the sterilisation of sewage; extraction of bromine
from carnallite and seawater; de-tinning of scrap tin-plate; removal
of objectionable odours from gasoline, etc. At one time considerable
quantities were used in the extraction of gold, but this process has
now been largely superseded by the cyanide and amalgamation
processes. Much chlorine is used in the manufacture of chemicals;
it is burned with hydrogen to yield hydrochloric acid; with lime
it gives bleaching powder; it is consumed in preparing chlorides,
chlorates and hypochlorites, etc.

Wool is chlorinated to increase its resistance to "felting" during
laundering. It is easier to wash as the surface after chlorination
is hydrophilic and is readily cleansed by soap.

Chlorine finds an enormous demand in the preparation of
various chlorinated organic derivatives. Amongst these may be
mentioned carbonyl chloride or phosgene, COC1 2 , used in the dye
industry and as an asphyxiant in chemical warfare; 200 ppm in
air constitute a fatal dose in 2 minutes. Carbon tetrachlonde or
"CTC", CC1 4 , and pentachlorethane, CHC1 2 .CC1 8 , are used for
extinguishing fires, the former also as a solvent and degreaser;
trichlorethylene, CHC1:CC1 2 , known commercially as triklone or
simply tri, is a degreaser and an anaesthetic; chlorpicrin, CCl 8 NO a ,
has been used in the extermination of rats by the Russians in the
Caucasus, to effect the elimination of bubonic plague communicated

*DAVY, Phil. Trans., 1811, pp. i and 32. The Bakerian Lecture for 1810.

47

THE CHEMICAL ELEMENTS

to humans by rat fleas; DDT., (C1C 6 H 4 ) 2 .CH.CC1 8 , is an in-
valuable insecticide. These will suffice.

jGaseous chlorine was first used as an asphyxiant in chemical
warfare in April 1915 when the Germans launched a cloud
attack against the Africans, Canadians and French in the Ypres
salient. There were 20,000 casualties of which 5000 were fatal,
whilst many others were damaged for life. Very small amounts of
chlorine in the air help to ward off colds and to relieve them when
once they have gained a hold. After the first world war chlorine
chambers were used in America and the custom received a fillip
when President Coolidge himself in May 1924 received treatment
in one and was able to state afterwards that he felt considerable
relief from his cold. The maximum safe concentration is I ppm
in air for more or less prolonged inhalation; 32 ppm constitute
a lethal dose in 30 minutes.

Iodine

Iodine was the second halogen to be discovered*. It was first
observed by Courtois, a manufacturer of nitre, in 1811, but this
was not announced until two years later by Clement and Desormes.
Like so many other important discoveries that of iodine is what is
popularly called "accidental". That is to say it was not the result
of a specific search for the element, but of a chance observation by
an intelligent observer.

In the preparation of nitre from seaweed or wrack (French
varecK) the dried plants were burned and the ashes leached for the
sodium and potassium salts. Upon concentration sodium chloride
separated first, followed by potassium chloride and sulphate, other
salts of these metals, such as sulphites and carbonates, being left
in solution. These were destroyed by addition of sulphuric acid.
On one occasion the acid was probably more concentrated or in
larger quantity than usual and a violet vapour arose with an
irritating odour not unlike that of chlorine. This condensed to a
solid crystalline deposit on cold objects without formation of liquid.
For a time this new substance was referred to as X, an appellation
used many years later to designate the unknown rays discovered
by Rdntgen in 1895 an< ^ nowadays often employed in cases of
blackmail. As Courtois had insufficient laboratory facilities he

* A valuable compilation of data in connection with iodine is published by the
Iodine Educational Bureau, maintained by the Chilean Nitrate and Iodine
Producers under the title "Iodine Facts".

48

THE HALOGENS

asked his friends Clement and Desormes to undertake the study
of X. Its analogy to chlorine suggested its elementary nature and
this was subsequently demonstrated by Gay-Lussac in 1814 and
independently by Davy. Gay-Lussac suggested the name tone
(Greek ion y the violet) whilst Davy proposed iodine from Greek
ioeideSy violet coloured as being more analogous to chlorine and
fluorine and less likely to lead to confusion with other terms.

Iodine in minute quantity is a normal constituent of the human
body and the average person requires a daily dose of 0*000,017 gm.
Absence of the requisite amount leads to general debility and in
more severe cases to goitre or "big-neck". In very severe cases
mental weakness develops known as cretinism, from Latin creta,
chalk, because of its prevalence in Alpine districts. In Switzerland
sodium iodide is added to table salt by legal regulation to ensure
that everybody receives his necessary "ration" of iodine. In
Britain there are several areas of iodine deficiency in the soil and
addition of iodides to the feeding-stuffs of cattle, etc, effects an
enormous improvement in the herds.

Iodine is used largely in medicine owing to its powerful germ-
icidal action. The brown solutions of iodine in alcohol or aqueous
potassium iodide applied as "paints" to wounds, etc, are familiar
to alb Iodine is the main constituent of iodoform; it is also used
in photography and in chemical laboratories.

Bromine

In 1825 Ldwig, one of Gmelin's students at Heidelberg, began
to study a red liquid obtained by chlorination of the concen-
trated waters from a salt spring at Kreuznach. Before, however,
he could complete his study Balard* announced the discovery in
1 826 of a new element extracted with chlorine from the Montpellier
brines after first removing the sodium chloride. This element was a
dark red liquid identical with that of L6wig and to it he gave the
name muride in view of its presence in brine. But this name was
not acceptable to chemists in view of probable confusion with
muriatic acid and the name was changed to bromine^ from Greek
brbmoSy a stench.

Liebigf had narrowly missed the same discovery. A German
firm had asked him to examine a red liquid which he regarded as
chloride of iodine and not worth further attention. Upon the

*BALARD, Ann. Chim. Phys., 1826, (n), 36, 377.

fSHBNSTONB, "Justus von Liebig, His Life and Work" (Cassell, 1901), Chap. 3.

49

THE CHEMICAL ELEMENTS

announcement of Balard's bromine Liebig realised the mistake he
had made; on his shelves this very element had been standing
unrecognised.

Bromine is used as a disinfectant; bromum solidificatum is merely
kieselguhr saturated with bromine. Bromine is a valuable raw
material in the manufacture of dyestuffs and drugs, A recent use
is in the preparation of ethylene dibromide, C2H 4 Br 2> required
for anti-knock motor fuel. The simpler methyl bromide, CH 8 Br,
finds application as a fire extinguisher. Bromine has been used,
generally in conjunction with other gases, as an asphyxiant in
warfare. Some 31 ppm in air are usually fatal within 30 to 60
minutes.

Fluorine

Fluorine was the last halogen to be isolated. Fluorspar* has been
known for many centuries. Georgius Agricolaf, who earned for
himself the title of "Father of Metallurgy", referred to the use of
fluorspar as a flux in his work "Bermannus", circa 1529, whence
the name of the mineral, from Latin fluere, to flow. When gently
warmed the mineral emits light; this is termed fluorescence, a word
showing that the growth of a language may cause derivatives to
assume a meaning entirely different from that suggested by their
roots.

In Napoleonic times Derbyshire fluorspar was exported to France
where it was termed the bleu jaune or blue-yellow stone; it was
shaped into fancy articles which were subsequently re-imported
into Britain as the anglicised Blue John.

It is usually stated that the corrosive action of hydrofluoric acid,
which is readily obtained by the action of sulphuric acid upon the
mineral in the warm, was first observed by Herr Swanhardt, an
artist of Nuremberg, in 1670. Some accidentally fell on to his
spectacles and etched the glass; from that time onwards Swanhardt
etched glass with the vapours from fluorspar and sulphuric acid.
But this pretty legend has been exploded by Partington^: who

*Will the student notice that this is not "flour" spar. Judging from exam-
ination papers many students appear to confuse the two words.

fGEORGius AGRICOLA, 1490 (or 1494) to 1555, was a physician who took
unusual interest in metallurgy and mining. His monumental work "De re
Metallica" did not appear until 1556 but the MS was evidently finished several
years before that as it bore a dedication dated 1550. He was author also of several
other works, including "Bermannus".

JPARTINGTON, Chemistry and Industry, 1941, p. 109. Mem. Manchester Lit.
Phil. Soc., 1922-3, 67, 73.

50

THE HALOGENS

finds that the first authenticated mention of the acid is in 1720; he
further adds that the discovery of the acid was probably a British
achievement. t>

In 1771 Scheele was the first to recognise in fluorspar the cal-
cium salt of a new acid which latter he obtained later by distillation
of fluorspar with sulphuric acid using a tin retort. He called the
product fluoric acid and in 1807 Gay-Lussac and Thenard prepared
the anhydrous acid. In accordance with Lavoisier's theory the
acid was regarded as a compound of water with the oxide of an
element "fluorium" and hence contained oxygen.

In 1810, however. Ampere suggested to Davy that the acid was
probably a compound of hydrogen with an unknown element and
contained no oxygen. In 1813 Davy in turn developed these views.
Assuming fluorspar to be analogous to calcium chloride in that it
contained an element analogous to chlorine, he suggested the new
element be called fluorine.

Every effort to isolate fluorine was futile until Gore obtained a
little momentarily in 1869 by electrolysis, but it immediately
combined explosively with hydrogen. It was not until 1886 that
Moissan succeeded in obtaining pure fluorine by electrolysing a
solution of anhydrous potassium hydrogen fluoride in hydrofluoric
acid, using electrodes of an alloy of platinum and iridium.

Despite its intense chemical activity which rendered its isolation
so difficult, its first oxide, F 2 O, was not discovered until 1927 by
Lebeau and Damiens.

Fluorine, like iodine, in minute amount is essential to the human
body; it enables the teeth to develop a hard enamel and resist
decay. But this is a case in which it is easy to have too much of a
good thing. In 1934 the children at Maiden in Essex were found
to be suffering from mottled teeth a name that explains itself.
This was traced to the presence of excess fluorine ions in the water
to the extent of 4-5 to 5 ppm. Small quantities up to about
I ppm appear to be beneficial.

Fluorine has a great affinity for carbon; considerably greater
than that of hydrogen or the other halogens, so that the fluorides of
carbon are extremely stable. This is evident from the bond strengths
which are believed to be as follows; C H, 80; C Cl, 83; C F,
1 20 Calories per gm.-atom. A relatively new thermoplastic,
known technically zsfluon has been made by polymerising tetrafluo-
ethylene, F 2 C:CF 2 , yielding (C2p 4 ) n , variously known as poly-
tetrafluo-ethylene or PTFE. It is of special interest to engineers

51

THJ& CHEMICAL ELEMENTS

on account of its inertness. There appears to be a wide field opening
up for research on fluocarbons and their value in industry.

^From the Periodic Table it seems that element 85 should be
the highest member of the halogen group. In 1931 a claim was
made* that the presence of the element had been detected and it
was given <the name alabamine. This story requires confirmation.
For the element obtained synthetically through fission of uranium
the name astatine has been suggested.

* ALLISON and CO-WORKERS, Physical Review. 1931, 37, 1178; 1930, 35, 285.

52

CHAPTER 5

CARBON

CARBON, in the forms of charcoal, graphite and diamond, has
been known from very early times. Acquaintance with charcoal
would be roughly synchronous with that of fire (p. 8). In later
years the charcoal was used by man as a pigment in decorating the
walls of his caves ; later still it played a great part in his metallurgy.

Graphite would certainly be a much later discovery than charcoal ;
nevertheless it was known in early times and esteemed because of
the greyish black streak left behind when it was rubbed against a
roughened surface. The word is derived from the Greek grapho y I
write; the names plumbago and black lead show that the mineral was
regarded as a form of lead. The Greek word molybdos was apparently
employed to denote lead and materials that resembled lead in
physical appearance, and thus included galena, PbS, graphite and
molybdenite, MoS 2 , these two latter minerals being regarded as
identical. Indeed pencils have been found containing molybdenite
.instead of graphite. Pliny (A.D.23 to 79) used the words molyb-
daena and galena synonymously. It was Scheele, in 1779, who first
distinguished between graphite and molybdenite. Acting on them
with nitric acid he obtained with the one merely gaseous carbon
dioxide, whereas the other yielded a white solid which Scheele
termed molybdic acid. From that time onwards the two minerals
have been recognised as distinct, the term graphite being given to
the one consisting of carbon only, and molybdenite to the other,
namely molybdenum sulphide. In 1800 Mackenzie showed that
graphite burns like charcoal, producing carbon dioxide.

The exceptional properties of graphite are due to its unique
structure which is the most perfect example known of layer
lattices. It consists of sheets of carbon atoms linked hexagonally
like wire netting (fig, 4) each sheet representing a gigantic, two-
dimensional molecule. Adjacent atoms are 1-421 A apart* and
statistically rather more than three valencies out of the four of each
carbon atom are absorbed in the C C bonds in each layer. The
valency forces left over are absorbed in holding the various layers

*A = angstrom unit, that is io~ 8 cm.

53

THE CHEMICAL ELEMENTS

together, the bonding assuming the form similar to that in metals.
The electrons are but loosely bound and, in consequence, graphite
possesses metallic conduction in the direction of the planes.

These planes, too, are 3 -354 A apart and, as interatomic forces
are inversely proportional to about the eighth power of the distance
between thp centres of the atoms, the layers can easily slide over
each other like the leaves of a book. Thus graphite functions as
a lubricator. Normally the different layers are out of step as shown
in Fig. 4.

3-354A

1-421 A
Fig. 4 The structure of graphite

All forms of carbon seem to possess a graphite structure with
the exception of the diamond (p. 59). So-called "amorphous"
carbon consists of small sheets of hexagonal structure and the
smaller the sheets the more widely do they tend to lie apart. A
variation in the properties of carbon with its fineness of division is
thus to be expected.

Some 1 2 per cent of the world's graphite is used in the pencil
trade. The finest graphite in the world was found at Borrowdale
in Cumberland, but the supplies are now largely worked out. The
Keswick pencils were world-famous. In early days the mineral
Was cut to shape and inserted in grooves in cedar wood to form
the pencil ; but the result was poor as only short lengths of graphite
were possible, and even these contained the natural grit of the
mineral. Now the graphite, whether natural or artificial, is pulver-
ised, mixed with a little clay and gum solution to a paste, and
squeezed through a die.

Foundries consume considerable quantities of graphite; the
pattern is buried in moulding sand, the surface of which, after
removal of the pattern, is coated with graphite often mixed with
talc to provide a smooth surface and prevent the casting from
sticking.

54

Graphite is also used for making crucibles for meltiftg^tg$l :anj;
brass; as a lubricant, sometimes alone and sometimes" fmxed-witl:
grease or water; as a constituent of paint, stove polishes; ofoi
coating blasting powders to protect from damp; for electrode!
and electrodeposition of metals on non-conducting surfaces, suet
as wax, etc. Graphite is used in the construction of atomic piles
but for this an extremely pure product is essential and this is
manufactured in the electric furnace at such a high temperature
that virtually every trace of impurity volatilises. Indian ink is finel)
pulverised graphite baked with a glutinous paste.

Diamond

The word "diamond", derived from the Greek adamas> in-
vincible, bears witness to its extreme hardness, and the term was
used in reference to this stone in A.D.I 6. Pliny speaks of the
diamond as the most valuable of gems. The brilliant lustre and
play of colours of the "cut" stone are due to its high refractive
index and dispersive power. Sometimes diamonds are also doubly
refracting, in consequence of internal strain; such specimens have
been known to crack and even burst spontaneously.

Although mentioned by name several times in the Old Testament
it is considered unlikely that the early Hebrews were acquainted
with the diamond. The "diamond" of Exod. xxviii. 18, anq
xxxix. u, was an engraved stone, and could therefore hardly havl
been the gem we know under that name. It was probably quartz!
The so-called Bristol, Cornish, and Derbyshire "diamonds" art
merely quartz (p. 61). The later references in Jer. xvii. i, ant
Ezek. xxviii. 13, may possibly be genuine. I

Diamonds were first discovered in the sands of India; ther
were not known in Europe until Alexander the Great returneE,
from India 327 B.C. The Romans introduced them into Western;
Europe and used them for graving tools, producing cameos arji
intaglios in hard stone. They do not appear to have used diamonds!
as jewels. The Indian industry was centred round Golconda, neta
Hyderabad; it was a fortress and market for the gems, but |^
now merely a ruined city.

In his "Voyages and Travels" Marco
Venetian traveller (1254 to 1324), known as

*'The Voyages and Travels of Marco Polo".
Chap, xxviii. Marco was probably the first Eurnnean
territory of India.

THE CHEMICAL ELEMENTS

East Indies, states that he visited a district in India known as the
Kingdom of Murfili, now generally identified with Golconda.
Here were rocky mountains and steep precipitous valleys into which
men were afraid to venture partly because of the large number of
venomous serpents. He was informed that after the rainy season
these valleys were rich in diamonds which lay on the surface having
been washed down from the mountain sides. To obtain them the
men were wont to throw chunks of raw flesh into the valleys;
perceiving which the local white eagles would swoop down and
pick up the flesh in their talons, with the soil and diamonds
clinging to it, and carry it to their nests. When the eagles left
their nests again the men raided them for diamonds.

Marco gives a very human touch to his story when he adds that
"the kings and great men in this country keep the fairest and
finest stones to themselves and suffer the merchants to sell the rest."
Nevertheless the reader may be pardoned if he queries the accuracy
of the story as it stands. Probably it took its rise from some
sacrificial custom in connection with the worship of the goddess
of riches, Ammarwaru. The flesh cut from a slaughtered cow or
buffalo was probably thrown on the ground as an offering and would
naturally be picked up and carried off by the birds*.

In 1725 diamonds were found in Brazil; miners searching for
gold had found some curious pebbles and, unaware of their value,
used them as counters and gave them to children to play with. An
officer who had spent several years in the East Indies was struck
by the appearance of the pebbles and sent some to a friend in
Lisbon to be examined. They proved to be diamonds, equal to
those of Golconda. But popular prejudice against Brazilian diamonds
was strong; to be fashionable the diamonds must come from India;
many therefore were shipped from Brazil to India and re-exported
from thence to Europe as "Indian" diamonds, when they were
readily marketed. The soil at Diamantino in Brazil appears to have
been singularly rich in small diamonds; a negro is reported to
have found one of 9 carats among the roots of some vegetables
from his own garden; diamonds have also been found in the crops
of chickens. John Mawef, in an account of his travels in Brazil
mentions that a negro wrote to the then Prince Regent announcing
the discovery of an enormous diamond which he begged to have
the honour of showing to his majesty in person. A carriage and

V. BALL, Nature, 1881, 23, 490.

f JOHN MAWE, "Travels in the Interior of Brazil" (London, 1812).

56

CARBON

escort were accordingly sent and the negro was brought to the
royal presence when he handed over the precious stone weighing
nearly i Ib. It was sent to the royal treasury and deposited in the
hall of gems, its value being estimated as at least a million sterling.
One or two persons at court, however, appear to have entertained
some doubt as to the genuineness of the stone and when Mawe
was in Rio de Janeiro he was requested, as a known authority, to
examine it. At a glance he saw that it was merely quartz and con-
firmed his opinion by scratching it with a diamond. The negro
who had been brought to Rio in such pomp had to find his way
back home as best he could.

In 1867 even more important deposits were found in S. Africa.
An intelligent pedlar noticed that a Boer child on a farm near
Hopetown on the Orange River was playing with some peculiar
pebbles and submitted one to a mineralogist who identified it as
diamond; it was shown in the Paris Exhibition in the same year.
There was in consequence a rush to S. Africa and extensive river
diggings Were undertaken which extended to the R. Vaal. By 1869
dry diggings had begun in several shallow depressions or "pans"
and this led to the founding of Kimberley. In 1888 Cecil Rhodes
effected the amalgamation of the Kimberley mines into the De
Beers Consolidated Mines.

Sir Isaac Newton as early as 1704 suspected that the diamond
might be combustible, and it was shown by Lavoisier in 1772
that such was the case provided air was present, carbon dioxide
being produced. Tennant, in 1797, showed that when equal
weights of diamond and graphite are separately burned, equal
quantities of carbon dioxide result. It was still necessary to prove
that there were no other products. The matter was clinched by
Sir Humphry Davy who had a wealthy wife; he burned with the
sun's heat a diamond in oxygen in Florence, during March 1814,
using the great lens then recently acquired by the Cabinet of
Natural History in that city. He used the precious lens with
characteristic agility which made the savants tremble lest he should
break their newest acquisition. But Davy did not; instead he
showed that there was no change in volume of the gas when the
diamond had disappeared and that the sole product was carbon
dioxide. The diamond and charcoal were thus chemically identical.
Up to that time it was generally believed that bodies could not
have the same chemical composition if their physical properties
were different. Davy's experiments showed this to be untrue and

57

THE CHEMICAL ELEMENTS

paved the way for the later conceptions of allotropy and poly-
morphism. It was Berzelius who, in 1840, described the different
varieties of an element as allotropes (Greek al/os y other; tropes,
manner).

The weight of a diamond is expressed in carats* ', the carat being
originally the average weight of the seed of the locust, Kuara, or
carob tree a native of Africa. The word is said to be derived
from the Greek keration, which refers to the horn-like shape of the
pods. The seeds are remarkably uniform in the pod, those at the
ends being as large as the middle ones; they have been used from
time immemorial for weighing gold, and were transported to India
in early times and there used for weighing diamonds. In 1888
the Board of Trade fixed the English carat at 3*1683 grains,
equivalent to 205-310 milligrams. The metric carat, now universally
adopted, was legally fixed at 200-000 mgm. The. metric carat
became compulsory in Britain in 1914.

Many attempts have been made to produce the diamond
artificially. In 1880 Hannay obtained diamonds of microscopic
size by heating to dull redness for many hours a mixture of paraffin
and bone oils with metallic lithium in a closed wrought-iron tube.
On opening the tube minute isotropic crystals were extracted from
the black residue; they were sufficiently hard to scratch all other
crystals. For many years doubt was expressed as to the identity of
these crystals with diamond, but X-ray examination has justified
Hannay's claimf.

Moissan, the French chemist, who was the first to isolate fluorine,
also claimed^ to have synthesised the diamond by causing it to
crystallise out from molten iron under great pressure. The minute
crystals conformed to all known tests for the diamond, but un-
fortunately the X-ray method, which could have placed the matter
beyond all doubt, was not then known.

Not all diamonds are of gem quality; some 60 per cent of the
raw stones are unsuitable for gems; industry absorbs about 80 per
cent of the diamonds by weight, the remaining 20 per cent being
used for jewellery, etc. Black diamonds known as carbonado^
have no gem value; they are peculiar to Bahia in Brazil and contain
up to 2 per cent of impurity. They are nevertheless as hard as the

*A historical account of the carat is given by DR. SPENCER in the Mineralogical
Magazine, 1910, 15, 318.

fBANNiSTER and LONSDALE, ibid., 1943, 26, 315.

JSee "The Electric Furnace" by MOISSAN, English Edition, 1904.

The largest carbonado was found in Bahia in 1895 and weighed 631*9 grams.

58

CARBON

pure stone and tougher; they show no cleavage tendency. They do
not soften when heated and are in great demand for drills. The
Simplon tunnel opened in 1906 was the first major operation with
diamond drills. Irregular aggregates of bad colour and flawed are
known as bort (Old French bort, bastard) ; they are obtained mostly
from the African fields and are extensively used ae an abrasive
dust, for dies, for "cutting" and faceting precious stones* and for
drillings.

The first diamond ever cut in Birmingham occupies a place of
honour in the Lord Mayor's chain. It lies at the centre of a Maltese
cross in the badge suspended from the central link of the chain.
Beneath this is a wreath suggesting laurel and oak; it surrounds a
shield on which appear the Birmingham Arms, in enamel. Above
the shield, mounted on a plate of gold, is the motto "Forward"
and on the back is engraved: "This diamond, the first cut in
Birmingham, was manufactured, mounted in badge, and presented
to the Corporation of his native town, by William Spencer, 1873
(during the mayoralty of Ambrose Biggs)." v

Diamond tools are now made to obtain a high finish necessary
for many engine components, particularly for aircraft. Diamond
dies are made by rotating a needle fed by diamond dust and ore,
and are sometimes of minute diameter; they are so hard that they
will pass many miles of wire without change in diameter; this is
important when uniformity is essential as in electrical work such as
tungsten filaments (p. 246), resistances, etc. Diamonds are also used
for cutting glass, for drilling glass and porcelain, for engraving
metal work, etc.

The diamond possesses cleavage planes in four directions and
despite its phenomenal hardness it may be easily shattered by a
blow. An old method of testing stones reputed to be diamonds was
to strike them on an anvil. If they broke they were not diamonds!
Probably many a valuable stone was lost in that sad way.

The hardness of the diamond is due to its symmetrical structure.
Each C atom has four others arranged tetrahedrally and perfectly
symmetrically round it (Fig. 5). The diamond is thus one huge
molecule with no weak spot. Carborundum, SiC, has a similar
structure and is also extremely hard. It might be thought that
close-packing would explain the hardness, but the diamond has a
relatively open structure; if close packed it would be possible for

*The pioneer in this art was Louis de Berquem, of Bruges, who, in 1476,
conceived the idea of using diamond dust for this purpose.

59

THE CHEMICAL ELEMENTS

12 spheres to touch the central one, in which case the density of
the aiamond would be 7-653, instead of 3-01 to 3*56*.

The beauty of the diamond is due to its high refractive index
coupled with great dispersive power. The crude diamond as found
looks anything but attractive; the art of the lapidary consists in
cutting the stone and polishing it to bring out its brilliancy.

Fig. 5

(i) Tetrahedral arrangement of carbon atoms
(ii) Arrangement of carbon atoms in the diamond

The purest diamonds are crystal clear and colourless. Such stones
are described as of the "first water" or as " blue-whites". Diamonds
may be of any colour; when ruby red they are almost priceless.
There was a small ruby red one among the Russian Court Jewels
many years ago.

In 1926 a small red diamond was found in alluvial diggings
near Kimberley and was expected to weigh 6 carats when cut and
to be worth close upon 1000. A clear apple green stone of 41
carats is known as the Dresden Diamond, an Indian stone purchased
in 1743 for the Crown of Saxony. Blue stones are almost as rare
as the red, the most famous example being the Hope Diamond
(p. 62); it is thought that the Brunswick Blue Diamond may have
been cut from the same stone. Yellow is the most common colour,
the most famous being the Austrian Yellow Diamond (p. 61), the

*The theoretical value for the perfectly pure diamond is 3-515.

60

CARBON

Tiffany Yellow from Kimberley, 1878, the Tennant and Colenzo
stones.

When strongly heated in air absence the diamond either ^ub-
limes or is converted to graphite; it never melts. The somewhat
slippery feel is regarded as due to the assumption by the electronic
oroits of surface atoms of a pseudo-graphitic structure.

In 1663 Boyle observed that diamonds become luminous if
rubbed in the dark; they become luminous, too, after exposure
to light or to cathode rays. When exposed to ultraviolet light
some diamonds yield a blue glow. They are more transparent to
X-rays than other gems and after prolonged exposure to radium
a colourless diamond becomes green.

Many stones that are not genuine diamonds are popularly so
called. Thus Brazil, Bristol*, Cornish*, Derbyshire, Alaskan,
Arkansas, Marmora and German "diamonds' 1 are quartz. Matura
or Ceylon "diamonds" are white zircons. The Saxony "diamond"
is white topaz; the Simili or Strass "diamond" is merely a paste
(glass). Carbonado and coal are frequently termed black diamonds
and not without reason.

Some famous diamonds

The story of the diamond could hardly be complete without
some reference to a few of the more important diamonds known to
the civilised world. The diamond is the only gem stone that
comprises one element only. It appeals to popular taste because of
its rarity, unique hardness, which prevents it from being scratched,
and exceptional optical properties.

The Austrian Yellow or Grand Duke of Tuscany Diamond,
known also as the Florentine Diamond, is probably of Indian
origin; it was cut as a briolette in 1476 for Charles the Bold. It is
pale yellow in colour, and weighs 137-27 metric carats. Prior to
World War II it was kept in Vienna. It was one of the heirlooms
of the Royal House of Austria.

The Cullinan Diamond is a famous stone. In 1897 Thomas
Cullinan purchased a fajrm near Pretoria in the Transvaal, which
was believed to contain diamonds ; and so it proved ; in a few years
the land was valued at 20 million. In 1903 a diamond mine was
discovered there which came to be known as the Premier Mine,
and in January 1905 a diamond was unearthed, the largest gem

"These are mentioned by C. MERRET, Phil. Trans., 1866, 12, No. 138, p. 949.

61

THE CHEMICAL ELEMENTS

ever found in historic times*; nevertheless it was probably only
a portion of a still larger stone as it had one large cleavage surface.
It measured 4 X 2^ X 2 cubic inches and weighed 621*2 grams
or 3016 metric carats, equivalent to 1*3695 Ib. (avoir). It was
named after (later Sir) Thomas Cullinan.

In 1907 the Transvaal Government, acting on the suggestion
of General Botha, purchased the diamond for 150,000 and
presented it to King Edward vn. The stone was remarkably pure,
of the first water or bluish white; it was cut yielding two magnificent
brilliants, 7 smaller stones and 96 still smaller ones. The total
weight of the cut diamonds was 1063-65 carats, equivalent to a
yield of about 34 per cent of the rough stone, the remainder being
converted to dust. The two largest stones are set in the English
Crown.

The De Beers Diamond found in 1888 in the De Beers mine at
Kimberley was pale yellow and weighed 88 grams or 440 metric
carats. When cut it yielded a magnificent brilliant of 234*5 carats.

The Excelsior Diamond was found in June 1893 * n t ^ ie Jagers-
fontein diamond mine in the Orange Free State of S. Africa. Next
to the Cullinan it was the largest of known diamonds, weighing
in the rough 199-04 grams or 995*2 metric caratsf. A glass model
is in the possession of the British Museum, and measures 2*3 X
2*15 x i-o8 cubic inches, approximately. It was not cut until
1903 when it was converted into 21 brilliants ranging in weight
from 69*68 metric carats downwards.

The Hope Diamond has been much to the fore in recent years.
Dull, slaty blue in colour it is generally acknowledged to be the
world's most perfect blue diamond. It weighs 45*5 carats. It has
had a chequered history. Its existence was revealed by the Great
Mogul for the first time to a European, the celebrated French
traveller Jean Baptist^ TavernierJ, who was his guest in the
middle of the seventeenth century. He said that, in a temple in the
ancient town of Pagan, there was an idol nzmedRamaSita, adorned by
a magnificent blue diamond, Tavernier was interested; he was a

*The Bahian carbonado (p. 58) was a little larger, but it was not a gem.

fSpBNCER, Miner alogical Magazine, 1911, 16, 140.

t TAVERNIER (1605 to 1689) was the son of a German map engraver who had
settled in Paris. He travelled widely, made much money by trading in jewels and
was ennobled by Louis xiv, becoming Baron d'Aubonne. For a detailed account
of his travels see ''The Six Voyages of John Baptista Tavernier, Baron of
Aubonne, through Turkey into Persia and the East Indies" (London, 1678).

62

CARBON

connoisseur of gems having been supervisor of the treasures of Louis
xiv. After leaving the Mogul, Tavernier went to Pagan to visit the
temple; this was easy; he was the friend of the Great Mogul.
With several accomplices he stole into the temple at the dead of
night, bound and gagged the priests, extracted the diamond from
the forehead of the idol and fled. The curse of the Indian god is
reputed to fall on all who possess the stone. Certainly its career has
been accompanied by misfortune. Tavernier sold it to Louis xiv
and died soon after*. The stone remained a French Crown jewel
until the Revolution. After receiving the stone Louis xiv lost
several members of his family and himself became gravely ill. One
of his mistresses, Mdlle de Montespan, wore the stone on several
occasions and then fell from favour. Another, Mdme de Lavallire,
wore it and became strangely depressed, so entered a convent.
Marie Antoinette, wife of Louis xvi, wore it and was guillotined
soon after her royal husband. The Assembly annexed the royal
jewels but the diamond was stolen, reappearing later in Amsterdam,
where it was cut by Fala, whose son stole it, sold it, squandered
the money and then committed suicide. Eventually the stone came
into the possession of Francois Beaulieu who cut it in two, sold the
smaller part and took the larger to London where it was purchased
by Henry Philip Hope, a wealthy Londoner, for 18,000; it was
described in the catalogue of his collection in 1839, the year of
his death, and thus came to be known as the Hope Diamond.
Henry was a bachelor, but the diamond remained in the family
passing in due course to Lord Francis Hope. The latter became
involved in financial and domestic difficulties; his actress wife
May Yohe, at her divorce proceedings in 1902, attributed all
their ill-luck to the stone. The gem was sold and became the
property of a Polish prince in 1908 who lent it to a Paris actress
who was shot from a box whilst on the stage. The prince was himself
stabbed to death a couple of days later.

The stone now came into the possession of Abdul, Sultan of
Turkey, who shot his wife whilst wearing it and was himself later
deposed. A Persian merchant who next had it was drowned. In
1911 Edward McLean, a Washington millionaire, purchased it,
paying, it is said, some 60,000, and gave it to his wife Evelyn
Walsh McLean. She very naturally scoffed at the idea of ill-luck;

*Some say he was killed by wild animals on his travels. Different accounts of
;he diamond vary considerably in the details of its early history. The Author has
mdeavoured to include only the most authentic data.

63

THE CHEMICAL ELEMENTS

nevertheless to be on the safe side she arranged for it to be blessed
by a priest. This apparently, didn't do much good, for Evelyn
sa^p her eldest son run over by a car and killed; her husband
became involved in financial difficulties and she divorced him in
1933. He died insane. Evelyn herself broke her leg and it never
healed properly. In 1941 her 25-year-old daughter married and
Evelyn wore the diamond at the wedding. In 1946 the daughter
was found dead in her home in Washington as the result of sleeping
tablets. Evelyn once asked the Bishop of Washington to hide the dia-
mond in his cathedral, but this the reverend gentleman was unwilling
to do. "I do not know" wrote Mrs McLean "if the bishop was
afraid of the diamond's curse, but I do know that I could not
persuade him to have anything to do with it." Mrs McLean died
from pneumonia in 1947. In April 1949 it was announced that
Mr Harry Winston, a New York jeweller, had purchased the
diamond, the purchase price not being named. "It is childish", he
said, "to suppose that diamonds themselves exert any influence
for good or evil; it is not the diamonds themselves that cause
misfortune, but the people who handle them." We will let it rest
at that.

The Imperial Diamond, known also as the Victoria or Great
White Diamond probably came from the Jagersfontein mine of
the O.F.S. It appeared on the London market in 1884 and had
been presumably stolen from the mine. Its original weight was
given as 457 carats; it was cut into an oval brilliant of 180 carats
and a smaller round brilliant of approximately 19-6 carats. The
former was purchased by the Nizam of Hyderabad.

The Jonker Diamond is the fourth largest gem diamond known.
The story of its discovery is a real romance. Jacobus Jonker, a
South African farmer and prospector, had a claim at Elandsfontain,
not far from the Premier Mine near Pretoria. For 18 years he
toiled with unexampled perseverance but with little result. In due
course his luck turned. After a heavy rain storm in January 1934
he put a native to work on gravel that had been washed up. He
found a stone in size and shape like a hen's egg, about 2| inches
long by i^ inches wide and deep, weighing 145-2 grams or 726
carats. That night the stone was hidden in a stocking tied round
Mrs Jonker 's neck and the hut was guarded by armed men. Next
day it was taken to safety; in due course it was purchased by Sir
Ernest Oppenheimer, Chairman of the Diamond Corporation, and
sent to London by ordinary registered post what a tribute to the

64

CARBON

postal system of those days! It was seen by the King and Queen
but a suggestion that it should be added to the Crown jewels did
not materialise. It was kept in the vaults of the Corporation until
it was sold in 1935. Because of heavy insurance it cost about 10
per day to keep the diamond. The purchaser was Mr Harry
Winston of New York, who recently purchased the Hope Diamond
(p. 64); he paid 150,000. The next problem was tfo get it cut.
This was done by Lazare Kaplan who studied the stone for a whole
year in order to ensure that he had diagnosed its cleavage planes
correctly; an error in their determination might ruin the diamond
which even Lloyds were not prepared to insure against accident.
At long last, taking his courage in both his hands, Lazare began
his task which ended in complete success. The diamond yielded
12 gems weighing about 400 carats, the largest gem weighing
about 170 carats, some 300 carats being "lost" as dust. The cut
stones were then valued at 400,000.

The Kohinoor Diamond or Mountain of Light, is a magnificent
stone. Many centuries ago a beautiful diamond was found in one
of the Golconda mines ; according to Hindoo tradition it belonged
to Kama, a King of Auga, 3000 years ago, but that is typical oriental
exaggeration. The stone was kept by the rulers of the kingdom of
Golconda until they were conquered in the seventeenth century by the
Moguls. During a visit to India in the second half of the seventeenth
century, the French traveller Tavernier (p.62) was shown a diamond,
known as the Great Mogul, by the Mogul ruler Aurungzebe,
whose guest Tavernier had the honour to be. In the rough it
weighed about 300 carats and was sometimes worn by the Mogul
himself or it adorned his famous peacock throne. In 1739 the
Mogul Empire was over-run by the Persians under Nadir Shah,
into whose keeping the Mogul treasures now passed. When Nadir
Shah was murdered by his own subjects, a large diamond, believed
to be the Great Mogul, was carried away by Ahmed Shah and re-
mained in his family until 1800 when the then owner was over-
thrown by Shah Shuja, who, himself in 1813 was compelled to
hand over the stone to the Rajah of Lahore, who wore it as an
armlet and sometimes decked his horses with it.

On the annexation of the Punjab a diamond, known as the
Kohinoor, and believed to be the Great Mogul, was handed to the
East India Company and by them to H.M. Queen Victoria, being
brought to London in 1850. Up till then the stone had only been
rough cut; it was now re-cut to a brilliant of 108-9 carats and

65

THE CHEMICAL ELEMENTS

exhibited at the famous 1851 Exhibition. It was unfortunately cut
too broadly for its depth and does not in consequence show its full
brilliance. It is a Crown jewel and the superstitious Indians regarded
its 'loss as the downfall of their empire.

The Pitt or Regent Diamond, is a remarkably clear stone said
to have been found in the Kistna River at Hyderabad in 1701, but
may equally well have been stolen from some mine in the Golconda
area. It was bought by Thomas Pitt, known thereafter as Diamond
Pitt, Governor of Fort St. George, Madras, and grandfather of the
great English statesman, the Earl of Chatham. He paid some
20,000 for the diamond in 1715. Two years later he sold it, still
in the rough, to the Duke of Orleans, Regent of France, for
135,000, for presentation to Louis xv. The rough stone weighed
410 carats and was cut as an extra deep brilliant of 135 carats, an
operation that took two years. When Louis xv was crowned the
diamond was set in his crown; later it was worn in a brooch by
his queen Marie Leczincka. During the Revolution it was stolen,
but recovered and adorned the state sword of Napoleon. During
the Franco-Prussian War it was placed for safety in the arsenal at
Brest and later in the hold of a French warship. It is now exhibited
in the Louvre, Paris.

The Sanci Diamond is believed to be the first to be cut and
polished in Europe. It weighed about 53^75 carats. It belonged to
Charles the Bold, Duke of Burgundy, who wore it at the Battle of
Nancy in 1477, where he was defeated and killed. The diamond
was found by a Swiss soldier on the field of battle; it was sold to a
Frenchman named Sanci and kept in his family for nearly a century,
when Henry in desired to borrow it from one of the captains of
his Swiss troops to whom it had descended. This young Sanci
accordingly gave it to a trusted servant to take to the king, but
both man and diamond mysteriously disappeared. Sanci had the
greatest confidence in his servant and made a thorough search for
him, learning later that he had been waylaid by robbers, murdered
and buried in a forest. He proceeded to the spot indicated, had the
body disinterred and cut open. In the man's stomach lay the
diamond. The faithful minion had swallowed the stone sooner
than allow it to fall into wrong hands.

The diamond later came into the possession of the English
crown and was taken across to France by James n when forced to
leave England in 1688. Louis xv wore it at his coronation. In 1835

66

CARBON

it was purchased by a Russian nobleman for 86,000. Presumably
it now lies behind the "Iron Curtain".

In 1948 Tanganyika presented H.R.H. Princess Elizabeth, on
the occasion of her wedding, a pink diamond, the largest and
purest known, weighing, when cut, 23 carats.

67

CHAPTjER 6

THE METALLOIDS BORON AND SILICON

THE term metalloid was introduced by Erman and Simon in
1802 to indicate such elements as possess metallic physical
properties, but non-metallic chemical properties. These include
boron, silicon, arsenic, antimony, selenium and tellurium. Some-
times iodine is added to the list. Unfortunately in 1 8 1 1 Berzelius
employed the term metalloid as synonymous with non-metal and
at the present time the French still adhere to its use in that sense.
In the present chapter we shall deal with boron and silicon only.

Boron

Borax has been known in commerce for many centuries, its name
being derived from the Arabic bauraq probably from the Persian
burah. The word occurs in early alchemical writing, but may not
always have referred to the same substance since the Arabs applied
the term also to nitre. Agricola (circa 1530) called it chrysocolla
(Greek krusos y gold) because of its use in soldering gold, but that
name is now reserved for another mineral, namely copper meta-
silicate, CuSiO 3 .2H 2 O. Borax was originally obtained from a salt
lake in Tibet and sent to Europe in the crude state as tincal.

In 1 702 Homberg prepared the free acid from borax and called
it sal sedativum. In 1747 Baron discovered that borax is a compound
of soda and sal sedativum ; in other words, it is a salt and with the
establishment of Lavoisier's system of nomenclature, introduced
in conjunction with de Morveau, Berthollet, and Fourcroy in 1787,
the incorrect appellation sal sedativum gave place to boracic acid,
subsequently shortened to boric acid. Lavoisier regarded it as an
oxide. The news reaching Paris early in 1808 that Davy had, in
the previous October, isolated the alkali metals potassium and
sodium stimulated chemists generally to attempt the isolation of
other metals. Gay-Lussac and Thenard prepared potassium that
year (1808) by a new process, namely heating potash with metallic
iron, a method which Davy himself subsequently adopted as more
convenient than his own electrolytic one. The potassium was now
heated with boric anhydride in a copper tube and, after cooling,

68

THE METALLOIDS BORON AND SILICON

the residue was washed free from soluble matter, and christened
bore. To complete their investigation they oxidised some of this
bore, converting it to boric acid. About the same time D?,vy
similarly prepared boron, and his paper announcing his success was
read before the Royal Society in June 1808. As obtained in this
way the boron was very impure. It was not until 1909 that a really
pure sample was obtained by Weintraub.

Although compounds of boron are widely used in industry, the
element itself is seldom if ever required. Ferro-boron, an alloy
with iron, has been used to a limited extent in the manufacture of
boron steels.

Silicon

Silicon, like boron, possesses too great an affinity for oxygen to be
found free in nature. Next to oxygen it is the most abundant
element in the earth's lo-mile crust, of which it constitutes some
26 per cent. Its oxide in one form or another has been utilised by
man from primeval times, as witness the flint implements dating
back even to eolithic ages. In more civilised times quartz, onyx,
agates and opals came to be prized. The word silica is derived from
the Latin stlex, flint. The scientific history of silicon compounds
dates back to the time of Becher (1635 to J 682) who stated that
siliceous minerals are suitable for glass making and contain an
"earth" which he called terra vitrescibilis. Tachenius showed in 1660
that this earth was acidic because it would combine with alkali.
Davy thought that silica was undoubtedly the oxide of an unknown
element and endeavoured to decompose it electrolytically in the
same way as he had tackled the caustic alkalis, but without success.
Gay-Lussac and Thenard were probably the first to obtain the
element, albeit in a very impure form, by a method similar to that
already adopted with success in the case of boron. In 1809 they
passed silicon tetrafluoride, discovered by Scheele in 1771, over
heated potassium and obtained a reddish-brown, combustible solid.
Crystalline silicon was first obtained in 1854 by Deville. He was
preparing aluminium by the electrolysis of fused sodium aluminium
chloride which contained silica as impurity. The silicon crystallised
from the aluminium on cooling and remained behind when the
mass was treated with acid just as graphite is left when cast-iron is
similarly treated.

Compounds of silicon are widely used in industry. The element
is much less in demand. At one time it had a restricted use as a

THE CHEMICAL ELEMENTS

de-oxidiser in metallurgy. Silicon steels were invented by Hadfield
in the early eighties of last century and may contain up to 20 per
cent silicon. With 14 to 15 per cent the steels are very resistant to
attack by chemicals and are useful for chemical* plant. With 20
per cent they are even more resistant, but are brittle. Stalky is an
alloy with iion containing 3 to 4 per cent silicon whilst silicon
bronze, a copper-tin alloy containing merely a trace of silicon, is
used for telegraph wires. Cast-iron is really an alloy of silicon (up
to about 3*5 per cent) and iron containing some 3 per cent of
carbon with smaller amounts of manganese and other elements.
Alloys with aluminium are now stepping into prominence and are
mentioned in connection with this latter element.

With the extension of radio-communication to ultra-high
frequencies the use of point-contact crystal rectifiers in telecom-
munication circuits has become an established practice. Both
silicon and germanium (p. 174) crystal rectifiers are now in use.

70

CHAPTER 7

THE SULPHUR GROUP

THE sulphur group comprises sulphur, selenium, tellurium and
polonium. Although polonium belongs chemically to this group it
is convenient to discuss it later along with the radio-elements (p. 3 1 1).

Sulphur

Sulphur or brimstone occurs native in many parts of the world and
could hardly fail to be observed in those districts at an early date.
The word sulphur or sulfur is Latin. The term brimstone or burning
stone refers to its combustibility. Its occurrence in the neighbour-
hood of volcanoes and the disagreeable smell produced when it
burned caused it to be regarded as symbolic of the powers of evil.
In ancient writings the term brimstone frequently refers to the
idea of combustibility, and not to the material element as explained
on p. 22. Thus, in the Old and New Testament alike, fire and
brimstone are frequently associated in terms of punishment. On
the other hand, the disinfecting properties of the pungent fumes
appear to have been recognised in early times, for Homer, circa
880 B.C., represents Odysseus, after the slaughter of the suitors,
as calling for fire to burn some sulphur for general cleansing. A
millenium later Pliny mentioned the fumigation of houses with
sulphur, and Ovid (43 B.C. to A.D, 17) referred to the use of eggs
and sulphur for a similar purpose.

In later years the term sulphureous was synonymous with
inflammable. The early alchemists represented fire by an equi-
lateral triangle. Fire, or heat, was known to effect the decomposition
of most substances; it was supposed to penetrate into them and
split them up. An equilateral triangle has the most acute angles of
any regular two dimensional figure. So it was chosen to represent
fire. As the spiritual sulphur represented the essence of fire or
inflammability it, too, was represented by an equilateral triangle,
but with the sign of the cross beneath it, thus ^.

This double meaning, spiritual and material, for the term
sulphur naturally led to much confusion. Material sulphur came to
be recognised as an element only when Lavoisier explained the

71

THE CHEMICAL ELEMENTS

process of combustion generally as due to union with the oxygen
of the air, although Davy, as late as 1812, suspected sulphur to
contain hydrogen on account of its inflammability.

The sulphur-mercury theory of metals has already been
discussed (p. 15).

The Codex, Germanicus, circa A.D. 1350, says that pure sulphur
will crackle if held in the warm hand, and that this may be used as
a test, because impure sulphur does not. This, of course, is generally
true.

The invention of gunpowder, a mixture of charcoal and nitre
with sulphur, is usually attributed to Roger Bacon about 1242, but
tradition ascribes the discovery of its propellent force to a second
monk, one Berthold Schwarz, a century later.

At one time the main uses of sulphur were in the manufacture
of gunpowder and of sulphuric acid. Nowadays its use for these
purposes is more restricted. Sulphur is used in the manufacture of
carbon disulphide, ultramarine, vermilion and numerous other
compounds. Vulcanisation of rubber may be effected with sulphur.
Enormous quantities are converted to bisulphites for treating wood
pulp in the manufacture of paper. Sulphur is employed as a
preventive of the growth of fungus on vines, and mould on hops;
it is burnt in the oast house to improve the flavour of the hops;
it is used as a disinfectant, a familiar form being "sulphur candles".

Sulphur also finds application medicinally. Our thoughts at once
revert to Mrs Squeers of Dotheboys Hall in Dickens's immortal
"Nicholas Nickleby". That worthy, or perhaps better described as
unworthy, dame was wont to give the young hopefuls under her
care substantial doses of brimstone and treacle each morning
'partly because if they hadn't something or other in the way of
'medicine they'd be always ailing and giving a world of trouble,
and partly because it spoils their appetites and comes cheaper
than breakfast and dinner."

Pliny mentions the use of sulphur in combination with turpentine
as a cure for skin diseases, the mixture being known as harpax, from
the Greek meaning to carry away.

Selenium

The oldest copper mine in Sweden is at Fahlun, about 100 miles
N.W. of Stockholm, once the home of Gahn and Sefstrom, the
discoverers of manganese and vanadium, respectively. The copper
occurs as pyrites and the sulphur obtained by distillation from these

72

THE SULPHUR GROUP

was used at Gripsholm for the manufacture of sulphuric acid by
the chamber process. A red deposit was observed to collect on the
floor of the chambers when the Fahlun sulphur was used, but jiot
when sulphur from other sources was employed. Both Berzelius
and Gahn held shares in the works at Gripsholm and became
interested in the phenomenon. As the result of a preliminary investiga-
tion in 1817 they concluded that the deposit was tellurium, but
by February 1818, Berzelius had satisfied himself that he was
dealing with a new element. As it closely resembled the element
then recently named tellurium by Klaproth, Berzelius suggested
that his be called selenium from the Greek selene, the moon.
Sometimes, to emphasise its metalloidal nature, it is called selenion.

Selenium exists in several allotropic forms; the grey "metallic"
allotrope sustains an enormous increase in its electrical conductivity
when exposed to light and loses it again in the dark. Observed by
W. Smith in 1873, this remarkable property is utilised commercially
in various ways, as for example, in the optophone, photophone and in
television. Thus, it is possible to transmit photographs by wire to
illustrate newspapers ; to synchronise sounds with moving pictures ; to
register the moment the runner reaches the tape and the racehorse
passes the finishing post; to measure the density of smoke emitted
by chimneys, stacks or apparatus designed to produce smoke
screens. The feeble light or stars may be measured with the aid of
selenium ; explosives may be fired at a distance with a beam of light
and a selenium cell ; burglar alarms are based on the same principle.

The main use of selenium is in the glass and ceramic industries.
Small amounts serve to decolorise glass which would otherwise
show a green tint owing to the presence of iron, although manganese
is now largely used as it imparts a pinkish tint. With larger
selenium content ruby glass is obtained, the selenium being in
colloidal form, just as gold is in the classical ruby glass. The
selenium ruby glass is particularly useful for signals, tail lights on
automobiles, etc, because it transmits virtually all the red rays,
and eliminates almost all others. Red enamels and glazes are
similarly produced. The total world consumption of selenium is
of the order of 300 tons annually.

Tellurium

In 1782 Miiller von Reichenstein, chief inspector of mines in
Transylvania, extracted from a bluish white gold ore, now recog-
nised as an auriferous native tellurium, but then known variously

73

THE CHEMICAL ELEMENTS

as aurum problematicum, paradoxicum or album, a substance thought
to resemble antimony, but which he regarded as new to science. He
despatched a fragment to Bergman, then recognised as one of the
leading analysts in Europe, who satisfied himself that it was not
antimony; but, with so small a piece at his disposal, he would not
commit himself further. Seven years later, in 1789, a Hungarian
chemist, Kitaibel, independently discovered the same element.
Klaproth, a famous Berlin mineralogist, read a paper on the gold
ores of Transylvania and called attention to Mtiller's discovery,
which had been either forgotten or overlooked by chemists.
Klaproth had confirmed the existence of the new element and
suggested the name tellurium, from Latin tellus, the earth. He was
the first to isolate the metalloid by igniting a paste of the oxide
with oil in a glass retort. On cooling, globules of tellurium were
found. Like beryllium, therefore, tellurium was not named by its
discoverer an unusual state of affairs. A systematic study of the
element was first effected by Berzelius in 1835.

For a long time tellurium was a puzzle to chemists because its
atomic weight exceeded that of iodine, which was contrary to what
was to be expected from Mendeleeff's periodic table. Believing in
the absolute truth of Mendeleeff's system, many chemists made a
study of the atomic weight of tellurium and probably methods of
purification of no element have ever been so carefully studied as
those of tellurium. The classical research of Baker and Bennett* in
1907 appeared to confirm for all time that tellurium must be
regarded as an exception to the Periodic Law. As a mean of 43
determinations obtained from various highly purified derivatives
of the element a mean value of 127-605 (O = 16-000) was found
a value that is accepted to-day (1950) by the Committee on Atomic
Weights of the International Union of Chemistry, in the form of
127*61.

In 1889 Brauner suggested that tellurium was a mixture of two
elements which could not be separated by chemical means, and was
severely attacked by Wyroubofff in 1896 for his heretical views.
"He has therefore submitted tellurium" wrote this cynic "to all
the tortures which a substance can undergo. He has melted it,
sublimed it, oxidised it, hydrogenised it, dissolved it, precipitated
it and finally arrived at the result, which everybody had reached
before him, that the atomic weight varies between the wide limits

*BAKER and BENNETT, Trans. Chem. Soc., 1907, 91, 1849.
fWYROUBOFF, Chem. News, 1896, 74, 30.

74

THE SULPHUR GROUP

of 125 and 129. Hence he concludes that we have here a complex
body composed of two elements of very different atomic weights.
What are these weights and what are the distinctive properties, of
tellurium a and tellurium ft he does not tell us for he has not been
able to separate them."

There is invariably stern opposition and oft-times, as here,
ridicule for those who suggest revolutionary ideas ; yet how true
Brauner was in his ideas. We now know that*tellurium consists of
not merely two but actually four forms, chemically indistinguish-
able. We call them isotopes, all having the same atomic number 52,
and possessing atomic weights of 130, 128, 126 and 125
respectively in order of abundance. Had the element possessed a
higher proportion of isotope 126 and/or 125, the anomaly would
not have occurred. Iodine has no isotopes; there is only one form.
It is sometimes incorrectly stated that iodine has one isotope; but
this is a "terminological inexactitude". The word isotope (Greek
tics, equal ; topos y position) is intended to indicate that the varieties
have the same atomic number and therefore occupy equal positions
in the Ideal Periodic Table. If there is only one form its position is
unique and not equal to that of another. The only child is not a
twin.

Turning now to its properties and commercial applications,
tellurium is not very poisonous but human beings are easily
indisposed by small amounts. Workers are apt to acquire a very
offensive "tellurium breath".

Tellurium is used as a colouring agent in glass and porcelain,
yielding a blue to brown colour. Certain alloys possess high
electrical resistance and have been used in electrical equipment.
Addition of 0-05 to 0-085 P er cent tellurium to lead greatly
increases its strength and hardness; it is recommended (1933) for
pipes carrying water. Tellurium is sometimes added to copper
alloys to assist machining; it is used for staining silver in electro-
plating, the ware being dipped into a solution of tellurium chloride,
when a dark "platinum" finish is acquired.

75

CHAPTER 8
fi

THE PHOSPHORUS GROUP

THE phosphorus group comprises phosphorus, arsenic, antimony
and bismuth.

Phosphorus

This term (Greek phbs light, pherb I bear) was applied in the
seventeenth century to any substances that luminesced in the dark.
Thus in 1602 a Bolognese shoemaker, Casciorolus by name,
observed that the mineral now called barytes became phosphor-
escent when ignited with a combustible substance; such was the
origin of Bolognian phosphorus or lapis bononiensis. In 1693 Homberg
heated salammoniac and lime, a phosphorescent calcium chloride
resulting, known as Homberg s phosphorus.

About this time there lived in Hamburg a merchant, Hennig
Brand not to be confused with the Swedish chemist, Georg
Brandt (p. 292) who discovered cobalt. Brand is described as a
charlatan and was ironically called Dr. Teutonicus. He became
wealthy by marriage and spent his days in his laboratory, seeking
to make yet more money, as many a worse man has since tried to
do. He turned his attention to urine. Why? Probably because of the
doctrine of signatures which was widely believed at the time. This
doctrine is discussed more fully later in connexion with nickel;
suffice it to say that natural objects of a golden colour were
supposed to contain gold, this being Nature's way of assisting
mankind to understand her mysteries. Though urine did not give
Brand gold directly, it did so indirectly. It yielded him, in 1669, a
waxy, easily melted, highly inflammable substance which lumin-
esced in the dark. This was the "Fiihrer" phosphorus; very
phosphorus of very phosphorus, if one may venture to adapt an
ancient quotation.

The process was kept secret. Probably the urine was evaporated
to small bulk, allowed to ferment and then distilled with sand, the
distillate being collected under water. Brand was patronised by
dukes and urged to hide himself in the Hartz mountains lest his
secret should leak out. Leak out it did.

The news of the discovery spread rapidly throughout Europe.

76

THE PHOSPHORUS GROUP

Kirchmaier gave a description of it in 1676 and Brand, who had
shown the element to Kunckel, eventually sold the secret to Dr.
Krafft, of Dresden, for 200 thalers. Krafft exhibited "das kalte
Feuer" at various courts including that of our English King Charlfes n
in 1677. The fact leaked out that the phosphorus was obtained from
urine and Johann Kunckel or Kungelius, at one time Counsellor
of Metals to Charles xi of Sweden, experimented with the liquid
until he succeeded in 1678 in preparing phosphorus and casting
it into sticks. He designated it phosphorus mirabilis. Robert Boyle
saw the element at court and apparently independently worked out
a method of extracting it from urine in 1680. He described the
method in a sealed paper which was deposited with the Royal
Society and published in 1693. Boyle's assistant, Hanckewitz and
his son Ambrose Godfrey, prepared this noctiluca commercially
and even exported it to the Continent. It was there known as
English Phosphorus and Boyle's Phosphorus. Godfrey made fame and
fortune from it. When continentals wrote to him they addressed
their letters to "Mr Godfrey, Famous Chemist in London". That
was sufficient.

For a century phosphorus remained an expensive chemical
curiosity. In 1769 Gahn recognised it as a constituent of bones
and Chel, a pupil of Bergman, showed how phosphoric acid
could be obtained from calcined bones by treatment with sulphuric
acid. It was then only necessary to mix the acid with charcoal
powder and distil off the phosphorus. The price accordingly fell
instanter. The elementary nature of phosphorus was first recognised
by Lavoisier in 1777.

The match industry

Large quantities of phosphorus are used in the match industry,
the total annual consumption being estimated at 1000 tons. In
England alone 125,000 million matches are consumed annually
despite the extensive use of automatic lighters by cigarette smokers.
The first chemical matches are generally supposed to have been
made by Chancel of Paris in 1805 an( ^ were manufactured from
1812 on. They contained no phosphorus, however, but consisted
of sticks of wood the ends of which had been dipped in molten
brimstone and then coated with a mixture of sugar and potassium
chlorate then newly discovered by Berthollet. To ignite, they were
dipped into a bottle containing asbestos moistened with oil of
vitriol. These "oxymuriate matches" continued to be sold down to

77

THE CHEMICAL ELEMENTS

1845. I* 1 *8 2 7 the first commercially successful friction matches,
known as friction lights, were invented in England by John Walker,
a chemist of Stockton on Tees not to be confused with Johnnie
Walker of 1 820, still going strong! His sales book is still in existence
and shows that he sold his first box of matches on yth April 1827,
to a local solicitor. They again contained no phosphorus, being
tipped with' a mixture of stibnite, potassium chlorate, and gum.
Rubbing on sandpaper effected their ignition, and Walker sold
the sandpaper in the shape of a cocked hat with his matches. His
invention was not patented and his matches became superseded
about 1834. These later matches were called lucifers the name
being invented by Samuel Jones, a vendor in the Strand, London*.
In 1 833 matches were first prepared containing phosphorus and were
known as Turin Candles. These were made simultaneously in several
countries, but as they were found to be somewhat dangerous,
the chlorate was later replaced by lead dioxide and pyrolusite.

In 1844 Arthur Albright of Birmingham suggested to his
partner that phosphorus ought to be manufactured on a large scale
and placed more cheaply on the market. He accordingly built a
sulphuric acid plant in Birmingham, where Roebuck in 1746 had
introduced his leaden chambers to replace the earlier and more
costly glass globes. Calcium phosphate was obtained from South
America, and production began.

In 1845 Albright went to Galatz on the Danube, to buy bones
left from canning beef. Dodging the Turkish quarantine regulations
he found Wagner's beef bones rather odorous to say the least; so
he built a furnace to calcine them on the spot.

The same year (1845) Schrotter of Vienna showed that white
and red phosphorus are chemically identical. As soon as Albright
learned of this he decided to manufacture red phosphorus and
obtained the necessary patent in 1851. He had been greatly im-
pressed by the death through phosphorus poisoning of large
numbers of young girls in the German match-making industry
and he hoped it might be possible to avoid this by using the non-
poisonous red phosphorus in place of the white. As is well known,
white phosphorus is extremely poisonous; two grains may prove
fatal. The workers engaged in the manufacture of lucifers were
subject to "jaw disease" > Phossy jaw or necrosis of the lower jaw.
In addition to this, even when finished, the ordinary match made
*See CLAYTON, Chem. News, 1911, 104, 223. Also anon., Nature, 1898, 58, 345.

78

THE PHOSPHORUS GROUP

with white phosphorus was a source of danger, being both liable
to spontaneous ignition and poisonous. Children had frequently
died as the result of using them as playthings; they moreover
absorbed moisture and became useless by age.

By using red phosphorus Albright thought that the position
would be greatly improved, and an end would be put to necrosis.
Red phosphorus is much less chemically active than white. As it
is insoluble in most ordinary solvents it will pass through the
animal system if taken internally and duly excreted without doing
much harm. It evolves no poisonous fumes, is not luminous in the
dark, and is less likely to ignite spontaneously.

But here was a difficulty. When red phosphorus is brought
into contact with potassium chlorate a slight touch is sufficient to
induce an explosion. Many attempts to form a paste for the match
head were made, but none with success ; indeed in some cases fatal
accidents occurred. Prizes were offered by manufacturers but still
the problem remained unsolved. At last, however, someone hit
upon the happy idea of splitting the process. Instead of attempting
to use a paste containing both phosphorus and oxidiser, the two
were kept separate until ignition was required, by putting the red
phosphorus on the box and the oxidiser on the match head*. When
wishing to obtain a light the consumer himself brings the two
together as he "strikes a match* '. It is said that Bottger prepared
the first safety matches in 1848. These were tipped with gum,
sulphur, and chlorates. They could be ignited by rubbing on a
surface containing red phosphorus, gum, and antimony sulphide.

In 1851 Albright moved his works to Oldbury, and the same
year he exhibited a specimen of his new red phosphorus at the
Great Exhibition. This eventually brought him a large order from
a Swedish firm, the Lundstrom Brothers, who had large match
factories in Sweden and wished to protect their workers from
phosphorus poisoning by introducing the safety match. At first
Albright refused to consider the order.

"Gentlemen," he wrote, "amorphous phosphorus in such
quantities as stated in your letter can, to the best of my judgment,
only be used for the purposes of war." But the Swedes convinced
him that in matches it was to be used "for the enlightenment of
mankind".

Phosphorus is now prepared on a very large scale, in England
by Messrs Albright and Wilson at Oldbury, as the raw material
*TOMLINSON, Nature, 1876, 13, 469.

79

THE CHEMICAL ELEMENTS

for the manufacture of the various compounds of phosphorus used
in industry. Calcium phosphate, in the form of apatite,
CaCl a .3C%(PO 4 ) 2 , or some other mineral, is heated in a furnace
with sand and some form of carbon, the distillate being collected
under water. Thus

Ca3(P0 4 ) 2 + 3Si0 2 = 3CaSi0 8 + P 2 O 6
P 2 6 + 5C = 5CO + 2P

In this way very pure products are obtainable; the standard grade
of white phosphorus is over 99-9 per cent pure and contains only
the merest traces of sulphur and arsenic. It is extremely reactive
chemically and it is said that an excise officer once found this out
very much to his cost. When prowling round Albright's factory
he wrapped a piece of the curious "barley sugar" or "lemon rock"
in paper, and put it in his pocket and lived to regret it.

Red phosphorus is used as a deoxidising agent in the manu-
facture of non-ferrous alloys. It is common practice to prepare
phosphor-copper, containing 10 to 12 per cent of phosphorus, and
other alloys of high phosphorus content and to use these as
deoxidisers. White phosphorus is used also in chemical laboratories,
in rat poisons, fireworks, smoke bombs, etc. The standard grade of
the red has not less than 97 per cent of phosphorus and is free from
its white allotrope. Apart from its use in the match trade, already
mentioned, it is used as a "getter" in electric lamp manufacture;
it is also used in certain organic syntheses and to some extent in
the manufacture of non-ferrous alloys for de-oxidising purposes,
although white phosphorus is normally preferred owing to its lower
cost. Heated with copper turnings for example, it yields copper
phosphide used in the manufacture of phosphor bronzes (p. 106).

Much of the phosphorus is burned to the pentoxide from which
phosphoric acid and the numerous phosphates of commerce are
prepared. These include, for exajnple, the ammonium phosphates
used in fireproofing of timber, sodium metaphosphate or calgon
(calcium gone) for water softening ; calcium and sodium phosphates
used in flour and various medical preparations ; organic phosphates
used in ever increasing amounts as plasticisers in the plastics
industry. Some phosphorus is consumed in preparing metallic
phosphides such as calcium phosphide in Holme s signals, etc ;
ferrophosphorus, a convenient reagent for introducing phosphorus
into steel when needed; zinc phosphide, an effective poison for
rats and mice.

80

THE PHOSPHORUS GROUP

Arsenic

Ancient prehistoric implements of arsenical bronze, containing up
to 4 per cent of arsenic, have been found in Egypt, They were
"natural" alloys produced by reduction of arsenical ores, and not
with the intentional addition of arsenic. Arsenical compounds have
been used from very early historic times. The n?tive yellow
sulphide, As^, now known as orpiment (Latin auri of gold,
pigmentum pigment) was used at Tell el Amarna in the Eighteenth
Egyptian Dynasty. Aristotle (384 to 322 B.C.) used the term
sandarake in his writings and is believed to yefer to the ruby
coloured sulphide, As^g, often called realgar (Arabic rahj al gahr y
powder of the mine). The Greek herbalist Dioscorides (circa
A.D. 50) uses the term arsenikon, presumably for realgar, and
recommends as a cure for asthma that it be burned with resin and
the fumes inhaled. Pliny similarly recommended its use and this
may possibly account for the presence of the realgar discovered in
the Roman stratum on the floor of Wookey Hole, near Wells,
Somerset* ; there is no indication of its use as a pigment for mural
decoration there.

The word arsenic would thus appear to have reached us from
the Greek ; it meant masculine, or powerful, and evidently referred
to the great activity of the substance as a medicine. Possibly the
word is connected with the Persian zarnick or zirnuk, zar meaning
gold, with reference perhaps to the yellow colour of orpiment. During
the first century of our era the sandarach mines of Pompeiopolis, in
Paphlagonia, were worked by slave labour, involving enormous
losses of lifef.

The sesquioxide, As^g, known familiarly as white arsenic,
must also have been known at an early date. In Shakespeare's day
it was known as ratsbane because of its use in poisoning vermin.
Thus in Henry vi, Act v, Scene iv, the old, broken-hearted
shepherd says to his much-loved daughter, Joan la Pucelle,
commonly called Joan of Arc,

"I would the milk

Thy Mother gave thee, when thou suckst her breast,
Had been a little ratsbane for thy sake."

Then had she not been compelled to suffer at the stake or he to
witness it.

* FRIEND, Nature, 1937, 139* 72.
fSTRABO, "Geographia" 12, (3), 40.

81

THE CHEMICAL ELEMENTS

Roger Bacon, the inventor of gunpowder (p. 72), in "Breve
Breviarum de dono Dei" (thirteenth century) showed that arsenicum
album resulted on heating orpiment with iron scale and the substance
soon became familiar to medieval alchemists. Zosimus* in the
fifth century A.D. is believed to have described the preparation of
elementary, arsenic; but Albertus Magnusf is usually credited
with being the first to obtain it; he heated orpiment with twice its
weight of soap, Paracelsus (p. 85) stated that arsenic metal could
be obtained by ignition of "arsenic" with eggshells whilst Schroeder
in 1649 mentioned that metallic arsenic resulted on reduction of
white arsenic with charcoal or the sulphide with lime.

The alchemists viewed arsenic as a "bastard metal" or semi-
metal^:. Some regarded it as akin to quicksilver, its red sulphide
resembling cinnabar, and the volatility of its compounds that of
mercury salts. To it they gave the symbol o o often accompanied
by a coiled snake. Brandt observed that white arsenic, AsgC^, was
the calx of the semi-metal.

Arsenic is sometimes used in the manufacture of its compounds,
but more often in alloys. Small quantities, o-i to 0-2 per cent, are
added to lead for the production of shot (p. 196). Arsenical lead
anodes are used in the electrolytic production of zinc. Alloys with
antimonial lead containing i to 2 per cent of arsenic and sometimes
other elements are used for sheaths for electric cables, etc. Arsenical
coppers and bronzes are used for high temperature work such as
locomotive fireboxes, etc.

Antimony

Bronze age implements have been found in Hungary containing
copper alloyed with antimony up to 4 to 5 per cent. Like the
Egyptian arsenical copper already mentioned, this was purely a
natural alloy. Undoubtedly metallic antimony was known in very
early times. A vase, found by de Saizec at Tells in Chaldea, was
analysed by Berthelot in 1887, who found it to consist of almost
pure antimony, whilst a copper ewer and basin dating from the
Fifth or Sixth Egyptian Dynasty have been shown to be coated
with antimony (p. 93). Ancient beads of fairly pure antimony
were found by Petrie in a tomb at Illahun dating back some 800 B.C.

*BERTHELOT, Ann. Chim. Phys., 1888, (6), 13, 430.

fALBERTUs MAGNUS, "Theatricum Chemicum", 1613 Edition, 4, 931. He lived
1193 t 1280.

J BRANDT, Arch. Akad. Upsala, 1733, 3, 39.

82

THE PHOSPHORUS GROUP

It is difficult, however, to trace the history of metallic antimony
back through history because both terms antimonium and stibium
are used to indicate sometimes the metal itself and sometimes^ its
naturally occurring sulphide, stibnite. The last named, under the
Arabic name of kohl, was used in the form of a fine powder in the
toilet, of oriental women. It was used to paint the eyejprows and to
increase* the apparent size of the eye, whence the term platy-
ophthalmon ore (Greek plains, broad; ophthalmos^ eye). Reference to
this .practice apparently occurs in Holy Writ for we are told
(2 Kings ix. 30) that Jezebel, true to her feminine instincts, when
she heard that Jehu had slain her son Jehoram (842 B.C.) and
reacl^d Jezreel, first painted her face and then looked out of an
upper window on to the conqueror, hoping thereby to win favour
in his eyes and preserve her life. But Jehu was not so easily beguiled.
Ezekiel (xxiii. 40) refers in terms of reproach to the painting of the
eyes, and Jeremiah (iv. 30), that embodiment of human cheerfulness,
speaks in like manner. What these venerable prophets would have
said had they seen the modern species with their bloodred finger
nails can hardly be imagined. Dioscorides, the Greek physician
who lived in or about the second century A.D. gathered much
scientific information on science and medicine during his travels
with the Roman army, which he accompanied on several expeditions
as medical adviser. Later he wrote his monumental work "Peri
Hules latrikes" which for many centuries remained one of the
authentic medical treatises, the first Latin edition appearing in
1478. Dioscorides mentions that in order to roast the crude
stibnite it must be heated in a current of air until it burns; if more
strongly heated it ignites and melts like lead. From this it is
concluded that Dioscorides was acquainted with metalloidal
antimony.

For a long time antimony and bismuth were not distinguished
from each other; even Andreas Libavius (1540 to 1616) confused
the two.

The word kohl referred to above as denoting stibnite in a finely
powdered state came gradually to mean any fine powder. Thus
reduced iron was known as alcohol of Mars, and as late as 1812
Davy referred to flowers of sulphur as alcohol of sulphur. In the
theatrical profession pigments used for darkening the eyes are
still known as kohl. Francis Bacon in his "Sylva Sylvarum or
a Naturall Historic", 1626, p. 739, says "The Turkes have a black
powder made of a mineral called alcohole."

83

THE CHEMICAL ELEMENTS

As powders obtained by sublimation were very fine, kohl came to
mean a sublimate. It was not a great jump for it eventually to
me^n a distillate, for sublimation and distillation are closely
analogous processes. Thus in 1773 Baum, in his work entitled
"Chymie Experimentale" defined an alcohol as either

(i) A powder of the finest tenuity, or
(ii) Spirit of wine rectified to the utmost degree.

The distillation of alcohol had then been known for about 400
years and in course of time it was felt that this was the only
distillate worth bothering about by the man in the street; it was
therefore designated as the kohl or alkohl, which soon became our
alcohol, the Arabic prefix al being merely the definite article.

Pliny referred to two varieties of antimony which he terms male
and female. The latter was white and shiny and bore several names,
such as stibi and larbasis. This is thought to be the native element.
By the male form Pliny probably meant the less attractive stibnite.

The origin of the word antimonium is uncertain. A popular story
credits its origin to the escapades of a mythical monk, Canon of
the Priory of St. Peter at Erfurt, Basil Valentine, who is supposed
to have lived in the fifteenth century, though some authorities
have suggested earlier dates. The worthy monk, after experimenting
with antimonial compounds, threw his residues out of his cell
window. Some pigs ate them up greedily, were promptly sick and
then began eating vigorously to make up for lost meals. This
fattened them in a very gratifying manner for Christmas. Basil, a
keen observer of nature, thought it would be good to treat his
frugal colleagues in a similar manner, and invited them to partake
of this antimonial refreshment. Their bodies, weakened by asceti-
cism, could not stand the strain and several perished; whence the
term antimony or anti-monakhos, that is, monk's bane. It is a mere
bagatelle that the word antimonium was in use long before Basil
was thought of!

In those days the semi-metals or metalloids were regarded as
variations of true metals, probably much as we regard allotropic
forms to-day, though of course their ideas were confused. Basil
thus termed antimony -plumbum antimonii> that is, the antimonial
form of lead. He was familiar with the characteristic fern leaf and
star appearance on the surface of the solidified metalloid which, he
stated, the learned before his time had termed the philosophical
signet star.

84

THE PHOSPHORUS GROUP

In his book* entitled "The Triumphal Chariot of Antimony"
Basil gives instructions for the preparation of the Fire-stone, an
inferior type of Philosopher's stone which would transmute silver
into gold, but could not change iron or copper, whereas the true
Philosopher's stone was all-powerful. After devoting several pages
to the process he naively ends up by the words "I have told you
enough; and if, after all that has been said, you do not discover
the secret, it will not be my fault." To use an army term, Basil was
an adept at "passing the buck".

Antimony compounds were largely employed in the Middle
Ages in medicinal preparations. Paracelsusf used them; his
pharmacy was a strange mixture of chemistry and superstition.
His real name was Philipus Aureolus Theophrastus Bombast von
Hohenheim, but he used Paracelsus for short. His arrogance and
self assurance give the word bombast its present meaning. He
made butter of antimony, as the trichloride SbCl 3 was first called, by
distilling corrosive sublimate, that is mercuric chloride, with
stibnite; it was at one time thought to be a compound of mercury,
but Glauber disproved that in 1648. At the end of the sixteenth
century the trichloride was introduced into medicinal preparations by
the Veronese physician Algarotus, under the name pufois angelicus.
Probably this was a mixture of the trichloride and oxychloride,
which latter became known as powder of algaroth.

Basil Valentine refers to the use of antimony in medicine in his
characteristic bantering style. Thus

"Antimony, you affirm, is a poison; therefore let everyone
beware of using it I

But this conclusion is not logical, Sir Doctor, Magister or
Baccalaureus ; it is not logical, Sir Doctor, however much you
may plume yourself on your red cap.

Theriac is prepared from the venom of the viper, the most
deadly poison in the world. Does it therefore follow that
Theriac ought not to be used as a medicine?

You know that it is so employed."

The word theriac as used by Valentine deserves explanation. It
has long been believed that "like cures like". As the viper brews a

*This book, purported to have been written by Basil, is well worth reading for
its humorous style. An English translation, in 1893, by WAITE, of the Latin
version of 1685 is as entrancing as a Dickens novel.

t Paracelsus is variously stated to have been born in 1490, 1491 and 1493.
Various dates are given for his death, ranging from 1535 to 1541.

85

THE CHEMICAL ELEMENTS

deadly poison in its body, how comes it that it does not poison itself? It
was supposed that the blood of the snake possessed its own
antidote. If therefore a person were bitten all he had to do was to
catch the viper, slit it open and bind it on the wound.

But one could not always be sure of catching the viper, it was
better to have the remedy to hand in advance; the Greeks therefore
compounded a medicine containing vipers' bodies. Now the Greek
word therion referred to any savage animal and came to be applied
specifically to the viper. The medicine prepared as above came to
be known accordingly as theriaka from which our word "treacle",
used as early as 1124 by Fourcher de Chartres, is derived. Thus
Venice treacle comprised 12 adders soaked in white wine, and in
France a charlatan or quack doctor was known as a triacleur\ in
course of time the word was used to denote any thick and viscous
medicine. It was used in that sense in the so-called "Treacle Bible",
published in 1568, in which the well-known words of Jer. viii. 22
"Is there no balm in Gilead" are rendered as "Is there no treacle
in Gilead" a perfectly correct rendering, be it said, in those
times. Eventually the word was used to indicate any viscous fluid
until the time came that there was only one such fluid worth
bothering about, namely that obtained from the crystallisation of
sugar.

During the sixteenthand seventeenth centuries antimony cups were
used by the monks, particularly in Germany. Wine kept in these
became slightly impregnated with antimony, and monks who had
partaken too freely of the good things of life were made to drink this
wine which functioned emetically. The cup was known as poculum
emeticum. This practice persisted to the time of Boyle.

Antimony pills were in use about this time, also known as "the
everlasting pills". It is recorded that a lady swallowed one and was
alarmed at its not passing through. The physician comforted her,
however, saying that it had already passed through 100 patients
without difficulty!

The alchemist sign for antimony was an inverted copper
sign and a wolf. Boyle (1627 to 1691) was familiar with the
starred appearance of the cast metal which he termed in 1772 "the
starry regulus of Mars and antimony".

The great majority of liquids contract on solidification and with
some organics this contraction is very considerable, amounting in
the case of acetic acid to 16-7, and of naphthalene to 16-2 per cent.
Ice, on the other hand is exceptional in that it expands on freezing,

86

THE PHOSPHORUS GROUP

namely by 9*06 per cent. The majority of metals also contract
upon solidification, gold by 4-92, silver by 4-76 and copper by
3*89 per cent. Were it otherwise, and our coinage metals expanded
on solidification, our coins could be cast and the expensive procfess
of stamping avoided. Antimony, bismuth and gallium are excep-
tional Like water they expand on solidifying, antimony by about
0-96, bismuth by 3*43, and gallium by 1-84 per cent/

This expansion by molten antimony upon solidification renders
it a valuable constituent of many alloys. A familiar example is type
metal, an alloy of lead, tin and antimony (p. 197). Babbitt's metal
(p. 2 1 2), pewter (p. 211) and Britannia metal (p. 212) also contain
antimony.

Alloys of antimony and aluminium look very much like silver
and have been used in the past in forging our coins. One such
florin analysed by the author in 1911 contained aluminium 53*40,
and antimony 46-38 per cent with traces of lead, arsenic and iron.
With copper a violet alloy, probably a compound SbCu 2 , is formed
known as regulus of Venus. Small amounts of antimony are used in
stiffening lead. Antimony oxide is used, associated with titanium
oxide, as a white pigment, as for example in titanox.

Bismuth

Apparently the earliest reference to metallic bismuth is that of
Agricola in "De re Metallica" in 1556. In recognising bismuth as a
separate metal he was in advance of his time, for even as late as the
eighteenth century the miners regarded it as a variety of lead, well
on the way to being transmuted to silver. If they happened to
strike the ore they would say "Alas, we have come too soon."

No doubt bismuth was known at a much earlier date, but its
history is confused because it was called marcasite^ a name that has
been used for many other substances also and is now mainly used
to denote a rhombic variety of iron pyrites FeS 2 . Most of the later
writers regarded it as a semi-metal. Barba, a South American priest,
wrote in 1640 that bismuth had been discovered in Bohemia and
that it was "a metal somewhat like a cross between tin and lead,
without being either of the two". It was apparently used in the
manufacture of pewter rendering it harder and more sonorous.
Hellot, the French chemist noticed that Cornish smelters added it
to their metal, and in 1737 he succeeded in preparing a button of
bismuth from a cobalt ore. Geoffroy in 1753 showed conclusively
that bismuth was not a variety of lead, but a distinct metallic species.

87

THE CHEMICAL ELEMENTS

For a long time it was confused with antimony (p. 83). It is one of
the few solids that contracts on fusion (p. 87).

The origin of the name is uncertain, but a possible derivation is
from the miners' term wis mat (German Weisse Masse) white mass*.

The main industrial use of bismuth is in alloys, notably those of
low melting t point, called fusible metals. These are useful as fuses in
electrical work and for a variety of automatic contrivances where
undue rises in temperature will cause them to melt and function in
one way or another. Wood's metal contains bismuth 50, lead 24, tin
14 and cadmium 12 or thereabouts, and melts at about 70 C. In
bending thin-walled tubes of other metals this alloy can be used
as a filling to prevent kinking and is readily removed after bending
by steaming. An amalgam of bismuth and mercury has been used
in dentistry. As alloys of bismuth with other metals expand on
solidification they yield sharp castings.

*Smythe Palmer connects bismuth with the ancient Egyptian Mesdemet, eye-
paint. "Some Curios from a Word Collector's Cabinet'* (Routledge, p. 150).

88

CHAPTER 9

THE COINAGE METALS

THE coinage metals are copper, silver and gold.

Occurrence of native copper

Although not generally plentiful in Europe, native copper occurs
in Cornwall in many of the mines near Redruth; one huge mass
from Mullion weighed about three tons. The native metal occurs
more plentifully in Australia and in various parts of the New
World. The most famous locality is the Lake Superior copper
region near Keweenaw Point in Northern Michigan. Here the
copper is practically all in the native state and is found in an area
over 200 miles in length. Dana* states that the yield of native
copper from this region in 1887 was about 37,000 tons. In 1857
a huge mass of copper was found in the Minnesota mine weighing
some 420 tons; it was 45 feet long, 22 feet at its greatest width
and 8 feet at its thickest part. Silver was present in the copper,
sometimes in visible grains or lumps; occasionally, when polished,
the metal appeared sprinkled with large silver spots resembling a
porphyry with felspar crystals.

Copper, like silver, sometimes occurs as fine threads. These,
when intertwined or matted together, are known as copper moss.

Native copper was known to stone age man many thousands of
years ago. He no doubt regarded it as a particularly useful kind
of stone that could be hammered or cold-worked into various
shapes for personal use or adornment. Within the environs of
Lake Superior, where native copper is relatively abundant,
numerous axe and lance heads and other primitive implements of
native copper have been unearthed at various times, all shaped by
hammering.

Primitive metallurgy of copper

When man first observed that copper or its alloys could be obtained
by heating certain kinds of "stone" in an ordinary fire he made a

*DANA, "A System of Mineralogy" (Chapman and Hall, 1914) 6th Edition,
p. 22.

89

THE CHEMICAL ELEMENTS

real epoch-making discovery. He passed from the age of stone to
that of metals and thus opened up vast new realms to exploit and to
conquer. It has been suggested that the discovery of copper
originated in the ordinary domestic fire of neolithic man, the metal
being reduced from its ore which by chance formed part of the
ring of stones of his primitive hearth. "The camp fire" wrote
Gowland* "was in fact the first metallurgical furnace, and from it,
by successive modifications, the huge furnaces of the present day
have been evolved."

This sounds reasonable enough and its probability is supported
by the fact that the presence of metal has sometimes been made
evident within historic times in a similarly accidental manner.

The presence of silver at Pasco in Peruf was discovered in this
way three centuries ago by an Indian shepherd. Whilst watching
his flock he lit a fire on the side of a hill, for the weather was cold,
and lay down to rest for the night. Next morning he awoke to find
that the stone beneath the ashes of his now dead fire was overlaid
with silver. He told his master and a rich vein of silver ore was laid
bare; works were erected for the extraction of the precious
metal and the "Discovery Mine" as it was called, soon became
locally famous.

Beads of copper have been found on the sites of native camp
fires in the Belgian Congo. These resulted from reduction of
surface ores on which the fires had been laid. History repeats itself.

Gradually the camp fire of the primitive metallurgist was mod-
ified to increase the yield of metal. Furnaces came to be constructed
with shallow circular cavities in the ground, about 12 inches in
diameter, into which the molten metal trickled. Fortuitous wind
supplied the blast. When sufficient metal had collected, the fire
was raked away; as soon as it had solidified, the metal was dragged
out and broken to pieces for subsequent re-melting and casting.
At the copper mine of Kapsan in Korea this primitive procedure
was still being practised in 1884, when Gowland visited it.

As time progressed the cavity in the ground was made bigger
and its capacity increased also by surrounding with a wall of stones.
As obtained in this way the metal was dirty, soil and ashes
being included in its bulk. To obtain a cleaner product the hearth
cavity was subsequently lined with clay. Finally this clay lining was
made detachable; in other words it became a crucible which could

*GOWLAND, J. Inst. Metals, 1912, 7, 24. The Engineer, 1912, p. 65
fW. JONES, "The Treasures of the Earth" (Warne) p. 40.

90

THE COINAGE METALS

be lifted out of the furnace so that the metal could be teemed direct
into moulds, thus obviating a second melting. The blast, too, was
improved by building furnaces on the windward side of hills or
a forced draught was initiated by the use of bellows, as depicted r m
Egyptian mural paintings dating back some 1500 B.C.

The composition of the crude metal thus produced^would vary
according to circumstances. In Hungary, where copper ores are
associated with those of antimony, the early implements consisted
of copper containing up to 4-5 per cent of antimony. Implements
from Germany have been found with 2 to 4 per cent of nickel,
those from Egypt with a like amount of arsenic all for the same
reason. In Cornwall, copper and tin ores are found together and
the earliest metal implements are in consequence "natural" bronzes.

The intentional addition of tin to copper to increase its hardness
was a later procedure and represented a more advanced knowledge
of metallurgical technique. In Ireland the first metal implements
were essentially copper as neither ores of tin nor those of copper
containing tin were known there in early times. The Irish copper
age lasted for about 700 years before the introduction of bronze,
the knowledge of which probably spread from Britain.

Stone age man might thus pass direct into the bronze age, or
stepwise through the copper or chalcolithic age to the bronze age,
according to local circumstances. A curious reversal of this
procedure appears to have taken place with the Sumerians who,
after using bronze, reverted to copper. Possibly this was due to
shortage of tin*.

In early Sumerian dynastic days copper was already being used
extensively for religious purposes. Thus, at Al'Ubaid a flight of
stone steps led up to a shrine built in the first dynasty, circa 3100
to 3000 B.C. At the stair head was a porch with wooden columns
overlaid with copper or with a mosaic in mother of pearl, etc. The
entrance to the shrine was flanked by life-size heads of lions
worked in copper, with inlaid eyes and teeth. Above the door was
the Imgig Relieff or Copper Imgig (Plate i) which represents the
lion-headed eagle of the Lagashite god Ningirsu grasping two
stags by their tails; it measures 3 J feet in height and 7 feet 9^ inches

* "Copper through the Ages" (Copper Development Association, 1934) P- I2 *
^British Museum Quarterly, 1927, 1, (4), 85. FRIEND and THORNEYCROFT,
/. Inst. Metals, 1929, 41, 105. Plate i is reproduced through the kind permission
of the late Dr H. R. Hall, when Keeper of the Department of Egyptian and
Syrian Antiquities.

91

THE CHEMICAL ELEMENTS

across and is one of the most important existing relics of the
nascent art of Mesopotamia of the period. Even the nails fastening
the relief to the wood back are of copper. The antlers were made of
hkmmered copper bar and had been fixed into the heads of the
stags with lead poured into the root-holes (p. 1 90). The walls of the
shrine, made or mud-brick, were adorned externally with copper
statues of bulls modelled in the round with a copper frieze in
relief*. The relief may be seen at the British Museum.

Copper and the Egyptians

The Egyptians were highly skilled in the art of working metals
at a very early date (p. 10); it is possible that copper was the first
metal known to them as it occurs in early predynastic graves,
whereas gold, silver and lead do not appear until middle pre-
dynastic times. Both casting and hammering or forging of the
metal were practised.

In the First Dynasty, circa 3500 B.C. copper wire was in use; it
was not made by drawing through dies, however, but by the
laborious process of cutting thin strips from sheets and hammering
them into round shape.

The waste wax or cire perdue method of making hollow castings
is believed to have originated in Egypt about this timef. A nucleus
of suitable material such as sand or clay was prepared and coated
with wax. The wax envelope was suitably shaped and the whole
covered with a layer of fine clay and then with loam. The wax was
now melted and allowed to flow away whilst molten metal was
poured into the hollow mould thus produced.

Who has not heard the legend of Daedalus who, with his son (or
nephew) Icarus, was gaoled by King Minos of Crete? Daedalus
fixed wings with wax to their shoulders and they escaped, flying
across the sea. Unfortunately Icarus flew too near to the sun, the
wax melted and his wings became detached; he fell into the sea
and was drowned; whence the name of the Icarian Sea. Daedalus,
however, reached Greece in safety. This is now regarded as the
legendary way of stating that Daedalus was the inventor of the
sails or wings of ships, and that, moreover, he introduced the
cire perdue or waste wax method of casting.

*WOOLLEY, "The Sumerians" (Oxford, 1928), pp. 41, 42.
fCooK, The Metal Industry, 1937, 50, 534. Also "Copper through the Ages"
(Copper Development Association, 1934) p. 16.

PLATE 1

[Facing p. 92

The Imgig Relief

The Imdugud or Imgig Relief ( early

Sumerian dynastic days (circa 3100 to 3000 B.C.) and
comes from above the door of a shrine at Al'Ubaid.
It is a representation in copper of the lion-headed
eagle of the Lagashitc god Ningirsu grasping two
stags by their tails. One oft lie most important existing
relics of the nascent art of Mesopotamia of the period,
it measures 3| feet in height and 7 feet 91 inches across.
The Relief is in the possession, and the illustration is
reproduced by permission, of the British Museum
Authorities. (See page 91.)

THE COINAGE METALS

Icarus has been chosen by Dr Baade, of the Mt. Palomar
observatory, as the appropriate name for a new minor planet he
discovered in June 1949*. It is a tiny body, probably less than a
mile across, with an eccentric orbit which takes it from beyoad
the orbit of Mars to within the orbit of Mercury nearer to the
sun than any other known asteroid. It can approach to well within
four million miles of the Earth. It is quite possible that Icarus will
eventually enable the first really reliable estimate of the mass of
the planet Mercury to be made; the present figure of 0-04 times
the mass of the Earth is admittedly an uncertain one.

The Sinaitic Peninsular was one of the earliest and most
important sources of Egypt's copper. As the ore is free from tin,
the true bronze age in Egypt was late in development, reaching its
zenith during the Sai'te Period, which included the 25th to 2yth
Dynasties, 712 to 332 B.C. All the same, bronze was probably
known in the First Dynasty. The existence of ancient mines, ruins
of settlements, remains of furnaces, slags, crucibles, moulds and
weapons all confirm the early working of copper ores in the Sinai
area. Inscriptions tell the same tale. From the amount of slag left
it has been estimated that some 10,000 tons of copper may have
been obtained, enough to keep ancient Egypt going for a long time.

During the pyramid age copper water or drain pipes were made
from hammered sheet; copper swords were in use and soldiers'
helmets were constructed with copper and leather. A painting on
the tomb of Rekh-my-Re, dating back to the middle of the 1 5th
century B.C., depicts the casting of two copper doors for the temple at
Karnak. Old cast bronzes are frequently found to contain from 6 to 1 2
per cent of lead, added presumably to increase the fusibility; later
hammered bronzes sometimes contain I to 2 per cent of iron,
which renders them hard. The iron probably came from the copper
pyrites used. No tinned copper vessels have been found as yet in
Egypt, but a copper basin and ewer belonging to the 5th or 6th
dynasties, circa 2750 to 2475 B.C. were found coated with a hard
adherent film of antimony. This may have been effected by boiling
the metal in a bath of stibnite and sodium carbonate solutionf, but

*J.B.A.A., 1950, 60, 96. B.A.A. Circular, 1950, No. 316. Icarus is one of a
number of small bodies, moving in similar eccentric orbits, which have been
discovered since 1932. In 1937 one f them, Hermes, came within one million
kilometres of the Earth (less than three times the distance of the moon). Apart
from size, there is probably no distinction between these objects, meteorites, and
certain meteors (cf. HOFFMEISTER, Observatory, 1950, 70, 70).

fFiNK, Industrial and Engineering Chemistry, 1934, 26, 236.

93

THE CHEMICAL ELEMENTS

other methods are possible. Both vessels showed wear and were
evidently not new when put into the grave; nevertheless the
antimony bottoms had not been worn off during their life before
bing put into the tomb. This indicates how hard and closely
adherent the film had been.

Copper in Holy Writ

Copper and "brass" are mentioned by name in Holy Writ; the
"brass", mentioned 84 times, was usually our bronze. The "tin"
of the Old Testament was not the metal we know by that name but
an alloy of copper and tin, richer in the latter than bronze.

"Brass" is mentioned before the Deluge (Gen. iv. 22), Tubal
Cain being named as the first worker in that metal as also in iron.
Copper itself is named only once (Ezra viii. 27) when reference is
made to "two vessels of fine copper, precious as gold". The book
of Ezra was probably written about 300 B.C. The coppersmith is
likewise referred to but once in the Bible, this time by St. Paul in
his letter to Timothy (2 Tim. iv. 14) wherein he says "Alexander
the coppersmith did me much evil ; the Lord reward him according
to his works" a pious wish, very human, but not altogether
consonant with his Master's injunction to offer the other cheek
(Matt. v. 39) when smitten.

Palestine is described as "a land whose stones are iron, and out
of whose hills thou mayest dig brass" (Deuf. viii. 9). David
prepared "brass in abundance" to be employed in building
Solomon's Temple (i Chron. xxiii. 3). Upon request, Huram,
King of Tyre, sent to Solomon the son of a man "skilful to work
in gold, and in silver, in brass, in iron, etc" (2 Chron. ii. 14).
Job (xxviii. 2) says that "brass is molten (i.e. melted) out of the
stone", which presumably means that it was obtained by the usual
primitive method of setting fire to a mixture of fuel (wood) and ore.
This would appear to the lay observer like melting the stone. No
doubt the Hebrews acquired their BfrSwledge from the Egyptians,
but such large castings as were required for the temple pillars, etc,
required more skill than the Hebrew workers possessed; hence the
need of assistance from Tyre.

Copper and the Romans

The Romans had vast supplies of copper at their disposal for they
were able to work the mines with slave labour in various parts of
their far-flung empire. Pliny specially mentions Cyprus where, he

94

THE COINAGE METALS

says, copper was first discovered, Corduba in Spain, and other
localities which are less easy to identify. The Romans mined copper
extensively in our Islands, notably in Cumberland and North
Wales, including Anglesey. Roman cakes of copper have btfen
found in North Wales; one found near an old mine at Llandudno
was stamped with the words Socio Roma that is, "to my partner at
Rome", indicating that the metal was intended for export*.

Copper and itsalloys were used extensively by the Romans for
statues, temple ornaments and later for domestic furniture such
as banqueting-couches, and the like. Plinyf states that the first
bronze image cast in Rome was that of Ceres, the goddess of corn,
after whom our element cerium was named many centuries later
(p. 182). In later years statues were erected in honour of prominent
citizens, and were sometimes gilded. An amusing story is told by
Pliny of the sale of a bronze lamp-stand, the condition of sale being
that the purchaser must also take, as part of the lot, a hunch-backed
slave of hideous aspect. The purchase was made by a member of an
ancient noble family at Rome, a lady named Gegania. At an
entertainment to her friends she exhibited her purchases and, for
the further amusement of her guests, made the deformed slave
attend the assembly entirely unclothed. Gradually, however, she
became infatuated with the hunch-back, recalling to our minds
Shakespeare's Titania who fell in love with the clown with the
ass's head, and eventually left him all her estate.

The earliest Roman bronzes that have come down to us date
from the fifth century B.C. and contain tin about 7 per cent, and
lead from 19 to 25 per cent. This was the alloy used for casting
the large coin (8 to 1 1 oz) of the Republic, known as the "As' .
These ternary alloys were continued in use as coinage until 20
B.C. but from that date until two centuries later lead is seldom
found in Roman coins except as an accidental impurity. The lead
was no doubt added partly to increase the fusibility of the alloy
and also because of its cheapness as compared with copper and tin.
Roman bronze statues often contain 6 to 12 per cent of lead.
Gowland states that the Japanese were accustomed to add lead to
bronze, not merely for cheapness and increased fluidity but also to
enable the development, under suitable treatment, of a rich brown
patina^ . Pliny gives a tip to the house- wife. When bronzes are cleaned,

*GOWLAND, /. Inst. Metals, 1912, 7, 40.

tPLiNY, Opus, cit., Book 34, Chaps. 6, 9, 21 and 22.

{GowLAND, /. Inst. Metals, 1912, 7, 41.

ft*

THE CHEMICAL ELEMENTS

he says, they oxidise more quickly than when left alone unless
rubbed over with oil.

The Romans knew how to use copper for joining pieces of iron
together a process that may be regarded as the fore-runner of
modern brazing (p. 273).

Copper in Bi itain

Although the conquest of Britain by the Romans undoubtedly led
to a great increase in the mining of copper, the metal and certain
of its alloys were already well known in the British Isles. Prehistoric
relics have been found in Ireland, such as flat celts, made of almost
pure copper, many specimens containing no more than o- 1 per cent
of tin and cannot therefore be classed as bronze. They may date
back as far as 2500 B.C.

In England bronze objects have been found in burial mounds
of the late Neolithic period, some 2000 B.C. As the objects are small
it may well be that they indicate merely the beginning of the bronze
age; as the years rolled on, metal objects increased in range and
dimensions. Riveted bronze cauldrons and buckets have been
found from time to time; a cauldron recovered from the Thames
near Battersea, 16 inches high and 22^ inches in diameter is shown
in the British Museum and possibly dates from about 700 B.C.

In 1914 a hoard of bronze vessels was found at Wotton in Surrey;
it comprised amongst other things several perforated bowls or
water-clocks and a curious vessel very much like a frying-pan. It
appears that the bowls, perforated at the base were placed empty
in larger bowls containing water and as the water slowly entered
the perforation the bowl gradually sank until it reached the bottom
of the larger containing vessel. R. A, Smith* considers that the
vessels of frying-pan shape were gongs which were suspended,
perhaps to a wall, and every time the bowl sank the gong was struck
by an attendant whose duty it was to keep a check on the time.
Similar methods of measuring the time have been used in India.
This type of water clock, however, was not known to the Hindoos
till after A.D. 350; it appears, therefore, to have been a British
invention.

For several centuries after the Romans had left these islands
very little copper was produced, practically all the metals required
were imported from Europe.

*R. A. SMITH, Proc. Soc. Antiquaries, 1907, 21, 319; 1915, 27, 76. FRIEND,
"Iron in Antiquity" (Griffin and Co., 1926) pp. 59 et seq.

96

THE COINAGE METALS

The English are supposed to have used brass or bronze cannon
for the first time during the reign of Edward in (1327 to 1377),
possibly at the siege of Cambrai in 1339 or a few years later at
Crecy in 1346. These were perhaps imported from abroad, but
cannon are believed to have been made in Britain not long after;
the experience that had been gained in the bell foundries (p. 107)
no doubt proved invaluable.

Brass guns are said to have been made for the Sheriff of
Northumberland in 1385; but guns of this alloy soon proved too weak
and were superseded by wrought-iron and cast-iron cannon
(pp. 274, 277)^

It was not wise, however, for Britain to be dependent on the
good-will of her neighbours for her copper. A war might cut off
the supplies and leave her stranded. An effort was therefore made
in the sixteenth century by Henry vm (i 509 to 1 547) to develop the
home-mining of both copper and zinc, and skilled workers were
invited over from the Continent to assist. In 1566 a rich deposit
of copper ore was discovered at Newlands near Keswick in
Cumberland, whilst calamine (zinc carbonate) was found at Worle
near Weston super Mare in Somerset.

At this period the woollen industry was of supreme importance
to Britain; copper and brass wires were required in quantity for
"wool cards* ' used for working short fibres into a fluffy mass prior
to spinning. These were wooden instruments with wire teeth on
one side set in leather.

The wires had been mostly imported, but in 1582, during the
reign of Elizabeth (1558 to 1603), a brass factory was opened at
Isleworth near London to meet the need. Hitherto such wire as
had been made in England had been done by very primitive
processes involving either hammering or drawing. In the latter
case the method was extremely crude. Two men sat facing each
other on swings. Each man had a waist belt to which one end of the
same strip of brass was attached. Moving the swings with their
feet they were able to swing apart thus stretching the brass strip
into a crude form of wire.

By the close of the century, the continental method of drawing
wire through a die had been introduced; it is believed to have first
been used in Nuremberg in the fourteenth century and operated by
hand labour; but machinery driven by water or other power was
subsequently employed.

About this time, also, hammers worked by water-power were

97

THE CHEMICAL ELEMENTS

introduced from Germany for the production of sheet metal,
ingots being beaten into plates by a variety of hammers, some
weighing as much as 500 Ib. The difficulty of course lay in obtaining
a uniform thickness, but this was remedied later by the introduction
of the more efficient rolling-mill late in the seventeenth century,
with the result that battery works gradually faded from the picture.

By the accession of James i (1603 to l ^ 2 S") ^ e manufacture of
brass pins had become an important industry and at the close of the
century about a ton of wire was produced weekly at Esher in
Surrey, alone, most of which was used in making pins. The wire,
after drawing, was pickled in waste acid liquors, rubbed with the
pulp of rotten oranges to give it a clean finish, drawn again and
made into pins. It is said that the best workers could produce some
24,000 pins a day.

At first wood and charcoal were used in smelting copper ores,
but in 1632 Edward Jorden patented the use of coal, peat and turf,
whilst four years later Sir Phillibert Vernatt patented the use of
coal alone as fuel. These inventions stimulated the production of
copper, especially in South Wales where coal was abundant. By
the close of the eighteenth century Britain was the largest producer of
copper in the world. This could not last for long. In 1830 the
enormous Chilean deposits began to be developed; the resources
of Australia and North America rapidly followed suit; the tables
were now turned in earnest, the procedure of Henry viu reversed,
and expert smelters from Britain now travelled to all parts of the
world to show others how best to carry on.

Copper and the alchemists

Copper was regarded by the alchemists as under the patronage of
the planet Venus, and, as we have seen (p. 13), was designated by
the symbol $, known as Venus's looking-glass.

Every schoolboy knows the trick of initialling the blade of his
penknife with copper. The blade is dipped in molten wax; on
cooling, the initials are scratched out with a pin and the blade
dipped into a solution of copper sulphate. Where the naked metal
makes contact with the solution, iron dissolves and an equivalent
amount of copper is deposited. The alchemists used to try the
same experiment in front of a credulous laity, claiming to have
transmuted iron to copper.

Round 1735 a company was floated in Paris for the trans-
mutation of iron into copper. The fraud was exposed by Claude

98

THE COINAGE METALS

Geoffrey, and the manager disappeared with the cash leaving a
quantity of copper sulphate and some old iron.

The copper springs in the County of Wicklow, Ireland, owed
their discovery to a chance experiment of this kind. About thfe
middle of the eighteenth century a workman left an iron shovel in a
part of the Crone-Bawn mines, through which a stream was
passing. Some weeks later on fetching the shovel he found it to
be thickly encrusted with copper, due to copper salts in the stream
reacting with the iron. This suggested the laying of iron bars in
the water; and 500 tons were accordingly spread out in the pits;
the copper was precipitated out as a fine mud, each ton of iron
yielding i\ tons or more of dried mud, each ton of which in turn
produced 1 6 cwt. of commercially pure copper.

In order to ascertain whether or not copper is present in an ore
miners will drop a little nitric acid on the mass and, after a while,
dip a feather into the acid and draw it over the polished blade of
a knife. The presence or absence of copper is immediately indicated.
Many modern "wet processes" for the recovery or extraction of
:opper from waste products or ores are based on this principle.

Brass

Brass was known long before metallic zinc. Although beads of
line blende, ZnS, have been found in Predynastic Egyptian graves
there is no evidence that the early Egyptians were familiar with
brass. The alloy termed brass by early translators of the classics
was usually bronze. Thus, in Holy Writ, Tubal Cain is named as
"he first worker in "brass" as in iron, but true brass was generally
unknown in Old Testament times (p. 94) although it was occasionally
nade by accident by reduction of a copper ore containing zinc, a
'natural" brass resulting. Macalister states that brass containing
&3'4 per cent of zinc has been found in Palestine dating back to
i period between 1400 and 1000 B.C. This alloy was probably used
for cymbals and bells. Zinc is present in some Grecian alloys
jp to 2 per cent, but merely as impurity. It is also found in
;arly Roman coins in like capacity; but in the reign of Augustus,
lo to 14 B.C., zinc ore was added intentionally to that of copper,
:hus producing, on reduction, a true, synthetic brass. An early
:oin dating back to 20 B.C. was found to contain 17* 31 per cent
rf zinc.

The Romans were thus the first intentional makers of brass,
ind coins were made of it even down to the time of Diocletian

99

THE CHEMICAL ELEMENTS

(286 to 305)5 during whose reign 6 parts of brass were equivalent
to 8 of copper. The proportion of zinc was very variable ranging
from about n to 28 per cent. The alloys containing 15 to 20 per
cent of zinc, possessing a maximum ductibility, were used for
scale armour and ornamental purposes. Several rosettes and studs,
which had formed the mounts of a casket, unearthed in 1 900 in
the Roman city of Tilchester, possessed a rich golden colour. 1
These were analysed by Gowland* and found to contain 17 or 1 8
per cent of zinc. This alloy is virtually identical with the imitation
gold known as Tournay's alloy (82-5 copper, 17*5 zinc) which is
used in the manufacture of French jewellery.

The Roman method of making brass consisted in mixing
ground calamine with charcoal granules and small fragments of
copper, and heating in a crucible to a temperature suitable for
reducing the calamine to metal, but not sufficiently high to melt
the copper. The zinc vapour penetrated the copper, converting it
to brass. The temperature was then raised to melt the brass which
was then poured into moulds.

The Indian alchemists were familiar with this method of making
brass at quite an early date. The Tantra Rasaratnakara (p. 114),
written during the seventh or eighth century A. D. purports to give the
wisdom of Nagarjuna, circa A.D. 150, and contains an obvious
reference to brass. Amongst its recipes we read that "calamine . . I
roasted thrice with copper converts the latter into gold."

The Roman method was so efficient and easy to manipulate
that it remained the standard European procedure for many
centuries, the product being known as Roman or Calamine brass.

It appears that by the eleventh century considerable pains were
being taken to purify copper used in making brass for ornamental
purposes. Brass containing lead was difficult to gild, so the removal
of this element was important. Rugerus Theophilus*j", a monk who
lived in the earlier years of the eleventh century, described in detail a
method for doing this. The copper was heated in a clay-lined iron
dish under charcoal until it melted; the liquid was then stirred with
a dry stick to which the lead scum adhered.

In 1781 John Emerson patented the method now universally
used for making brass, namely addition of metallic zinc to copper.
This gradually superseded the Roman method, although this

*GOWLAND, /. Inst. Metals, 1912, 7, 44.

fTHEOPHiLUs, "An Essay upon Various Arts", translated by HBNDRIE,
(Murray, 1847), p. 313.

100

THE COINAGE METALS

latter was still employed at Pemberton's works in Birmingham
until shortly before 1861.

Brasses are easily machined, spun, stamped and polished. They
resist corrosion well and are used in the form of sheet, strip, rod,
wire, tubing and castings. Cartridge brass with copper 70, and
zinc 30, is particularly tough and strong.

Uses of copper

The ease with which copper conducts the electric current has
enabled it to play a vital part in most phases of electrical develop-
ment. It had been noticed as early as 1678 that contraction of the
muscle occurred when a silver wire in contact with the nerve
touched a copper wire on which the muscle rested. It cannot be
said that science moved rapidly in those days, for it was not until
1786 that similar observations were made by Galvani, professor
of anatomy at Bologna. The story goes that Madame Galvani was
ill; some luscious edible frogs, intended to make soup for her,
were lying on a table in a laboratory in which stood a machine for
generating frictional electricity. It was observed that every time a
spark was emitted from the machine, the frogs would twitch,
although they had been dead for hours.

Galvani's attention having been drawn to the matter he decided
to investigate it more fully. During a thunderstorm he connected
the leg of a dead frog with a lightning conductor, and found that
the limb kicked every time the lightning flashed. Next he attached
several dead frogs by means of copper or brass hooks to an iron
trellis in his garden in anticipation of another storm. As it happened
the weather proved fine and sunny, with no suspicion of thunder
in the air, yet each time he pressed a metal hook against the trellis
the leg fixed to it twitched, and the twitching was continued as long
as the contact was maintained.

Galvani concluded that the electric "fluid" was already present
in the frog's legs and that the metals merely served to release it,
just as pipes can draw off water from tanks or reservoirs.

This conclusion, though incorrect, is quite understandable
because at that time the attention of scientists had been directed
to the peculiar electric shocks given by certain eels. In 1793,
however, Volta, professor of natural philosophy at Pavia, dissented
from this view in a paper presented to the Royal Society and
suggested that the observed agitation was caused by an electric
discharge due to contact of the two dissimilar metals, copper and

101

THE CHEMICAL ELEMENTS

iron. In 1799 Volta described his "pile" and "battery", with which
it became possible for the first time to produce at will a continuous
electric current. The pile consisted of discs of zinc resting on silver,
ekch pair being separated from the others by moist pasteboard.
On connecting the uppermost zinc with the lowest disc of silver
an electric current would flow. The voltaic battery was similar,
strips of zinc and silver or copper being dipped into cups
containing dilute acid which took the place of the pasteboard
in the pile.

Before long a large battery was installed for research purposes
in the Royal Institution under the direction of Humphry Davy,
It had 2000 pairs of plates copper and zinc with a total
surface of 890 square feet. With its aid in 1807 Davy was able to
isolate for the first time the alkali metals sodium and potassium
(p. 144). It was soon realised that, of all the base metals, copper was
the finest conductor of electricity. It was rapidly put into use in
the construction of lightning conductors for chimneys, etc, and by
1 8 1 1 it was similarly employed for the protection of ships' masts.
If it was not an unqualified success in this capacity, it was not
altogether the fault of the copper. Examination of one Man-of-War
showed that a conductor had actually been laid through the powder
magazine !*

A few years later it was realised that messages might be sent by
electricity for long distances with extreme rapidity through copper
wires with the aid of a pre-arranged code. The railway authorities
felt that this might be a valuable method of communicating the
movement of trains and in 1837, a month after the first train had
steamed into Euston station a telegraphic system was installed on
a section of the L.M.S. railway between Euston and Chalk Farm.
This was the first to be put into commercial use. It was an enter-
prising innovation, however, for Euston only boasted six trains a
day, three in and three out. But what was lost in magnitude was
gained by drama. The guard wore resplendent scarlet, and gaily
tootled a hunting horn. In 1843 a similar service was installed on
the G.W. line between Paddington and Slough; but these were, in
a sense, specialised applications and did not interest the public in
general. In 1845, however, an event happened that thrilled the
man in the street, and opened his eyes to the enormous possibilities
of the inventionf. A woman was brutally murdered not far from

*" Copper through the Ages" (Copper Development Association, 1934) ? 4 X
fC. A. MITCHELL, "Science and the Criminal" (Pitman, 1911), p. 24.

102

THE COINAGE METALS

Slough. A neighbour, hearing her screams, ran to the spot just in
time to see a man in Quaker garb hurrying away. The man
succeeded in reaching Slough station unchallenged and boarded
a train to London. The police, however, telegraphed through and
the man was met by detectives and later arrested. In due course he
was tried at the Aylesbury Assizes, convicted and executed.

The next important move was to connect England with France
by telegraph. In 1850 a copper wire, insulated with gutta-percha
but otherwise unprotected, was laid across the Channel. It worked
all right until it broke after one day's operation. But the
principle had been established and a year later an armoured copper
cable was laid and this proved successful.

A more ambitious scheme was now embarked upon, namely
the connecting of this country with America by cable. To bridge
the "herring pond" some 2,500 miles of cable were required. The
first attempt in 1857 was unsuccessful; a second attempt with
3000 miles of cable was successful for the moment but failed after
but a few weeks of service. The third attempt was permanently
successful, the cable being put into commercial operation in 1866.
More than 365 tons of copper were used in the construction of
this cable.

These were but small beginnings; to-day tens of thousands of
tons of copper are in use in various ways in electrical plant and in
the distribution of electricity. A single building may have many
miles of copper wire laid on so that its rooms may be illuminated,
warmed, and provided with an adequate telephone service. The
electrical industry absorbs nearly 60 per cent of the world's
production of copper.

Because of its elasticity, copper wire is favoured by rope dancers.

The resistance of copper to corrosion renders copper particularly
valuable for water tanks and pipes, cooking utensils, sheathing of
ships, etc. It possesses many advantages over lead for the covering
of domes and other outdoor structures. It was used in a temple
frieze at Al 'Ubaid (Plate i), near the ancient city of Ur of the
Chaldees, Abraham's reputed city, some 3000 to 4000 B.C.,
worked up from sheet copper, and has been used by numerous
peoples for like purposes ever since. The dome of the Library of
the British Museum, London, dating back to 1857, is the largest
copper-covered dome in the world. St Paul's Cathedral is lead-
covered; Wren would have preferred copper, but his workmen
appear to have been unequal to the task (p. 195). Copper possesses

103

THE CHEMICAL ELEMENTS

four main advantages over lead

(i) It is less dense and can be used in thinner sheets so that its
weight is much less.

\ii) Copper has a higher melting point, 1083 C, than lead,
327 C. In case of fire, therefore, there is much less danger of its
melting and .injuring firemen and others.

(iii) Copper does not "creep" like lead.

(iv) Copper ultimately develops a decorative and protective
green patina that is pleasing to the eye, whilst lead is always dull
and "leaden". It should be mentioned that the green patina is not
verdigris, as is popularly supposed. In the neighbourhood of
cities it is, in the limit, largely basic copper sulphate,
CuSO 4 .3Cu(OH) 2 , of similar composition to the mineral broch-
antite, admixed with more or less basic copper chloride,
CuCl 2 .3Cu(OH) 2 , similar to atacamite, in proximity to the sea*.

All of these compounds are bactericidal and the ancients knew
that they helped to prevent wounds from festering. Accordingly,
Achilles has been represented in ancient pictures as scraping the
"rust" or oxidation products from his bronze sword or spear into
the wound of Telephusf. These oxidation products are frequently
but incorrectly called verdigris, which latter is really a basic acetate
of copper, and is not produced by ordinary atmospheric corrosion
of the metal or its alloys.

In this connection it is interesting to note that Pliny was aware
of the curative properties of copper for he mentions that nowhere do
ulcers heal more rapidly than in the neighbourhood of copper mines.

Annealed copper is soft and easy to work. It admits also of
being easily jointed by soldering, brazing or welding. This is an
important advantage, particularly valuable in connecting electrical
conductors, water pipes, etc, and in the manufacture of many
domestic and other articles now on the market. Copper can be
hardened and its tensile strength more than doubled by what is
known as "cold working", that is by such treatment as hammering,
rolling or drawing the metal at more or less ordinary temperatures.
A still harder and stronger metal is obtained by the addition of
small quantities of other metals. Thus, the addition of even less
than one per cent of cadmium increases the tensile strength with-

*VERNON and WHITBY, /. Institute of Metals, 1929, 42, 181; 1930, 44,389;
1932, 49, 153; 1933. 52, 93-

fPLiNY, "Natural History". Translated by Bostock and Riley (Bohn, 1857).
Book 25. Chap. 19.

104

THE COINAGE METALS

out seriously affecting its electrical conductivity. Addition of some
five per cent of tin will suffice to double the strength of copper
whilst a little beryllium may render it as strong and hard as a mild
steel. As these beryllium alloys are not easily "fatigued" they are
particularly useful for the manufacture of springs.

Bronzes are alloys of copper and tin. The word "brqnze" is not
very ancient. It appears to have been introduced in the fifteenth or
sixteenth centuries. In his Pirotechnia, published in 1 550, Vannuccio
Biringuiccio, an Italian, stated that alloys of copper and tin were
termed bronzo. This is thought to be a contraction of the Latin aes
Brundusinum, the brass of Brindisi. Some ancient bronzes contained
up to 50 per cent of tin as in the case of ancient Chinese mirrors
of the Chou period 1249 to 1122 B.C. But usually in ancient
bronzes the tin content was very much lower. In Mesopotamia, for
example, about 2000 B.C. an alloy containing 10 per cent of tin
was made; it was almost what one might call a standard bronze,
being suitable for most purposes. Bronze was known, however, in
Mesopotamia at a much earlier date, probably before 3000 B.C.
and in Egypt it has been found in a tomb dating back to the First
Dynasty, circa 3300 B.C. The life-size statue of Pepi i of the
vnth Dynasty, now in Cairo Museum, is catalogued as bronze. By
the xvnith Dynasty, circa 1580 B.C. bronze was in considerable
use and reached its highest development under Psammetik i
about the time of the fall of the Assyrian empire, coincident with
the capture of Nineveh in 612 B.C.

Bronzes are to-day used for various architectural and ornamental
purposes. The magnificent bronze gates of Henry vu's Chapel in
Westminster Abbey, built 1503 to 1519, are the pride of that
historic building. They are adorned with heraldic devices referring
to the King's ancestry and his claims to the throne; the crown on
the bush recalls the coronation on Bosworth Field in 1485; the
Roses are those of Lancaster and York united by his marriage;
the Lions are those of England, the Fleurs de Lis of France.
Bronze lends itself admirably to decoration such as this.

Bronzes are used for statues, propellers, fire-boxes, etc.

Bronze coins have been circulated among the nations for several
thousand years. Some unearthed at Snettisham in Norfolk in 1948
are of Celtic origin and date back to 85 to 75 B.C. They are perhaps
the earliest minted in Britain.

Copper is used in all our coins including gold, silver and base
metal. Our "nickel" threepenny bit contains 79 of Cu, 20 of Zn

105

THE CHEMICAL ELEMENTS

and I of Ni. Until 1 942 our pennies contained 3 per cent of tin
together with a little zinc but, in order to conserve our tin supplies,
the tin content was reduced in that year to half a per cent and would
no doubt have been abolished entirely had not the coinage acts
required the presence of some of the metal. A ton of bronze will
make pennies to the value of approximately 448, but farthings or
half-pennies, being relatively heavier, amount to only 373. In
1943 the output of half-pennies, all of the "Ship" variety, reached
the 76,200,000 mark, almost the greatest on record. Since this
design was first struck in 1937, something like 400 million had
been issued by 1944. There are still plenty of "bun" pennies, as
they are called, in circulation estimated at some 90 millions, on
which Queen Victoria is depicted as a young woman with her hair
done neatly in a "bun" at the back. These coins were issued until
1894, by which time the young girl had become an elderly lady;
they were then superseded by a more appropriate figure.

Much modern bronze contains 10 of tin, 2 of zinc, the remainder
being copper. An alloy consisting of Cu:Sn:Zn as 16:2*5:1 was
used in the construction of the Imperial Standard Yard in 1845
(p. 308).

Miscellaneous alloys

Our silver coins since 1928 have contained 40 per cent of copper,
but in 1945 it was decided to replace them by a copper-nickel
alloy, and that is gradually being done (p. 296).

After the invention of gunpowder, supposedly by Roger Bacon
(1214 to 1294), a bronze containing 8 to 1 1 per cent of tin was
found to combine great strength and resistance to shock and was
thus valuable for making guns. It came to be known as gunmetaL
The modern alloy usually contains also a little zinc up to about 3
per cent.

Mention should be made also of phosphor-bronze (p. 80)
containing 5 to 15 per cent of tin and from a trace up to 1-75 per
cent of phosphorus which imparts great hardness, elasticity,
toughness and resistance to corrosion to the alloy. It finds
application in pump plungers, valves and bushes of bearings, etc.
Phosphor-bronze wire is used in stay ropes exposed to corrosive
atmospheres; armature binding wires, overhead transmission cables,
springs in electrical switches, and in wire cloth used in paper-
making machines.

Manganese and silicon bronzes are also in vogue, the term

106

THE COINAGE METALS

bronze being retained though the tin may be entirely absent.
Bronze bearing-metal, employed for the bearings of locomotives,
is an alloy of copper containing tin 8 and lead 1 5 -per cent. The lead
reduces local heating and diminishes loss by wear. The function of
the tin is to facilitate the mixing of the lead and copper. Other
alloys are bell metal (below), white bronze (p. 213), Muntz metal,
brass (p. 99), the nickel silvers (p. 297), silver solders (p. 120)
and duralumin (p. 163).

Small additions of copper to steel render it more resistant to
atmospheric corrosion.

Bell metal

Once bronze came into use for cooking utensils it would soon be
noticed that, upon being struck, the latter emitted a musical sound.
The earliest "bells" would thus be cooking vessels used as gongs
(p. 96). From these were evolved the bells and gongs known to the
ancients. It was ultimately found that the best sounds could be
obtained from alloys containing from 15 to 25 per cent of tin, the
remainder being copper.

Although fairly large bells may have been made in China and'
used in the temples at an early date, church bells are supposed to
have been used in Europe only since about A.D. 400. At first they
were small; by the eleventh century a bell weighing 2600 Ib. was
given to the church at' Orleans, France. In A.D. 1400 a bell weighing
some 1 5,000 Ib. was cast in Paris, and from this time onwards bells
increased very much in size and weight. In 1497 a bell weighing
30,250 Ib. was cast at Erfurt, Germany, the supposed home of
that elusive monk, Basil Valentine (p. 84).

Bronze bells had been cast in England as early as the eleventh
century and by the twelfth century the industry had attained national
importance; in later years numerous bell foundries opened up in
various parts of the country. The bell founder was known as a
"bellyeter", and Billiter Street, off Leadenhall Street, London, E.G.
derives its name from this as it was once a centre of the
industry.

The largest bell in England is Great Paul of St Paul's Cathedral,
London. It was cast at Loughborough in 1882 and weighs 39,200
Ib; it is rung daily for 5 minutes at I p.m. Even bigger is that at
St Peter's in Rome; 42,000 Ib. That at Notre Dame in Paris is
somewhat less, namely 35,600 Ib. But all of these are dwarfed by
the Great Bell or Monarch of Moscow cast in 1735 and weighing

107

THE CHEMICAL ELEMENTS

approximately 200 tons. It is, however, inarticulate. This gigantic
casting, 24 inches thick at its thickest place and 6 inches at its
thinnest, cracked in several places on cooling, one portion weighing
10 tons falling away. The crippled bell lay in its casting pit until
1836 when it was lifted out and placed on a granite foundation for
all to see. Itsjnscribed date is 1732 but this refers not to the date
of casting but to that of making the mould.

The carillon of Bruges Belfry is considered to be the finest in
Europe and dates from 1745 to 1748. There are 48 bells, the
largest weighing 11,589 Ib. and the smallest 12 Ib. The total
weight of all 48 bells is 55,166 Ib. The Bourdon or largest bell in
the clock weighs 19,000 Ib.

Silver

Silver, the "Queen of the Metals" does not often occur free in
Nature and for this reason did not come into such early use as gold.
It did not play an important part in primitive culture.

The earliest sources of the metal for economic use were most
probably argentiferous lead ore or plumbiferous silver ores. In
most cases the ore would belong to the former class and would
usually be galena, that is lead sulphide, PbS, which usually
contains some silver. Thus, for example, British galenas contain
on the average some 4 to 5 oz. of silver per ton whilst some
Devonshire ores contain up to 170 oz. (p. 189).

Galena has a brilliant, silvery lustre which could not fail to
intrigue primitive man; but the brittleness of the ore made it
impossible for him to use it direct to good purpose. But if by
chance or intention a piece of galena were to fall into a blazing
wood fire* it could easily be reduced to metal, that is, to lead with
a certain amount of silver dissolved in it; if this alloy remained in
the fire for some time, the lead would be oxidised leaving a small
lump of silver. Thus would originate the economic discovery of
silver, and the camp fire would thus constitute the first smelting
furnace.

Some famous silver mines

The Gogerddan mines near Aberystwyth two or three centuries
ago were very productive of silver; the ore was galena. It is said
that they yielded to Sir Hugh Myddleton a profit of some ^25,000
a year which enabled him to pursue and complete in 1613, with

*PERCY, "The Metallurgy of Lead" (Murray, 1870) p. 213.
108

THE COINAGE METALS

the help of James i, his great scheme of bringing water to London
from near Ware in Hertfordshire by the "New River" a
distance of some 40 miles.

The expense was so great that, although an act had been passed
in 1607 empowering the City Corporation to construct the river,
no attempt was made by the Corporation to implement it. The
story goes that, after completion of the scheme, the'King himself
once fell into the river when riding an unfortunate reward for
his efforts but no doubt a joy to those who had opposed the scheme
on the ground that the "ditch" would prove dangerous to hunters.

The Salcedo Mine in Peru had an interesting history. It was very
rich in silver and was given as dowry in the middle of the seventeenth
century to Salcedo, a poor Spaniard married to an Indian girl, by
the girl's mother who had herself discovered it. Salcedo worked
the mine most successfully and became sufficiently wealthy to
excite the envy of the Spanish Governor of Peru. This worthy
endeavoured to obtain possession of the mine and suggested to the
Spanish Government that Salcedo was using his wealth in an
endeavour to raise an insurrection amongst the Indians and throw
off the Spanish yoke. Although there was not a vestige of truth in
this, Salcedo was arrested, subjected to a mock trial and sentenced
to death. It was dangerous in those days to be successful and
Salcedo was duly hanged. Whilst in prison he had begged
permission to send to Madrid and appeal to the Crown for mercy;
he had promised to give the Governor a daily bribe of a silver bar
for every day that the vessel took to sail from Callao to Spain and
back again; but in vain. The vessel would take 12 months or more,
and the mine must be marvellously productive, mused the Governor,
if Salcedo can promise that. But the Governor over-reached himself.
As soon as Salcedo was hanged, his mother-in-law caused the mine
to be flooded and the works destroyed; the entrance was closed
and camouflaged so effectively that no one could find it. When,
afterwards, some who had known the mine were caught and
questioned, both promises and torture failed to reveal the position
of the mine, which is unknown even to-day.

The San Jose Mine in Huancavalica, Peru, is another very rich
one. The owner was desirous that the Governor should be god-
father to his first born and this was agreed to; but as important
affairs of state prevented the Governor from attending the
christening he sent his wife instead. To show his appreciation of
the honour done to him and his family, the owner caused a triple

109

THE CHEMICAL ELEMENTS

row of silver bars to be laid the whole distance from his residence
to the church where the ceremony was to be performed. Over this
silver pavement the party passed to and from the christening.
When the Governor's wife departed the owner presented her with
the whole of the silver road.

These anecdotes give some idea of the enormous wealth of Peru.

Silver and the Egyptians

There were no silver mines in Egypt and, even as late as the rule
of the Hyksos or Shepherd Kings circa 1780 to 1580 B.C. silver
was twice the value of gold. But during the i8th Dynasty, which
lasted from 1580 to 1350 B.C. the position was reversed, for silver
became more abundant, 3 parts of gold being worth 5 of silver*.
The reason for the greater abundance of silver was undoubtedly
because of Egyptian marauding expeditions into Palestine and the
North. Thothmes in, the Napoleon of Egypt circa 1500 B.C.
captured huge quantities of silver in Asiatic cities which he
repeatedly visited; he used gold and silver rings for trading
purposes ; some of these rings were very heavy, weighing as much
as 12 Ib. The Egyptian ladies of the period were wont to adorn
themselves with silver chains of varying length up to five feet.

Even in the seventeenth century silver and gold were of equal
value in Japan. To be born "with a silver spoon" in one's mouth is
an old expression based on the once high cost of silver tableware.

Silver, being a soft metal, was sometimes used, like gold and
lead, in the form of plates or tablets for keeping permanent
records of important treaties or documents of state. During the
reign of Rameses n, the King who was once regarded as the
Pharaoh of the Oppression, the Kheta or Hittites were a source of
considerable trouble to the Egyptians. In 1333 B.C. a treaty was
drawn up between Rameses and Kheta-sar, which was inscribed
on a tablet of silver and deposited in the palace fortress in the Nile

Dcltaf.

In later days the Egyptians both knew of and practised the
separation of silver from gold by the chloride method, but we
cannot fix the date of its innovation.

Silver in Holy Writ

There are many references to silver in the Old Testament, but

*PARTINGTON, "Origins and Development of Applied Chemistry" (Longmans,

1935) ? 43-

fBUDGB, "A History of Egypt" (Kegan Paul, 1902), vol. v ( pp. 48 et seq.

110

THE COINAGE METALS

although both iron and "brass" are referred to by name before the
Deluge, some 4000 B.C., there is no mention of silver. By the time
of Abraham, who lived possibly 2160 to 1985 B.C., silver was
common. Abraham is described as rich in both silver and gold ;* it
is recorded that he paid 400 shekels of silver for a burial place for
Sarah, his wife (Gen. xxiii. 15). The site chosen was the cave at
Macpelah. The money was not in the form of coin but Was weighed
out in the presence of witnesses (Gen. xxiii, 15-16), just as it is
weighed out even to-day in China because the silver coins are
frequently cracked or in pieces in consequence of repeated stamping
on changing hands.

The Jewish shekel was a unit of weight, equivalent to some
1 6 grams or slightly more than 0-5 oz. avoir. The word is derived
from the Hebrew Shakal, to weigh: 50 shekels made one mina and
60 minas one talent. A talent was thus equivalent to approximately
106 Ib. avoir., 128 Ib. Troy or nearly I cwt.

It was not until many centuries later that the Jews had silver
coins of their own, the word shekel then referring to a coin of
approximately the same weight as the earlier bars. Two large
hoards of silver coins, one found in Jerusalem and one in Jericho,
are described by Reinach*. Some of the coins, the heavy shekel,
weighed 14 grams, others, the light or half shekel, weighed just
half this amount. They date back to the time of Simon
Maccabseus circa 138 B.C. Judaea was then a free state and had
been authorised to strike silver money of its own; it founded a
mint and issued an entirely new coinage in which it endeavoured
to portray its own peculiar national character. On the obverse was
a chalice; on the reverse a branch of lily with three flowers; these
were described by earlier numismatists as a "pot of manna" and
"Aaron's rod budding".

The Hebrews were expressly forbidden (Exod. xx. 23) to make
gods of silver just as they were censured for making a golden calf;
no doubt they had ample silver to make them with; on leaving the
Nile Delta they "borrowed" jewels of silver from the Egyptians,
presumably on as generous a scale as they borrowed the gold
(p. 127) for we read that "they spoiled the Egyptians" (Exod.
xii. 36).

In Old Testament times silver was used in large quantity in
domestic and ceremonial vessels. It was his own silver cup used

*REINACH. "Jewish Coins 11 , translated by Mary Hill (Lawrence and Bullen,
Ltd. 1903), p. 4.

Ill

THE CHEMICAL ELEMENTS

for divining (Gen. xliv. 15) that Joseph caused to be placed in
Benjamin's sack of corn as the Brethren left Egypt after their
second visit in search of food.

. Silver was used on a lavish scale in constructing the Ark of the
Covenant (Exod. xxvi.) and in Num. vii. we are given a detailed
account of the offerings brought to Moses. These included silver
chargers 01" flat dishes weighing 1 30 shekels (4 Ib.) and silver bowls
weighing 70 shekels massive vessels these. Tarshish, the
modern Andalusia of Spain, is mentioned as the trading centre in
silver as well as the base metals iron, lead and "tin (Ezek. xxvii.
12).

In later years, when the Hebrews had become firmly established
in Palestine, silver became very plentiful. Solomon, some 950 B.C.,
"made silver to be in Jerusalem as stones" (i Kings x. 27).

The later Hebrews are said in Num. xxxi. 23, to have practised
the refining of silver by fire. It is probable that cupellation is
referred to for Ezekiel (xxii. 18) mentions "the dross of silver"
which suggests litharge of cupellation, otherwise it is less easy to
understand the analogy, given in verses 21 and 22, "I will gather
you and blow upon you in the fire of my wrath ... as silver is melted
in the midst of the furnace."

The fining pot for silver is mentioned twice in the Book of
Proverbs (xvii. 3; xxvii. 21) in connection with the furnace for
gold and may be a reference to the chloride process used in
removing silver from gold as practised by the Egyptians (p. 133).
The "silver cord" mentioned in Eccles. xii. 6 is thought to refer
to the spinal cord because of its bright appearance even in a dead
body. Silver is but seldom mentioned in the New Testament. In Acts
xix. 24, we read that Demetrius made silver shrines for Diana. This
was evidently one of the trades in Ephesus.

Silver and the Romans

Pliny, after a lengthy dissertation on gold (p. 120), devotes a chapter
to silver*, "the next folly of mankind", and mentions Spain as the
best source. In the time of Strabo (p. 133) the silver mines were
private property; they did not belong to the state like the gold
mines. Enormous quantities of silver found their way into Rome as
the result of her conquests. Cornelius Lentulus, for example, when
circa 200 B.C. he was proconsul of Spain, brought 43,000 Ib. of

*PLINY, "Natural History", translated by Bostock and Riley (Bonn, 1857),
Book xxxiu, Chapters 31, 50 and 52.

112

THE COINAGE METALS

silver to the city on the occasion of his entry in ovation. The
Romans appear to have been very fond of silver plate and silver
ornaments, many individuals possessing large supplies. One cannot
help smiling at the Carthaginian ambassadors' sarcasm with
reference to the Roman use of silver plate. No people, they
declared, lived on more amicable terms among themselves than
the Romans, for that wherever they had dined they '(the ambas-
sadors) had always met with the same silver plate. This, of course,
was intended to indicate that the silver was lent from house to
house for the occasion and that the Romans were not as wealthy as
they pretended. "And yet, by Hercules!" says Pliny, evidently
annoyed at the sneer, "to my own knowledge, Pompeius Paulinus . .
had ... a service of silver plate that weighed 12,000 Ib." Bravo
Pliny!

Sometimes the dishes were very heavy. Pliny mentions a silver
charger weighing 500 Ib., for the manufacture of which a workshop
had been specially built. This charger was part of a set comprising
eight other dishes, each weighing 250 Ib. Pliny naively asks
Who were to be the guests served therefrom? Dean Swift would no
doubt have supplied them from Brobdingnag.

An analysis of Roman silver objects in the British Museum
showed them to contain from 92-5 to 92-6 per cent of silver.
Couches on which ladies reclined, and banqueting couches were
often covered with silver, as were ladies' baths. Vessels of silver
were used "for the most unseemly purposes" whatever that may
mean.

The ease with which silver tarnishes has always been regarded
as a disadvantage. Pliny knew that silver is readily blackened with
the yolk of an egg and gives a useful tip to the housewife by saying
that the tarnish is removed by rubbing with vinegar and chalk.

Galena invariably contains some silver (p. 189) and the Romans
knew how to extract it by cupellation. The furnace or hearth was
a shallow cavity lined with bone-ash, that is, calcined bones ground
to powder. A charcoal fire was made and the lead placed on it to
melt. When sufficient had collected in the hollow, the fire was raked
to the sides and a blast of air introduced, which oxidised the lead
but not the silver. The scum of lead oxide was absorbed into the
bone-ash leaving a cake of silver, containing, however, any gold
that was originally present.

Incidentally it may be mentioned that at about this time the
Indian alchemists were also familiar with cupellation; an early

113

THE CHEMICAL ELEMENTS

MS. containing the wisdom of Nagarjuna (p. 100) who lived about
the second century A.D. states that "silver alloyed with lead and
fused with ashes becomes purified". A later MS. dating back
prpbably to the eleventh century and known as the Tantra
Rasahridaya of Bhikshu Govinda speaks of a cupel made of ashes
from the bones of a goat.

Silver and the alchemists

Silver has a beautiful appearance unequalled by any other ordinary
white metal. The word silver is Anglo-Saxon; the Latin name
argentum, from which the chemical symbol Ag is taken, is allied
to the Greek arguros, silver, from argos, shining. The Hebrew name
kesseph is derived from a root meaning "to be pale". Owing to its
ready tarnish and solubility in acids, silver was not regarded by
the alchemists as so perfect a metal as gold. They therefore gave
it only half a circle as its symbol, suggesting merely partial
mathematical perfection; at the same time indicating a supposed
connection with the crescent moon (p. 13).

The metal was known to the alchemists as luna, and its salts as
lunar salts. Thus silver nitrate was termed lunar caustic and was
prescribed during the Middle Ages for brain disorders, it being
held that the moon controlled the mental faculties.

The alchemists were fond of producing the "silver tree" or
arbor Dian<* by suspending some suitable metal in a solution of a
soluble silver salt such as lunar caustic (silver nitrate) in much the
same way as the better known "lead tree" is grown (p. 194). It is
very beautiful to watch under the microscope the growth of silver
on a piece of metallic copper*.

Uses of silver

The attractive appearance of silver has caused it to be in great
demand for ornamental purposes. As has been mentioned, its main
disadvantage lies in the ease with which it tarnishes, particularly in
our centres of industry because of the presence of sulphur com-
pounds in the atmosphere which induce the formation of a black,
dull superficial layer of silver sulphide.

To counter this, plating with rhodium has been successfully
applied to jewellery (1936); the process is known as rhodanising,
but the details are kept secret. It may be applied equally well to
old silver as to new (p. 305). Rhodium is a white metal like silver

*J. H. GLADSTONE, Nature, 1872, 6, 66.
114

THE COINAGE METALS

and is exceptionally resistant to tarnish. Unfortunately it is also
extremely expensive; further, any scratching or mechanical
abrasion of the thin rhodium coating cannot easily be repaired
except by stripping and re-plating. *

The most hopeful line of attack in preventing the tarnishing of
silver appears to lie in the addition of some metal or metals which
will form an adherent and protective oxide skin on the surface
which will renew itself if and when damaged. Such skins are termed
"self-healing".

If a really untarnishable silver could be produced it would no
doubt have a ready sale; the chief difficulty lies in the insistence of
the public that the metal shall be hall-marked, that is, it must be
certified as containing at least 92-5 per cent fine silver. This
allows only 7-5 per cent as a maximum for alloying elements, and
hitherto that has proved insufficient. Although several non-
tarnishing alloys have from time to time been placed on the market,
none has so far given satisfaction.

Silver has long been popular for "challenge" cups, shields and
other trophies. Some years ago it was used more frequently than
now for vases and "the table", silver teapots, cream-jugs and the
like being highly esteemed as lending brightness to the meal.

During the early years of the nineteenth century there was an old
tavern in Peck Lane, Birmingham, known as the Minerva and kept
by one Joe Lyndon. At this tavern the "cups" or tankards were of
solid silver and the property of regular patrons. None of inferior
metal was permitted. Uniform in size and shape the name of the
owner was legibly engraved across the bottom of the "cup" in such
a way that when hung in front of a top shelf in the bar it could be
distinctly read.

There were 37 such cups. In addition there was another silver
cup that held three pints; it was known as the "Fine Slapper"
because if anyone committed a breach of good manners he was
liable to a fine of "a slapper of ale" that is, three pints*. He was
thus little likely to attempt to cover up lack of intelligence by
rudeness.

Chance visitors to the tavern, who had no "cups" had to put up
with jugs of the plainest brown earthenware! Unfortunately the
tavern was demolished when the site was required for the New
Street Railway Station, and there are no slappers now for the
modern boor.

*R. K. DENT, "Old and New Birmingham", 1880, p. 316.

115

THE CHEMICAL ELEMENTS

Sheffield plate*

Much silver was at one time consumed in the "Sheffield plate"
industry, the invention of Thomas Bolsover, a cutler of Sheffield
i'n 1742. Whilst making a knife in which both silver and copper
were used, Bolsover noticed that the two metals could be made to
adhere very firmly by merely beating and rolling together. A silver
plating or veneer could thus be worked on to a copper base. It took
a little while for the idea to be adopted, but gradually small articles
came to be made, including snuff boxes, buttons and the like. The
plating proved so excellent, however, that gradually a big demand
arose and increasingly larger articles were produced. The industry
flourished for about a century but production declined when the
commercial electrodeposition of silver was invented in 1840. The
plating was applied not merely to copper, but to brass and other
base metals.

When fully established the Sheffield plate industry was concerned
mainly with the production of fairly large articles; these were
frequently copies of genuine silver wares under the name of
"holloware".

About 1750 John Taylor introduced the process into Birming-
ham where the material was used for making small articles, such
as buttons, buckles and trinkets of all kinds that comprised the
toy trade of the city, the latter being described by Edmund Burke
(i 730 to 1 797) as "the toy-shop of Europe".

Electrodeposition of silver is widely adopted both for purely
ornamental purposes and also for table ware. In 1825 Justus von
Liebig, professor of chemistry at Giessen, observed that when
acetaldehyde is warmed with a slightly ammoniacal solution of
silver nitrate in a glass vessel, metallic silver is deposited on the
walls of the vessel appearing as a brilliant mirror when viewed from
outside. The process is most widely used in making household and
other types of mirrors; it also finds application in the manufacture
of Dewar and Thermos flasks, silvered electric light bulbs and small
glittering objects such as adorn the Christmas tree at the festive
season. The thickness of a film may vary from 1-2 X io~ 6 inch
(30 X icr 6 mm.) to six times that amount. The process has been
extended to include deposits on plastic materials, cast phenolics
and vinyl resin giving good results.

The method widely used for silvering the mirrors of astro-
nomical reflecting telescopes and other optical parts is a modification

*See E. A. SMITH, /. Inst. Metals. 1930, 44, 175.

116

THE COINAGE METALS

of Liebig's process due to John Brashear* of Philadelphia. Its great
advantage lies in the fact that it can be effected at temperatures
little removed from atmospheric. In 1877 Brashear, wishing to
observe the favourable opposition of Mars in that year, set himself
to grind and polish the mirror for a 1 2-inch telescope. Being then
a rolling-mill foreman, with little time to himself, it was several
months before the delicate task was completed and the mirror had
the desired excellence of figure. Then tragedy ensued. During the
silvering process a current of cold air struck the mirror as it was
lifted from the hot solution and the brittle glass snapped in two.
Not to be daunted, Brashear, within two months, had ground and
polished a 1 2-inch disc superior even to the first. Meanwhile he
had experimented with silvering odd pieces of glass and had found
the method now known by his name. Forty years later, we are
told

Brashear stood beside the icoinch mirror at Mt. Wilson,

with Professor George W. Ritchey, the man who had ground and

figured it, and remarked at the brilliance of the silver coating on

that magnificent glass.

Said Ritchey "It ought to be a good coat it's silvered

by Brashear's process"j\

Considerable attention is now being given to vaporisation
> methods of producing silver films, the advantage being that a more
rigid control is possible. One method consists in placing small
pieces of silver on the loops of a tungsten or molybdenum coil
filament suspended in a chamber containing the articles to be
silvered. The whole is evacuated; on passing the electric current
the temperature of the filament rapidly rises, the silver melts, but
does not fall away because it "wets" the filament. The molten
silver evaporates and the vapour condenses on the cooler objects
round it. In this way beautiful deposits may be obtained not merely
on glass but on certain plastic materials, metals and enamels.
Cellophane and paper have also been silvered in this way.

Silver coins

One of the most important uses of silver has hitherto been for
coins. Silver pennies were used by our Saxon ancestors. "Standard

* BRASHEAR, J., English Mechanic, 1893. Accounts of the process will also be
found in most books on telescope making or optical workshop practice; e.g.
TWYMAN, F., "Prism and Lens Making" (and edition, in the press, Hilger & Watts
Ltd, London).

fPENDRAV, G. E., "Men, Mirrors and Stars" (1935, New York).

117

THE CHEMICAL ELEMENTS

silver " was established for British currency during the reign of
Henry n (1154 to 1189) who brought coiners from Eastern
Germany, where the coinage was famous for its purity, to improve
ttte quality of British currency which at that time was debased. It
was ordained that standard silver should contain 92-5 of pure or
"fine" silver with 7-5 of base metal, usually copper. It remained
at this figure until 1920 except for a brief lapse of some 20 years
during the sixteenth century, when debasement was permitted. The
inhabitants of Eastern Germany were known as Easterlings and
our word sterling as applied to currency appears to be derived from
this. John Stow* writing in 1603 says "the Easterling pence took
their name of the Easterlings, which did first make this money in
England in the reign of Henry n."

It is customary to express the silver content of coins in parts
per 1000. Thus, sterling silver was described as "925 fine"
meaning that it contained 92-5 per cent of silver. Very similar
alloys were in use in Saxon and Norman times; a coin of William
the Conqueror (1066 to 1087) was found to assay 922*8 of silver
not very different from the alloy used by the Romans (p. 1 1 3). This
standard silver has been and still is largely used for "silver plate",
but another legal standard for silver wares was introduced in 1696
containing 958-3 per thousand; this is softer and less resistant to
wear and tear; it is known as "Britannia silver" because it is stamped
with the figure of a woman commonly called Britannia instead of
the lion passant, used by Government offices in hall-marking silver.

In 1920 the market price of silver had risen to 8s. per oz. so
that illegally melting it down offered considerable profit. The
government therefore reduced the silver content to 50 but did
not state what the other constituent(s) should be. At first an alloy
of equal amounts of silver and copper was tried. It had been used
in England before in 1544 but discarded as unsatisfactory. An
analogous alloy had also been tried in Russia, but it discoloured on
circulation. Our coins soon resembled gorgonzola cheese, so a new
alloy was tried containing silver, 50; copper, 40; and nickel, 10.
For this, cupro-nickel coverings of bullets were used, relieving
the Disposals Board of much lumber. The new coins were bright
but too hard to work; they damaged the dies and many were
imperfectly struck. In 1927 an alloy containing silver, 50; copper,
40; nickel, 5; and zinc, 5 was decided upon. It proved very

*JOHN STOW, "A Survey of London", 1603, p. 52.
118

THE COINAGE METALS

satisfactory; it was pickled prior to issue to give it a good appearance.
The richer silver coins were gradually withdrawn from circulation.
It took the banks some 1 8 years to collect the pre-war coins.

Wars have curious effects on the circulation of coins,. Simple

Ssople often bury their money hoping to return and dig it up.
uring World War II the florin enjoyed unusual popularity, next to
the cupro-nickel threepenny bit it was the baby of our monetary family.

When the first silver florin was issued in 1849, the familiar
letters DG, standing for Dei Gratia, by the will of God, were
omitted from Queen Victoria's titles. This caused an outcry and
the issue, which became known as the Godless florin, was stopped.
Since 1937 no five shilling pieces have been struck. Two distinct
patterns of our English shilling have been struck since 1937; one
bears the King's English crest on the "tail", the other his Scottish
crest a graceful tribute to his Scottish Queen.

In 1945 it was estimated that 2000 million silver coins were in
circulation corresponding to some 1400 tons of silver; it was
decided to replace them gradually by an alloy of nickel and copper.
All silver coins struck before 1947 are being withdrawn, and
the reclaimed silver is to be sent to the U.S.A. in part payment of
silver sent to this country under Lend-Lease. The recoinage will
take at least 20 years.

It has been suggested that in time of war we could save metal
by calling in our pennies and replacing them by a smaller coin of
the same or some other metal. But even if the Mint dropped all
other duties it would take some 10 years full-time work to replace
the pence, so that the proposed saving in metal would take a long
time to mature, and would have little effect on the general position
during a merely temporary shortage.

Silver is resistant towards organic acids, and large silver
components, sometimes weighing 3 or 4 cwt, are used in acetic
acid manufacturing plants. Silver vats are employed in the vinegar,
brewing, cider and milk industries because of their resistance to
attack. Chemical plant need not, however, be composed solely of
silver. A plant of copper is frequently rendered resistant to corrosion
by coating with silver either by electrodeposition or by lining after the
fashion of Sheffield plate. Thin coatings obtained by the former
process are liable to be porous, whilst thick ones may peel on service,
leading to expensive repair. The lining process is therefore favoured,
a thin silver sheet, some 0-03 inch in thickness, is sweated or
hammered on to the copper thus yielding a non-porous coat.

119

THE CHEMICAL ELEMENTS

Modern silver solders are copper-silver alloys to which small
additions of phosphorus or zinc have been made. They function
as de-oxidants. The melting points of these alloys are much below
tht of copper; the joint is strong and resistant to corrosion; so
silver soldering is useful where welding would be difficult or
inadvisable. f Until recently the main use of silver solders was for
jewellery and other fine work. Now, however, they are being used
in engineering, partly because of the strength and neatness of the
joint, as in refrigerators and aircraft.

Silver is so ductile that I gram of the pure metal can be drawn
out into a wire more than a mile in length; its malleability enables
it to be beaten into leaf 0-00025 inch in thickness. Both wire and
foil are used for ornamental purposes.

Silver is used in the "quartation" of gold. Pharmacists coat
pills with silver not merely to enhance their appearance but also
to act as preservative, largely against moisture.

Owing to its excellent electric conductivity properties - it is
the best known metallic conductor silver is employed in many
electrical instruments.

Silver conducts heat more readily than any other metal. It is
often convenient to take its thermal conductivity as a standard,
namely 100, and express all others relatively thereto. On this basis
the conductivity of copper is 92, gold 70 whilst that of nickel silver
is only about 8. It is thus easy to understand why silver teaspoons
rapidly become hot when dipped into a cup of tea whereas the
common or garden variety of spoon does not.

Gold

Gold has been prized from the earliest times partly because of its
colour and lustre, but also because of its resistance to tarnish and
general incorrodibility. Pliny* lays particular stress on this
latter feature. "Those persons" he writes "are manifestly in error
who think that it is the resemblance of its colour to the stars that
is so prized in gold." He then proceeds to eulogise the resistance of
gold towards fire and other disintegrating forces. "Gold is subject
to no rust, no verdigris, no emanation whatever from it, either to
alter its quality or to lessen its weight. In addition to this, gold
steadily resists the corrosive action of salt and vinegar, things
which obtain the mastery over all other substances." To this

*PLINY, "Natural History' 1 , translated by Bostock and Riley (Bonn, 1857)
Book 33, chap. 19.

120

THE COINAGE METALS

catalogue of virtues the modern chemist would add one more,
namely that there is only one single acid that by itself can dissolve
gold, namely selenic acid.

The element is believed to owe its name to its brilliant appear-
ance, the word "gold" being derived from the Sanskrit Jva/, to
shine, a word cognate with "yellow". The Hebrew word for gold
is ZaAdv also meaning to shine. The modern slang term for a
golden sovereign, namely shiner, would appear to be quite
appropriate.

Some gold mines of interest

The Clogan mine has a romantic history. It stands above the .great
expanse of Barmouth estuary, fronting the lonely precipices of
Cader Idris, which rise some miles away across the estuary. It has
been worked at intervals from very early times, possibly by the
Romans, who had a camp and a settlement near.

Early last century copper was mined there on a considerable
scale, and about 1845 t " ie miners found a lode in which small lumps
of peculiar yellow metal were imbedded. When it was tested this
proved to be gold, but attempts to work the mine further for gold
failed owing to the very patchy character of the deposits.

The old refuse of the copper mine, however, yielded rich
treasure. Gold was recovered from it in considerable quantities,
one ton of refuse alone yielding gold valued at 6000.

In 1919 another vein of gold was struck in this mine, but was
soon exhausted. In 1930 the Secretary of Mines instituted an
inquiry into the gold position in Wales generally with a view to
possible development of gold production. But the results were not
encouraging; experts held out no hope of anything more than
mere sporadic finds. The wedding rings of several members of the
Royal Family, including the Queen Mother and Princess Mary,
have been made of Welsh gold. In October 1934 it was announced
that the wedding ring of Princess Marina was to be made of gold
from North Wales mines and from the Pumpsaint mine in
Carmarthenshire; so presumably this was done.

Gold has been found also in Ireland; tradition ascribes its
discovery in County Wicklow to a poor schoolmaster who found a
small nugget whilst fishing in one of the streams descending from
the Croghan Mts*. Further search revealed more and the cautious

*W. JONES, "The Treasures of the Earth" (Warae), p. 25.

121

THE CHEMICAL ELEMENTS

pedagogue enriched himself gradually by disposing of the spoil to
4 goldsmith in Dublin. He preserved the secret for many years but
Inarrying a young wife he imprudently made her his Delilah "and
told her all his heart" (Judg* xvi. 17). She, of course, couldn't keep
the secret, she must perforce tell her people, with the result that in
1795 th e existence of gold became popular knowledge and
thousands oY adventurers of every age hurried to the spot in one
mad search for the precious metal.

The gold was so pure that the Dublin goldsmiths were wont to
put gold coin in the opposite scale to it when purchasing and thus
give weight for weight. In a couple of months the Government
stepped in and took control until 1798 when all the machinery was
destroyed in an insurrection. The gold was found in nuggets of all
sizes up to one extraordinary mass weighing 2 2 oz. irregular in shape,
measuring 4 inches long, 3 inches in greatest width and nearly
one inch in thickness. A gilt cast of it could, and probably can still,
be seen in Trinity College, Dublin.

The first discovery of gold in California was the result of accident.
In 1847 Captain Suter erected a saw-mill in a pine forest; the water
to work it washed down mud and gravel from the upper reaches of
the stream. This mud was found to contain glittering particles
which proved to be of gold. Public attention was soon drawn to
the neighbourhood, for so remarkable an observation could not
long be kept secret, and San Francisco became a centre of attraction
to gold-seekers from all parts of the world. For some years gold
was won exclusively from alluvial washings but by 1852 quartz
mining had become the order of the day, some of the quartz veins
being of very considerable size.

Great as was the Californian output of gold, it was soon eclipsed
by that from Australia. In 1851 news reached this country that
gold had been found in quantity in N.S. Wales, near Bathurst. An
educated aboriginal returning home from tending sheep stated
that he had seen a large mass of glittering metal among some
quartz; his employer, Dr Kerr of Wallowa, went to investigate
and three blocks of quartz containing about I cwt. of gold were
discovered. As soon as it was bruited abroad, the discovery caused
the greatest excitement and persons of all trades and pursuits set
off in quest of gold.

Gold was found about this time also in Victoria* where mining
operations began in 1851 and in a few years this area was producing

*See The Engineer, 1890, 49, 15.

122

THE COINAGE METALS

far more of the precious metal than any other in Australia. There
was a fruitful field at Sandhurst distant about 100 miles from
Melbourne; the old name of the town was Bendigo and any
Bendigonian who had lived there prior to 1855 was known as> an
"old identy". Early in 1851 Bendigo Creek and the surrounding
areas were known only to shepherds, the gullies and flats being
covered with green grass and box trees. But before tAe middle of
the year all this was changed, for it had become noised abroad that
here gold was to be had for the digging. Men began to arrive from
all parts of Australia, and not from Australia only. A motley group,
they came in twos and threes, and then in tens and twenties. Some
were shepherds, others included those who had "done time",
run-away naval men, men who sought the solitude of the bush to
escape from the consequences, and possibly the memories also, of
a seamy life; it was hardly safe to inquire into a man's antecedents.
As the weeks rolled by, town-dwellers were drawn to the spot;
clerks, labourers, bankers, publicans and tradesmen. They came
on horseback, in spring carts, by coach, by bullock dray, whilst
not a few trudged on shanks' pony. Many of these had not known
till then what entire liberty meant; few if any knew the meaning
of unlimited money; each man was a law unto himself; no one was
without some means of protection from assault. The majority
resembled mobile arsenals, carrying pistols and knives in their
belts; some had tents, others lay at night under the vast vault of
the heavens. Jack was as good as his master; perhaps better; each
had a pair of hands and arms ; education, knowledge, culture
these counted as nothing. By 1853 some 60,000 men had assembled
on the field, with only about 100 women. Each digger was allowed
8 feet square of ground for which he had to pay the Government
a rental of 30 shillings monthly. The miners would dig square
holes in their plots and, after taking off the surface loam, at a depth
of some 7 or 8 feet they came to the "wash dirt" which contained
the gold; this dirt being the last few inches overlaying the bed
rock. The lumps of gold were now picked out or "nuggeted" with
a knife, like taking the plums out of a cake; the residue was taken
to the creek where the soil was washed away, leaving a residue of
gold. The reward of a morning's work for four men would often
amount to some 20 Ib. weight of gold; in that case the men felt
they had earned an afternoon's rest and in the evening the metal
was dried and cleaned.

So long as the gold lasted, life continued much the same. The

123

THE CHEMICAL ELEMENTS

gold was squandered; men would throw nuggets to their favourite
actresses instead of bouquets of flowers. But the time came when
this rich ground was becoming exhausted and the miners found
the <f ent of 303. oppressive. They approached the Commissioner
and asked for a reduction. The Commissioner said he had no
power to grant this but would forward their wishes to the
Government at Melbourne and advised the miners who had
collected into a body of 20,000, to go quietly back to their tents.

The Government panicked on hearsay, printed notices on calico
announcing the reduction of the licence to los, and sent soldiers
with them to tack them on to trees that all might read and this,
before the Commissioner's report had reached them! At first the
miners were surprised; then they realised their power; union was
strength; together they could defy the Government. One man
named Brown, determined td make capital out of this. He
organised a band of ruffians who levied blackmail on storekeepers
and had a guardroom with sentries and a system of passwords. A
warrant was issued for his arrest, but the police hesitated to put it
into execution with the result that Brown became increasingly
troublesome.

One night a young cadet, Brooke Smith by name, quietly left
his officer quarters and, dressed in diggers' clothes, went off to
interview "Captain" Brown at his HQ. Arriving there he inquired
if the captain was in. Yes, he was, but could the visitor give the
password? No, said the cadet, but as his business was of exceptional
importance, would the captain see him. On being informed that a
young digger was waiting outside with an important message, the
unsuspecting captain came out and, lured by the cadet's air of
simplicity, he walked with him to the centre of the main street; the
cadet now drew close to him and pushing a revolver into his ribs
said "Captain Brown, I am a Government officer and arrest you".
Brown, of course, started and began to tell the cadet that by merely
raising his hand he could call a thousand men to his assistance. But
the cadet calmly told him that if he attempted anything of the sort
he would be shot at once.

Discretion was the better part of valour and with the revolver
at his ribs, Brown was marched off to the guardroom, where he
was handcuffed, placed in a cart and galloped off to Melbourne
with an escort on horseback. They went at such a rate over the
rough ground that Brown was almost killed by the jolting, but
they reached their destination safely and Brown was duly sentenced.

124

THE COINAGE METALS

The ignominy of the capture made the whole thing so ridiculous
that the captain's sentries disappeared and his gang was broken
up for ever.

New gold areas continued to be found for many years in Australia
but it was not until 1892 that William Ford and a chance acquaint-
ance discovered gold in Coolgardie in Western Ai\stralia. Ford
died in Sydney as recently as October 1932.

The discovery of gold in Australia is regarded by the credulous
as having been predicted several centuries earlier by that somewhat
nebulous person known as Mother Shipton. This curious "witch
is supposed to have been born at Knaresboro* about 1486 and to
have died at what was then considered to be a very advanced age
in 1561. It is claimed that she was buried at York. Remarkable
predictions attributed to her were published in 1641 and again in
1873. O ne runs as follows

Gold shall be found, and found
In a land that's not yet known.

The discovery of Australia certainly took place during the period
in which she is supposed to have lived.

The exact date is unknown ; the existence of Australia was not
made generally known in Europe earlier than 1511 or later than
1 542. We put it that way because both the Dutch and the Portuguese
appear to have known of its existence some years earlier, keeping
it secret for commercial reasons, just as the Phoenicians kept the
secret of the Cassiterides or Tin Islands to themselves (p. 200). It is
fair to say that Mother Shipton could never have heard of Australia,
and certainly gold was not discovered there until many centuries
later (1851). There are other lands, however, that might claim the
same distinction; two of these are Tasmania and New Zealand,
discovered by Tasman around 1642. Whilst so large a part of the
world remained undiscovered, Mother Shipton's prediction stood
a very good chance of verification. But what are we to make of the
addendum to her prophecies

The world will then be near the end
And Germany will have to bend.

Is this a kind of world destruction by the atomic or hydrogen bomb?
One wonders.

Canada has yielded gold for many years, official records going
back to 1858 in which year some 34,000 oz. were won. Of course
gold was worked there many years before that, but on a small

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THE CHEMICAL ELEMENTS

scale. The first outstanding event in Canadian gold-mining was
the Klondike rush of 1897 which focused the attention of the world
on this bleak and dreary region. In September 1896 it had been
reported to the Canadian Government that rich discoveries of gold
had been made on Bonanza Creek, a tributary of the Klondike,
which flows into the Yukon. The news spread rapidly and miners
travelled in sleds over the snow from many places in the area until
by January 1897 some 2000 men had assembled with scanty
supplies and little protection against the frosts which brought the
thermometer down to some 50 below zero Fahrenheit, that is
82 degrees of frost*.

In July the first miners from Klondike reached San Francisco,
accompanied by about 400,000 in gold. The excitement reached
fever heat and thousands started for the Yukon without sufficient
supplies. Great sufferings were endured; nevertheless miners
continued to flock to Klondike. Throughout 1898 and succeeding
years gold was worked feverishly, reaching its maximum of
870,750 oz. in 1901. Since then the output has fallen.

Although the Portuguese brought gold-dust from South Africa
to Europe in 1 445, it was not until the nineteenth century that serious
attention was directed to gold winning in this area. The first
South African gold-mining company was the Limpopo, floated in
London in 1868. This was the year also during which diamonds
were discovered on the banks of the Vaal and it was generally
believed that these would prove a more lucrative investment than
gold-mining, so the latter was continued in but a half-hearted
manner. In 1873 the Lydenburg gold-field in the Transvaal was
opened up, and by 1884 it had been discovered that the Banket
Reef was auriferous. T. B. Robinson was greatly impressed by the
appearance of the ore and purchased the Langlaate Farm for some
20,000. This he subsequently floated as a public company for
close upon half a million sterling.

The City of Johannesburg was founded on one of these farms,
and sterile, unsaleable property of 1886 now became a much
coveted land of promise; poor men became immensely wealthy
almost "over night". The story reads almost like a novel.

Gold has from time immemorial formed one of the principal
exports from Tibet. The principal gold-fields are found in the
Chang-Tang, or Northern Desert, and also in the territory east of

T. K. ROSE, Nature, 1897, 56, 615.
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THE COINAGE METALS

Lhasa, between that city and the Chinese frontier. The Tibetan
gold-miner, however, only collects gold-dust, believing that should
he remove any nuggets the supply of gold-dust will cease, as the
nuggets are supposed to be alive and to produce the dust by
breeding (p. 19).

It is stated that some years ago the Tibetan Government sent
3ne of their most promising young men to this country t6 be trained
is a mining engineer and metallurgist, and on his return instructed
him to search for gold.

In a short time he discovered gold in large quantity and proceeded
to extract it. Numbers of nuggets were also found. Just as the work
was getting into full swing the local lamas arrived on the scene and
lot only forbade further operations but directed that all gold
dready taken out should be put back. The young engineer
ippealed to the Tibetan Government to sanction his carrying on
work as the find was of great value and would give very considerable
- evenue. The lamas retorted that unless their instructions were
:arried out to the letter ill-fortune would surely come to the
:ountry, and especially to the State religion.

In the face of this attitude of the priests the Government was
powerless and, in consequence, one of the richest gold-fields in
Tibet, and possibly in Asia, must lie undisturbed for an indefinite
Deriod.

Sold in Holy Writ

There are 267 references to gold in Holy Writ. The first occurs
n Genesis ii. 1 1, where Havilah, a land washed by a branch of the
iver flowing out of Eden, is said to yield the metal.

The statement (verse 12) that "the gold of that land is good"
>eems to imply a power to discriminate between different grades
)f the native metal.

There are frequent references to rings and chains of gold. When
foseph had interpreted the dreams of Pharaoh, the latter in his
gratitude "took off his ring from his hand and put it upon Joseph's
land, and arrayed him in vestures of fine linen and put a gold chain
ibout his neck" (Gen. xli. 42). When, many years later, the Hebrews
escaped from Egyptian domination under the leadership of Moses
:hey "borrowed" jewels of gold (Exod. xii. 35) from their late
>ppressors. This "borrowing" must have been effected on a fairly
extensive scale because, after the departure from Egypt, the ear-
ings alone, worn by the Hebrew men and women, sufficed

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THE CHEMICAL ELEMENTS

to enable Aaron to fashion a golden calf to be worshipped as
an idol.

The worker in gold was an important member of the community;
h% is mentioned in Nehemiah iii. 8 by name, along with the
apothecary and, indeed, given pride of place before him. Gold was
worked in various ways; it was refined in furnaces (Prov. xvii. 3),
cast (Exod. xxxii. 4) and beaten into plates the goldbeater
being referred to as the carpenter in the Authorised Version.

Many references to gold in the Old Testament suggest the
presence of enormous quantities of the metal. Very possibly the
amounts are exaggerated. The Hebrews led by Moses are stated
to have taken jewellery from the Midianites to the extent of
16,750 shekels (Num. xxxi. 52) or roughly 0-25 ton. Gold was used
lavishly in the construction of the Ark of the Covenant and its
furniture (Exod. xxv). Moses was instructed to overlay the wood
of the Ark with pure gold and put four rings of gold at the four
corners thereof.

Centuries later, when the Hebrews were established in the
Promised Land, King David accumulated enormous quantities of
gold and silver, spoil from his defeated enemies, and consecrated
them to the Lord (2 Sam. viii). His son, Solomon, used enormous
quantities of gold in adorning his Temple, erected circa 967 to
957 B.C.

Josephus* states that in his day (37 to 100) the Temple had ten
gates, nine of which "were on every side covered with gold and
silver, as were the jambs of their doors and their lintels; but there
was one gate . . . which was of Corinthian brass and greatly excelled
those that were only covered over with silver and gold/'

This Corinthian "brass" was an alloy of gold, silver and copper
which, according to an old legend, was accidentally produced
when Corinth was burnt at the time of its capture, 146 B.C. It was
highly esteemed in Roman days and was often used by the wealthy
for domestic utensilsf.

Sacred vessels used in Solomon's Temple were of gold as they
had been in the Ark before it; they comprised basins, spoons,
candlesticks, lamps, snuffers and even flowers^ It is not difficult to
believe that the description is substantially true for the building
was closely paralleled, more than two millenia later by the Sun
Temple of the Peruvian Incas (p. 135).

*JOSEPHUS, "Wars of the Jews", translated by Whiston, Book 5, Chap. 5, 3.
f PLINY, Opus cit. t Book 34, Chap. 3.

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THE COINAGE METALS

Solomon was not less lavish in the use of gold in his own royal
household ; all his drinking vessels were of gold, it being specifically
stated that "none were of silver" (2 Chron. ix. 20).

Gold was used in Biblical times, as now, in making crowns for
royalty. When David fought the Ammonites, Joab besieged Kabbah
and destroyed it "and David took the crown of their king from off
his head and found it to weigh a talent of gold, and there were
precious stones in it; and it was set upon David's head" (i Chron.
xx. 2).

It would appear from the above quotation that kings wore their
crowns in battle, and we are reminded of our own king, Richard in
who, at the Battle of Bosworth Field in 1485, realising that defeat
was inevitable, rushed into the thick of the fight, with the crown
on his head, and met a soldier's death.

The crown of the Ammonite king is stated above to have weighed
a talent, that is about 106 Ib. (p. 1 1 1) or nearly one cwt a load
that no king would voluntarily carry into battle on his head.
Probably this is a mistranslation, the original Hebrew scribe
intending to convey the meaning that the beautifully wrought and
decorated crown was "valued at" one talent of gold. This would be
reasonable.

The desire to possess gold has at all times led some men to
crime. Biblical times were not exempt from the curse of cupidity
any more than we are. On the fall of Jericho, about 1400 B.C. it
was ordained that the gold and silver together with the vessels of
"brass" and iron were to be deposited in the treasury of the Lord.
One man, Achan, could not resist the temptation to steal and kept
back a little of the spoil for himself and his family. As he later
confessed to Joshua "When I saw among the spoils a goodly
Babylonish garment and 200 shekels of silver and a wedge (or
tongue) of gold of 50 shekels' weight, then I coveted them and
took them" (Joshua vi and vii).

During excavations at Gezer in Palestine, a tongue of gold was
found measuring xoj inches long, f inch thick, i inch broad at
one end and | inch at the other. It was rather narrower in the
middle and slightly curved. It weighed 27-6 oz. approximately
equivalent to 50 Babylonian heavy gold shekels*. If this is not a
mere coincidence, it indicates that these tongues or ingots were
made into definite sizes for trade purposes and could thus be used
as currency for large amounts.

*MACALISTER "The Excavation of Gezer 1 ' (Murray, 1912) Volume 11, p. 259.

129

THE CHEMICAL ELEMENTS

Man's cupidity

The first use of gold was undoubtedly for ornaments, but it was an
easy step to employ it for barter and hence in later years to utilise
it fos coinage. The desire to possess this precious metal has led to
many marauding expeditions, the classical example being per-
petuated in the Legend of the Golden Fleece*. The cupidity of man
is also well illustrated by the familiar story of Midas, King of
Phrygia, who prayed of Bacchus that everything he touched
might be turned to gold.

"Gold, gold, money untold 1"
Cried Midas to Bacchus, beseeching.
Said the god "I'm afraid,
By the prayer you have made,
You are vastly too over-reaching. "

Nevertheless the prayer was granted. But Midas soon had
cause to repent his greed as the very food he attempted to eat was
transformed into indigestible metal, so that starvation stared the
multi-millionaire in the face. His touch was as inconvenient as that
of Autolycus, the classical thief of whom Hesiod wrote that
"whatever he touched became invisible".

In despair Midas was compelled to ask the god to take back his
dangerous gift. He was ordered to bathe in the river Pactolus. As
the Jordan washed away the leprous scales from Naaman so did
the Pactolus wash the golden touch from Midas. Where the king
trod as he entered the water the sands were turned to gold, in proof
of which the sands of the river, even to this day, yield alluvial gold
to him who works for it.

Another ancient story pointing to the same moral is Chaucer's
well known "Pardoner's Tale".

On the other hand the pursuit of gold has been an important
factor in building up modern civilisation, though the cynic
may urge that that is nothing to boast about. The pursuit of
gold has led adventurous spirits into unknown lands, and our
geographical knowledge has been greatly increased; the sciences
of geology, metallurgy and mining have likewise been richly
endowed.

*An excellent interpretation of this legend is given by ROBERT GRAVES in
"The Golden Fleece" (Cassell, 1944).

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THE COINAGE METALS

Gold in Egypt

Gold was known to the Egyptians in predynastic* times and the
goldsmith's art had already reached a high state of proficiency
before the First Dynasty, about 3500 B.C. Examples have bfien
found of solid gold hieroglyphs neatly let into ebony strips forming
part of articles of furnituref. Among later pictorial rock-carvings
in Upper Egypt there occur illustrations of the processes used in
extracting gold from rocks. The latter were broken with stone
hammers, ground in querns, and the matrix washed away with
flowing water, the gold by virtue of its high density being left
behind. Inscriptions depicting this process occur on monuments
as early as the Fourth Dynasty, that is some 3000 B.C. *

The washing of alluvial deposits in the Sudan was a flourishing
industry at the time of Amenemhat n, 2200 B.C.

Until quite recent times the Japanese were following the ancient
practice of grinding gold ores in querns before washing. The fine
mud thus obtained was washed on inclined tables on which sheets
of cotton were spread. The particles of gold were caught on the
rough surface of the cloth whilst the earthy material was carried
away by the water:}:.

There were no silver mines in ancient Egypt, and during the
reign of the Shepherd Kings, circa 1780 to 1580 B.C., gold was less
expensive than silver (p. no).

The position was reversed, however, by the i8th Dynasty,
1580 B.C., silver being more plentiful and proportionately less
precious. Large quantities of gold were taken as tribute and spoils
of war from Palestine and neighbouring lands after conquests by
warlike kings and carried back to Egypt. Amongst the spoil taken
by Thothmes in, circa 1530 B.C., on capturing Megiddo, were two
chariots plated with gold, together with gold and silver rings
weighing 966 lb. His son, Amenhetep n, after one of his foraging
expeditions, took back to Egypt some three-quarters of a ton of
gold. Year after year expeditions of this kind were undertaken by
various monarchs whilst Egypt was at the zenith of her power and

*GARLAND and BANNISTER, "Ancient Egyptian Metallurgy" (Griffin & Co.,
1927), p. 6.

fThe Art of Egypt through the Ages", edited by SIR E. D. Ross (Studio Ltd,

JGowLAND, "Huxley Memorial Lecture for 1912". Royal Anthropological
Institute of Gt. Britain and Ireland.

BUDGB, "A History of Egypt" (Kegan Paul, 1902) Volume 4, p. 36.

131

THE CHEMICAL ELEMENTS

the sum total of gold, silver and other precious booty must have
been prodigious.

Special interest centres around the tomb of Tutankhamen*.
Tkis youthful sovereign ruled over Egypt for a bare six years,
about 1360 to 1354 B.C.; his tomb in the Valley of the Kings was
discovered jn 1922 by Lord Carnarvon and Howard Carter. The
mummy was enclosed in three coffins, the two outer ones of oak
overlaid with sheet gold, the innermost being solid gold elaborately
chased and embellished with superimposed cloisonn work. The
King's death mask was of beaten gold and represented the king at
the age of his death about 1 8 years. Mention should also be made
of a 4 statuette of Tut representing him as the youthful warrior
Horus, throwing a javelin. It was carved in hardwood and overlaid
with thin sheet gold.

One of the great difficulties facing the amateur collector in
Egypt is the number of skilfully executed forgeries which so
closely resemble genuine relics that even the expert may be non-
plussed. In this connection Wakelingf tells an excellent story
which we must not spoil by too close inquiry. At the time that
predynastic graves were discovered in Nubia, there was a rush on
the part of museums from all over the world to acquire specimens.
The bodies were found in the graves lying upon one side with their
legs drawn up and one hand placed before the face. They had not
been embalmed; that was unnecessary owing to the dryness of the
climate; the skin had the appearance of Tight-coloured leather.
Around the body were placed jars and rough vessels, perhaps
those that had been used by the occupant of the grave when alive.

As the demand for graves increased, the prices rapidly rose and
the Arabs vied with a Coptic dealer in finding and selling graves,
which were then taken whole to the museums. In course of time
demand exceeded supply and the Arabs were hard put to it to
supply their customers. But, as usual, where money was concerned,
their native adaptability rose to the occasion. With sublime un-
concern they killed their Coptic rival Aboutig, and buried his body
in the approved position; the body rapidly dried before
decomposition had a chance to set in and poor old Aboutig soon
resembled a genuine predynastic mummy. Later on when a special
request came from an important museum that could afford to pay

*HOWARD CARTER, "The Tomb of Tutankhamen" (Cassell, 1927).
fWAKEUNG, "Forged Egyptian Antiquities" (Black, 1912), pp. 117-118.

132

THE COINAGE METALS

well for the grave, the Arabs "found this one, duly replete with
jars, and sold it for a good round sum.

The Arabs could not keep their mouths closed and soon were
openly heard to boast in the village that they had sold old Aboyitig
for 450!

We owe to Egypt the first mining map in the world*. It
represents a mining district in the time of Seti i or of Ms immediate
successor Rameses n, some 1320 B.C., the actual site of which has
not been determined. It is crudely drawn on a papyrus, now in the
Turin Collection, and depicts two parallel valleys among gold-
bearing mountains, with houses for storage and tracks for transport.

Of course the gold contained varying amounts of silver, byt the
early Egyptians were unaware of this. By the second century B.C.
however, the chloride method of removing silver from gold appears
to have been practised in Nubia, for Agatharchides mentions that
salt and bran were added to the native gold before melting. The
salt would convert the silver to chloride and thus effect its elimina-
tion as dross or scum. As late as 1872 Gowland found that the
Japanese were using this self-same method.

Gold and the Romans

Vast quantities of gold were accumulated by the Romans who
obtained it partly as spoil from their conquered foes and partly by
working the mines in various countries within their empire. As an
example of the former, Livyf records that in 200 B.C. Cornelius
Lentulus, proconsul of Spain, on the occasion of his entry "in
ovation" J into Rome, brought 2450 Ib. of gold with 43,000 Ib. of
silver.

The mines of Spain were perhaps the most important sources of
the precious metal, particularly those of Andalusia, probably the
Tarshish of Ezekiel xxvii. 12, the Turdetania of Strabo and part
of the Iberia of Diodorus. Strabo waxes eloquent on the mineral
wealth of Turdetania and states that the gold mines were the
property of the State whilst the silver mines were privately owned

*GOWLAND, loc. cit. t p. 255.

fLivv (59 to 18 B.C.), "History of Rome", translated by Sage (Heinemann,
*935) Book 31, Chapter 20.

JAs merely a proconsul he was not entitled to enter "in triumph". The
ovation was a less important honour.

Strabo was born in Amasia, Pontus, 64 or 63 B.C. The quotation is from the
translation by H. L. Jones of STRABO'S "Geography" (Heinemann, 1917 +).
Book 3, Chapter 2. 8 to 10.

133

THE CHEMICAL ELEMENTS

(p. 112). "Up to the present moment" he writes "neither gold nor
silver has been found anywhere in the world in a natural state,
either in such quantity or of such good quality."

Diodorus*, writing over the period 56 to 36 B.C. gives a lengthy
account of mining in his "Bibliotheca Historica" and mentions the
use of the "Egyptian screw, which was invented by Archimedes of
Syracuse at 'the time of his visit to Egypt", about 220 B.C., for
pumping out the subterranean waters from the mines. He speaks
of the screw as a masterpiece of mechanical invention. Several of
them have been found in modern times in Southern Spain. This
kind of pump is still used by the fellahin of the Nile Delta in
raising water from the Nile for irrigation. The modern engineer
would not share the enthusiasm of Diodorus for the efficiency of
these screws. Twenty of them, each worked by a slave, would be
needed to raise water 100 ft.

The Romans were, and could afford to be, lavish in the use of
gold for religious, ornamental and utility purposes. Plinyf quotes a
current belief that the first massive statue of gold, solid throughout
known as a holosphyrata, i.e. solid hammerwork as opposed to
cast and hollow within was one erected in a temple to the
goddess Anai'tis. This was stolen during the Parthian War. On one
occasion Emperor Augustus was dining with a Roman veteran and
during the course of conversation reference was made to this
statue, Augustus then asked his host if he was aware that the
soldier who had desecrated the statue by taking it away from the
temple had been smitten with blindness, paralysis, and finally with
an early death a warning to those who anger divinities. The
soldier laughed and replied that it was he himself who had
committed the sacrilege and, horribile dictu> the golden plate, from
which his august Majesty was even then partaking, was shaped
from one of the legs of the goddess.

Gold being so abundant when Rome was at the height of her
power, one can almost forgive the arrogance of Poppaea, wife of
Nero, who had her favourite mules shod with it.

Pliny^ was aware that native gold usually contains silver ranging
from small amounts up to about 1 2 per cent. Electrum was an alloy

*Diodoms was born at Argyrium in Sicily. The quotation is from "Diodorus
of Sicily" by OLDFATHER (Heinemann, 1933 +)> Book 5, Chapters 36 to 38.
RICKARD, Journal of Roman Studies, 1928, 18, 129.

f PLINY, Opus cit., Book 33, Chapters 24, 17 and 49.

JPLINY, Opus cit., Book 33, Chapter 23; Book 34, Chapter 48,

134

THE COINAGE METALS

containing 20 per cent of silver, and Pliny records an old belief
that it possessed the power of detecting poisons for, in such case,
"semi circles, resembling the rainbow in appearance, will form
upon the surface of the goblet and emit a crackling noise, likfr that
of flame, thus giving a twofold indication of the presence of poison."
Pliny also states that base metal articles were sometimes gilded
by dipping into molten gold in the same way as copper was tinned.

The gold of the Incas

South America is rich in gold. When the Spaniards conquered the
Incas of Peru early in the sixteenth century they were amazed at the
lavish profusion of gold in the temples and royal palaces. The
Sun-Temple* of the ancient city of Cuzco was outstanding for its
magnificence and for the treasures contained therein. The walls of
the main hall were covered from top to bottom with gold; at the
eastern extremity was a representation of the sun with solid gold
rays encircled with a frame of costly gems, whilst along the side
walls were ranged the golden thrones on which sat the mummified
bodies of former kings. The Temple doors were overlaid with gold
or silver and a strip of gold as thick as a man's finger, twice as
broad as his hand and surmounted by a golden cornice encircled
the entire building. In one of the Temple Courts was the "Golden
Garden", with "golden sacred columns, golden figures of animals,
silver bushes and trees whose delicate branches trembled in the
breeze, heads of maize with silver leaves and stalks bearing golden
grain, bearded with the most delicate silver filaments; on the
branches golden birds; cockchafers and butterflies with wings of
sparkling gems seemed to fly in the air, whilst lizards, serpents,
snails and little mammals, all made in gold or silver with eyes of
precious stones, crept along the ground. Wonderful fantastic
flowers adorned the beds and amidst all this artificial magnificence
rose the natural beauty of real shrubs kept moist by the water
flowing in golden pipes to basins of the same precious metal."

Gold was esteemed for its beauty and incorrodibility alone; it
did not excite cupidity amongst the Incas who had no money and
knew nothing of finance.

In spite of the almost incredible amount of golden treasures,
scarcely any of the Inca works of art remain. The Spaniards

*HANSTEIN, "The World of the Incas", translated by Barwell (Allen and
Unwin Ltd, 1924) pp. 65 et seq.

135

THE CHEMICAL ELEMENTS

melted down everything they could into ingots for convenience in
transport to their wretched capital.

Gold and the alchemists

The attitude of the alchemists towards gold and the possibility of
transmuting base metals into the more precious one have already
been discussed. The symbol for gold was a circle, the hall- mark of
mathematical perfection (p. 12).

Although the quest of the alchemists ended in disappointment,
the mass of chemical and metallurgical data* they accumulated
proved of great value in laying the foundations of the modern
sciences of chemistry and metallurgy.

Uses of gold

One of the most important uses of gold and its alloys is for jewellery.
The craftsman has endeavoured throughout the ages to retain the
attractive colour of the pure metal in alloys containing large
admixtures of other metals. It is usual to express the quantity of
gold present, not as a percentage, as is usual in most other alloys,
but in carats. Here again, the carat is not the unit of weight as
applied to diamonds (p. 58). The gold carat is a fractional part of
24; thus 24 carat is pure or 100 per cent gold; 18 carat is ^fths
pure gold, equivalent to 75 per cent and so on. The recognised
carats in Britain since 1932 are 22, 18, 14 and 9. Wedding rings
by tradition were invariably 22 carat and thus contained 2200 -f- 24
or 91*7 per cent of gold: 7 carat gold is used for cheap ornaments
and is not hall-marked.

Gold is very ductile and can be fashioned into wire or threads
which may be spun or woven like wool. Plinyf quotes the statement
that "Tarquinius Priscus celebrated a triumph, clad in a tunic of
gold; and I myself have seen Agrippina, the wife of the Emperor
Claudius, on the occasion of a naval combat . . . attired in a military
scarf made entirely of woven gold without any other material. "

Being soft and malleable, gold tablets were long used inscribed
with treaties, laws, orders, etc, for which permanency was required.
Pliny refers to the same practice with lead plates in his day (p, 189)
and Rameses n in 1333 B.C. used silver for the same purpose
(p. no). When Marco Polo, the Venetian (p. 55) was, in 1290,
about to set out on an expedition at the request of Cublai Khan, he

*Will the student try to remember that data is plural; datum is the singular.
fPLiNY, Opus cit. t Book 33, Chapter 19.

136

THE COINAGE METALS

was given a golden tablet, duly inscribed and signed with the
Khan's name, which served as a passport throughout the Khan's
empire. It called on the governors of provinces and cities to afford
Marco every facility in the course of his duties and to defray lys
expenses,

Gold coins

The commerce of the nations has been built up on what is called
the "gold standard". Gold has been used in coinage in the Western
World since about 700 B.C. The parting of gold and silver was then
practised and ancient Greek coins containing some 99*7 to 99*8
per cent of gold have been unearthed. ,

The famous "golden penny", first struck in Britain in 1257
during the reign of Henry in, consisted of pure gold and weighed
44 grains. But although it was our first golden penny, it was not
our first penny. Silver pennies were used by our Saxon ancestors;
in the eighth century a pound of silver yielded 240 pennies, and this
is perpetuated in our Troy weight measure, namely 20 penny-
weights make one ounce, and 12 ounces one pound. Henry m's
golden penny was valued at 12 such silver pennies.

But pure gold is a soft metal and for most purposes it is now
hardened with small quantities of silver, copper or other suitable
metal. British gold coinage contains 916*6 parts of gold and 83-4
parts of copper; this is 22 carat gold (p. 136;. The copper not only
hardens the metal, thus increasing its resistance to wear and tear,
but also lowers the melting point from 1062*6 to 949 C. which
is an advantage metallurgically. The molten metal contracts on
solidifying and this is the reason why our coins must be struck, a
more . expensive process than casting.

Pliny* speaks of an alloy called electrum which could be produced
by melting silver with gold ; he was also aware of the presence of
silver in native gold and that its amount varied with the locality.
If the native metal contained 20 per cent of silver it was called
electrum just the same as the synthetic alloy.

Homer, writing about 880 B.C. refers to elektron, and from the
fact that this is mentioned in connection with gold ornaments it is
possible that the word was used to denote some sort of shining
alloy. The word was later used by the Greeks to denote either the
alloy or amber. The modern alloy called electron contains no

* PLINY, Opus cit. t Book 33, Chapter 23.

137

THE CHEMICAL ELEMENTS

gold, but about 95 per cent of magnesium, with some 4-5 of zinc
and a little copper (p. 152).

The so-called white gold alloys were introduced to resemble
tJatinum when that metal was prohibitive in price, and their use in
jewellery has been very successful. The earliest white gold
contained ,gold, nickel and zinc. Gold-palladium alloys are easier to
work and with 20 per cent of the latter element are completely
white, but the high price of palladium militates against their use
except in the most expensive jewellery. Green, blue and purple
alloys are also easily made by addition of cadmium, iron and
aluminium respectively.

Gold leaf

The malleability of gold has been noted from the earliest times. In
the Old Testament we read of beaten gold on many occasions, as
for example I Kings x, 1 6 ; Numbers viii. 4, etc. The gold beaters'
craft is one of the most ancient that survives to-day. Pliny* mentions
that gold was beaten out into thin leaves and used for gilding. The
modern method is the same as that used in bygone centuries, save
that machinery in the form of highly polished steel rolls is employed
to reduce the cast alloy usually containing from 95 to 96 per
cent of gold, the remainder being silver and copper to sheet or
ribbon about o-ooi inch in thickness. Subsequent reduction to
0-000,004 inch is effected entirely by hand.

At the beginning of this century there were some 1500 gold
beaters in Britain, but to-day only about one tenth of this number is
employed, a considerable proportion in Birmingham. The machined
rolled metal is cut into inch squares each being placed between
the leaves of a cutch of 200 sheets of vellum 4 inches square and
beaten until the metal has spread out to the size of the cutch. The
leaves are then removed, quartered and placed between the skins
of a shoder, containing 800 coarse skins, 4^ inches square. Beating
is continued with a 1 2 Ib. hammer until the gold leaves have spread
out to the size of the shoder. Again they are quartered and placed
in a mould of gold beater's skin, 5^ inches square and hammered
once more. This is the most highly skilled part of the operationsf
and when the leaves have spread sufficiently they are trimmed and
put into thin paper books ready for sale.

*PLINY, Opus cit., Book 33, Chapter 19.

fSee DOWNS, Chemistry and Industry, 1942, 61, 156.

138

THE COINAGE METALS

Gold leaf is used by book-binders for gold lettering, book-edges,
etc. Carvers, gilders, picture-frame makers and sign writers use it,
and many other trades. The intrinsic value of the gold itself is small,
for i oz. Troy can yield 250 sq. feet of leaf; taking gold at its present
price of 2488. per oz., I sq. inch of 23 carat metal is worth only
about iV penny.

A considerable quantity of gold is used in the electroplating
industry, the article to be plated being made the cathode in a bath
of potassium auro-cyanide. The deposit aimed at is usually of the
order of 0-0005 inch, but depends partly on the nature of the base
metal to be coated and the use to which it is to be put. Plated
surfaces take a high polish and are not liable to tarnish.

Cathode sputtering or dispersion is a recent development in
processes for covering surfaces with a film of gold. The object is
placed in a chamber fitted with an aluminium anode and gold
cathode. On evacuation and passage of a high voltaged current
the cathode disperses covering the object with a thin film of gold,
less than one-millionth of an inch in thickness.

A vaporisation process is sometimes used, the gold being
electrically heated to its melting point in a high vacuum, the
vapour condensing in a molecular film on any article placed within
the chamber. Spectacles lenses are sometimes treated in this way
for people suffering from iritis \ they exclude ultra-violet light and
allow rays of a greenish, restful colour to pass.

In making gilt wire, a bar of silver, alloyed with copper, approx-
imately 2 inches in diameter is plated with gold and drawn down
to wire in the usual way. It is then used for weaving into gold braid
and embroideries such as one sees on uniforms, clerical and masonic
vestments, etc.

Rolled gold is manufactured by soldering or welding a plate of
gold or alloy on to a base metal or silver and rolling to the required
thickness. The gold film produced is hard and impervious, so that
it resists wear and tear more effectively than ordinary electroplated
films. Rolled gold consequently finds application in watch cases,
pencils, spectacle frames, cufflinks and cheap forms of jewellery.
Very thin coverings of gold, about 0-000,005 inch are used for
toys and trinkets and of course quickly wear off. In better class
rolled gold objects the gold film may reach a maximum of o-oi
inch in thickness.

Prior to the introduction of rolled gold, imitation jewellery was
made chiefly of copper or brass gilded with pure gold; the soft gilt

139

THE CHEMICAL ELEMENTS

surface, however, soon wore off. Towards the close of the eighteenth
century, at the time when the manufacture of "Sheffield plate' ' had
reached its zenith, the rolled gold industry was born in
Birmingham*. The two processes are virtually identical, save that
in Sheffield plate a base metal is veneered with silver whereas in
rolled gold, silver is replaced by gold (p. 1 1 6).

Gold use c d for pottery is practically pure ; it is usually applied as
"liquid gold" with a brush before firing. The liquid consists of
some organic gold derivative in oil, with some suitable adhesive.

Gold is used in producing some types of ruby glass; originally
the gold was used in the form of purple of Cassius, a mixture of
colloidal gold and colloidal tin oxide. This was the method
employed by Kunckel (1630-1703). Later it was found that gold
chloride would do equally well. By transmitted light gold is green;
in glass the ruby colour is not that of gold but it is the colour of the
light scattered by the gold particles of colloidal size within the
glass. A similar effect is produced by selenium (p. 73).

Gold is used for chemical plant and laboratory ware on account
of its resistance to acids and alkalies. The only single acid that will
attack gold is selenic acid, H 2 SeO 4 . In the laboratory, dishes and
crucibles made of a high melting palladium-gold alloy, melting at
1370 C. have been used when the cost of platinum has been
prohibitive. In chemical plant gold-lined base metals are sometimes
used and for the distillation of essential oils a solid gold still and
condenser have been used; the thermal efficiency is high and cor-
rosion does not occur.

Alloys of gold and the platinum metals are used in the manu-
facture of artificial silk. The viscous liquid used to produce the silk
is extruded through fine holes in a spinneret. As these holes may be
only 0-003 inch in diameter they must be perfectly smooth, and
gold-platinum metals alloys serve the purpose admirably.

Gold has long been used in dentistry both for fillings and
dentures; the latter are now usually made by pressure casting of a
hardened alloy containing some 30 to 40 per cent platinum.
Vulcanite plates may be strengthened by gold gauze or perforated
gold sheet. The employment of gold in dental operations dates
back to very early times. In the Corneto museum on the coast of
Italy there were, and probably still are, two specimens of artificial
teeth found in Etruscan tombs probably dating from four or five

*E. A. SMITH, /. Inst. Metals, 1930, 44, 175.

140

THE COINAGE METALS

centuries B.C. The graves contained the bodies of two girls; on the
jaw of one, two incisors were attached to their neighbours by small
gold rings*. In the other grave the rings remained but the artificial
teeth had fallen out. These latter had evidently been taken from
the mouth of some large animal. Cicero (106 to 43 B.C.) quoted a
law forbidding the incineration or burial of costly golden articles
but allowing an exception in the case of "teeth fastened Vith gold"f

Amongst the numerous miscellaneous uses of gold may be
mentioned its application as target in X-ray work, as a rival of
tungsten; in certain thermocouples, such as the pallador thermo-
couple, for measuring high temperatures; as heat fuses; for hair
springs for chronometers; for electrical equipment for measuring
the speeds of aircraft engines; in radium therapy for the containers
of the disintegration products of radon.

The annual world output of gold is about I ooo tons, the value of
which in pounds sterling is placed at approximately 260 millions.
From 90 to 95 per cent of this is absorbed in bars of statutory
400 oz. Troy weight for monetary purposes, international trade and
exchange. The world's stock in hand of gold is believed to be
worth some 4000 to 5000 million pounds sterling.

Nature. 1885, 31, 564.
\Ibid., 1885, 31, 578.

141

CHAPTER 10

THE ALKALI METALS

THE alkali metals include lithium, sodium, potassium, rubidium
and caesium.

The name alkali is derived from the Arabic al-qaliy^ calcined
ashes, 'and refers to the carbonates of sodium and potassium which
were obtained by lixiviation of plant ashes. Natron^ an impure
sodium carbonate, was known in Egypt in very early times. It has
been found in vases in tombs dating back as early as the xvinth
Dynasty; Lucas regards it as probable that natron was already
used for embalming royalty in the ivth Dynasty. The Latin word
used by Pliny was natrum, but the salt came to be called Egyptian
nitre, perhaps by confusion with the Greek word nitron. A reference
to this salt occurs in Holy Writ "As vinegar upon nitre so is he
that singeth songs to an heavy heart" (Prov. xxv. 20). This was a
puzzling statement, for vinegar does not visibly affect European
nitre, i.e.) saltpetre, and the point of the proverb was lost until
Boyle obtained a sample of Egyptian nitre in 1680 and found by
direct experiment that it readily effervesced with acids. The meaning
of the proverb then became clear. The ancient Hebrews prepared
an impure carbonate of potash under the name borith by passing
water through vegetable ashes, probably from the salt-wort. This
is referred to as soap in Jer. ii. 22, and Malachi iii. 2. It was not
until the eighteenth century that sodium carbonate or soda became
well known in Western Europe. It was then prepared from the
ashes of marine plants. Potash or pearl ash was similarly obtained,
namely by extraction with water from the white ashes of burnt
wood, whence the word pot-ash. These two carbonates were
termed "fixed alkali" to distinguish them from the volatile
ammonium carbonate.

That a difference existed between soda and potash was only
gradually realised. In 1702 Stahl distinguished between "natural"
and "artificial" alkalis, evidently referring to soda and potash,
noting that salts of the former sometimes possessed a different
crystalline form from the corresponding salts of the latter. In 1736
Duhamel de Monceau observed further differences between
"mineral" alkali, that is soda, and "vegetable" alkali or potash,

142

THE ALKALI METALS

whilst in 1758 Marggraf noted the variation in the flame colorations.
>It was known to Geber in the eighth century that mild alkali, that is
soda, could be converted into caustic alkali by the action of slaked
lime, and soap was prepared at an early period by the action of this
caustic alkali on fat. The causticity was attributed to lime dissolved
in the alkali, but in 1756 Black proved that mild alkalis contained
"fixed air" that is, carbon dioxide and no lime, whereas the caustic
alkalis contained neither fixed air nor lime. They were regarded as
elements by many chemists until the beginning of the nineteenth
century. Indeed they conformed to Lavoisier's definition of an
element, in that they had never been split up into anything simpler.
Other chemists, however, doubted their elementary nature and
the time for proving it was rapidly drawing near.

In 1799 the Italian physicist Volta, Professor of Physics in
Pavia, described a method of producing an electric current using
what are known as the 'Voltaic pile" and "battery" (p. 102). The
first battery to be used in England was in the possession of
Nicholson and Carlisle who, the following year, effected the
decomposition of water with its aid into its two constituent gases.
They used platinum wires. In 1803 Berzelius and Hisinger made
the further observation that aqueous salt solutions could be de-
composed in a similar manner, the acid of the salt collecting round
l^ie electrode at which the oxygen was liberated and base round
the other electrode.

In 1 80 1 Davy, on the invitation of Count Rumford, went to
London to take charge of the laboratory at the Royal Institution*.
This Count Rumfordf, one of the Founders of the Royal
Institution, was an interesting personality. His original name was
not Rumford but Thompson ; American by birth, he spent most of
his life in England and on the Continent. In 1791 he was made a
Count of the Holy Roman Empire and chose the name Rumford.
In 1796, puzzled by the large amount of heat evolved in boring
cannon, he began experiments from which in 1798 he concluded
that heat was a form of energy the first scientist to suggest this.

*See JOHN DAVY, "Memoirs of the Life of Sir Humphry Davy" (London,
1836). This authoritative and detailed work is somewhat marred by John Davy's
almost spiteful recurrent criticisms of the "Life of Davy" written in a delightful
popular style by his friend Dr. Paris in 1831. Probably Paris gave a truer picture
of the man, Humphry Davy, than did John who appears to have suffered from
hero worship.

JGEORGE E. ELLIS, "Memoir of Sir Benjamin Thompson, Count Rumford,
with Notices of his Daughter" (Boston, 1873).

*'' 143

THE CHEMICAL ELEMENTS

Up to that time heat had been regarded as a fluid. In 1801 he
married Mdme Lavoisier, widow of the famous scientist executed'
in 1794.

In 1802 Davy was promoted to the Professorship and in 1805
to the Directorate of the Royal Institution.

Davy was keenly interested in the new applications of electricity
to chemical problems, and prepared a powerful battery for his own
use. Experimenting with solutions of caustic potash he found that
hydrogen and oxygen alone were liberated; so then he tried the
effedt of the current on solid caustic potash, rendered sufficiently
moist by brief exposure to air to conduct the current. The experi-
m?nt was an immediate success and raised Davy instantaneously
to the pinnacle of fame. At the electrode where, in previous
experiments, hydrogen had appeared, globules like mercury,
possessed of high metallic lustre and great chemical reactivity
were seen. Some of them ignited explosively and burned with a
bright flame, others remained and soon tarnished. His laboratory
book, dated I9th October 1807, bears the comment "A capital
experiment". This new metal Davy named potassium. Shortly after
Davy had isolated the metal, Dr. George Pearson called at the
Royal Institution. Seeing the lustrous metal he said "Why, it is
metallic to be sure", and then, balancing it on his finger, remarked
"Bless me, how heavy it isl"* How easily we are misled by our
preconceptions! To Dr. Pearson all metals were necessarily heavy.
Actually, the density of potassium is well below that of water, and
less than one-third that of aluminium.

Flushed with his success, Davy repeated his experiment a few
days later, this time using caustic soda, and was rewarded by the
liberation of his second new metal sodium. He also obtained this
element by decomposing sodium chloride with metallic potassium.

Dr. Paris, in his very charming life of Davy published in 1831,
states that Napoleon was extremely angry that the honour of
discovering the alkali metals should have fallen to the English, the
nation that stood between him and the conquest of Europe and
who, though he knew it not then, were destined to rob him of the
victor's laurels and consign him to eat his heart out in solitude at
St. Helena. He called the French scientists together and demanded
of them why they had not forestalled Davy. For want of a better
answer they replied that they did not possess an electric battery

PARIS, "Life of Sir Humphry Davy", 1831, vol. I, p. 268.
144

THE ALKALI METALS

sufficiently powerful. Napoleon commanded them to have one made
at once and when it arrived he called at the Academy to see
it. Before any one could stop him he placed the terminals in his
mouth to try the strength of the current. The shock on ])is
tongue must have been terrific; he left the Academy without a
word!

Of the two metals it is only sodium that is used to any extent in
its metallic state. It is required in manufacturing sodium peroxide,
cyanide and sodamide. An alloy with potassium is liquid at the
ordinary temperature and is used in thermometry. Sodium is a
useful reagent in organic chemistry as in the manufacture of
synthetic rubber; it was at one time used in manufacturing
metallic aluminium and magnesium by replacement in the chlorides ;
but these metals are now obtained electrolytically. An alloy with lead
finds application in the manufacture of "ethyl", that is, lead
tetraethyl, for anti-knock motor spirit. Its property of emitting
electrons when exposed to light enables it to be used in photo-
electric cells.

Lithium

The next element of the alkali group to be discovered was lithium in
1818, by Arfvedson* who was working under Berzelius in his
famous laboratory at Stockholm. Arfvedson was examining the
mineral petalite, then recently discovered by d'Andrada in the iron
mine at Uto, Sweden, and so named from the Greek petalon, leaf,
because of its cleavage. The mineral was thought to be sodium
aluminium silicate, but analysis on this assumption exceeded 100
per cent. Examination of the alkali portion of the mineral showed
that it was not sodium but a new element which it was decided to
call lithium from the Greek lithos, stone, in recognition of its being
discovered in the mineral kingdom whereas the two previous
alkali metals occurred in the vegetable world. Petalite is now
regarded as lithium aluminium disilicate, LiAl(Si 2 O 6 ) 2 . The
characteristic red colour imparted to the flame by lithium salts was
observed by C. G. Gmelin in 1818, but neither he nor Arfvedson
succeeded in isolating the metal, although they tried both to reduce
the oxide with iron and carbon, and to electrolyse its salts; their
voltaic pile was evidently insufficiently powerful. Both Brandes
and Davy in 1820, however, succeeded in decomposing lithia

*ARFVEDSON, Schweigger's /., 1817, 22, 93; Ann. Chim. Phys., 1819, (2), 10, 82.

145

THE CHEMICAL ELEMENTS

electrolytically, but only in small amount. It was Bunsen* and
Matthiessen who, in 1855, obtained metallic lithium by electrolysis
of the fused chloride in sufficient amount to enable them to make a
careful study of its properties.

Lithium is used to a limited extent in industry in various alloys.
It increases the tensile strength and resistance of magnesium alloys
to corrosion; a calcium-lithium alloy is used in purifying copper
for high conductivity work. Addition of about o-i per cent of
lithium to aluminium-zinc alloys enhances their tensile strength.

Rubidium and caesium

The story of the discovery of rubidium and caesium introduces
the' spectroscope as an important adjunct to the chemist's equipment.
In 1852 Bunsen succeeded Leopold Gmelin in the chair of
chemistry at Heidelberg. He felt that chemists ought to collaborate
as fully as possible with physicists, and when the chair of physics
fell vacant in 1854 he strongly advocated the appointment of
Kirchhoff who had been his colleague at Breslau. The two men
then collaborated. Kirchhoff showed Bunsen that it was more
efficient to examine the flames coloured with various salts through
a prism than merely through coloured glass, and the two designed
the Bunsen-Kirchhoff spectroscope, which proved invaluable both
for chemical analysis and for the discovery of new elements. In 1859
Kirchhoff found the cause of the dark lines in the solar spectrum/
first measured by the Munich optician Fraunhofer and now known
as the Fraunhofer lines. As a result of extensive researches on the
emission spectra of different elements, Bunsen and Kirchhoff in
1860 established the following fundamental principles

(1) Every element when sufficiently excited in the gaseous
state yields its own characteristic spectrum.

(2) The vapour of an element can be inferred with certainty
when its spectral lines are present.

These conclusions were of unusual importance. To begin with
they made it possible for the first time, apart from the examination
of meteorites, to determine the chemical composition of celestial
bodies such as the sun. We have already seen (p. 42) that in 1868
the presence of helium was detected in that luminary and since
then some 40 more of our terrestrial elements have been detected
there also. >

Another direction in which these optical principles have proved
*BUNSEN, AnndUn, 1855, 94, 107.
146 ,

THE ALKALI METALS

valuable has been in detecting the presence of traces of substances
in various materials. The eye is extraordinarily sensitive to light. If
an ordinary pea is allowed to fall through an inch under the
influence of gravity it yields a certain amount of potential energy,
extremely minute, but none the less definite. If that minute amount
of energy were converted into light, the average human eye could
just detect it.

For many years the spectroscope afforded the only general
method of detecting minute traces of elements and as it led to such
far-reaching results much attention has since been paid to the
detecting of traces by this and by other means, so that micro-
chemistry has now become an extremely important branqji of
chemical science.

In 1860 Bunsen and Kirchhoff* announced the spectroscopic
discovery of a new alkali metal in the mineral waters of Dtirkheim.
The waters had been concentrated and the spectrum examined
with the result that two very characteristic new blue lines were
observed, close together, indicating the presence of a new element.
It was proposed to call the new metal caesium from the Latin
caesius, sky blue. Some 50 grams of the hexachlorplatinate,
CsaPtCl e , were ultimately obtained by evaporation of 40 tons of
the waters, more than a kilogram of lithium carbonate being
obtained as by-product. A few months later, namely early in 1861,
Bunsen and Kirchhoff announced the discovery of a second
element, this time in lepidolite, which yielded, in addition to others,
two magnificent dark red lines in its spectrum. The name rubidium
was suggested, from the latin rubidus^ dark red. Lepidolite or
lithium mica, so called because of its bright scaly appearance
(Greek lepidos scale, lithos stone) is essentially a fluo-siiicate of
lithium and aluminium.

Caesium is not only of interest as being the first metal to be
discovered spectroscopically. As early as 1846 Plattner had exam-
ined polluxite, then believed to be merely potassium aluminium
silicate, but the analysis, on this assumption, did not work out at
100 per cent. Some alkali appeared to be missing. After the
discovery of caesium, Pisanif, in 1864, re-examined the mineral
and showed it to contain this new element, and not potassium,
whose salts its own so closely resemble. The higher atomic weight

*BUNSEN and KIRCHHOFF, Pogg. Annalen, 1861, US, 342; 1863, 119, I.
Annalen, 1862. 122, 347; 1863, 125, 367.

fPiSANi, Compt. rend., 1864, 58, 714. Annalen, 1864, 132, 31.

147

THE CHEMICAL ELEMENTS

of the caesium explained the missing percentage of alkali. Polluxite,
usually given the formula Cs2O.Al 2 O 3 .5SiO 2 .H 2 O, but more
probably represented by iCs^.sAljOg^SiCVHjjO, is the main
soijjrce of caesium compounds to-day; clear, colourless crystals of
polluxite from Oxford County, Maine, U.S.A. have been used as
gem stones. Caesium beryl, 3BeO.Al 2 O 3 .6SiO 2 , contains up to
4-56 per cent of caesium, calculated as CsaO. It is usually pink and
is known as morganite after James Pierpont Morgan.

Bunsen succeeded in isolating rubidium in 1863 by electrolysis
of the fused chloride, but nearly twenty years elapsed before
caesium was first isolated by Setterberg in 1882 by electrolysis of
the cyanide in the presence of barium cyanide.

Rubidium has been, and caesium now is, used in photo-electric
cells and thermionic valves.

Numerous attempts have been made to find ^-caesium, the
element of atomic number 87, that would normally occupy the
position in the periodic table between radon and radium. In 1931
Papish, of Cornell University, claimed to have detected it in
samarskite, a complex niobo-tantalate named after the Russian
von Samarski; but the evidence is not substantiated. The name
suggested was virginium. In 1933 Remy-Gennetfe suggested that
the helium content of certain minerals may have originated from
the decomposition of ^-caesium, which has now almost if not
entirely disappeared. In 1936 Professor Horia Hulubei, in Paris,
believed he had detected the X-ray "L" spectrum of No. 87 in
alkali metals obtained from polluxite and suggested the name
moldavium*. Element 87 was discovered in 1939 by Mile Percy
in Paris as a branch product of the actinium series and the name
francium or franconium suggested.

*HULUBEI, Compt. rend., 1936, 202, 1927; 1937. 205, 854.

148

CHAPTER 11

MAGNESIUM AND THE ALKALINE
EARTH METALS

THE group to be considered in this chapter includes magnesium,
calcium, strontium and barium. Radium is discussed later (p. 313).
The modern conception of an earth is little different from that
given by Nicholson in 1796 in his "First Principles of Chemistry ",
We now know their chemical compositions however. Briefly
defined, they are refractory metallic oxides, incombustible, infusible,
insoluble in water, and destitute of metallic splendour to use
Nicholson's words. They may be conveniently divided into four
groups, namely

(1) Alkaline earths, such as lime and baryta.

(2) Acid earths, including silica and tantala.

(3) Rare earths, such as ceria and yttria.

(4) Earths proper, e.g., ferric oxide and alumina.

We may now consider the first of these groups.

Owing to their prevalence among surface rocks, chalk, limestone,
dolomite, magnesite, and other compounds of magnesium and the
alkaline earths have been known to and used by man from very
early times. But, of course, they were not distinguished the one
from the other. The Romans referred to lime under the name of
calx and both Dioscorides (circa A.D, 50) and Pliny (23 to 79)
described lime-burning, which was probably even then an
ancient process. Early mortars were made with equal quantities of
sand and lime, but modern ones contain 2 of sand to i of lime as
experiment shows this to give better results.

Mention has already been made (p. 76) of the fact that in 1602
a Bolognese shoemaker, Casciorolus, observed that "heavy spar",
our barytes, became luminescent after ignition with a combustible
substance and from that time Bolognian phosphorus became famous.
Cronstedt called the mineral marmor metallicum and in 1750
Marggraf found it to contain sulphuric acid, but mistook the base
for lime.

In 1774 Scheele gave a detailed account of his researches on
pyrolusite, then known variously as manganese or magnesia. This

149

THE CHEMICAL ELEMENTS

mineral frequently contains barium compounds, and Scheele
mentioned that in addition to lime it contained "a new species of
earth which, so far as I know, is as yet unknown."

This earth was shown by Gahn the following year to be the same
as that present in heavy spar, or barium sulphate, and in 1779
Scheele showed that the earth in heavy spar was quite distinct
from lime. *

Guyton de Morveau, who with Lavoisier, Fourcroy, and
Berthollet, devised a more appropriate system of chemical nomen-
clature 1 than then existed, suggested barote as a suitable name for
this earth; Lavoisier preferred baryta (Greek bartu heavy) and
Kirwan, the Irish chemist, called it barytes a name that has been
retained for the mineral.

In 1782 Withering, the famous Birmingham doctor who
introduced the foxglove into medicine, discovered barium carbonate
in the Leadhills, Scotland. This was called terra ponderosa aerata,
but later the cumbersome appellation was altered to Witherite. i

Shortly after this a mineral found in lead mines at Strontian in
Argyll was mistaken for witherite. In 1790 Crawford suggested
that it contained a new earth which he called strontia. His views
were confirmed by numerous other investigators. The mineral was
named strontianite\ it is the carbonate, SrCO 3 . The sulphate was
first found by Clayfield near Bristol, where it is still incorrectly
called "strontia" in the trade. The beautiful blue colour of some
specimens led to the name celestine; it is probably caused by
traces of colloidal gold.

The medicinal value of Epsom spring water was discovered in
the reign of Queen Elizabeth (1558 to 1603). According to local
tradition it happened this wise. One very dry summer a farmer dug
round a spring to make a pond for his cattle. But although dying of
thirst the poor beasts would not touch the water. He marvelled at
this, tasted the water, and marvelled no more. It was "bitter", but
one thing it did do: it kept the flies off. The relaxing action of the
water was soon noticed and by 1640 Epsom Spa had become
famous; in 1695 Nehemiah Grew, a London physician, wrote an
account of the medicinal salt from the spring. In 1700 George and
Francis Moult established a factory for obtaining the salt from a
spring at Shooters Hill near London. In England the salt was
called Epsom Salt, but on the Continent it was referred to as Sal
Anglhum. In such high esteem were the Epsom Salts held that at
St. Bartholomew's Hospital alone, in the early years of the

150

MAGNESIUM AND THE ALKALINE EARTH METALS

century, no fewer than 2^ tons were consumed annually. No
wonder the springs became exhausted and Epsom lost its early
prosperity as a spa.

About this time a white powder was sold in Rome as a medicine,
and its source was kept secret a procedure not unknown e\ten
in recent times with patent medicines. It was a basic carbonate of
magnesium and was called magnesia alba in contrast with black
oxide of manganese, which was often called simply magnesia or
magnesia nigra. It was Black, who, in 1755, first distinguished
between chalk, lime, and slaked lime and between these and
magnesia. He pointed out that the latter gave a soluble salt with
oil of vitriol, whereas lime gave an insoluble compound.

Although up to the close of the eighteenth century lime* was
generally regarded as an element, Lavoisier thought otherwise. He
argued that if certain metals had a greater affinity for oxygen than
carbon had, it might not be possible with the means then available
to reduce their oxides. Hence many substances classed generally
as earths might merely be refractory oxides. Davy was of a like
opinion and his view was supported when he succeeded in isolating
metallic sodium and potassium from their hydroxides. In
November 1 807, only a few days after his successful decomposition
of the alkalis, Davy was taken seriously ill. His medical adviser,
Dr. Babington, attributed it to overwork and excitement. It was
not until March the following year (1808) that he was able to
continue his researches. He then attempted to decompose the
alkaline earths electrolytically. His efforts, however, were unavailing
until he received a communication from Berzelius to the effect that
Pontin and himself had succeeded in preparing amalgams of
calcium and of barium by electrolysing an intimate mixture of
mercury and lime (or baryta). Davy now tried again; he mixed
moist lime with one-third of its weight of mercuric oxide and laid
it on a platinum plate which was made anode. A small cavity in the
centre of the mixture was filled with mercury and rendered cathodic
with a platinum wire. Sufficient amalgam was obtained to enable
Davy to distil off the mercury and obtain a little (impure) calcium*.
[n a similar manner he obtained barium, strontium, and magnesium.
The last-named metal he named magnium, lest it should be confused
svith manganese because, as mentioned above, pyrolusite was known

*DAVY, Phil. Trans., 1808, 98, 341. Also "Alembic Club Reprint 1 ', No. 6, 1894.
BERZELIUS and PONTIN, Gilbert's Annalen, 1810, 36, 255. FRIEND, Nature, 1950,
166, 615.

151

THE CHEMICAL ELEMENTS

variously as manganese, magnesia, and black magnesia; but the
name magnesium has, by common consent, been retained.
Magnesia was the name of a peninsular in East Thessaly where
magnetic iron ore was found (p. 256), and the names of both
mknganese and magnesium appear to have been derived from this
source.

Although barytes is dense the metal barium on isolation was
found to be by no means dense (D 3-78) and E. D. Clarke*,
Professor of Mineralogy at Cambridge from 1808 to 1822,
suggested that the name barium was in consequence a misnomer.
He claimed to have obtained the metal by heating the monoxide to
a high temperature in the oxyhydrogen flame and suggested
that plutonium would be a more appropriate name. In Thomas
Thomson's "System of Chemistryf" the metal is referred to by
this name (p. 326).

Davy's specimens of the metals were both small in amount and
impure. Magnesium was first prepared in coherent form by
Bussy:): in 1829. He ignited a mixture of magnesium chloride and
metallic potassium. Upon extracting the potassium chloride with
water, shining globules of magnesium were left.

Of the various metals of this group, magnesium is by far the
most important in industry.

Magnesium is usually manufactured by electrolysis of the
double chloride KCl.MgCl 2 . It is used in pyrotechny, Bengal and
flash lights. The metallurgist finds it useful in preparing brass free
from blow-holes and in improving nickel castings. It was used
during the war very extensively in making incendiary bombs
which contained some 93 of Mg and 7 of Al. As ribbon and wire it
is used in the degasification of radio valves ; as rods, bars or plates
to replace zinc in batteries as it gives a higher E.M.F. Magnesium
enters in small or large amounts into several important alloys such
as duralumin, magnalium, and electron, the last named consisting
of approximately copper 0-5, zinc 4-5, and magnesium 95 per cent.
The high per cent magnesium alloys are valuable when lightness
combined with strength is required as in aircraft and automobile
industries. Sheet and tubing are utilised in aeroplane fuselages,

*WEBB, Nature, 1947, 160, 164. Reference is made to REV. W. OTTER, "Life
and Remains of Edward Daniel Clarke" (London, 1825).

fTHOMAS THOMSON, "System of Chemistry" (London, 1817) 5th Edition,
Vol. i, p. 342.

JBussv, /. Pharm. Chirn., 1829, 15, 30.

152

MAGNESIUM AND THE ALKALINE EARTH METALS

cabins and steering parts, electric fans and in some musical instru-
ments.

The main use of metallic calcium is as a de-oxidiser in steel
manufacture ; as a hardening agent for lead when it rivals antimony
or tellurium in quantities or less than I per cent; with lead it yields
bearing metals when present in quantities exceeding i per cent;
the Bahn-metall used by German railways contained calcium,
sodium and lead. An alloy .known as ulco comprised lead with less
than i per cent of calcium and barium; it is harder than ordinary
commercial lead alloys, expands on solidification and gives tastings
free from blow-holes. It has been used in shrapnel bullets. Calcium
has also been used in the production of high vacuum, the separation
of argon from nitrogen, as a reducing agent, and also for desiccation
purposes in the laboratory.

Metallic strontium has no industrial application. Metallic
barium finds a limited use in several alloys; e.g., with lead and
calcium in bearing alloys; with aluminium, magnesium or nickel
for radio-valves.

Although radium belongs chemically to this group of elements
it is convenient to discuss it later in a section dealing with the
radio-elements (p. 313).

153

CHAPTER 12

THE ZINC GROUP

THE zinc group comprises oeryinum, zinc ana caamium.

Beryllium

The emerald has been prized from very early times and Cleopatra's
Emerald Mines in Upper Egypt were worked in 1650 B.C.
many* centuries before that famous queen saw the light. Stones
with a bluish-green cast are known as aquamarines and H.M.
Queen Elizabeth is said to have a collection of these, her favourite
stones. The aquamarine is regarded as a lucky stone.

The famous French crystallographer, Ren6 Just Hatiy, enun-
ciator in 1784 of the Law of Rational Intercepts, believed
that substances of identical crystal form must haVe the same
chemical composition as well as the same constitution. This we now
know to be absolutely true. This rule must not be confused with
Mitscherlich's Law of Isomorphism which, of course, is not rigidly
true only approximately so.

Now Hatiy observed that the beryl and the emerald were
geometrically identical and he asked Vauquelin to compare their
analyses. The beryl had hitherto been regarded as calcium alumin-
ium silicate, but Vauquelin showed that not only were the beryl
and emerald identical chemically but that they contained a new
element, the oxide of which he called terre du BeriL This result was
published in 1798 and the new earth was called la glucine at the
suggestion of the editor of the Annales de Chimie et de Physique
because Vauquelin stated that its salts were at first sweet to the
taste. The Germans, however, adopted the term Eeryllerde and the
names glucinum and beryllium were subsequently adopted to
denote the metal itself. In 1924 the Chemical Society decided to
adopt the name beryllium instead of glucinum a very sensible
decision, though perhaps somewhat long overdue.

The metal itself was not isolated for many years. In 1828
Bussy* and Wflhlerf independently obtained it by reduction of the

*BUSSY, Dingier' s Poly. /., 1828, 29, 466.
fWdHLER, Ann. Chim. Phys., 1828, (2), 39, 77.

154

THE ZINC GROUP

chloride with metallic potassium. It is now usually prepared by
electrolysis of the double fluoride, K ? BeF 4 .

Owing to the resemblance of its compounds to those of
aluminium it was at first thought that beryllium would be trivalent.
This received support from specific heat determinations and the
application of Dulong and Petit's rule. The combining weight of
beryllium was found to be 4-7, and Berzelius regaVded it as
trivalent, so that its atomic weight was roughly 14. Its specific heat
between o and 100 C. was 0*42 giving an atomic weight of
approximately 6-4 -f- 0*42 or 15-2. This supported Berzelius.

Mendel^eff had no room in his Periodic Table for an element
with this atomic weight ; he had, however, a vacancy for one f of 9
and in his table dated 1869 (? I 7) ^ e placed beryllium between
lithium and boron, ascribing to it a valency of two. Confirmation
was afforded when in 1884 Nilson and Pettersson* determined the
vapour density of its chloride, showing its formula to be BeCl 2 , and
again when in 1887 Mallardf observed that crystallised beryllia
is isomorphous with crystallised zinc oxide, ZnO, and must there-
fore have a similar structure, namely BeO.

Beryllium is too expensive to be widely used as a metal by itself
or as the main constituent of alloys. It is claimed that 2-5 per cent of
beryllium added to copper is useful for springs, giving a sixfold
tensile strength and higher fatigue endurance limit especially under
conditions of corrosion. One per cent added to silver is said to make
it resistant to tarnish. The alloy is heated in hydrogen to 400 with
a little water vapour whereby a thin protective film of oxide is
produced.

Pure beryllium is now being used in the construction of the
metal "windows" of X-ray tubes as it is more transparent to the
rays than aluminium.

Zinc

Metallic zinc was not known to the ancients. The "brass" of the
Old Testament was not usually our alloy of copper and zinc, but
bronze, that is an alloy of copper and tin, although apparently
brass was occasionally made by accident when copper ores contain-
ing zinc were reduced (p. 99). Certainly metallic zinc was not known,

*NILSON and PETTERSSON, Compt. rend., 1884, 98, 588; Ann. Chim. Phys., 1886,
(6)' 9 554* COMBES (Compt. rend., 1894, 119, 1222) proved in a similar manner
that Be is divalent in its acetylacetonate, Be(C,H 7 O g ),.

fMALLARD, Zeitsch. Krysl. Min. t 1888, 14, 605; 1888, 15, 650.

155

THE CHEMICAL ELEMENTS

cither, to the Egyptians as they had no word for it. Brass was well
known to the Romans, but they made it by reducing calamine, or
natural zinc carbonate, with charcoal in the presence of copper;
brass was thus produced without the isolation of the zinc.

The Indians appear to have been the first to obtain the metal.
In the Rasarnava Tantra*, written about A.D.I 200, a flood of light
is thrown on the scientific knowledge of the Hindoos of the twelfth
century. The tantra takes the form of a dialogue between the God
Siva and his consort. We are told that "calamine mixed with wool,
lac, ." . . and borax, and heated in a covered crucible yields an
essence of the appearance of tin." Obviously this "essence" was
zinc, although the Indian alchemists did not at first recognise it as
a separate metal. But in the medical Lexicon ascribed to King
Madanapala, written probably in 1374, zinc is clearly regarded as
an individual metal under the name of Jasada. It would thus
appear that the smelting of zinc was first carried out in India.
From thence the art may have been carried to China or it may have
been independently developed there. The Chinese were certainly
acquainted with the metal'in the sixteenth century; slabs of zinc of
98 per cent purity have been found in the Kuang Tung Province,
dating back to 1588. A primitive method of extracting the metal
from its ore is described in the Chinese book Tien kong kai wu
of 1637.

The term zinkum was apparently first used by the arch-
alchemist Paracelsus (1493 to 1541) and was applied, for long
after, to both ore and metal. The word spelter, applied to commer-
cial zinc, is regarded as allied to German Spiauter or Spialter
pewter, and dates from the time of Boyle.

In 1546 Agricola (p. 50) mentioned a white metal counter/ ei
found on the walls of furnaces smelting lead ore at Goslar in the
Harz. This may have been zinc.

During the seventeenth century the nature of zinc was mis-
understood; it was frequently confused with bismuth. In 1695
Homberg identified it as the metal in blende and about 1700
Johann Kunckel von Lflwenstein recognised that calamine contains
a metal that alloys with copper in the manufacture of brass. It may
be recalled that both Homberg and Kunckel played an important
r6le in the discovery of phosphorus (p. 76). Percy states that
Henckel was the first person in Europe to make metallic zinc from

*P. C. RAY, "A History of Hindu Chemistry" (Williams and Norgate), 1902,
Volume i, pp. 39, 86.

156

THE ZINC GROUP

calamine direct in 1721. In 1738 William Champion patented a
method of obtaining the metal, likewise from calamine, and in 1743
erected a zinc factory at Bristol. The first Continental zinc works
were established at Lige in 1807. The production of zinc in this
country in the middle of the eighteenth century was small, "the
metal being imported from China and India as required. In 1731 it
cost some .260 per ton. By 1820 the production had increased so
much that the export of zinc from England about equalled the
total imports, so that the country was in effect self-supporting as
regards the metal.

Metallic zinc in one form or another finds a very wide application
in commerce. Zinc dust, under the name of zinc fume or, blue
powder which is really a mixture of zinc and its oxide is used
as a reducing agent, for example, in dye manufacture. Zinc
shavings are precipitants for gold and silver. Zinc is sometimes
used in coinage as sharp impressions are obtainable. In 1920, after
World War I, Belgium was using zinc coins. They were very
unpleasant to handle and left one's pockets in a messy state. In
France zinc is used for statuettes, etc, these being usually coloured
or bronzed afterwards. Some of the statuettes contain about 1 7 per
cent copper as the alloy yields a sharp impression on casting.
Important alloys such as brass, delta metal, nickel silver (p. 297)
and our silver coinage (p. 1 17), have already been referred to or are
dealt with later. Motor-car handles are made of an alloy containing
94 to 95 zinc, 4 Al, i to 2 Cu and 0-25 to 0-5 Mg.

An enormous amount of zinc is used in wet galvanising, a
process that was patented by Crawfurd in 1837. It is still a more
or less rule-of-thumb procedure and although only one quality of
galvanised iron is recognised the amount of zinc actually present
on the steel varies greatly. As a rule the resistance is roughly
proportional to the amount of zinc present. In 1935 R. H. Vallance
and the writer analysed several galvanised articles and were
surprised at the variation in zinc content. A few of the results are
as follow

Sheet iron (i) . . . . . . 0-54 oz. per sq. ft.

(ii) 0-72

Soap rack .. .. .. 1-23

Bucket 1-36

Handbowl . . . . . . 1*94

The thickest Admiralty Specification is 1-25 oz.

157

THE CHEMICAL ELEMENTS

Sherardising) a process which was introduced by Cowper Coles in
1900, and since 1923 firmly established as a trade in this country,
as well as the direct spraying of zinc, afford further uses for the
metal. Minor uses are in making the so-called zinc-copper couples,
in granulated form in various chemical experiments in laboratories,
as anodes in cells such as Lechanch and dry cells used extensively
for bells in domestic service. Zinc "plating** of the inside of the
nose was prescribed at one of the London Hospitals in 1937 as
part of "defence measures" for hay fever victims.

Cadmium

The, discovery of cadmium solved a puzzling pharmaceutica
problem. Friedrich Stromeyer*, professor of medicine at Gftttingen
was also the Inspector General of the Hanoverian pharmacists. In
1817 he noticed that zinc carbonate was being used in a certain
area instead of the prescribed zinc oxide in compounding a certain
preparation. Upon inquiry he was informed that, on ignition to
oxide, the zinc carbonate developed an orange-yellow colour,
though apparently free from iron and lead. As this rendered it un-
suitable for the purpose in hand, white zinc carbonate had been
substituted. On dissolution in acid, the coloured oxide gave a
yellow precipitate with hydrogen sulphide which it was feared was
arsenic sulphide.

"This information induced me", wrote Stromeyer,"to examine
the oxide of zinc more carefully and I found, to my surprise, that
the colour it assumed was due to the presence of a peculiar
metallic oxide, the existence of which had not hitherto been sus-
pected. I succeeded by a peculiar process in freeing it from the
oxide of zinc and in reducing it to the metallic state." -

This metal Stromeyer named cadmium, since cadmia is an old
name for calamine or zinc carbonate, derived from the Lat. calamus
reed, in allusion to its slender stalactitic forms. To avoid confusion
it should be mentioned that American mineralogists know natural
zinc carbonate under the name of smithsonite, after Smithson, who
founded the Smithsonian Institute at Washington, and who
analysed the mineral in 1803. Unfortunately, the Americans use
the term calamine to designate our hemimorphite, ZnjSiC^.HjO,
or more probably Z^OH^.ZnaSiaCVHgO, since one half of the

*STROMEYER, Ann. Chim. Phys., 1819, (2), 11, 76. Gilbert's Annalen, 1818, 60,
193. Schweigger's /., 1818, 22, 362.

158

THE ZINC GROUP

total water content can be removed without destruction of the
crystal, but not more than half.

The pure metal is used in the cadmium and Weston standard
cells, invaluable for the accurate determination of E.M.F's. It is
sprayed on to steel to protect against corrosion ; sometimes it is plated
on to steel prior to chromium plating. Alloys of cadmium with 2 per

cent of Ni, or of 2-25 Ag plus 0-25 Cu are used in ^automobiles
etc, as handles, and for other purposes.

Many alloys melting at low temperatures contain cadmium;
these are useful as fusible metals. Thus, Wood's alloy contains
4 Bi, 2 Pb, i Sn and i Cd; it melts at about 70 C. (p. 88).
Extensive use is made of cadmium in bearing alloys, the other
metals being nickel, nickel -f- silver, copper -f- silver, or copper -f-
magnesium. These alloys have low coefficients of friction, greater
resistance to fatigue, and are harder than the tin-base Babbitts.
Unfortunately, they are easily attacked by organic acids in lubrica-
ting oils. To improve their resistance to these they are first plated
with indium and then heated to permit diffusion of indium into the
Hoy. Such alloys are known as cadmium base white bearing metals
(p. 1 66).

Both the metre and the yard have now been measured in terms
of the cadmium red spectral line (p. 308).

159

CHAPTER 13

THE ALUMINIUM GROUP

THE aluminium group comprises aluminium, indium and thallium

Aluminium

The Romans used the term alumen to denote substances of an
astringent taste. One of these was a crystalline substance well known
to Geber (died A.D. 765) and the later alchemists, who classed it
with the vitriols. This was our "alum".

The production of alum is an industry of great antiquity. Until
about 1450 most of the alum used in Europe came from Asia
Minor, the trade being mainly in the hands of the Genoese. In 1451
Henry vi, being "hard up", confiscated all the Allow foyle belonging
to the Genoese merchants at Southampton to the value of 8000
a very considerable sum in those days. Presumably Henry sold this
alum to English purchasers and thus obtained the needed ready
money*.

The alum trade in those days was a most important one; it even
formed the subject of papal bulls and interdicts, and entered into
the correspondence of kings, popes and cardinals.

It was during the fifteenth century that several alum works were
established in Italy. The most famous of these was at Tolfa near
Civitavecchia, the seaport of Rome, and the ancient Centum Cellae,
whose harbour was planned by Trajan about A.D. 100. Tolfa is the
chief place among volcanic mountains of the same name which,
although extinct, still emit vapours. In this district the manufacture
of so-called "Roman alum" was for centuries an industry of great
importance. Baedeker summarises the present position somewhat
laconically in the words "The mines are no longer of great import-
ance, but the scenery is picturesque."

Pope Pius ii described the origin of this industry. He stated
that in May 1462, Giovanni de Castro, of Padua, whilst travelling
over the mountains of Tolfa, observed a plant which*he knew also
grew on the alum mountains of Asia Minor. This led him to look

*A detailed account of the alum trade is given by RHYS JENKINS, Trans.
S.E. Union of Scientific Societies, 1914, p. 57. Science Progress, 1915, 9, 488.

160

THE ALUMINIUM GROUP

for alum and he found some white stones with a salt-like taste
which proved to be of a similiar nature to alum. It was alunite, or
alum rocky a basic double sulphate of aluminium and potassium
usually formulated as K 2 SO 4 .A1 2 (SO 4 ) 3 .4A1(OH)3. It was 9nly
necessary to leach with water and crystallise the alum from the
clear solution.

It is better, of course, to calcine and treat the product with
dilute sulphuric acid. This gives a solution containing excess
aluminium sulphate, and addition of potassium sulphate enables all
the aluminium salt to be converted into alum. This has long been
the recognised procedure.

De Castro hastened to acquaint His Holiness with his discovery
and the latter, after a little initial scepticism, saw in this discovery
the hand of God. With true Christian charity he "determined to
employ the gift of God to His Glory in the Turkish War and
exhorted all Christians henceforth to purchase alum only from him
and not from the Turkish infidels." The mine was soon in operation
and by 1463 some 8000 persons were engaged, and the papal
treasury was enriched to the tune of some 100,000 ducats per
annum. The following year Pope Paul n, who succeeded Pius n,
launched a Bull excommunicating all who purchased alum from
the unbelievers and thus set up a papal monopoly of alum in
Europe. There was a rise in price and Charles the Bold decided in
1467 to allow his people to buy their alum anywhere they liked.
This annoyed the Pope who threatened Charles with personal
excommunication, and he capitulated.

The Tolfa alum was markedly superior to that brought from the
east and was largely purchased by dyers and the demand rapidly
increased. Despite the papal Bull, however, our Kings, with
characteristic British independence reserved the right to purchase
alum where they chose, and one Pietro Aliprando, writing in
December 1472 to the Duke of Milan, was very outspoken in
his views of the obstinate British. "In the morning", he wrote,
"they are as devout as angels, but after dinner they are like
devils, seeking to throw the Pope's messenger into the sea," In
1545, King Henry vin arranged to take papal alum in exchange
for lead, of which he had immense quantities presumably as the
result of spoliation of the monasteries. The alum was brought by
sea from Cadiz and stored in the "late dissolved house of Fryer
Augustynes". This was regarded as a good transaction because alum
was necessary for the dyeing industry.

161

THE CHEMICAL ELEMENTS

Alum was also produced from alum shale at an early date. Alum
shales contain pyrites which on prolonged weathering, disintegrate
and oxidise to sulphuric acid, which attacks the clay essentially
alujninium silicate yielding aluminium sulphate and other
substances. Both Agricola (1494 to 1555) and Libavius (1540 to
1616) knew that, in order to obtain crystals from the solution
obtained by leaching the weathered shales, it was necessary to add
an alkali. Both writers mention the practice of adding decomposed
urine for the purpose. The salt obtained would thus be essentially
ammonium alum, whereas the papal alum was obviously the
potassium salt. It was not until 1797 that Chaptal and Vauquelin
showed that ammonia and potash are vicarious in alum. This
explained why alum could be obtained from alunite without
addition of alkali, since the potash was already present as sulphate,
whereas it was not present in the Whitby shales.

The discovery of the alum shales in the Upper Lias in the N.
Riding of Yorkshire was due to Thomas Chaloner who, with others,
obtained a joint patent for the manufacture of alum in England for
31 years in 1607. The work was so successful that King James i
(1603 to 1625) became interested and decided that the Crown
should share the profits. In 1609 Chaloner's monopoly was trans-
ferred to the Crown and, to stifle competition and thus counter the
adverse effects that might follow through any rise in price due to
maladministration, the importation of alum from abroad was
prohibited. The usual result of "nationalisation" accrued; for many
years the industry was not a success; by 1637 things had improved
and the Yorkshire industry reached its zenith in the latter half of
the eighteenth century; it then gradually declined to extinction.

In 1754 Marggraf showed that alumina and lime are two distinct
earths and that alumina is the earth present along with silica in clay.
Davy, after his brilliant success in isolating the alkali and alkaline
earth metals by electrolysis, endeavoured in a similar manner to
obtain aluminium, but failed. But Oersted, discoverer of the
magnetic action of the electric current, succeeded in 1825 by
acting on aluminium chloride with potassium amalgam. The
resulting aluminium amalgam was then distilled in the absence of
air, leaving a residue of metallic aluminium, which in colour and
lustre was stated to resemble tin. In 1827, W6hler, who found
himself unable to repeat Oersted's experiment, obtained the metal
by decomposing the anhydrous chloride with metallic potassium.
In both cases the products were impure.

162

THE ALUMINIUM GROUP

The French chemist, Henri St. Claire Deville was the first to
obtain pure aluminium. In 1854, he prepared the double chloride
NaCl.AlQ 3 , and, by heating this with sodium, succeeded in isolating
pure aluminium.

In June 1881, James Fern Webster patented a process for
producing aluminium and erected what is claimed to be the world's
first factory at Solihull Lodge, near Birmingham. The output was
about 20 tons weekly and in 1883 a large consignment was sent to
the Calcutta Exhibition, where it was awarded two gold medals.
Although one or two patents were taken out the main process was
secret.

In 1886, Charles Hall, an American, and the Frenchman, Paul
H6roult, solved the problem of producing aluminium electro-
lytically from alumina in a bath of molten cryolite. Hall died in
1914, leaving a fortune of nearly 6 million. H6roult died the same
year ; both men were only 5 1 years of age at the time of their decease.

The first authentic article of aluminium was a rattle for the
infant destined later to become Emperor Napoleon in. In 1854, an
aluminium medal was struck and presented to him, and he both
authorised and financed experiments to manufacture the metal on
a larger scale. He had visions of supplying his troops with helmets
and breastplates of aluminium, but its price of over 100 per Ib.
.rendered the proposition hopeless. After the invention of the Hall-
H&roult electrolytic process the price fell to about 85 per ton in
1914. The world consumption in 1938 was 550,000 tons, and by
1941 it was close upon one million tons. It was stated in October
1939, that bullet-proof duralumin armour was among Germany's
new methods of warfare on the Western Front.

Owing to its low density, 2-7 (tin is 7-3) aluminium and its
alloys, also of low density, are particularly valuable for aircraft
production. Small quantities of certain alloying elements increase
the tensile strength to that of mild steel. Thus duralumin, contain-
ing up to 5 per cent copper and small amounts of magnesium,
manganese, silicon and iron, may have a tensile strength of 30-5
tons per sq. in., and will weigh only one third as much as corres-
ponding steel plates.

Cooking utensils are made of aluminium, and elaborate
experiments indicate that, if any aluminium thereby enters the
system, it soon leaves the system and does no harm.

Aluminium is used in electric transmission in place of copper;
it is added to molten steel prior to casting to prevent blow holes. It

163

THE CHEMICAL ELEMENTS

is useful as a reducing agent in the production of certain metals, and
in the manufacture of thermit. The action of this latter is due to the
enormous heat of union of aluminium with oxygen, namely,
399,040 gram calories per 54 grams of metal.

In 1938 an aluminium wire was on exhibit at the Glasgow
Empire Exhibition, of diameter o-oooi in. It was calculated that
i oz. of this wire would cost some 5 million and would encircle
the earth at the equator 1200 times. Some 600 of these hairs would
be equivalent to a human hair.

Although it readily combines with oxygen, aluminium is
resistant to atmospheric corrosion because a thin film of closely
adherent oxide is formed which protects the underlying metal from
attack. Aluminium powder is therefore used as a pigment in anti-
corrosive paints.

In 1936 sen coins in Japan were made of aluminium.

The excessive wear of aluminium pistons in internal combustion
engines has been traced to oxidation with production of amorphous
oxide, A1 2 O 8 , which hardens to corundum, which is strongly
abrasive. To prevent this, magnesium is added to the aluminium;
this on oxidation gives spinel, MgO.Al 2 O 3 , which is amorphous,
stable and not abrasive. This is termed "spinelising".

The surface of aluminium may be allowed to undergo superficial
oxidation and then dyed with various dyes to give beautiful effects.
The explosive ammonal, used in mining, consists of 4 to 6 parts of
aluminium the remainder being ammonium nitrate.

Aluminium yields many valuable alloys. Magnalium consists of
aluminium with I to 2 per cent of magnesium ; duralumin contains
up to 5 per cent of copper with small amounts of Mg, Mn, Fe, and
Si; it has a low coefficient of expansion with rise of temperature, and
plates of duralumin are only one-third the weight of equally strong
steel ones. There is a growing interest in aluminium bronzes,
alloys of aluminium and copper which are resistant to seawater and
certain concentrations of sulphuric acid. Alloys of aluminium and
silicon are also becoming important.

The first bridge of aluminium alloy was opened at Sunderland
in 1948, It has a span of 95 feet and is designed to carry road and
rail.

Indium

In one sense the discovery of thallium led to that of indium as did

164

THE ALUMINIUM GROUP

the discovery of caesium to that of rubidium. Ferdinand Reich*,
professor of physics at Freiberg, was examining some local zinc
ores and in 1863 obtained a yellow precipitate (In 2 Sg) on passing
hydrogen sulphide into an almost neutral solution, arsenic, etc,
having been previously removed from the ore by roasting. He
concluded that this contained a hitherto unknown element and asked
his assistant Hieronymus Theodor Richter to examine the
precipitate spectroscopically as he himself was colour blind. Richter
noticed a brilliant line ^45 12 in the dark blue region which did not
coincide with either of the caesium lines 4555, 4593- This was
taken to confirm the existence of a new element, and it was
appropriately decided to call it indium from indigo. The element was
studied in detail by Winklerf a few years later.

Indium occurs in widespread association with both zinc and
tin ores. It seems improbable that this can be due to chemical
segregation, for isomorphism of indium and tin compounds, for
example, appears to be ruled out by their difference both in valency
and atomic radius. It has been suggested^ that the tin isotope 115
has gradually been transmuted into iAdium 1 1 5 by loss of an
electron and a neutrino. The process is presumed to take place
extremely slowly so that in finite time it escapes observation. Tin
has eleven natural isotopes; of these Sn 115 constitutes 0^44 per
cent. Indium comprises In 115, 95*5, and In 113, 4-5 per cent.
The high percentage of isotope 1 1 5 in natural indium is in harmony
with the above suggestion.

The chlorides of indium are of considerable historical interest.
Kekul regarded valency as a fundamental property of the atom, as
unchangeable and invariable as the atomic weight. This view he
retained to the last. Apparent exceptions certainly existed. Carbon
monoxide could, however, readily be explained on the assumption
that the two unused valencies of the carbon atom saturate each other;
mercurous salts, such as the chloride, possessed the double formula,
Cl-Hg-Hg-Cl, and so on. In 1888, however, Nilson and Pettersson
showed that three distinct chlorides of indium can exist in the
vapour state. To these they gave the formulae InCl, InCl 2 and

*REICH and RICHTER, /. prakt. Chem., 1863, 89, 441; 1863, 90, 172; 1864, 92
480. RICHTER, Compt. rend., 1867, 64, 827.

fWiNKLER, /. prakt. Chem., 1865, 94, i; 1865, 95, 414; 1867, 102, 273.

{EASTMAN, Physical Review, 1937, 52, 1226. But AHRENS dissents from this
view (Nature, 1948, 162, 414).

NILSON and PETTERSSON, Trans. Chem. Soc., 1888, 53, 814. Zeitsch physikal
Chem., 1888, 2, 657.

165

THE CHEMICAL ELEMENTS

InQ 3 , respectively. This was the first clear example of an element
showing three valencies; these could not be explained away by
association or self-neutralisation in Kekul^'s manner, and were
regarded as definitely establishing the principle of multiple valency.
Ncf one doubts this principle to-day, though indium may not of
necessity be divalent in InCl 2 ; it may perhaps be a complex, such
as In[InO 4 ] or indium tetrachlorindiate, the indium atoms
functioning with valencies of one and three, respectively.

On account of its relatively low melting point (i56'4 C) and
high boiling point (2087 Q indium has an unusually large liquid
range; its use in high temperature thermometry has been advocated.
An alloy of 1 8 per cent of indium with Wood's metal (p. 1 59) melts
at 46 C. Small amounts up to 5 per cent are added to jewellery to
increase the hardness. A 42 per cent alloy with silver is untarnish-
able; but the cost is high and the alloy is difficult to work. It is
more usual, therefore, to plate silver with indium and then by
suitable heat treatment to induce the formation of a thin surface
layer of untarnishable alloy. Indium is also used in dental alloys;
it is also plated on to cadm'ium base white metal bearing alloys, and
heated to 340 F (170 C) to diffuse it inwards whereby resistance
to corrosion by organic acids in lubricating oils is enhanced.

Thallium

Thallium was discovered independently by Sir William Crookes*
in England and by the Belgian chemist M. Lamy. Crookes was
the first to make the discovery. He was the founder and editor of
the now defunct Chemical News which, in its day, was a valuable
contribution to scientific literature. In March 1861 he was engaged
in extracting selenium from a deposit obtained from a sulphuric
acid factory at Tilkerode in the Harz. Bunsen and Kirchhoff had
just announced their discovery of caesium and rubidium with the
aid of the spectroscope (p. 147), so Crookes tested his material in a
similar manner.

He noticed a new line in the green portion of the spectrum and
in accordance with the Bunsen-Kirchhoff rule then recently
enunciated, concluded that a new element was present to which he
gave the name thallium from Greek thallos^ a young shoot or green
twig.

*CROOKES, Chem. News., 1861, 3, 193, 303. Phil. Mag., 1861, (4), 21, 301.
FOURNIER D'ALBB, "The Life of Sir William Crookes" (Unwin, 1923), Chapters
7, 8 and 13.

THE ALUMINIUM GROUP

At first Crookes thought the new element was probably a metalloid
like selenium. His early work was hampered by lack of material,
but eventually he found that thallium was a metal and in May 1862
was able to exhibit a few grains in powder form.

In April 1862, Claude August Lamy* independently observed
the same green line due to thallium in the spectrum obtained from
slime from a sulphuric acid works at Loos, where Belgian pyrites
were used. More fortunate than Crookes he had considerable
quantities of material at his disposal and soon established the
metallic nature of thallium. In May of the same year he, was able
to display a lump of the metal and before the end of the year he
isolated several hundred grams and gave a fairly complete account
of the physical and chemical properties of the metal. *

For some time the question of the priority of these two chemists
was an unfortunate cause of dispute. There can be no doubt, how-
ever, that Crookes was the first to observe the green line and it
appears highly probable, too, that he was also the first to obtain the
metal ; he claimed to have obtained it as a black powder as early as
1st May 1862.

At this time the Periodic Classification had not been formulated
and it was difficult to decide to which group of elements thallium
should be assigned. The metal resembles lead in many of its
physical properties and a number of thallous compounds likewise
resembled those of lead. Other thallous salts were found to be
isomorphous with those of potassium and the spectrum of thallium
was simple like the spectra of the alkali metals. To add to the
uncertainty, thallic compounds resembled those of aluminium.
For these reasons Dumas referred to thallium as "the paradoxical
metal" and "the ornithorynchus of the metals". Mendeleff, with
characteristic courage, classed thallium with the aluminium metals
in his Periodic Table in 1869, and subsequent research has fully
justified this arrangement. With an atomic number 81 it lies
between mercury (80) and lead (82) and whilst in the monovalent
state it shows analogy with the alkali metals, in the trivalent state
it is a true congener of indium.

*LAMY, Compt. rend., 1862, 54, 1255; 1862, 55, 836. Ann. Chim. Phys., 1863,
(3), 67, 385-

167

CHAPTER 14

MENDELEEFF'S PREDICTEES

MENDELEEFF'S predictees include scandium, gallium and german-
ium.

When once the Atomic Theory, as enunciated by John Dalton,
circa 1803, had been accepted, numerous attempts were made by
chemists to discover some method of grouping together those
isola/ed portions of matter known as elements.

In 1 8 1 6 Doebereiner directed attention to the curious fact that
certain triads of elements existed in which the elements showed
both a peculiar regularity in their atomic weights and a close
similarity in chemical properties. For several years, however, the
subject was allowed to drop into abeyance until Dumas in 1851
again brought it to the fore; both he and other chemists added to
the examples. Sulphur, selenium and tellurium were typical; the
atomic weight of selenium was practically the mean of those of
sulphur and tellurium. Five such triads were found, namely

Atomic
Weights

Means

Atomic
Weights

Means

Lithium
Sodium
Potassium

6-940
22-997
39-096

23-018

Sulphur
Selenium
Tellurium

32-06
78-96
127-61

79-84

Calcium
Strontium
Barium

40-08
87-63
I37-36

88-72

Chlorine
Bromine
Iodine

35'457
79-916
126-92

81-19

Phosphorus
Arsenic
Antimony

30-98
74-91
121-76

76-37

At first it was hoped that all the elements might ultimately be
grouped into these triads and that in this way a complete system of

168

MENDELEEFF'S PREDICTEES

classifying might be evolved, for the Periodic Classification had
not then been introduced. These hopes were, however, doomed to
failure and a severe blow was struck at the utility of the triads when
Cooke showed that some of them actually broke into natural
groups of four or five closely related elements, as in the case of 4he
halogens and the alkali metals respectively.

A second group of triads was also known in which *the atomic
weights of the constituent elements were closely similar; these
were the iron and platinum metals. In the accompanying list the
modern atomic weights are used as in the previous table..

Iron .. 55-85 Ruthenium.. 101-7 Osmium .. 190-2
Cobalt .. 58-94 Rhodium .. 102-91 Iridium .. 193-1
Nickel . . 58-69 Palladium . . 106-7 Platinum . . 195-23

Some years later, when the atomic weights had been revised by
Cannizzaro, Chancourtois observed that certain remarkable reg-
ularities were brought out by arranging the elements in the order of
increasing atomic weights, and in 1862 he arranged them in a
spiral round a vertical cylinder divided into 16 vertical sections
known as the Telluric Screw. The elements in any vertical section
were seen to possess analogous chemical and physical properties.

About this time Newlands was working along similar lines and
in a series of papers from 1864 to 1866 introduced his generalisa-
tion known as The Law of Octaves. In a series of short papers he
showed that when the elements are arranged in order of increasing
atomic weights, similarities between their properties become
apparent periodically between the first and last of every eight
elements. Thus lithium, sodium and potassium resembled each
other; counting lithium as I, sodium was 8; with sodium I,
potassium was 8, and so on. Hence the term octave. At first
Newlands' papers were ridiculed and the coincidences ascribed to
chance. In 1866, at a meeting of the Chemical Society when a
paper entitled "The Law of Octaves and the Causes of the
Numerical Relations among the Atomic Weights" was being
discussed, one cynic inquired if Newlands had ever examined the
elements according to their initial letters and suggested that such
a study might prove profitable. Newlands, however, did not pursue
the subject.

In 1869 and in subsequent years Lothar Meyer and Mendel^eff
independently made similar observations and these generalisations
came to be known as the Periodic Law.

169

THE CHEMICAL ELEMENTS

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170

MENDELEEFF S PREDICTEES

Can any good come out of Nazareth? Prophets often remain
unrecognised in their own country. As soon as Meyer and
Mendel^eff recognised the periodicity of the elements, the British
began to think that after all there might be something in Newlands'
observations. At that time, however, not only was the number/ of
elements known to the chemist relatively small but the values
assigned to their atomic weights were often faulty, even* when their
equivalent weights were known with reasonable accuracy. Thus
the atomic weight assigned to beryllium was 14, indium 76 and
uranium 120, and these values threw them out of their true
positions. As more elements were discovered and their atomic
weights correctly determined, the general truth of the Periodic
Law came to be appreciated and attempts were made to bring; the
recalcitrant elements into line.

The periodic table drawn up by Mendel6eff in 1869, as it
appeared when published in English in 1871, is shown on p. 170.
It is much the same as the modern Ideal Periodic Table^ shown
on page 5, in which the elements are arranged in the order
of the increasing electric charge on tho atomic nucleus, which is
much the same as the order of increasing atomic weights. There is
one important difference, namely the inclusion of the inert gases in
column "o" by William Ramsay; these gases were of course unknown
in 1869. This scheme was an enormous advance on anything
which an arrangement based on the Doebereiner triads could hope
to be. The vertical groups held not only all the triads but the other
elements associated with them, so that natural groups were no
longer dissected. Thus the 5 alkali metals and the 4 halogens fell
into groups i and vi respectively. There were, however, certain
difficulties; but Mendel^eff, believing in the real existence of
periodicity, felt that these were due to incorrect data and sought
means of harmonising all the discrepancies.

Taking the three elements mentioned above, Mendel^eff
suggested that, as their equivalent weights were well known, it
might well be that the valencies assigned to them were incorrect.
Thus from its resemblance to aluminium, beryllium was regarded
as trivalent and its atomic weight was in consequence taken as
4*7 X 3 or 14-1; if, however, the analogy were mistaken and
beryllium ought really to be compared with magnesium and
calcium, its valency would be 2 and its atomic weight in consequence
4*7 x 2 or 9*4. In that event there was room in his table.
Mendeleff therefore assumed that this was correct and boldly

171

THE CHEMICAL ELEMENTS

placed beryllium at the head of group n. Similarly he assumed that
indium was trivalent, resembling aluminium rather than zinc, so
that its atomic weight became 1 13 instead of 76; he also assumed
that uranium was hexavalent like sulphur, not trivalent like iron,
tht;s raising its atomic weight from 120 to 240. These three
recalcitrant elements then fell into line. Subsequent work has fully
justified these manoeuvres.

Even so there remained three important gaps in the fourth and
, fifth rows of the table. Mendel^eff again took his courage in both
hands and suggested that these pointed to the existence of three
elements as yet unknown to science. He named them eka-boron,
^-aluminium and eka-si\icon respectively; moreover he went so
far as to indicate the general properties these elements would
be found to possess when discovered.

In due course these elements were discovered and christened
scandium, gallium and germanium respectively. They were found to
possess properties remarkably close to those predicted by
Mendeleeff, and their discovery removed all lingering doubts as
to the importance of the Periodic Law.

Scandium

In 1879 Nilson was extracting ytterbia from euxenite a complex
niobo-tftanate of yttrium and uranium and from gadolinite a
basic ortho silicate of iron, beryllium, and the yttrium earths
named after Gadolin, the Finnish mineralogist. He used the method
adopted the previous year by Marignac, the discoverer of ytterbia,
and obtained some 63 grams of "earth" which he converted into
nitrate and fractionally decomposed by heat a favourite method
of fractionation, first adopted by Berlin in 1860. To his surprise he
found that it contained a small amount (actually only 0*3 gram) of
an entirely new earth characterised by feeble basicity, a very low
chemical equivalent, and a new spark spectrum. To this new earth
he gave the name scandia in honour of his native Scandinavia. A
little later Nilson obtained a further supply of scandia, described
some salts, and determined the atomic weight of the metal,
scandium. It was Cleve who, in the same year (1879), pointed out
that the properties of the element agreed with those predicted by
Mendeleff for eka-boron.

In many respects scandium resembles the rare earth metals, but
not so closely as does yttrium (p. 178). Like the rares it is found in
small quantities in many minerals, it is trivalent yet yields neither

172

MENDELBEFF'S PREDICT EES

an alum nor alkyl or aryl derivatives; its oxalate is insoluble in
water and dilute acids and it yields double platino-cyanides. Never-
theless, it is not now usually regarded as a true rare earth, since in
many ways it presents notable contrasts. Thus, for example, its
acetyl acetonate sublimes without decomposition, like that* of
thorium; its fluoride, ScF 3 , again like that of thorium, ThF 4 , is
insoluble in mineral acids and affords a convenient 1 method of
separating scandium from the rare earth metals whose fluorides
are soluble. A further difference lies in the tendency for scandium
sulphate to yield complex ions in aqueous solution. Addition of
barium chloride does not at once precipitate all the sulphate ion as
barium sulphate. It is concluded that the salt has the constitution
Sc[Sc(SO 4 ) 3 ], that is, it is scandium sulphato-scandiate, analogous
to cadmium iodo-cadmiate, Cd[CdI 4 ]. In each of these and in many
other ways the scandium derivative behaves differently from the
corresponding rare earth one.

For many years an atomic weight of 44-1 was accepted for
scandium, but in 1923 Aston showed that the element had no
isotopes and that its atomic mass relative to oxygen 16 was 45.
As a result of fresh chemical investigation, the atomic weight 45-1
was accepted by the International Committee in 1925, and this
value is accepted to-day (1950).

Gallium

In August 1875, Boisbaudran observed a pair of violet lines in the
spark spectrum of some material he had separated from zinc blende
from the Pierrefitte mine, from which he concluded the presence
of a new element. This he named gallium in honour of his native
country. Later in the year he obtained a small quantity of the free
metal by electrolysis of a solution of gallium hydroxide in caustic
potash. It was Mendel^efF himself who, in November 1875,
suggested the identity of this element with ^-aluminium, and further
study of its properties and those of its compounds confirmed this view.
Gallium has a very wide range of liquidity; it melts at 30 and
boils at 1 600 C, and may therefore be used as the liquid indicator
in a quartz thermometer at temperatures much higher than the
ordinary mercury thermometer.

Germanium

Towards the close of 1885 Welsbach discovered a new mineral in
the Himmelsfiirst mine near Freiberg, Saxony. This he called

173

THE CHEMICAL ELEMENTS

argyrodite from its metallic lustre and the fact that it contains silver
(Greek arguros, silver). On the assumption that the mineral was
essentially silver sulphide, which a qualitative analysis by Richter
had indicated, Winkler (1838 to 1904) was requested by Welsbach
to tnake a quantitative analysis. He did so, but, as in Plattner's
examination of polluxite (p. 147), his analysis only added up to
some 93 pel* cent. For several months he puzzled over this, but at
last was able to isolate a new base from which, in 1 887, he prepared
a new metal. In honour of his fatherland he called it germanium.
Argyrodite is 4Ag 2 S.GeS 2 . It was at first thought that the new metal
would fill in the supposed gap between antimony and bismuth, but
it was soon recognised as Mendeleff's ^-silicon.

For a long time germanium was very rare, but in 1916 a new
mineral, germamte^ was discovered in S. Africa. It is a complex
copper pyrites and contains some 8 per cent of germanium and
I or gallium, together with varying amounts of nearly twenty other
elements. It is the only mineral known to contain both gallium and
germanium in appreciable amounts.

Germanium has at present few uses in industry. With the
extension of radio communication to ultra-high frequencies the
use of point-contact crystal rectifiers in telecommunication circuits
has become an established practice. Both silicon (p. 70) and ger-
manium crystal rectifiers are in use. The germanium crystals
are obtained from ingots formed in vacuo and slowly cooled.

174

CHAPTER 15

THE RARE EARTH OR LANTHANIDE

SERIES

THE rare earth metals constitute a group of fifteen contiguous
elements, numbers 57 to 71 inclusive, in the Periodic Classification
to which is added yttrium (No. 39) because of its very close
analogies generally and particularly with those with the higher
atomic numbers. For reasons already given, scandium (21), althoiigh
a congener of yttrium and belonging to the same vertical group of
the Periodic Table, is not included amongst the rare earths proper.

The modern acceptation of the term "earth" was discussed in
connexion with the alkaline earths. The so-called rare earths are of
peculiar interest. They even attracted the attention of H.I.H.
Prince Louis Lucien Bonaparte who prepared pure ceria and
several salts of cerium in 1843. It is convenient to retain the
specific adjective "rare" although it is well recognised that many
of the earths are quite plentiful although others may be extremely
scarce. Indeed their distribution is remarkably uneven. It has been
estimated* that they, all told, constitute only o-ooi per cent of the
earth's crust. Cerium is relatively abundant; it rivals tin and is :
three times as plentiful in the earth's lomile crust as lead, as is
evident from the table on page I76t

Yttrium, neodymium and lanthanum are more plentiful than
lead, and all are more so than silver, with the single exception of
illinium with regard to the existence of which considerable doubt
now exists.

Although the figures shown are always liable to modification as
our knowledge of the composition of the earth's crust is extended,
they are probably of the right order. One feature is very pronounced,
namely that the metals of even atomic number are invariably more
plentiful than their immediate odd congeners. This is clearly shown
m Fig. 6.

*WASHINGTON'S estimate, quoted by HOPKINS, Trans. Amer. Electrochem. Soc. t

I935> 66, 49-

(Numerous estimates have been published. The data in the Table are sub-
stantially the same as those given by GOLDSCHMIDT, /. Chem. Soc., 1937, P- 656.

175

THE CHEMICAL ELEMENTS

Rare-earth Metals in the Earth's crust

Atomic
No.

29 Copper

58 Cerium

50 Tin . .

39 Yttrium

66 ' Neodymium

57 Lanthanum . . 19
&2 Lead . .

.. 16

62 Samarium . . 6*5

64 Gadolinium . . 6*3

5 9 Praseodymium 5 6

Grams Atomic
per ton No.

66 Dysprosium

70 Ytterbium

68 Erbium

67 Holmium
63 Europium
65 Terbium

7 1 Lutecium

69 Thulium
6 1 (Illinium)

100

44
40

31

24

Grams
per ton

4'3
, 2-6

2 '4

. 1-2
. I'O
. I'O

. 0-7
. 0-3

I

Lo Ce Pr Nd - Sm Eu Gd Tb Dy Ho Er Tm Yb Lu
57 58 59 60 61 62 63 64 65 66 67 66 69 70 71

Symbols and atomic numbers

Fig. 6 Abundance of rare earth metals

176

THE RARE EARTH OR LANTHANIDE SERIES

In their chemical properties the rare earths resemble one another
very closely; there is a gradual change in properties as we pass along
the series from lanthanum (57) in order of increasing atomic
number towards lutecium (71), and although it is easy to distinguish
between and to separate elements of widely removed atomic
numbers, like the two mentioned, it is sometimes extremely difficult
to separate two contiguous elements. It can be done qualitatively in
most cases by repeated fractionation of one kind or another,
usually by fractional crystallisation, but the method cannot give
quantitative results. Two contiguous elements frequently' resemble
each other much more closely than the platinum metals and in this
respect lie between these and some isotopes, notably hydrogen and
deuterium.

The reason for this similarity is not difficult to find. The
chemical and optical properties of atoms are mainly decided by the
outermost electrons, as we have already seen. The arrangements of
the electrons round the nuclei in yttrium, scandium and the rare
earth elements are shown in the accompanying table.

Shell

K

L

M

N

O

P

Maximum No. of

Electrons

2

8

18

32

5

72

20 Calcium

2

8

8

2

21 Scandium

2

8

8+ I

2

38 Strontium

2

8

18

8

2

39 Yttrium

2

8

18

8+ i

2

56 Barium

57 Lanthanum . .

58 Cerium

59 Praseodymium

60 Neodymium . .

6 1 (? Illinium) . .

62 Samarium

63 Europium

64 Gadolinium . .

65 Terbium

66 Dysprosium . .

67 Holmium

2

8

18

2

8

18

2

8

18

2

8

18

2

8

18

2

8

18

2

8

18

2

8

18

2

8

18

2

8

18

2

8

18

2

8

18

18

8

18

8 +

t

18 + I

8 +

*

18 + 2

8 +

*

18 + 3

8 +

*

18 + 4

8 +

*

18 + 5

8 +

u

18 + 6

8 +

Jfe

18 + 7

8 +

18 + 8

8 +

18 + 9

8 +

*

18 + 10

8 +

*

2
2
2
2
2
2
2
2
2
2
2
2

177

THE CHEMICAL ELEMENTS

Shell .. K L M N O P
Maximum No. of

Electrons . . 2 8 18 32 50 72

68*Erbium ..2 8 18 18+11 8+1* 2

69 Thulium ..2 8 18 18+12 g + I* 2

70 Ytterbitim ..2 8 18 18+138+1* 2

71 Lutecium ..2 8 18 18+1484-1 2

72 Hafiflum
73 Tantalum

. . 2
. . 2

8

8

18
18

32
32

8 -f 2
8 + 3

2
2

According to a more recent view* the starred electrons in the
O-shell are held in the N-shell. For reasons explained later Seaborg
has suggested (p. 311) that the series of elements ranging from
lanthanum (57) to lutecium (71) be termed the lanthanide series^ a
term that calls attention to the actinide series, ranging upwards
from actinium (89) in which the O-shell gradually fills up.

It has already been mentioned (p. 172) that scandium bears a
resemblance to the rare earth metals and the electrons in the M and
N shells of the former certainly resemble those in the O and P shells
in the latter. But for reasons already given scandium is not regarded
as a true rare earth metal.

The structure of yttrium approaches even more closely that of
the rare earth metals, for like these latter its M shell is complete, and
in its chemical properties it so closely resembles those with the
higher atomic weights that elements 63 to 71 are frequently
classed as belonging to the yttrium group. We shall observe this
classification in the present section.

The characteristic valency of the elements is 3, but a few of them
can function in other capacities ; they then show marked differences
in the physical properties of their derivatives and can often be
separated very completely from their congeners in this way. For
example, oxidation of cerous (trivalent) compounds to eerie
(tetravalent) enables cerium to be separated. It yields, for example,
beautiful orange crystals of eerie ammonium nitrate,
Ce(NO 8 )4.2NH 4 NO 3) insoluble in concentrated nitric acid, whereas
the nitrates of its congeners are soluble. Similarly upon reduction
europium and ytterbium yield insoluble sulphates, EuSO 4 and

*Yosx, "The Rare Earth Elements and Their Compounds", p. 3 (Chapman &
Hall, 1947).

178

THE RARE EARTH OR LANTHANIDE SERIES

YtSO 4 , corresponding to barium sulphate, whereas the sulphates of
their congeners gadolinium, Gda(SO 4 )3.8H 2 O, and dysprosium,
Dy 2 (SO 4 )3.8H 2 O, are soluble and cannot be reduced. Such methods
are a very great help, for fractionation is slow and tedious; thus, in
preparing a very pure lutecium, Urbain in 1911 submitted hfe
material to fractionation some 15,000 times (p. 232).
t In discussing the history* of these elements it is convenient to
discuss them in two groups, namely, the cerium earths, comprising
elements 57 to 62, and the yttrium earths 63 to 71 with yttrium (39)
itself. '

The yttrium group

Let us be scriptural and take the last first. The story begins with a
Swedish mineralogist, by name Lieutenant Arrhenius, to be dis-
tinguished from Svante Arrhenius who, a century later, evolved
the theory of electrolytic dissociation. In 1788 Lt. Arrhenius
found a black mineral in a quarry at the little town of Ytterby, near
Stockholm, and regarding it as new to science he called itytterbite.
Six years later, in 1794, the Finnish mineralogist Gadolin, a native
of Helsinki, examined this mineral and concluded that it contained
a new earth. This was confirmed in 1797 by Ekeberg, destined
later to be the discoverer of tantalum. He showed that the mineral
contained beryllia, which had just been discovered by Vauquelin
although the result was not published until 1798, and a new earth
which he called yttria. In recognition of Gadolin's original observa-
tion, the original ytterbite came to be known as gadolinite^ and to-day
we assign to it the formula 3BeO.FeO.Y 2 O 3 .2SiO 2 . This new earth
yttria, however, proved to be complex, and in 1843 Mosander
separated three earths from it to which he gave the names yttria^
erbia, and terbia. The yttria was essentially the earth known by
that name to-day. The erbia gave a brown higher oxide on ignition
whilst the terbia was pink. In 1860, however, Berlin introduced a
method of fractionation depending upon the partial decomposition
of rare earth nitrates by heat; experimenting with the crude yttria
he failed to obtain the brown earth and most unfortunately called
the pink earth, the existence of which he was able to confirm, erbia.
In 1873 a mineral known as samarskite was found in quantity in
Mitchell County, North Carolina. This mineral had been found in
Russia many years previously by von Samarski and handed to

*Full references to the early histories of these elements are given in FRIEND'S
"Textbook of Inorganic Chemistry", Vol. iv. H. R V. Little (Griffin, 1917).

179

THE CHEMICAL ELEMENTS

Heinrich Rose for analysis. It is a complex niobo-tantalate contain-
ing numerous rare earth elements and Rose named it after its
discoverer. The finding of the mineral in Carolina enabled
chemists by 1877 to obtain fairly large amounts of raw material for
the study of the now "less rare 1 ' earths, and the work entered on a
new phase. In 1877 Delafontaine confirmed the existence of
Mosander's brown oxide-forming earth in samarskite, and owinr
to Berlin's unfortunate action, he had perforce to call it terbia. Thus
a most distressing confusion arose. The following year (1878),
Marignac confirmed the existence of this terbia in gadolinite as
Mosander had claimed. But it was only present to a minute extent,
its deep staining powder being characteristic. It was only many
years later that the brown higher-oxide forming earth was obtained
in a state of purity.

About this time Laurence Smith and Delafontaine obtained
what they believed to be two new earths, which they called
mosandra and phillipia respectively. Moseley's method of deter-
mining atomic numbers had not then been dreamed of, and it was
extremely difficult not merely to ascertain whether or not an earth
was simple, but also how many separate earths were to be expected,
as the Periodic Table gave no help at all. Suffice it to say that
Smith's mosandra and Delafontaine's phillipia were mixtures.

Returning now to Marignac, in 1878 he fractionated the earth*
from gadolinite, and Soret examined the absorption spectra of the
erbia fractions with the result that he concluded that at least two
earths were present. He suggested retaining the name erbia for the
earth which gave the absorption bands characteristic of the crude
erbia and designated the new element giving other bands, particularly
A 6404 and 5363 as X. He also observed a band A 6 840 which did
not appear to belong to either. Marignac meanwhile fractionated
the crude erbia and isolated a new earth which he called ytterbia,
which was shown to be complex by Auer von Welsbach and Urbain
many years later. In 1 905 Welsbach announced that it consisted of
two earths which he called Aldebarania and Cassiopeia; but Urbain
in 1 907 named them neoytterbia and lutetia, the latter name being
the Latin for Urbain's native city Lutetia Parisiorum. The Inter-
national Atomic Weights Committee, however, adopted the names
ytterbium and lutetium for the elements. It should be mentioned that
Charles James of New Hampshire University, U.S.A., simul-
taneously discovered lutecia, but delay in publishing his results
caused him to lose priority to Urbain.

180

THE RARE EARTH OR LANTHANIDE SERIES

The order of discovery of the yttrium earths is summarised
'in the following scheme

History of the yttrium earths
Ytterbite or Gadolinite

1797 Ekeberg

Beryllia

Already discovered
by Vauquelin

Yttria

1843 Mosander
proved complex

Terbia
gave pink salts

Erbia
gave a brown higher oxide

Yttria

1860 Berlin
isolated
and called it

Erbia

several
investigators

1877 confirmed
by Delafontaine
who had to
call it

Terbia

1880 Mosander
fractionated to

I .
Gadolinia

Terbia

Samaria
already known
to Boisbaudran
1879 (p. 184)

1879
Nilson

Scandia
Mendeldeff's
Eka-boron
(p. 172)

1907
Urbain

1879
Cleve

1878
Soret by
absorption
spectrum

Erbia Thulia Holmia

Element X

Lutetia

(neo-)
Ytterbia

Dysprosia
obtained pure
by Urbain in
1906

olmia

obtained pure
by Holmberg
in 1911

181

THE CHEMICAL ELEMENTS

Nilson, in 1879, obtained still another oxide from crude erbia
which he called scandia, in honour of his native Scandinavia. This
has already been discussed as one of Mendel^efFs Predictees
(p. 1 68). Cleve in 1879 a ^ so fractionated crude erbia after removal
of Marignac's ytterbia and Nilson's scandia. He concluded that in
addition to erbia, as characterised by Soret, there were two new'
earths wliich he called holmia, after Stockholm, and thulia, after
Thule, an old name for Scandinavia or possibly Iceland. In 1886,
ho\Yev.er, Boisbaudran showed that holmia was complex as its
absorption spectrum characterised two elements. Thulium was
responsible for Soret's band A 6840, whilst the new holmium was
idtntical with Soret's X. The third element, which gave bands at
^753 an d 45 1 5 Boisbaudran named dysprosium (Greek dysfrositos
hard to get at).

In 1880 Marignac showed that the "terbia" from samarskite
contained in addition to true terbia at least two other earths. One
was Samaria, which had been discovered in 1879 by Boisbaudran
(p. 183), and the other >vas a new earth to which Marignac gave the
name gadolima in 1886.

The cerium group

Turning now to the history of the cerium earths we hark back to
the close of the eighteenth century.

In the iron mine at Bastnas, near Vestmanland, in Sweden,
there was a mineral of high density known as the "heavy stone of
Bastnas", or "Bastnas tungstein", tung being Swedish for heavy.
The mine belonged to a wealthy Swedish family and Wilhelm
Hising, a member of the family who later was raised to the nobility
and became known as Hisinger, sent a sample to Scheele for
analysis. This was in 1781. Now Scheele expected to find tungsten
on account of the great density of the mineral, but in vain. He there-
fore replied that he was unable to find anything new in it.

For a while no further notice was taken, but in 1803 Klaproth
examined it and concluded a new earth was present which he called
terre ochroite, because it turned dark yellow when heated. Simul-
taneously and independently Berzelius and Hisinger studied the
mineral and discovered the same new earth to which they gave the
name ceria in recognition of the minor planet Ceres, then newly
discovered (in 1 801) by Piazzi and named after the Sicilian goddess
Ceres Ferdinandea, who is to be identified with Ceres, the Roman

182

THE RARE EARTH OR LANTHANIDE SERIES

goddess of corn. The mineral itself became in consequence known
as cerite.

In 1839 Mosander showed that the ceria obtained by Berzelius
was not a simple earth but a mixture. When suspended in potash
and chlorinated, a yellow, insoluble residue was obtained, which
Mosander regarded as true ceria and the earth present in the soluble
portion he called lanthana^ from the Greek lanthomo^ I lurk.
Precipitation of the lanthana yielded a brownish earth; but
Mosander rightly believed that it ought to be white and that its
brown colour was due to impurity, and in 1840 he proved this to
be the case by isolating a brown earth from it, leaving a colourless
lanthana. This new earth he called didymta, from the Greek didumos^
twin, regarding didymia as the twin brother of lanthana, the two
always being associated. In 1879 Boisbaudran isolated a new earth
from didymia extracted from samarskite and called it samaria. Six
years later Auer von Welsbach observed that didymium freed from
samaria was still complex, its salts on fractionation yielding green
and rose-red portions. He therefore termed the earth yielding green
salts praseodymia (Greek prason, leek) antl the one yielding rose-red
derivatives neodymia (Greek neos, new). Even now the tale was not
quite complete. The presence of small amounts of a new earth was
demonstrated by Demarcay in 1896, which he called Europia.

The method evolved by Moseley (1887 to 1915) of determining
the atomic number enabled chemists to ascertain, as has already
been seen, the maximum number of elements that can exist in serial
order between any two selected ones. As the atomic numbers of
lanthanum and lutecium are 57 and 71, it is clear that it is possible
for 13 elements to exist of atomic numbers between these. Now
europium was the twelfth to be discovered, but no element corres-
ponding to 6 1 had been recorded. This should lie between
neodymium (60) and samarium (62), and as early as 1902 Bohuslav
Brauner had predicted its existence. In 1926 Hopkins, of Illinois,
with his collaborators Harris and Yntema, announced the discovery
of a new element in the neodymium extracted from monazite sand,
the lines of the X-ray spectrum agreeing with those expected for
element 61. He called it Illinium.

About the same time, Prof. Rolla, of the Royal University of
Florence, announced that he had, a couple of years before, obtained
evidence of the existence of the same element and called itflorentium.
The results had been deposited in a sealed package with the Reale
Accademia in June 1924, and the contents were withheld from

183

THE CHEMICAL ELEMENTS

publication until November 1926 a singular procedure, to say
the very least.

Considerable doubt has been expressed as to whether element
6 1 has been detected in nature at all. As a general rule pairs of

The ordeV of the discovery of the cerium earths is summarised
in the following scheme

History of the cerium group

Bastnas Heavy Stone

1804 Berzelius
and Hisinger
Ceria

1839 Mosander

Ceria Lanthana

1840 Mosander

Didymia Lanthana

Samaria Praseodymia Neodymia ? Illinia

Boisbaudran Auer von Welsbach Hopkins etc.

1879

Samaria Europia

Demarcay
1896

stable isobares of adjoining elements are incapable of existence;
one must be unstable. Now the known isotopes of neodymium and
samarium are all stable, viz.

(60) Nd . . 142 143 144 145 146 148

(62) Sm . . 144 147 148 149 150

There is thus no room for a stable element 61 between them.
But an unstable 6 1 might exist. Evidence has been obtained of its

184

THE RARE EARTH OR LANTHANIDE SERIES

production by bombardment of neodymium and praseodymium by
deuterons, a-particles and protons, the products having half lives
ranging from 2*7 hours to 200 days, possibly indicating the
existence of various isotopes of varying stabilities. Also during
bombardment of uranium with neutrons, element 61 of mass 147
has been obtained, its half life being about 4 years*.

Its properties are found to agree with those to be expected from
its position in the Periodic Table. The names promethium and
cyclonium have also been suggested for this element in view of its
artificial production. * -

The position to be allotted to the rare-earth metals in the Periodic
Table has been the subject of much discussion. They cannot be
accommodated in the usual way and the present author "has
arranged them, purely for convenience, in a belt across the table
(see page 5). They do not conform in their properties with the
elements in the same vertical columns.

The rare earth metals are extracted from their oxides by the
alumino-thermic process. An indefinite mixture of these metals
obtained by reduction of the mixed earths is known as misch-metall
and is used for the reduction of other refractory oxides. Alloys of
cerium are used in automatic lighters, tracer bullets and lumin-
escent shells. Those rich in cerium are used as reducing agents and
for flashlight powders.

*See note, p. 5. Apparently even more stable is isotope 145, of half life approx.
30 years (BUTEMENT, Nature, 1951, 167, 400).

185

CHAPTER 16

THE HEAVY METALS
LEAD, TIN, AND MERCURY

Lead

OWING to its softness lead did not play an important rdle in the life
of primitive man. His interest in metals was mainly confined to their
uses as ornaments or as weapons yielding hard and sharp cutting
edges. Lead is not suitable for either of these purposes. It can be
hammered out into sheets and rolled into pipes, but of what use
would these be to the cave man or even to his immediate successors?
Only at a much later date would it occur to him that lead might be
moulded into containing-vessels and by reason of its density used
for sinking his fishing nets.

Primitive metallurgy of lead

The bright appearance of galena would attract early man, for it
often lay on or very close to the surface of the soil. Having already
learned how to reduce copper ores in his primitive furnace, he
would experience no difficulty in reducing galena. It was sufficient
merely to roast it in air, whereby the sulphur burned off and the
molten metal sank into the hearth.

The early hunters in Missouri practised a crude version of this
process ; they threw pieces of galena into a fire made in the hollow of
a fallen tree, or in an old stump, and scraped the resulting metal out
of the ashes. Much of the metal was of course lost in the slag.

The Indians of the Mississippi valley obtained their lead in a
somewhat more pretentious manner. They piled logs on the ground
and laid smaller pieces of wood round them; lead ore was now
thrown on to the heap. The fire was ignited in the evening and next
morning the ashes were searched for lumps of lead.

The early French settlers in S.E. Missouri dug a hole in the
ground in the shape of a large brick; in the centre of this a stick
was fixed so that, when the ore was reduced in the fire, the molten
lead collected in the cavity as an ingot with a hole. On cooling, a
raw-hide rope was passed through the hole to facilitate transport

186

LEAD, TIN, AND MERCURY

when the ingot was swung either on the shoulder of a man or upon
the back of a horse*.

Lead in Holy Writ

Lead is mentioned nine times in the Old Testament but, as'Vith
silver, not until after the Flood circa 4000 B.C. It was one of the
metals traded in the fairs at Tarshish, probably oifr Andalusia,
along with silver, iron and "tin" (Ezekiel xxvii. 12). The great
density of lead was a matter of common knowledge ; in the Song of
Moses, which celebrated the flight of the Hebrews frbm Egypt
and their escape from the pursuing troops of the Pharaoh, we read
that the chariots "sank as lead in the mighty waters" (Exod. 2jv. 10).

An interesting passage in Job reads as follows "Oh that my
words were now written! Oh that they were printed in a book!
that they were graven with an iron pen and lead in the rock forever!"
(Job xix. 23, 24). This evidently refers to the use of lead sheets as
writing material. The Book of Job was not all composed at the same
time. It appears to have been finally compiled in the fourth
century B.C., but portions of earlier MSS. were undoubtedly
incorporated into the text. Astronomers calculate that the curious
reference to Arcturus in Job ix. 9 probably dates back to 750 B.C.
Even at that date the practice of inscribing on soft metals had
already been long established for important documents. It was
paralleled in ancient Assyria by the customary habit of writing on
clay tablets which were afterwards baked to ensure permanency
of the record.

Hesiod^next to Homer the earliest Greek poet whose works are
still extant, lived during the eighth century B.C. and would thus be
co-eval with the passage in Job above referred to. He wrote seven
of his books on sheets of lead.

An inscription on lead has been found on the site of ancient
Nineveh, and thin sheets of the same metal, bearing amulitic texts,
have been unearthed at Babylon. The Phoenicians believed they
could communicate with the dead by dropping little rolls of
inscribed lead sheets into the tombs.

Lead and Egypt

Lead was known to the ancient Egyptians by whom it appears to
have been regarded as an inferior kind of silver. It has been found

*RICKARD, /. Inst. Metals, 1930, 43, 297.

187

THE CHEMICAL ELEMENTS

in predynastic remains almost as early as those in which silver first
occurs, being used for sacred figures and, in sheet form, as a cover
for wood. Beads of galena frequently occur in predynastic tombs ;
the powdered ore was used as an eye paint almost as commonly as
malachite (basic copper carbonate) both in predynastic and in First
dynastic times.

Lead and galena were not plentiful in the early dynastic periods,
but by the advent of the New Kingdom, circa 1580 B.C., the metal
was fairly common; the fishermen used it regularly for weighting
the edges of their nets as is done at present. By the sixth century
B.C. it was used on a much larger scale as, for example, in making
water tanks.

Lead* ores occur in Egypt and were worked there; but when at
the height of her power, Egypt received also much lead as "presents"
or tribute from neighbouring countries.

Sheet lead was used as a damp course in the walls of ancient
Babylon, and inscriptions were engraved by the Babylonians on
sheets of lead.

Lead and the Mediterranean

Lead was known to the peoples of the Mediterranean at a very
early date.

A hideous idol of metallic lead, evidently representing an ancient
goddess, was found in the second ancient city of Troy dating back
to circa 2200 B.C. Xenophon, writing circa 400 B.C., tells us that the
Rhodian slingers used lead balls whereas the Persians used stone
ones, as did David in combat with Goliath, about 1030 B.C. Roman
and Greek sling bullets, made of lead, have been found in Cyprus.
The Greek word for lead was molybdos (p. 53), but this word was
also used to denote plumbago. It is difficult to say when the ancients
learned to distinguish between lead and our modern tin.

Lead and the Romans

Pliny, writing at the beginning of the Christian era (see note p. 1 8)
was familiar with both tin and lead; he referred to lead us plumbum
nigrum^ whilst tin was plumbum album or candidum. Nevertheless, he
seemed to regard them as varieties of the same metal rather than as
separate species. Plumbum by itself invariably meant lead; the
word stannum or stagmum sometimes meant tin and sometimes an
alloy of lead and silver.

188

LEAD, TIN, AND MERCURY

The Romans used lead on an enormous scale for water pipes,
cooking utensils, etc, and lead poisoning appears to have been
frequent. They obtained much lead from Spain and later from
Britain. Lead pipes of Roman origin have been found in Bath with
walls nearly half an inch in thickness and of internal diameter^from
4 to 5 in. Lead pipes were made by folding strips of sheet lead into
the required shape, probably by beating round a wooden core or
mandrel until the longitudinal edges of the sheet met. The edges
were then either welded at the seam or joined with molten lead.

Rome in the first century of the Christian era had a remarkable
water supply system administered by a body of officials comparable
to the modern Water Board. The chief officer was the Curator
Aquarum; the supply of water was taken from nine different
sources, including springs and lakes from 10 to 60 miles from the
city; supplies suitable for potable purposes were kept apart from
less pure waters which were used for public fountains, baths and
sanitation. Each length of pipe bore raised inscriptions formed by
impressions in the sand bed in which the lead sheet was cast. The
inscriptions indicated the person authorised to receive the water.

Pliny states that the Public Acts in his time (A.D. 23 to 79) were
preserved on plates of lead. In 1699 Montfaucon purchased in
Rome an ancient book entirely composed of lead. It measured
about 4 inches long by 3 across, and not only were the two pieces
that formed the cover and the six leaves made of lead, but also the
stick inserted through the rings to hold the leaves.

Silver in lead

British lead ores invariably contain some silver; the average for
Britain as a whole is some 4 to 5 oz. per ton of lead. Ores in
Cornwall and Devonshire are very rich with some 30 to 70 oz. in
the former county reaching to 170 oz. in the latter*.

Pre-Roman lead does not appear to have been de-silverised,
but the Romans certainly knew how to abstract the silver by
cupellation (p. 190) long before they invaded Britain. Probably they
worked lead ores with the dual object of obtaining both silver and
lead. Many Roman lead pigs bear the inscription ex arg y that is,
silver extracted. Analysis of Roman pigs show their silver contents
to have often been very low. The following silver contents from

*H. Louis, loc. tit. E. A. SMITH, /. Inst. Metals, 1927, 37, 74.

189

THE CHEMICAL ELEMENTS

ancient samples of lead illustrate the great variation that has been
found to occur*

Silver
per cent
Sunoerian lead from Al 'Ubaid, Imgig Relief, 3100-3000

B.c.f 0-0131

Egyptian net sinker, circa 1400 B.C. . . . . . . 0-0282

Assyrian lead 700-600 B.C. .. .. ., o-on

Spartan lead 700-500 B.C. . . . . . . . . 0-0568

British lead net sinker from Meare Lake Village, Somerset,

250 B.C.-A.D. 50 . . . . . . . . . . 0-0077

Roman lead from Bath, A.D. 44-100 0-0027

Lead from Merlin's Cave, Wye Valley, A.D. 100-400 . . 0-0263
Lead from Glastonbury Abbey, A.D. 1 130-1184 . . 0-0327

Lead pipe from Rievaulx Abbey, A.D. 1 131-1500 . . 0-0084
Lead bullet from Marston Moor, A.D. 16444 . . . . 0-0073

Ordinary commercial lead (1920) . . . . . . . . 0-0020

Ordinary commercial lead (1928) . . . . . . . . 0-0004

The low silver contents 6f Roman lead as compared with earlier
eastern specimens and some of the western ones, notably those from
Merlin's cave and Glastonbury Abbey are a tribute to the efficiency
of Roman desilverisation processes.

Lead in Britain

There is no evidence that lead was produced in any quantity in
Britain before the arrival of the Romans ; on their arrival they found
large quantities of surface ores, and lost no time in turning the
mineral wealth of Britain to account. More than 50 Roman lead
pigs have been found in Britain, some near the ancient mines
where they were produced, others near the roads leading from them
to Roman stations. As these were merely "strays" it is evident that
enormous quantities of lead must have been produced during the
Roman occupation. This conclusion is supported by the vast extent
of Roman mining excavations and accumulations of slag and other

*FRIEND and THORNEYCROFT, /. Inst. Metals, 1929, 41, 105.

fThis Relief is described on p. 91 . The antlers of the left hand stag, made of
hammered copper bar, had been fixed into the head of the stag with lead poured
into the root holes. The lead had in both cases corroded and burst open the head.
Through the kindness of the British Museum Authorities a fragment of the lead
was made available for analysis.

{This was a genuine, authentic bullet, and its analysis confirms this.

190

debris*. In Mendip mines Roman lamps have been found made of
lead.

It is evident that many of the pigs were cast very shortly after
the Romans arrived here. As the pigs invariably bear inscriptions,
often with the Emperor's name, they can usually be roughly dated;
but only roughly, for news would travel but slowly to outlying posts
and an Emperor might well be dead for some time before the
miners became aware of it.

The mines were under the control of the state; the administrative
officer who regulated a mining area was known as the procurator
metallorum\ although sometimes worked by the state the mines
were usually farmed out by the procurator to private prospectors,
called occupations, from whom a royalty was demanded in the form
of a percentage, sometimes amounting to 50 per cent, of the
produce. This perhaps accounts for the fact that pigs of lead some-
times bear the name of some person other than the emperor,
representing the portion kept by the private prospector. The
miners themselves were largely slaves; but even so provision was
made for pit-head baths, the Romans thus setting an excellent
example in cleanlinessf.

Among leaden articles belonging to the Roman period are pipes,
coffins, cists, etc. The Romans also used articles of pewter (p. 211),
at that time an alloy of lead and tin in the ratio of I to 4. Probably
the two metals were deliberately mixed to produce the pewter, for
the Romans were familiar with solder. It is possible, however, that
pewter may have been produced in the first instance from a natural
mixture of tin and lead ores, just as bronze resulted from a mixture
of tin and copper ores (p. 91). Professor Louis has recorded such
an occurrence in the Far East, where he found the Chinese smelting
a natural mixture of lead and tin ores obtained by washing certain
alluvials in the State of Patain in the northern part of the Malay
Peninsula.

Large quantities of lead were used by the Romans in the con-
struction of the baths in the Somerset town of Bath. It has been
suggested that baths may have been there before the Roman
occupation, but the evidence is slight and the need for them
would appear to be even slighter, for the early British are usually

*GOWLAND, "Huxley Memorial Lecture for 1912", Royal Anthropological
Institute of Great Britain and Ireland, p. 275.
fWHEELocK, "Prehistoric and Roman Wales 1 ' (Clarendon Press, 1925), p. 269.

191

THE CHEMICAL ELEMENTS

regarded as having belonged to the great army of the unwashed.
The baths as we know them were founded by Vespasian or else by
his son and successor, Titus, that is between A.D. 69 and 81.
Originally there were two baths, divided by a street that ran from
north to south, and in the centre of each was a hot spring rising at
a temperature of some i I3F (45 C), The bottom of the bath was
paved with sheet lead, the whole being built below street level so
that pumps were not required. During excavations a unique lead
consecration cross was discovered, believed to date from the seventh
century A.D. It is worked on a plaque about 3 inches in diameter
and bears the names of the four evangelists with a Latin inscrip-
tion*.

When the Romans withdrew from Britain they left behind them
a firmly established lead industry. No doubt this continued through
the unsettled periods that followed, for the Venerable Bede or
Bseda (672 to 735) wrote in his "Historia Ecclesiastica Gentis
Anglorum", on which his literary fame rests, that Vents metallorum^
aerify ferri et plumbi et argenti fecunda y which means that Britain
"is rich in veins of the rfietals copper, iron, lead and silver". This
book was subsequently translated into Anglo-Saxon by Alfred the
Great (849 to 901), the word plumbum being rendered "leade"
(lead), this being the first recorded use of this English word.

Bede also stated that the Bishop of Lindisfarne removed the
thatch from his church and covered the roof and the sides with
sheets of lead. This would be circa A.D. 680.

Lead in Derbyshire

Lead was being worked at the time of the Norman invasion in 1066,
for reference is made in the Domesday Book to the lead mines or
plumbaria in Derbyshire and to the salt works and lead furnaces at
Droitwich in Worcestershire"]". The Normans used lead very
largely for coffins, for church ornaments and for roofing churches.
Wirksworth, now a producer of limestone, was from very early
days the chief centre of the lead industry of Derbyshire, but
lead mining has almost died out now. The expense of freeing the
deep workings from water raised the cost of production unduly and
enabled foreign ores to swamp the market. The lead was regarded
as amongst the finest in Britain.

*BADDBLBY, "Bath and Bristol" (Nelson, 1908), p. 21.

fSee A. BALLARD, "The Domesday Boroughs" (Clarendon Press, 1904), p. 62.

192

LEAD, TIN, AND MERCURY

It is estimated that there are between four and five thousand
derelict lead-mine shafts on the limestone uplands of Derbyshire;
all now fenced round as a safeguard for wandering animals. The
lead in the Wirksworth region was certainly worked by the Romans,
and the late Professor Windle believed that their town of Lududa-
rum was Wirksworth. Pigs of lead bearing Roman inscriptions
have been unearthed in the vicinity, the first, found in iy77> bearing
the mark of the Emperor Hadrian, about A.D. 120. In Saxon days
the manor of Wirksworth belonged to Repton Abbey, and early in
the eighth century an Abbess of Repton sent a coffin from* her lead
mines at Wirksworth to Crowland for the burial of St. Guthlac.

Defoe, who expressed little admiration for Derbyshire folk,
wrote of Wirksworth about 1720 "There is no very great trade to
this town but what relates to the lead works, and to the subterranean
wretches, who they call Peakrills, who work in the mines .... The
inhabitants are a rude boorish kind of people, but they are a bold,
daring, and even desperate kind of fellows in their search into the
bowels of the earth/'

Any man was at liberty to prospect for lead and mark out his
claim, and he had the right to a direct draw-way, three oxen wide, to
the nearest highroad, provided it did not pass through churchyard,
garden or orchard. A proportion of the ore was payable to the King
or the lord of the manor, and the lead was measured in wooden
dishes. These dishes had to be taken periodically to Wirksworth to
be tested by a standard measure. The only ancient standard now
known to exist is preserved in the Moot Hall at Wirksworth. It is
in fine bronze and holds fourteen pints. Part of the inscription, in
Old English characters, reads "This dishe was made the iiij day
of October, the iiij year of the reigne of Kyng Henry the VIII ...
This Dishe to Remayne in the Moote Hall at Wyrksworth hangyng
by a cheyne so as the Merchauntes or mynours (miners) may have
resorte to the same at all tymes to make the trw mesur after the
same."

The fuel problem

The rapid disappearance of our forests in the attempt to supply
the metallurgical industries with charcoal caused the authorities no
little concern. Cardinal Wolsey attempted to reduce his lead ore
with coal instead of with the more usual charcoal in his smelting
furnace at Gateshead-on-Tyne; but as he subsequently disposed of
the furnace, in 1527, to one Thomas Wynter, it would appear

193

THE CHEMICAL ELEMENTS

g-obable that the attempt proved a failure. In the reign of Queen
lizabeth two Acts of Parliament were passed, one in 1558 and
the second in 1584, with the object of preserving the timber (p. 278).
In 1678 a patent was granted to Viscount Grandison for smelting
lead ore in a reverberatory furnace with sea-coal. Fourteen years
later the famous London Lead Company was founded under a
charter of i William and Mary "for smelting down lead with pit
coal and sea coal". This company carried on lead smelting operations
continuously until it was finally wound up in 1905.

Lead and the alchemists

The alchemists used the sign $ to denote lead, as has already been
mentioned; the curved portion suggests a connection between lead
and silver. Lead was under the influence of Saturn and the symbol
was often called the scythe of Saturn. In consequence of the high
density of the metal the term saturnine became synonymous with
heavy, dense, or dull-witted. Minium or red lead was known as
saturnine red.

A favourite experiment*was the production of the "lead tree" or
arbor Saturni by suspending a piece of zinc in a solution of some
soluble lead salt such as the acetate, popularly known as "sugar of
lead". The experiment is popular to-day.

Lead was often regarded as a debased form of silver and in the
Middle Ages it was held that lead in progress of time became trans-
muted into bismuth and later into the more precious metal.

In A.D. 1 12 1 Al Khazini, an Arabian philosopher, wrote a book
on the physical properties of matter. He discussed the balance and
gave the density of lead as 1 1*33, coincident with the modern value
of 11-33 to 11-35.

Uses of lead

Commercial lead is a metal with a high degree of purity. The foreign
metals generally present include copper, antimony, zinc and iron;
less frequently bismuth and traces of tin and arsenic. Silver is
almost completely extracted by desilverising processes. The total
metallic impurities rarely exceed o- 1 per cent and may fall below
0*01.

Lead is used as sheets for gutters, spouts, etc. As strips for
"leaded lights", in pipes for water, gas, electric wiring, etc. It was
once used a great deal for roofing cathedrals and churches; but it
was very heavy. Wren used it for the dome of St Paul's Cathedral

194

LEAD, TIN, AND MERCURY

(begun 1675) because his workmen were not equal to the task of
using copper (p. 103). It is estimated that had copper been used the
weight or the roof would have been reduced by some 600 tons.
This would have greatly relieved the anxiety of those responsible
for the safety of Wren's masterpiece.

Owing to its resistance to acids lead is in demand for chemical
plants. As an example the lead chambers used in the manufacture
of sulphuric acid may be quoted. They are constructed of sheet lead,
about 3 mm. in thickness, the sheets being autogenously soldered
that is, lead is used as solder to prevent electrolytic action in contact
with acid or sealed by a blow-pipe flame. Chambers frequently
exceed 40,000 c. ft. in individual capacity, and a series of thrqe or
four is commonly used, the gases being conducted from one to the
other by lead pipes.

Thin sheet lead is frequently used as a lining for wooden cases or
chests in which tea is imported.

Hardened with a little antimony it is used in storage batteries or
accumulators, for cables, and occasionally for statuary. For this
last, however, it is not really suitable; its dull colour is not pre-
possessing. Bullets, etc, are made of lead hardened with 4 to 1 2 per
cent of antimony. Other important alloys are solder (p. 2 1 2), type
metal (p. 197) and bearing metals, which contain also tin and
antimony.

Pewter in Roman times contained I of lead to 4 of tin ; in the
Middle Ages i of Pb to 3 of Sn were used. The amount of lead was
gradually increased until the alloy became too debased and fell out
of favour. Modern pewter contains no lead (p. 212).

The density of lead makes it useful in making the builders'
plumb lines and for "sounding" apparatus at sea. It is this latter
use which has given rise to the expression * 'swinging the lead",
which indicates a shirking of duty.

In "sounding" the lead must be "heaved". The lead weighs from
10 to 14 lb, therefore "heaving the lead" is not light work, even
for a strong man. It is for this reason that a leadsman will make his
"swing" last several minutes before finally "heaving". So to
"swing the lead" became a recognised Navy term for an excuse for
shirking; in some way it passed into Army parlance, and so into
popular usage.

Archers were wont to carry heavy leaden mallets as part of their
equipment and this was an important factor in winning, for example,
the battle of Agincourt in 1415, the heavy mallets of the British

195

THE CHEMICAL ELEMENTS

archers crashing through the iron helmets of the French knights
whose horses were held fast in the mud.

Lead shot

Ac one time lead shot was made by cutting sheet lead into small
squares thus producing little cubes which were then rolled into
little balls or shot a laborious process, which has long since been.
discarded. The addition of a little arsenic to lead renders it less
viscous in the molten state, and the alloy thus produced is now used
in making shot by a more efficient and rapid process. The shot
tower erected on the south bank of the Thames has long been
famous. Fortunately, despite near misses, it escaped destruction by
German bombs in both of the Great Wars; during World War II
operations were carried on all the time, many thousand tons of lead
shot being turned out as its contribution to victory. The tower
looks like a tall chimney stack and has usually been regarded as
such by the casual visitor; if one looks more closely, however,
windows can be seen at various levels let into the wall, and near the
top is a gallery. Probably the tower was deliberately designed to
resemble a chimney stack in order to deceive the curious, as the
process of making shot in this way was kept a secret for many years.
The tower was taken over by the L.C.C. in 1948 and is now no
longer used for shot making; at the moment, it is adding interest to
the South Bank site of the 1951 Festival of Britain.

Molten lead passed as drops through a "card" or colander
perforated with numerous holes 1448 for the smallest shot
and fell into water which usually contained a little sodium sulphide.
This coated the shot with a thin layer of sulphide of a lustrous
black metallic colour which remained permanent in moist air. The
size of the shot depended not only on the diameter of the holes in
the colander, but also on the initial temperature and composition of
the molten metal. The shot was sorted by sieves and by roiling down
an inclined plane, the imperfectly shaped pellets remaining behind.
Finally the shot was polished by rolling with plumbago in a barrel
or rumble.

A curious story is told* of the invention of this process of making
shot. One night, about the year 1782, William Watts, a Bristol
plumber, dreamed that he was out in a shower, and the raindrops
were not water but lead shot. On waking he argued that, by allowing
molten lead to fall from a considerable height into water, the drops

*W. JONES, "The Treasures of the Earth 11 (Warne), p. 205.
196

LEAD, TIN, AND MERCURY

would become spherical, and a great improvement might thus be
effected in shot manufacture. The experiment was tried from the
tower of St Mary Redcliffe Church, Bristol, and proved successful.
Watts accordingly patented his idea, and erected a works which he
ultimately sold for 10,000. But here his beneficent angel left him;
he expended more money than he could afford in attempting to
build houses at Clifton, for which considerable excavation work was
necessary, and the half-finished parts of the buildings were for long
known as "Watts's Folly".

A more modern method of producing shot embodies the use of
centrifugal machines. The molten metal is poured in a thin stream
upon a rapidly revolving metal disc which breaks it up into drops,
the size of which depends on the rate at which the disc revdlves.
These drops are thrown off at a tangent by centrifugal force and are
stopped by a screen,

Type metals

Probably the greatest single use of lead alloys is for type metals*.
Long before these were introduced bpoks were printed from
engraved wood blocks, hard boxwood being a favourite. Each
page of the book was cut laboriously in reverse by hand, an
operation that took much time and required great skill. The Romans
were accustomed to cast lead plates with raised inscriptions (p. 189);
it is easy to be wise after the event, but it certainly seems curious
that the world had to wait until the early years of the fifteenth century
before a movable type became invented. The honour of this inven-
tion is usually given to Laurens Koster of Haarlem and to John
Gutenberg of Mainz about 1440. In 1476 Caxton introduced the
art into this country, having learned it when living abroad; he set
up his press near the western entrance to Westminster Abbey. The
following year was issued the first book ever to be printed in this
way in England, entitled "The Dictes and Sayinges of
Philosophres" "Emprynted by one William Caxton at West-
minster". The king, Edward iv, and his nobles used to visit and
watch Caxton at work. To them it was a new toy.

In 1450 the whole Bible, in the Vulgate Latin, was produced.

At first leaden type was used ; but it proved too soft and was later
hardened by addition of a little tin. But the alloy still failed to give
on casting a perfect type face, and subsequently antimony was
added. This reduced contraction when the casting solidified so that

*" Printing Metals" (Fry's Foundries Ltd, 1936), p. 33.

197

THE CHEMICAL ELEMENTS

the type had a good face and body. Early last century machines
were invented which greatly accelerated the production of type, but
even so each letter had to be set up by hand. Then came other
machines, such as the linotypes and monotypes which reduced
manual labour to a minimum and rendered possible the flood
of newspapers and other printed matters with which we are in-
undated tc-day. The alloy used for standard linotype metal is 86 Pb,
1 1 Sb and 3 Sn.

Tin*

It is, perhaps, unfortunate that the word "tin" should frequently
be used in a derogatory sense, when the element itself is not under
consideration. Thus a poor sounding bell is said to be "tinny"
whilst another, possessed of beautiful tones, is described as
"silvery". Money, the filthy lucre of Titus i. 7, is colloquially known
as "tin". The reason for this disparagement appears to lie in the
early belief that tin was not a genuine metal. Thus in Dyche and
Pardon's "English Dictionary", dated 1744, we read that "tin by
some is called an imperfect or compound metal, white and softer
than silver, and harder than lead and so imagined to be made up of
both ..." As a debased silver, therefore, tin was not a genuine
article. Although we know different to-day, the stigma remains; call
a dog a bad name and it can never be any good.

The word "tinker" is also used in a derogatory sense; to tinker
implies working in an inefficient or clumsy manner, and although
often associated with a man who works in tin the word has nothing
to do with that metal. It is derived from the Middle English tinken,
to tink, tinkle or make a sharp, shrill sound.

"Tinsel", again, is an entirely different word derived from the
Latin scintilla, a spark, and appears to be in no way connected with
"tin", which is Anglo-Saxon. Tinsel originally meant something
glittering, without any derogatory suggestion; but, apparently
through false analogy with tin, it now implies cheapness if not
indeed vulgarity. Thus Edmund Spenser (1553 to 1599) in his
Faerie Queen wrote

"Her garments all were wrought of beaten gold,
And all her steed with tinsel trappings shone"

There is no suggestion of paltriness here.

*A useful monograph "Tin through the Ages" by F. J. NORTH, was published
by the National Museum of Wales on the occasion of a Temporary Exhibition
in 1941.

198

LEAD, TIN, AND MERCURY

Ancient Chinese philosophers had peculiar ideas anent tin. They
believed that arsenic would generate itself in 200 years and after a
further like period would become tin. The observation that wine
kept in tin vessels sometimes became poisonous was regarded as
confirming the idea, transmutation not being complete*.

Tin was not known in Egypt at a very early date; the earliest
examples to be unearthed date only from the i8th Dyrfasty (1580
to 1350 B.C.). Tin is not even mentioned in the Ebers Papyrusf of
1550 B.C. although bronze has been found sporadically at a much
earlier date. It would appear therefore that in Egypt tin 'was not
at first reduced separately from its ore and added to copper to
produce bronze, but that the mixed ores of copper and tin ,were
smelted together, as usually elsewhere. Tomb pictures, however,
indicate that by the i8th Dynasty the alloy was made by the
former process. A tin vase dating back to circa 1200 B.C. has been
found in upper Egypt and from 700 B.C. onwards tin foil was used
in the wrappings of mummies.

Tin is not mentioned by name in Holy Writ before the Flood,
circa 4000 B.C. The word occurs five times afterwards in the Old
Testament and is mentioned along with silver, iron and lead as one
of the metals traded in the fairs of Tarshish, the modern Andalusia
of Spain (Ezek. xxvii. 12). As already stated, however, (p. 9) the
so-called tin was an alloy of copper and tin, but containing a
higher percentage of the latter metal than the ancient "brass" or
bronze.

Both Homer circa 880 B.C. and Hesiod, who lived a century
later, use the word cassiteros to denote tin. It is possible that it may
have been borrowed from the Sanskrit kastira^ tin, related to the
verb has, to shine. The Arabic word for tin is kafsdir, closely re-
sembling the Sanskrit, although the two languages are not
connected. On the other hand, Reinach has suggested that the
name Cassiterides is Celtic, comparing it with Cassivellaunus,
Cassignatus, Veliocasses, etcj.

The Romans at the beginning of the Christian era were using
considerable quantities of tin and clearly distinguished between it
and lead. Much of their tin was undoubtedly obtained from Spain

*GOWLAND, "Huxley Memorial Lecture for 1912", Royal Anthropological
Institute of Great Britain and Ireland, p. 247.

fWritten during the reign of Amenhetep i and found reposing between the
legs of a mummy.

{"Guide to Early Iron Age Antiquities", British Museum, 1925, pp. 4-5.

199

THE CHEMICAL ELEMENTS

where the metal was mined at a very early date. Pliny* called tin
plumbum candidum or album, whereas lead was written as plumbum
nigrum or simply plumbum (p. 188). He refers to the practice of
tinning copper by dipping into molten tin (p. 205).

c

Tin in Britain

Diodorus Siculus, writing about 56 to 36 B.C. mentioned Britain as
a source of tin. Herodotus circa 550 B.C. was the first to mention
the cassiterides as such and it has been assumed by many that the
Cassiterides were the Scilly Isles or, if Britain, Cornwall in
particular was meant. Others have suggested the islands in Vigo
Bay on the Atlantic coast of Spain. But this may be narrowing down
the meaning of the word too much. Most of the passages in the
ancient writers referring to these islands are quoted in Elton's
"Origins of English History" and discussed at considerable length.
Baileyf is of opinion that Cassiterides was originally a general name
for the tin localities of Western Europe, covering a wide area much
as we speak of the Middle East to-day without meaning Palestine
in particular. The writers *of those days had but a poor idea of the
geography of the West and they were by no means helped by the
Phoenicians themselves who did their utmost to conceal the goose
that laid the tin egg ; they not unnaturally wished to maintain their
monopoly of the trade just as in the sixteenth century the Dutch and
Portuguese guarded their secret of the discovery ^of Australia with
the utmost jealousy (p. 125). Strabo, writing about 7 B.C. (p. 133),
mentions that on one occasion a Roman vessel followed a certain
Phoenician trader hoping to find the source of his tin. But the
Phoenician purposely ran his vessel on to a shoal, leading his
pursuers into the same disaster; he managed, however, to escape
from drowning and subsequently received from the State the value
of the cargo he had lost.

PlinyJ states that there was a "fabulous story" of the Greeks
sailing in quest of tin to the islands of the Atlantic and of its being
brought in barks made of osiers covered with hides. There is nothing
incredible in this as Pliny seems to imagine, for in an earlier book
he had already mentioned that the British used boats of that kind

*'The Natural History of Pliny", translated by Bostock and Riley (Bonn,
1857), Book 34, Chapter 48.

fBAiLEY, "The Elder Pliny's Chapters on Chemical Subjects" (Arnold, 1932),
Part 2, p. 193.

{PLINY, Book 34, Chapter 37.

fPuNY, Book 4, Chapter 30.

200

LEAD, TIN, AND MERCURY

but perhaps he had forgotten. The Greeks called these boats coracles,
evidently a term borrowed or adapted from the Celtic cren or croen
meaning skin*.

The Phoenicians themselves stated that the inhabitants of the
islands where they traded were clad in black cloaks and in turyics
reaching to the feet, with girdles round their waists, and that they
walked with staves and were bearded like goats. So if^these were
indeed Cornishmen we now know what some of our ancestors were
like.

In Cornwall, tin was mined in the bronze age; the tin tradef was
already in existence at the time of Pythias, 325 B.C., and possibly
the trade had been carried on since 450 B.C. It is possible that the
Phoenicians sought tin in Britain as early as 1000 B.C. for 'it is
certain they had even then passed through the Straits of Gibraltar
and founded Cadiz. Irish gold work of about 1200 B.C. has been
found at Gaza, so there must have been some connection between
our Islands and the Mediterranean. The tin may have been
shipped from St Michael's Mount or from the Isle of Thanet;
possibly from both. It seems then to have found its way to the
Loire or the Garonne, or to both these rivers, and thence overland
to the Mediterranean. A Falmouth tradition holds that the
Phoenician trade with Britain was first transacted on the Black
Rock, a jagged islet at the entrance to the Carrick Roads.

Julius Caesar and other Roman historians were rather prone to
disparage the British whom they had defeated. This was foolish
and belittled their own efforts, for their soldiers found the British
very sturdy foes; warriors like Caractacus and Cassivellaunus were
no mean antagonists. For many years it was supposed that our
Celtic ancestors were barbarous folk, poor in physique and ill-clad,
their bodies being stained with woad. This is an entirely wrong
picture. British priests or Druids were a cultured and highly
educated sect, possessing a high standard of scientific attainment.
They had invented a water clock which enabled them to measure
the passage of time beneath our leaden skies ; sundials by day and
clock-stars by night, so valuable in the East, were of little avail
here. So great was the renown of the Druids that young men
flocked over to Britain from the Continent to receive instruction at
first hand from them. Britain was the university of Western Europe.
In addition to this, Britain carried on an extensive commerce with

*A. TYLER, Nature, 1883, 29, 84.
fBROMEHBAD, ibid., 1940, 146, 405.

201

THE CHEMICAL ELEMENTS

the mainland of Europe, and must even have been a naval power,
for the assistance she sent to the Veneti in Gaul evidently worried
Caesar and was made the pretext of the Roman invasion. Further,
Tacitus, writing about A.D. 115, speaks of London after Caesar's
invasion as a city of great importance. This was obviously no
mushroom growth that could spring up in a night.

There was a concentration of Roman roads at Venta Belgarum
or Winchester, as a glance at the map in Fig. 7 shows. Such roads
were clearly built mainly for military purposes but they must also
have been designed with an eye to easy transport of metallurgical
products. Of two roads to the north, one veered eastwards to

WALES

Gloucts

Ptvensty

Fig. 7 The Roman roads of Southern Britain

Silchester and thence to Londinium; the other turned westwards
ending in Fosse Way^ which connected Exeter and Aquaesulis or
Bath with Lincoln. To the west lay a road passing through Old
Sarum, that is Salisbury, and so to the Mendips, cutting Fosse Way
a few miles south of Bath, Almost due south a road led to Clausentum
the modern Bitterne, now included in the borough of Southampton.
A second road more to the east joined that from Clausentum to
Chichester at Porchester Castle. From Chichester the road, called
Stane Street^ passed through Bignor, Pulborough and Dorking to
Londinium. It was thus an easy matter to transport on the backs of
pack-horses, through Winchester to the Hampshire coast,
Cornish and Dartmoor tin, lead and iron from the Mendips, iron

202

LEAD, TIN, AND MERCURY

from S. Wales and lead from the north. On the coast were several
ports, notably Southampton and Portus Magnus or Portsmouth,
from which the cargoes could be shipped to Vectis^ the Isle of
Wight, and thence to Gaul. The metals were never sea-borne from
Britain to the Mediterranean, but followed an old trade route
through St. Valery-sur-Somme and Chalons-sur-Saone.

At the beginning of the thirteenth century the tin miners of
Cornwall began to make history of their own. Mining had been
carried on, as we have seen, for more than 1,000 years, and the
tinmen had formed a separate community. Their political position
was unique. The tinman or "stannary" worker paid taxes not as an
Englishman but as a miner. He lived, not by common law, but by
miners' law, his courts were miners' courts, his parliament the Miners'
Parliament. The parliament of the stannaries not only made its own
laws but possessed the power to veto any national legislation that
infringed the miners' privileges. These privileges were definitely
confirmed by John in 1201.

When, in 1337, Edward in created his son the first Duke of
Cornwall, it was done in order that the Black Prince might enjoy
the revenues, derived chiefly from the tin mines of the county.

Tin and the alchemists

The western alchemists called tin diabolus metallorum^ because of its
peculiar crackling "cry" when bent due to the crystals crushing
against each other. On account of its brightness coupled with its
cry, tin was associated with the thunderbolt of Jupiter and about
the sixth century received the sign 2[ (p. 1 3). Here again, as in lead,
the curved portion indicates analogy with silver. The sign of the
cross is once more in evidence. In ancient Persia tin was associated
with the planet Venus.

A favourite experiment was the production of the "tin tree" by
suspending a rod of zinc in a solution of tin chloride ; tin deposited
as the zinc dissolved yielding the arbor Jovis, analogous to the
silver and lead trees already mentioned.

Tin plague

Aristotle, 384 to 322 B.C. was aware that, when kept very cold, tin
undergoes a change which he described as "melting", for want of
a better term. Since then attention has on numerous occasions been
directed to this curious phenomenon. Thus in 1851 the tin organ-
pipes in the church at Zeits were found to be attacked, the metal

203

THE CHEMICAL ELEMENTS

crumbling to a powder. Some sixteen years later, after an extremely
bitter winter in Russia (1867 to 8), blocks of tin stored in the
Customs House at St Petersburg were found reduced to a greyish
powder. This is variously known as tin -plague^ tin pest and museum
sickness, and is due to the conversion of ordinary white tin into its
grey allotrope, the transition temperature being 13 C, below
which the grey tin is the stable form. As the temperature falls, white
tin tends to change to grey at an increased rate, a maximum velocity
being reached at 50 C. The white metal first tarnishes, then
becomes covered with a number of grey warts, finally crumbling to
a powdery mass. Fortunately, at the ordinary winter temperatures
in Britain the rate at which this change occurs is very small. But
the ''disease" is contagious and if a "sick" piece of tin is allowed to
remain in contact with white tin at a temperature below the transi-
tion point, the latter metal is more rapidly converted to grey than
would otherwise be the case.

Tin is an important constituent of solder (p. 212). During
Captain Scott's ill-fated expedition to the South Pole (1910 to 1912)
the petrol tins were found to leak. It is believed that, exposed to
the intense cold of the Antarctic, the solder disintegrated in con-
sequence of the tin changing into its allotropic grey form and thus
failed to keep the tins tight. Amundsen, who succeeded in reaching
the South Pole a few weeks before Scott, recorded that his petrol
tins required frequent re-soldering, presumably for the same
reason.

It may well be that the tin plague is largely responsible for the
paucity of ancient objects of pure tin. The addition of lead to tin
appears to retard this change and it is worthy of note that of many
hundreds of Roman tin objects that have survived until present
times and have been examined all contain some lead. A soldier's
button, which microscopic examination shows to have been cast,
contained 0*84 per cent of lead; a jug from Glastonbury, 12-22;
a cup 4-49; and a coffin from Ilchester, Somerset, 55*31 of lead,
this last-named alloy being close to common solder in composition.
On the whole, the Romans used a wide range of alloys or the two
metals ranging from 4 : I to I : 4, and presumably determined
by experience which alloys were best suited for any particular
purpose*.

*J. A. SMYTHE, Trans. Newcomen Soc., 1937-1938, 18, 255. RICHMOND and
SMYTHE, Proc. Univ. Durham Phil. Soc. t 1938, 10, 48. A. WAY, Arch. Journal,
1859, 16, 38.

204

LEAD, TIN, AND MERCURY

The tin-plate industry

The largest consumption of tin occurs in the tin-plate industry, the
history of which is extremely interesting.

Pliny* mentioned the application of protective coatings of tin to
copper and iron to preserve the underlying metal from corrosfon.
"It was in the Gallic provinces", he wrote, "that the method was
discovered of coating articles of copper with tin so as tcf be scarcely
distinguishable from silver. Articles thus plated are known as
incoctUia" The last term means "in-boiled", evidently referring to
the practice of immersing the article to be coated in the mblfen tin.
Pliny adds that this process was extended to coating base metals
with silver and gold. 9

Apparently during Norman times iron was coated with tin in
this country, but the application of the process was limited because
sheet metal had to be made by the laborious practice of hammering
out blocks of metal. The real tin-plate industry began in Bohemia
circa 1240.

Subsequently the Duke of Saxony, learning of the wonderful
properties of tin-plate and the great success of the Bohemian trade,
determined to introduce the same into his countryf. To this end he
obtained the services of a Roman Catholic priest who, disguised as
a Lutheran, went to Bohemia to pick up what information he could.
Spying of this kind seems to have been popular in the Middle Ages,
and it must be conceded that the priest did extremely well. He
returned to Saxony with the necessary information and in a short
time a thriving tin-plate industry was established. France now
wished to emulate Saxony, and Colbert, Minister to Louis xiv (1643
to 1715), friend of the British King Charles n, deputed Reaumur
to visit Saxony and in his turn glean all the information he could.
Ren de Reaumur (1683 to 1757) was a famous French scientist,
chiefly remembered to-day, perhaps, for his thermometric scale
(p. 226). As the result of Reaumur's visit, tin-plate works were set
up in France, the labour being apparently carried out by German
workmen; but the pay was regarded as insufficient, the workmen
"struck" or withdrew and the trade died out.

Early in the reign of Charles n (1660 to 1685) Thomas Allgood,
a native of Northamptonshire, went to Pontypool to extract

*PLINY, Opus cit., Book 34, Chapter 48.

fCHARLES WILKINS, "History of the Iron, Steel, Tinplate and other Trades
of Wales" (Williams, 1903), Chapter 33. P. W. FLOWER, "A History of the Tin
Trade" (Bell, 1880).

205

THE CHEMICAL ELEMENTS

copperas and oil from the coal. An iron trade had already been
established there, records of which date back to 1588. During the
course of his experiments Allgood discovered a method of varnish-
ing tin-plate so as to imitate the lacquered articles imported from
Japan, then known widely as Japanware. The necessary tin-plate
was accordingly imported from Saxony. To produce it in this
country and thus make Britain independent or foreign trade was
the aim of Andrew Yarranton*. In 1632, when a lad of 16, Andrew
was apprenticed to a linen draper in Worcester. But the work was
not to. his taste and he ran away. When civil war broke out he
joined the Parliamentary army, rising to the rank of captain. He
distinguished himself by uncovering a Royalist plot to seize
Doyley House in Herefordshire. For this he received the thanks of
Parliament together with the substantial honorarium of 500. On
sheathing his sword he started an iron works near Bewdley in 1652
and became interested in the development of canals and of river
transport. He was one of the first to recognise the value of clover in
agriculture.

On the accession of Charles n in 1660, people recalled that he
had been of the opposite faction, charges were trumped up against
him and he was thrown into prison. After an eventful escape, re-
capture and trial, he was released and in 1665 turned his attention
to the possibility of manufacturing tin-plate in Britain. In 1667 he
was sent out to Saxony, with a workman who understood iron, and
an interpreter, by a number of interested gentlemen, so that he
might learn the secrets of the process. "Coming to the works"
wrote Yarranton "we were very civilly treated and, contrary to our
expectation, we had much liberty to view and see the works go,
with the way and manner of their working and extending the
plates ; as also the perfect view of such materials as they used in
cleaning the plates to make them fit to take tinn, with the way they
used in tinning them over when clear'd from their rust and black-
ness." When he had found out all he needed to know Yarranton
returned to England and set up a factory in Worcester. In 1670
the Worshipful Company of Tmplate Workers was incorporated.
Trouble, however, arose at Worcester in connection with patents,
for his secret had leaked out, and Yarranton closed his factory.

John Hanbury now enters the picture. He was a Kidderminster
man, destined for the bar. But he was more interested in mines and

*See "Dictionary of National Biography" edited by L. STEPHEN (London, 1888)
206

LEAD, TIN, AND MERCURY

forges than in law. He was not without means which he made all
the more substantial by a prudent marriage, and settled in Pontypool,
Mon. Here he extended and "improved" the iron works to such an
extent that a visitor, some years later, described the place as "A
large, dirty, straggling town standing near the entrance of a once
picturesque valley filled with ironworks and collieries. "

At Pontypool the tin-plate was made as follows. She^t iron was
prepared by flattening out hot slabs of metal under a helve or
tilt-hammer; the slabs, when reduced in thickness, were doubled
over and piled, with other similarly thinned plates, under the
hammer, their surfaces being sprinkled with powdered charcoal
or coal to prevent welding. Hammering was continued until the
resulting sheets were of the desired thickness. They were then
pickled in dilute sour rye-water or vinegar to remove oxide and
other surface impurities, and finally immersed in a bath of molten
tin.

In 1728 Hanbury was joined by John Payne, and the same year
they introduced the method of rolling the hot bars of iron into
sheets between metal rollers. This was an enormous improvement.
Not only could sheets be produced more rapidly but they were
more uniform and even. The specification of the patent announced
that "barrs, being heated . . . pass between two large mettall
rowlers (which have proper notches or furrows on their surfuss) by
the force of the inventor's engine or other power into such shapes
and forms as required."

By 1 740 the German imports of tin-plate were dispensed with,
the plate produced in England being ample for home consumption.
By 1776 England herself was exporting. It was not until 1885,
however, that iron sheets were replaced by steel.

The fame of the Pontypool japanware lasted for 150 years and
then decline set in. Meanwhile Wolverhampton (circa 1720) and
other centres of industry had begun to manufacture the ware; even
after Pontypool had ceased to produce it, the ware was still known
as Pontypool ware.

The Old Hall at Wolverhampton, which occupied a site not far
from the present library, was a remarkable mansion surrounded by
a moat, built by the Levesons, a well-known county family, who
acquired great wealth in the wool trade. The Hall was eventually
let to the brothers Ryton, who had carried on the tin-plate trade in a
small factory in Tin Shop Yard, North Street, and their enterprise
made the Old Hall famous all over the world.

207

THE CHEMICAL ELEMENTS

A further wave of prosperity followed the improvement in
transport by the development of the Staffordshire and Worcester-
shire Canals, and then ensued a period when public taste demanded
goods of high artistic merit, and japanned tea-trays, tea-caddies,
cc/al-vases, and other goods were produced, cleverly decorated with
hand-painted designs and scenes by artists of repute.

Edward Bird, R.A., was apprenticed to the japan trade at the Old
Hall, and at one period Biblical scenes were the fashion. Then
followed elaborate decorations in gold and colours, in Indian and
Chinese designs, some splendid work being accomplished.

Another notable person associated with the Old Hall was Edwin
Booth, who was a skilled workman before he became famous as a
tragedian. He eventually emigrated to America and, sad to relate,
it was his son, Wilkes Booth, who assassinated President Lincoln
in the theatre at the close of the American Civil War.

One of the most far-reaching improvements on the manufac-
turing side of the industry was the introduction of Nasmyth's
steam-hammer process circa 1840. It was on the suggestion of a
foreman at the Old Hall works Mr Pinson, afterwards of
Pinson and Evans that Nasmyth (i 808 to 1 890) made alterations
in his steam hammer and adapted it for use in stamping articles of
hollow-ware from steel and iron sheets. Originally all tin articles
such as tea and coffee pots, saucepans and kettles, were made
entirely by hand, but a slow and laborious method of stamping had
been evolved just before Nasmyth's patent was applied. The hammer
head was raised by hand by means of a winch, and later by steam,
but Nasmyth's invention revolutionised the industry, and since
then the machinery for the production of hollow-ware and pressed
metal-ware generally has been continually improved by new inven-
tions and adaptations.

Good may come out of evil. Military campaigns may stimulate
research that ultimately proves to the good of man. Napoleon was
anxious to feed his troops in regions where insufficient or even no
food might be obtainable locally. He appealed to Nicholas Appert in
1808 to help him out. This man had already observed that rood in
airtight packages could be sterilised with heat and could then
apparently be kept indefinitely. IJe thought that contact with air
caused putrefaction. It was not until 1854 that Pasteur began those
researches that culminated in the discovery that putrefaction was
due to living micro-organisms.

208

LEAD, TIN, AND MERCURY

Appert's first experiments were carried out with stout glass
bottles as containers. In 1806 the French Navy tried out his
preparations and apparently found them very successful. In 1809
Appert was awarded a prize of 12,000 francs in recognition of his
work by the Bureau Consultatif des Artes et Manufactures.

In 1810 John Hall, founder of the Dartford Iron Works and his
associate Bryan Donkin, a scientist and Fellow of the Royal Society,
developed a similar process, evidently visualising an outlet for their
products if iron containers could be used in place of glass. The same
year patents were granted to Augustus de Heine and to Peter
Durand for the preservation of food in "tin" containers. Although
Durand is known both in this country and in America as the
"Father of Tin Cans" neither he nor Heine appears to have engaged
in canning on a commercial scale. By 1813 both the British Army
and Naval authorities were interested in the scheme*. Evidently
Wellington's attention had been drawn to the subject for a certain
C. C. Smith wrote on his behalf a letter, dated 3Oth April 1813,
saying that his Lordship (he was Lord Wellesley then) had found
the preserved beef very good. Was it a sen&e of humour which made
him add that his Lordship could not himself write owing to
indisposition?

Captain Parry took some of Donkin's tinned foods with him on
his three Arctic voyages of discovery (1819 to 1825) and found
them invaluable. Some tins of meat were landed on the ice when one
of his vessels, H.M.S. Fury, in the third expedition met her fate in
August 1825; they were found several years later by Captain Ross
during his voyages (1829 to 1833) and their contents were in
excellent condition. Two tins brought back by Parry himself were
opened as late as 1938 and the contents were still perfect after
114 years.

Two tins of meat left over from the stores of H.M.S. Blonde,
which went on a voyage of discovery to the Sandwich Islands in
1826, came later into the possession of Dr Alfred S. Taylor. In
1846 Taylor opened one of them before the chemistry students at
Guy's Hospital, London, and noted that the meat seemed perfectly
good. Unfortunately he was unable to analyse the food, for its
savoury appearance and odour induced some hungry hospital
assistants to sample it exhaustively. Nature did not exact any
retribution for their unauthorised repast, so evidently it was

*"Historic Tinned Foods" (International Tin Research and Development
Council, 1939). Publication 85.

209

THE CHEMICAL ELEMENTS

still wholesome. In 1867 the remaining tin, then 41 years old, was
opened, but the contents were bad; the tin had become perforated
with rust. Taylor therefore recommended that the tins should be
lacquered or painted as a protection against corrosion.

f By 1820 the tin can had been introduced into the U.S.A. For
70 years the cans were made there by hand, and a tinsmith who
could tur;i out 100 cans a day was a skilled workman indeed.
Towards the close of the century automatic can-making machinery
came in, and the "sanitary" top can was patented in 1904. To-day,
as many as 300 cans per minute are produced by a single unit or
"line" of can-making machinery in the modern plant.

The modern tin container, solderless, except for a small applica-
tioif on the outer edges of the side seam, represents a further
improvement.

Equally great strides have been made by the canning industry
in the methods used in canning foods. This improvement, together
with scientific methods of sterilisation and processing, now in use
by most canners, has practically eliminated "spoilage" of canned
foods. e

Tinned meats, fish, and fruits have long been on the market;
since 1935 tinned or "canned" beer has been obtainable in the
U.S.A. Some 40 per cent of America's tin consumption is absorbed
by the tin-plate industry. The French call tin-plate white iron.

The industry consumes more tin than any other. It is stated that
the quantity of tin-plate made in 1933 would suffice to form a belt
round the earth at the equator 100 ft. wide.

Even cast-iron is now being tinned ; cast-iron boxes required for
the manufacture of penicillin have been tinned.

In medieval times sword blades were sometimes tinned to
preserve them from rust, and analysis shows that inlaid inscriptions
were sometimes executed in tin instead of silver.

South Wales is the centre of British tin-plate manufacture; more
than 16,000 tons of tin and 1,000,000 tons of steel are consumed
annually. The tin coating is very thin, usually about o-oooi inch in
thickness and less than 1*5 per cent of the weight of an empty tin,
such as is used for meats, fruits, vegetables, etc, is really metallic
tin. For this reason it has been suggested that our so-called "tins"
should be called "cans". That would certainly be more logical, but
we should lose the history.

Copper coated with tin is used in the dairy industry, the tin
preventing the copper from flavouring the milk.

210

LEAD, TIN, AND MERCURY

Copper wires coated with tin are used in the electrical industry.
The tin prevents the sulphur in the rubber insulation from causing
the copper to deteriorate.

Tin foil

The existing oriental custom of making lace by the laborious hand-
beating of tin into foil and subsequent cutting into decorative design
originated in dim antiquity. One Ib. of foil will spread over some
11,000 to 14,000 sq. in., the usual thickness being 0-0035 to
0-0080 inch. Tin foil has in recent years been much favoured as a
harmless wrapping for sweetmeats, tobacco, cheese, and other
foodstuffs, although it is now displaced in considerable measure by
aluminium. The mechanical weakness of tin imposes a limit ofi the
thinness to which it can be rolled and yet retain its usefulness as a
wrapper. Greater strength is obtained by addition of a little zinc
and a trace of nickel and this alloy has proved useful for capping
milk bottles.

Pewter f

Tin is the essential constituent of pewter, which the Romans made
by melting together approximately four parts of tin and one of lead
(p. 191). This alloy dates mostly from the third and fourth centuries
A.D. In 1348, The London Guild of Pewterers, founded in 1300,
recognised this mixture as suitable, but three years later stipulated
that the amount of lead should not exceed one part in seven of tin.
Being relatively soft, malleable, ductile, and of pleasing appearance,
pewter was largely used for vessels of all kinds including plates,
flagons, tankards, salt cellars and the like. Even church plate,
particularly on the Continent, was made of pewter. Edward i (1272
to 1307) is said to have possessed over 300 pewter vessels. The
method of assaying was based on the fact that tin is less dense than
lead, hence, by comparison of the weight of a cast disc of pewter
with a similar one of pure tin, one could determine with ease
whether or not the correct amount of lead was present. From the
fifteenth to the eighteenth century pewter was largely used by the
middle classes.

King Charles i (1625 to 1649) prohibited the import of tin, and
directed "that all measures for wine and ale used in taverns,
victuallers' houses, and shops should be made of pewter or tin and
should receive the Royal stamp or seal." Unfortunately, after the
Restoration this very law nearly ruined the trade, owing to the delay

211

THE CHEMICAL ELEMENTS

in obtaining the Royal stamp. We hear similar complaints about
the inertia of Government Departments even in this enlightened
age. History repeats itself.

During the eighteenth century pewter became less popular for a
variety of reasons. One lay in the increasing appreciation of glass,
porcelain and pottery. Another was the debasing of pewter with
increasing (> amounts of lead which gave it a dull grey or black
appearance. This happened despite the attempt of the Pewterers in
1772 to regulate the quality of pewter by threatening members
who Disregarded their ruling with expulsion from the Guild.

Modern pewter contains no lead; it is roughly 95 per cent tin,
with a little antimony (4) and a small amount of copper (i). It
possesses a pleasing white lustre and is moreover very resistant to
attack by comestibles. Hammered pewter with a highly polished
facetted surface is popular in this country, whilst most Swedish
ware is duller. Britannia metal, introduced by James Vickers
towards the close of the eighteenth century and manufactured in
Sheffield, also contained a little antimony; it was made by adding this
element to high grade pewter, the product being harder, whiter and
more resonant. At the present time several alloys are classed under
the general name of Britannia metal. One of these comprises 93 of
tin with 4-6 of antimony and 2 of copper.

Solder

Some 22 per cent of the world's tin production enters into the
solders. The tinman's solder is 2 of tin and i of lead; the plumber's
solder is just the reverse; formerly soft solders had equal amounts.
The idea of the soft solder is that during soldering the lead will
harden before the tin which remains molten in the interstices of the
lead and thus keeps the whole plastic until the plumber has had
time to "wipe the joint".

Other alloys are type metal (p. 197) and fusible alloys (p. 88).

In 1839 Isaac Babbitt prepared an alloy of tin with some anti-
mony and copper which was more plastic than ordinary bronze and
specially suited for reducing friction between moving parts of
machinery. The alloy was white and was later modified until whole
series of "antifriction alloys" or "bearing metals" had been
produced. These are still known as Eabbitfs metaL A typical alloy
contains 83 of tin, 8-5 of antimony, and copper each. Bearing
metals with a high tin content are used in electrical generators and
aeroplane engines, in the main bearings and big ends of connecting

212

LEAD, TIN, AND MERCURY

rods of steam engines and internal combustion engines and
generally where risk of scoring shafts must be avoided.

Speculum metal (Latin speculum, a mirror) or white bronze contains
2 of copper and I of tin. It is whiter even than tin, extremely
brittle, and takes a high polish. It was used in Roman days for
making mirrors and in more recent times found application in
reflectors for telescopes. Later it was, of course, replaced by the
well-known silvering process (p. 116).

Collapsible tubes for paints, ointments, etc, are frequently made of
tin. In 1841 John Rand brought out the first patent for*nlaking
collapsible tubes, lead being used. By 1850 the lead was being
replaced by the less poisonous tin. At the present time som 800
million collapsible tin tubes are produced annually.

Sources of tin

A century ago, two-thirds of the world's tin came from Cornish
mines. Hot water welled up in the mines and was pumped out by
the steam pumps of James Watt and later Tfevethick. At the
present time the two chief mines are at Geevor, near Land's End,
and the South Crofty mine at Camborne.

Prior to World War II some 70 per cent of the world's tin ore
came from S.E. Asia, including Malaya, Dutch East Indies and
China. Other sources are Australia, Tasmania, Nigeria, the
Belgian Congo and Bolivia.

The tin of Nigeria is extremely easy to work, for the deposits are
all alluvial. It was secured in the early days of the industry by
simply washing the sands and gravel. The resulting product, black
tin, contained over 70 per cent pure tin.

The tin mining industry in Nigeria did not develop to any great
extent until the price of the metal reached 150 per ton, when the
mining world began to take an active interest in it. Since then it has
gone rapidly ahead, and in 1928 Nigeria produced over 10,000
tons of tin concentrates.

The opening up of the railways has aided the development of the
tin area by enabling modern machinery to be imported and by
reducing the carriage of the raw material to the coast. While the
shallower deposits are in some cases being worked out, the deeper
ones are now being exploited. Hand labour is giving place to the
hydro-electrical plant and steam shovels.

Prior to World War II nearly 40,000 natives were regularly
employed in the tin fields and a real standard of living had been

213

THE CHEMICAL ELEMENTS

established. In half a century the slave-driver and his works have
been forgotten.

In 1800 the world production of tin was less than 9000 tons; in
1900 75,000 tons and by 1940 238,000 tons, the increase being
mainly due to the enormous consumption in the tin-plate industry.

Mercury or, quicksilver

This was the latest of the seven metals to be discovered in pre-
Christian times. The word quick means living and is used in this
sense nir the old expression "the quick and the dead" a modern
version of which, since the advent of the motor car, is said to be
"the quick or the dead". When held in the palm of the hand the
surface of the metal is in constant motion, due to tremors caused
by the blood coursing through the veins and arteries. It thus seems
to be alive; this coupled with its bright silvery appearance, completes
the aptness of its early name. The alternative name mercury is
probably derived from the Latin merx, merchandise.

Mercury and the ancients

The metal has been found in Egyptian tombs dating back to some
1600 B.C. but is believed to have been introduced into these at a
much later date by Arabs, who used small bottles or phials contain-
ing the metal as amulets. Mercury is not mentioned in the Ebers
Papyrus, circa 1550 B.C. (p. 199) neither does the metal receive
mention in the Old Testament. In Numbers xxxi we read of the
spoil taken from the Midianites. This included (verse 22) gold,
silver, "brass", iron, "tin" and lead. We are then told of the "water
of separation" which the Lord commanded the Hebrews to use in
purifying the spoil. "Everything that may abide the fire, ye shall
make it go through the fire, and it shall be clean; nevertheless it
shall be purified with the water of separation." Many have inter-
preted this passage as referring to the use of mercury, but more
probably it merely refers to the usual "water of purification" used
ceremonially and prepared by burning a red heifer whole, mixing
the ashes with water and allowing to stand*.

The Greeks were already familiar with mercury before the
Christian Era. Aristotle (384 to 322 B.C.) referred to it as "liquid
silver"; this appears to be the first definite mention of the metal.
Theophrastus, circa 300 B.C., mentions the manufacture of chutos

*PARTINGTON, "Origins and Development of Applied Chemistry" (Longmans*
*935)> PP. 84, 193, 486.

LEAD, TIN, AND MERCURY

argyros or quicksilver from cinnabar, saying that it can be obtained
by rubbing the ore with vinegar in a copper vessel.

Mercury and the Romans

Pliny* has a good deal to say about mercury. It was apparendy
customary to distinguish between the native metal, that is argentum
vivum or quicksilver, and the same element prepared fronj cinnabar,
which was called hydrargyrum or "silver water". Pliny briefly
described the preparation of this latter, which he somewhat dis-
paragingly referred to as a "substitute" for the native metal. An
iron pot, containing cinnabar, was placed inside an earthen pan
and covered with a lid luted on with clay. The whole was then
heated from beneath with a fire kept going with the aid of belfows.
The vapour condensed on the lid to a liquid combining the colour
of silver with the mobility of water.

Pliny knew that quicksilver could be used in the purification of
gold for he states that "on being briskly shaken m an earthen
vessel with gold, it rejects all the impurities that are mixed with it.
When once it has thus expelled these superfluities, there is nothing
to do but separate it from the gold."

In 1 154 Al Idrisi described a similar process as being carried out
in his day in Central Africa. Auriferous sands were washed in
wooden tubs and the gold mixed with mercury. On heating the
amalgam over a charcoal fire the mercury volatilised leaving a
residue of gold. This, of course, is. the principle of the "amalgama-
tion process" for the extraction of gold and silver, once extensively
used. It was re-discovered by the Spanish about the middle of the
sixteenth century, after having apparently been lost for several
centuries.

Mercury and the alchemists

The alchemists placed a high value on mercury and their symbol
for it has already been explained (p. 13). They were fond of
experimenting with amalgams^ that is alloys of various metals with
mercury. The word amalgam, derived from the Greek malakos,
soft, is believed to have been introduced by Thomas Aquinas,
circa 1250, pupil of Albertus Magnus who introduced the term
affinity into chemistry (p. 1 6).

*'The Natural History of Pliny". Translated by Bostock and Riley (Bohn,
1857)1 Book 33, Chapters 32 and 41.

215

THE CHEMICAL ELEMENTS

Reference has already been made to the medieval conception of
mercury as a constituent, along with sulphur, of all metals. An
English MS. in the possession of the British Museum, dating back
to the fifteenth century refers to mercury as "the mother of all
njetals with sulphur"*.

To the Indian alchemistsf mercury was all-important. Their god,
Siva, was the mercurial deity, and mercury was used not merely to
transmute base metals into gold but also to prolong life beyond the
normal.

In the sixteenth century liquid mercury appears to have been fre-
quently prescribed as a medicine to be taken internally. Somewhat
later Thomas Dover (b. 1660), a reputable physician, was a great
advocate of its use ; it is said that a patient of his, to wit Captain
Henry Coit, took one-and-a-quarter ounces of metallic mercury
daily until he had consumed more than two pounds. Dover claimed
that mercury removed all vermicular diseases, opened all obstruc-
tions and purified the blood. But more gold could be accumulated
in those days by piracy, for might was right and the weaker were
thrust to the wall. So Dover threw up his medical practice and went
aroving in the South Seas under a scheme engineered by a group
of Bristol merchants, returning somewhat later with spoil estimated
at 170,000. During his voyages he landed on the island of Juan
Fernandez, where Alexander Selkirk was marooned in 1704
whose experiences are believed to have led Defoe to produce in 1719
his world-famous Robinson Crusoe.

The story of vermilion

Mercury occurs naturally as the sulphide cinnabar or coral ore.
Both names refer to the colour. The word cinnabar is believed to
come from India where it is used to designate the red resin known
to us as dragon's blood. The crushed mineral was used as a pigment
under the name vermilion and was much prized for its beautiful
colour. The Egyptians used it as long ago as 400 B.C. for painting
pictures of their gods. Its Roman name was minium, but it was so
frequently adulterated with what Pliny J termed "a second-rate
kind of minium", known to us as red-lead, that the name minium
passed from vermilion to its adulterant, and still clings to it, thus

*See RODWELL, Chem. News, 1873, 7, 206.

fP. C. RAY, "History of Hindu Chemistry" (Williams & Norgate), Volume I
(1902); Volume 2 (1909).

JQuoted from BAILEY, "The Elder Pliny's Chapters on Chemical Subjects",
(Arnold, 1929), Part i, p. 123.

216

LEAD, TIN, AND MERCURY

perpetuating the memory of man's dishonesty. A nation's language
bears the impress of the character of its people.

The quicksilver mines at Almaden in the province of Ciudad
Real, Spain, are the richest and most valuable in Europe, normally
producing about half the world's supply of the metal. They were
worked at the time of the Punic Wars, 600 B.C., and the first actual
excavations are believed to have taken place at this time** They cover
an area of some 1 2 square miles, and as yet but a small proportion
has been worked. In 1927 the output was 2,500 tons; in 1935 it
was 1,227 tons, the output having been restricted in 1930; the
present production is not known. Mercury mining is an unhealthy
task, and in the early days it was allotted to slaves ; later it was the
duty of convicts, and the Spanish Government at one time granted
exemption from military service to men who had been at Almaden
for two years.

Approximately 2000 men normally work in these mines, but
this number has often been exceeded. The present workings, which
date from the seventeenth century, are 1,200 feet deep, with twelve
galleries, one below the other. They are closed between April and
October, when there is a lack of water for the distillation process.

In by-gone years, however, the conditions were ghastly. Slaves
and criminals worked continuously throughout the seasons, through
hot and cold, through summer and winter. They seldom survived
three years of service, and as rapidly as they perished they were
replaced by others. Stories are told of men whose bodies became so
saturated with mercury that a piece of brass put into their mouths
would become white.

In 1 1 68 King Alfonso vm granted the mines to the Knights of
Calatrava who were, however, defeated by the Moors at the battle
of Alarcos, with the result that Almaden became the property of
the Caliphs of Cordova. The name Almaden is Arabic for mine>
which suggests that the Moors worked the mineral in their turn.
In 12 12 the tables were turned, the Christians defeated the Moors
at Las Navas de Tolosa, and the Spanish king again took over the
mines. The Knights of Calatrava then reminded the king of their
early rights and once more entered into possession, but this time
they had to share their profits on a fifty-fifty basis with the Crown.

A few centuries later, with the discovery of the vast quantities of
silver ore in Mexico and Peru (p. 109), the importance of Almaden
grew enormously, for mercury was essential to the old Spanish
amalgamation method of extracting silver.

217

THE CHEMICAL ELEMENTS

The mines are still extremely valuable; in war time they possess
a special interest, for mercury fulminate is then in huge demand as
a detonator.

The cinnabar mines of Idria in Hungary have been worked for
sewral hundred years. A merchant noticed globules of mercury
lodged in the hollows of a spring and thought that by excavating to
a sufficient* depth the source of the valuable metal might be dis-
covered. He obtained a grant of the ground from the Government
and began working; his efforts were to a large extent successful, but
it becurrte evident that much larger quantities of ore could be
obtained at greater depths than he could afford to work. So he sold
the works as a running concern to the Austrian Government and
they are now known to be extremely rich. In some places free
mercury is found in glistening globules, but of course the main
bulk of the metal of commerce has to be extracted from the ore.

About the year 1566 Henry Garces, a Portuguese, examined a
red earth used by the Indians for making paint. The colour
reminded him of cinnabar and after making a few experiments he
convinced himself that this red earth was indeed the same as that
mined in Spain. This led to the opening up of the mines at
Guancavelica in Peru, where thousands of workmen were sub-
sequently condemned to forced labour amid the deadly fumes.

The mines run deep and it is said that in the abyss are seen streets,
squares and a chapel where religious ceremonies are celebrated on
festive occasions. Very rich mines are worked in California and
elsewhere.

The Japanese were wont to utilise the antiseptic properties of
cinnabar in preserving the dead. The rich and noble were buried
in several square coffins, one inside the other, usually in a sitting
position, the nose, ears and mouth being filled with cinnabar to
arrest decay. In the case of the very wealthy the coffin might be
completely filled with cinnabar*.

Pliny mentions the use of vermilion as a pigment; he states that
in earlier days it had been customary on festive occasions to cover
the face of the statue of Jupiter with the pigment, whilst victorious
generals, returning triumphant from successful campaigns, likewise
stained their bodies red an emblem of blood and carnage!

Vermilion was expensive, and Roman artisan painters discovered
an ingenious method of pilfering it; in the interest of cleanliness

*LORD REDESDALE, "Tales of Old Japan" (Macmillan, 1910), p. 75.
218

LEAD, TIN, AND MERCURY

they would frequently wash their brushes when filled with pigment,
which latter, owing to its great density, fell to the bottom of the
water and was thus so much gained by the thief. Adulteration was
common (p. 216). Pliny was aware that cinnabar is poisonous and
mentions that "by Hercules*' some physicians used it by mistake
instead of Indian cinnabar, the resin now known as dragon's blood.
Let us hope that it was by mistake only, and not of malice afore-
thought. Pliny was fond of invoking Hercules when he wished to
express himself forcefully.

The Chinese were long regarded as the best makers of vermilion;
perhaps they took more pains with their work and thus produced a
finer substance, for they are a gifted people and their patience is
proverbial. The Chinese used vermilion as a royal colour in quite
early times. Marco Polo (p. 55) states that the paper currency of
Cublai Khan in the thirteenth century was stamped with the royal
signature in vermilion.

The Hindoos knew how to make vermilion at an early date. In the
Rasarnava tantra, circa A.D. 1200 a method of manufacture is given
which is essentially the same as that long 'practised "by the Chinese.

That mercury was a true metal was not generally admitted until
1759 when it was first frozen, its melting point being 3 8 '9 C.
Solid mercury was then seen to resemble lead or silver in its
physical properties. In 1849 Ross, when in Greenland, pierced a
wooden plank an inch thick with a bullet of frozen mercury, so low
were the temperatures he experienced.

Uses of mercury

Mercury is employed in thermometers, barometers and numerous
other instruments. Priestley introduced the mercury pneumatic
trough which enabled him to prepare and collect in a pure state
such gases as ammonia, hydrogen chloride and sulphur dioxide,
which are too soluble for collection over water.

Amalgams are of considerable importance. Some are at first so
soft that they can be moulded in the hand like wax, but harden later;
they are sometimes used by dentists for filling teeth.

As we have already seen, gold readily amalgamates with mercury,
so does silver, and amalgamation processes for the extraction of
these metals from their ores have long been practised, though they
are now largely superseded by the cyanide process.

Gold amalgam is used in fire-gilding; the metal article to be
gilded must of course be able to stand uninjured a temperature

219

THE CHEMICAL ELEMENTS

close to that of boiling mercury, namely 357 C. It is first "pickled"
or cleansed by dipping in acid, and then brushed with an acid
solution of mercury nitrate. A little of the metal dissolves causing
a thin layer of mercury to deposit, so that the article now appears
whitish, and is ready to receive the gold amalgam which is applied
with a stiff brush. The article is now heated to volatilise the mercury
and leave ta coherent coating of gold. The mercurial vapours are
extremely poisonous and though fire-gilding yields the more
durable coat, the process is being superseded by electro-deposition.
Fire-silvering was also practised.

Tin amalgam was formerly used for "silvering" mirrors, but the
process suffers from many disadvantages in addition to the
poisonous character of the emitted mercurial vapours. It has there-
for become virtually obsolescent.

Amalgams with the alkali metals are readily formed by plunging
the latter into warmed mercury. They are of interest in that by
using a mercury cathode, Sir Humphry Davy in 1807 was a ble to
isolate both potassium and sodium by electrolysis of potash and
soda (p. 144). Mercury is used to-day in the commercial manufacture
of caustic soda and hydrochloric acid by the electrolysis of brine. It
is used also as the raw material for the preparation of mercuric
oxide, vermilion, mercurous and mercuric chloride, fulminate and
other derivatives. The oxide is of special historical interest as it led
170 years ago to the discovery of oxygen (p. 21)

It has long been supposed that a loaf of bread loaded with
mercury and thrown into a river or lake in which a dead body lay,
would come to rest over the corpse and so reveal its presence. This
ancient belief was tested with dramatic success at Bedworth, near
Nuneaton, in October 1932 on the thirteenth of the month, too.
A girl of fifteen had disappeared four days previously. She had been
last seen on a path leading towards the Coventry canal, on the
banks of which her purse was afterwards found. Her uncle then
decided to test the old belief, putting some mercury into a loaf of
bread and launching it into the canal. Next morning, in company
with the police he searched for the loaf and found it resting on the
water at a spot a few yards from a bridge. Amid great excitement
drags were thrown into the water and the girl's body was
located and brought to the side. A similar experiment had been tried
on the Avon, near Amesbury, in May 1925, but without success.
The sceptic declared that the loaf had not been properly baked ;
the true believer maintained that the girl had not been drowned!

220

LEAD, TIN, AND MERCURY

Mercury vapour lamps are widely used for a variety of purposes,
as for example in the sterilisation of water and the irradiation of
milk to produce vitamin D. The use of mercury in making mirrors
has largely been superseded by silvering.

By bombardment of metallic gold with neutrons in an atoi\iic
pile one of the isotopes of mercury has been produced and isolated
m a pure state. Thus

Au (197) + n .Hg (198) + e

an electron being evolved. This is an inversion of the alchemists'
dream. Hg(i98) gives a pure monochromatic green light and its
wavelength is being carefully measured so that eventually the yard
and metre may be expressed in terms of wavelengths whicji are
believed to be absolutely permanent (p. 308).

The thermometer*

Mercury has been for many years, and still is, employed widely in
thermometry. It is curious that any serious attempts to measure
temperatures were so long delayed in scientific history. One of the
earliest written references to temperature differences occurs in the
book of Daniel, written probably about 170 B.C. and purporting to
give an account of events that had occurred several hundred years
earlier in the reign of Nebuchadnezzar, King of Babylon 604 to
562 B.C. Annoyed at the uncompromising behaviour of three
Hebrews, Shadrach, Meshach and Abednego, who refused to
worship the golden image he had erected, the king ordered them
to be thrown into a furnace heated "one seven times more than it
was wont to be heated" (Daniel m. 19). This appears to have been
quite a usual method of inflicting capital punishment in Persia
(Jeremiah xxix. 22) and was probably no more unpleasant than
being flayed alive, the custom of the Assyrians a century before.

The word thermometer appears to have been first used by Father
Leurechon, a French Jesuit, in his work entitled "Rcration
Mathematique", dated 1624. The credit of inventing thermometers
with a liquid indicator (actually spirits of wine) hermetically sealed
in a glass tube is usually given to Ferdinand n about 1650; he was
Grand Duke of Tuscany, a liberal patron of science and founder of
the Accademia del Cimento at Florence. Prior to these, air thermo-
scopes or baro-thermoscopes had been used for comparing relative

*A detailed history with full references is given by FRIEND, Nature, 1937, 139,
395-

221

THE CHEMICAL ELEMENTS

changes in temperature. These were (probably) invented either by
Santorio, professor of medicine at Padua and colleague of Galileo,
or by Galileo himself, about 1592*. The utility of these thermo-
scopes was severely limited by their susceptibility to changes in
atjnospheric pressure. As no standard temperature scale was
recognised, it was at first impossible, even with the Ferdinand or
Florentine thermometers, to collate the results of different invest-
igators. Tfiis very serious defect was soon realised, and steps were
taken to find a remedy.

A single fixed point

It was regarded by some as sufficient to select a single fixed point
at arj easily reproducible temperature and regard that as the zero or
null point. Other temperatures were measured by noting the
percentage or other fractional changes in volume of the liquid
indicator once the null point had been marked off on the thermometer.

Clearly the nature of the liquid medium was a matter of supreme
importance, for, if the results of different investigators were to be
collated, either the same liquid indicator must be used by all, or one
possessed of an identical* coefficient of expansion. Halley (1656-
1 742) directed attention to this, having observed that all liquids do
not expand by similar amounts with rise of temperature. Further,
the exact volume of the liquid in the bulb of the thermometer must
be known in order that the fractional volume change may be
calculated and the temperature evaluated.

Boyle (162791) proposed water. He recommended taking a
vessel of water and noting the volume of the liquid at the boiling
point. On cooling to a lower temperature, the latter could be
registered in terms of the contraction of the water as parts per
10,000 of the boiling volume. But this suggestion did not find
favour despite the abundance of water and the ease with which it
could be obtained in a pure condition. Water was regarded as
unsuitable for not only was its coefficient of expansion small, but
also its freezing point was too high for many meteorological
purposes, and it was for this kind of work that thermometers were
then mainly required.

Sir Isaac Newtonf (1642-1727) used linseed 0/7, noting its
volume at the temperature of melting ice and, like Boyle, expressing

*BOLTON, "Evolution of the Thermometer, 1592-1743" (Chem. Pub. Co.,
U.S.A. 1900).

fNEWTON, Phil. Trans., 1701, p. 824. The paper, entitled "Scala graduum
Galons' ', is anonymous and printed in Latin.

222

LEAD, TIN, AND MERCURY

its change in volume as parts per 10,000. Martine* quaintly refers
to his experiments as follows

Sir Isaac Newton thought the settling [of] the degrees of
heat and cold well worth his notice; and as he carried every-
thing he meddled [sic] with beyond what anybody had done
before him, and generally with a greater than ordinary
exactness and precision, so he laid down a method of adjusting
thermometers in a more definite way than had 'been done
hitherto.

But although linseed oil has a low freezing point and> a large
range of liquidity, its use in thermometry did not become general,
despite Newton's fame as an investigator and the fact that the oil
could be used at temperatures far above the boiling point of T vater.
This was probably due to the fact that, in consequence of its high
viscosity, the oil drains very slowly, particularly at the lower
temperatures, down the sides of the tube bearing the scale; the
thermometer thus takes a long time to adjust itself to new
conditions,

Ferdinand ordered his thermometers % to be made with spirit \
Boyle was quick to appreciate their merits and introduced them
into England, and Martine says they "came immediately to be of
universal use among the virtuosi in all the several countries,
wherever polite learning and philosophy were cultivated." The
scale divisions were approximately one fiftieth of the volume of the
bulb. Sagredo used 360 divisions, like the graduation of a circle;
hence the term degree, as applied to temperature.

The low freezing point and viscosity of spirit were excellent
features, but a really serious difficulty lay in the fact that the co-
efficient of expansion was found to vary greatly with the quantity
of admixed water.

Fahrenheit favoured the use of mercury as well as of spirit; indeed
he was the first to bring the mercurial thermometer into general
use.

Two fixed points

Some investigators, Martine included, advocated the use of a
thermometric scale based upon two fixed points. This had several
great advantages. Any suitable liquid could then be used as

* MARTINE, "Essays on the Construction and Graduation of Thermometers"
(New edition, Edinburgh, 1792). The first essay, from which these and succeeding
quotations are taken, is dated 1738.

223

THE CHEMICAL ELEMENTS

indicator, and the necessity no longer existed for determining with
great accuracy the volume of the bulb of the thermometer. All that
one had to do, and this was comparatively easy, was to note the
levels at the two fixed points and divide the distance between them
int9 as many parts or aegrees as was held convenient.

The lower fixed point

Boyle* recommended the freezing point of oil of aniseed (17 to
20 C) as zero, because it was not necessary to wait for frosty
weather Before it solidified. Halley thought a cave might be selected
where summer and winter temperatures are alike; one such cave
was known to Boyle, whilst Mariotte claimed that the cave under
the Royal Observatory at Paris was also isothermal. Both Hooke
and Newton chose the freezing point of water as their zero.

Boyle's suggestion is ruled out because oil of aniseed is a natural
product and as such does not possess a fixed composition ; its melt-
ing point is thus liable to vary. For geographical reasons, Halley's
idea is impracticable, as a particular cave could not be visited by
everyone desirous of checking his thermometer.

Ole Roemer (1644-1710), the Danish astronomer famous for
his measurement of the velocity of light from a study of the
movements of Jupiter's satellites, used a mixture of ice and common
salt or a similar one (ice and sal ammoniac) in obtaining his zero,
which was regarded as the lowest temperature then attainable in
the laboratory. This mixture was not entirely satisfactory and
Fahrenheit later pointed out that a different result might be obtained
in summer from that in winter (p. 226).

The suggestion of Hooke and Newton appears to be the simplest
and most convenient. Why then was it not generally adopted? The
reason appears to be that many believed the freezing point of water
was not constant, but varied with the latitude, Halley and others
asserting that, the farther north we go, the more cold is required
to freeze the water to use the then current phraseology.

Martine refers to this, and appears to have been the first to show
that such is not the case. He rightly attributes the observed
differences in the freezing point of water either to inaccurate
observation or to the use of imperfect thermometers. He says that
he marked the mercury level on a thermometer at Edinburgh, when
immersed in snow and water, whilst a friend did the same with
another thermometer in London. They then exchanged instruments

BOYLE, "An Experimental History of Cold 11 , 1665.
224

and tested them, finding them to agree perfectly. Evidently the
difference in latitude between the two cities had not affected the
freezing point. Later experiments as far south as Paris and Dijon
yielded similar results.

V

The upper fixed point

For this Newton chose blood heat which was regarded as absolutely
constant in a healthy person, Roemer and Fahrenheit used this
also.

Halley recommended the boiling point of spirit of wine, "only
it must be observed" he wrote "that the spirit of wine used to this
purpose, be highly Rectified or Dephlegmed for otherwise the
differing goodness of the spirit will occasion it to boil sooner or
later, and thereby pervert the designed exactness. "

Carlo Renaldini in 1694 recommended the boiling point of
water. He was the first to make this suggestion. Fahrenheit and
others were aware that the boiling point varied with the pressure of
the atmosphere but apparently this was not regarded as a serious
drawback.

Newton's thermometer

As we have seen, Newton's fixed points were the melting point of
ice taken as o and blood heat, which was designated as 12.

Roemer's thermometer

In "Adversaria", which was printed in 1910, the MS having
been mislaid for about 200 years*, Rcemer gives an account of the
ways in which he made and standardised his thermometers.

For his upper fixed point he either used the boiling point of
water, which he designated as 60, or blood heat, presumably when
the thermometers were intended only for meteorological use as it
would not then be necessary to graduate to so high a temperature.
Blood heat was taken as 22^. The thermometer was checked in
ice-water, the reading being 7^. How the zero was obtained is not
definitely stated but simple calculation shows that it corresponds
roughly to the temperature of a mixture of salt and ice. This, or a
similar mixture, was Fahrenheit's zero, and he admitted to having
copied Roemer's methods.

*KIRSTINB MEYER, Nature, 1910, 82, 296. "Adversaria" by THYRA and K.
MEYER (K0benhavn, 1910), reviewed in Nature, 1911, 86, 4. Also KIRSTINE
MEYER, "Temperaturbegrebets Udvikling gennem Tiderne" (K0benhavn, 1909).

225

THE CHEMICAL ELEMENTS

R&aumur's thermometer

Ren de Reaumur (1683-1757), the French scientist*, found that
the best spirits of wine of his day expanded by 8y parts per 1000
when warmed from the temperature of melting ice to that of
bailing water. Equal parts of his spirit and water gave an
expansion of 6yJ. He therefore for simplicity chose such a mixture
as expanded by 80 parts. Hence the Reaumur scale runs from o
to 80 between those two temperatures. The choice was not

accidental, as we frequently read, but by design.

The Centigrade thermometer

Celsius favoured the decimal system and in 1736 divided the
temperature interval between the melting of ice and the boiling of
water into 100, taking the former as 100 and the latter as o. This
meant that temperatures above the boiling point of water were
negative, so the scale was inverted in 1743 by Christin of Lyons.

In 1948 a General Conference on Weights and Measures was
held in Paris and Sevres and the suggestion was made that the term
Centigrade should be replaced by Celsius; this would bring the
Centigrade scale into line with those of Kelvin, Fahrenheit and
Reaumur.

The Fahrenheit thermometer

This was based on Rcemer's thermometer, as Fahrenheit candidly
admits. His zero was the temperature obtainedf "by the commixture
of ice, water and sal ammoniac, or even sea salt". From the fact that
he quotes sal ammoniac and sea salt as alternatives we gather that
Fahrenheit supposed they yielded the same temperature with ice.
We now know that their cryohydric points are 15 C (or
+ 5 F) and 22 C (or 8 F) respectively. Nevertheless,
Fahrenheit did realise that there was a difficulty in reaching the
true zero, for he naively remarks that "if into this mixture the
thermometer be put, it descends to o. This experiment succeeds
better in winter than in summer"!

* Reaumur interested himself in spiders. He thought their "silk" might be
used for textiles and sought to rear colonies of them. But they showed disgraceful
cannibalistic propensities, the females being even more voracious than the males,
and the experiments were not a success.

{FAHRENHEIT, Phil. Trans., 1724, 33, 78. Printed in Latin. This quotation is
from Hutton's Abridged Edition, 7, 22-24. See also ERNST COHEN and W. A. T.
COHEN-DE-MEESTER, Kon. Akad. Wet. Verhand. (Amsterdam), 1936, xvi, No, 2,
p. i. Chtmisch Weekblad, 1936, 33, No. 24.

226

Fahrenheit's upper fixed point was blood heat. On Roemer's
scale this was 22^, but he stated in a letter to Boerhaave* that in 1 7 1 7
he felt Rcemer's scale with its fractions to be both inconvenient and
inelegant; so instead of 22^ divided into quarters, that is, 90, he
decided to take 96 as blood heat. Retaining the same zero, the
meltingpoint of ice became 32, instead of 7^ divided into quarters
or 30. This scale he continued to use and was using at the time the
letter was written (that is, in 1729); he added that he had been
confirmed in his choice because he found it to agree, by pure
coincidence, with the scale marked on the thermometer liariging
in the Paris Observatory.

Fahrenheit gave no reason for regarding the number 96 as rnore
convenient than 90. Probably it was due to the fact that 96 is
divisible not merely by 3 but also by multiples of 2 and hence by 12.
The decimal system was not then in general use in scientific work,
otherwise Fahrenheit would no doubt have fixed blood heat at 100.
In that case the freezing and boiling points of water would have
been represented by numbers even more awkward and disconnected
namely, 33*3 and 221 respectively. So let us be thankful.

Although we retain a Fahrenheit scale to-day, it is not quite the
same as that which Fahrenheit used. The lower and upper fixed
points adopted are those deliberately rejected by Fahrenheit, ice
being taken to melt at 32 and water to boil under standard
conditions at 212.

*A few years ago there were found, in the Military Medical Academy at
Leningrad, some letters sent by Fahrenheit to Boerhaave during 1718 to 1729.
The letters were written in Dutch at Amsterdam and a literal translation of one
of them into German, dated i7th April 1729, given by the Cohens, throws con-
siderable light on Fahrenheit's procedure in graduating his thermometer. See
Nature, 1936, 138, 428. COHEN and COHEN-DE-MEESTER, Kon. Akad. Wet.
Verhand., Eersle Sectie, 16, No. 2, pp. 1-37. Amsterdam, 1936.

227

CHAPTER 17

THE TITANIUM GROUP

THE titanium group comprises titanium, zirconium, hafnium and
thorium.

Titanium

Years ago country clergymen were often keen students of nature
and 1 spent many hours of their free time in unravelling her secrets.
In his parish of Menachan, Cornwall, the Rev. William Gregor
noticed a black, magnetic sand, resembling gunpowder in external
appearance, washed by a meandering stream whose principal
source lay in the valleys of Gonhilly*. Analysis of the sand in 1791
showed it to contain, in addition to iron, a new element, the oxide of
which was reddish brow# and dissolved in acid to a yellow solution
which became purple when reduced with zinc. These results were
published in CrelPs Annalen in 1791; the sand was called
menachanite and the oxide menakine by Kirwan in 1829. They
attracted but little notice, however. Can good come out of Nazareth?
Can a country parson contribute anything of value to the scientific
world?

In 1795 Klaprothf was examining a brownish red mineral then
known as red schorl or schorl rouge^ but later called rutile. From it he
separated a red oxide which bore a close resemblance to that
described by Gregor as obtained from his black sand, menachanite.
Klaproth was fortunate in obtaining some of this latter mineral,
which he playfully called "iron shot titanite", and confirmed the
identity of the two oxides. Notwithstanding Gregorys priority,
which should have been respected, Klaproth suggested the name
titanium for the metal, although he did not isolate it, "borrowing"
as he wrote "the name for this metallic substance from mythology
and in particular from the Titans, the first sons of the Earth."
Gregor did not live to see his metal isolated; he died in 1817 of
tuberculosis, like his great contemporary, Karl Wilhelm Scheele.

"These place-names are given on the Ordnance Survey maps as Manachan and
Goonhilly Down.

t KLAPROTH, "Analytical Essays towards promoting the Chemical Knowledge
of Mineral Substances". Cadell and Da vies (London, 1801).

228

THE TITANIUM GROUP

Eight years later (1825), Berzelius, the renowned Swedish chemist,
reduced potassium hexafluotitanate, K 2 TiF 6 , with potassium and
obtained an impure amorphous specimen of titanium. In 1887, a
95 per cent pure sample was isolated by Nilson and Pettersson*
by reduction of the tetrachloride, TiQ 4 , with metallic sodium. By
a similar method, Hunter obtained titanium of some 99-9 per cent
purity in 1910.

Although titanium is surprisingly abundant in the Earth's
lo-mile crust (p. 7), greatly exceeding copper and lead, the pure
metal is not used commercially. In 1890 Rossi smelted titanium
ores and from them made superior steels; from this the titanium
alloy industry developed.

The alloy with iron known as ferro-titanium, is used in making
titanium steels and in combating "weld decay" in stainless steels.
It is used as final deoxidiser and denitrogeniser in steel manufacture.
Cupro-titanium and mangano-titanium are used as deoxidisers in
making brass and bronze castings. Manganese-titanium is also used
as a scavenger for certain white metal alloys especially for alloys of
nickel and chromium.

Zirconium

The jacinth or hyacinth, now also known as zircon, ZrSiO 4 , has long
been prized as a gem for its beautiful orange to red colour whence
the name zircon, from Arabic zarkun, cinnabar, and Persian zargun,
gold coloured. Unfortunately, the colour tends to fade on exposure
to light. The colourless, yellow and smoky varieties from Ceylon
are termed jargon, a word possibly derived from the same root.
The word jacinth occurs twice in the New Testament. In Rev. xxi.
19 to 20, we read that the foundations of the Holy Jerusalem
"were garnished with all manner of precious stones", the eleventh
being the jacinth. In Rev. ix. 17, the horsemen are described as
"having breastplates of fire and of jacinth and brimstone." The
"brimstone" here may well refer merely to combustibility, as
explained in a previous chapter (p. 22), but the connection of fire and
brimstone with jacinth is not clear. Possibly, however, the jacinth
referred to is not the stone we now know by that name. If it were
amber or some other organic substance it would naturally be
combustible.

Although zircons had been analysed before, it was not until 1789,
when Klaproth examined a specimen from Ceylon, that the presence

*NILSON and PETTERSSON, Zeitch physikal Chem., 1887, 1, 27.

229

THE CHEMICAL ELEMENTS

of a hitherto unknown "earth" was suspected. Zircons had been
regarded as merely aluminium silicates, the base we now call
zirconia being confused with alumina.

In 1808, Davy, having successfully decomposed potash, soda
ard the alkaline earths with the electric current, endeavoured
similarly to isolate the metal from zirconia. He was not successful,
however, but in 1824 Berzelius obtained an impure specimen of
zirconium by heating potassium hexafluozirconate, K 2 ZrF 6 , with
metallic potassium the method he subsequently adopted in
isolating titanium, as already mentioned. The product was impure;
many years were to elapse before a really pure specimen was
obtained by Lely and Hamburger*, who, in 1914, reduced the
chloride ZrCl 4 with metallic sodium. The pure metalf is now
obtained technically by heating crude zirconium and iodine in a
vacuum and dissociating the vapour of the iodide on a zirconium
wire at 1300 C. The zirconium "grows" on the wire in very pure
form and can be drawn to wire or rolled to thin foil 2Ofji thick. It is
also obtained by reduction of the tetrachloride with magnesium in
an atmosphere of helium (Kroll's method).

Zirconium has always been a difficult metal for the chemist.
Berzelius in 1824 gave it a valency of six, like that of sulphur and
wrote the oxide as ZrO 3 in modern nomenclature; later he
altered this to Zr 2 O 3 by analogy with alumina. But analogy is the
fruitful parent of error, as Davy was wont to say, and it led Gmelin
astray also, for likening zirconia to lime he wrote the formula as
ZrO. In 1857, however, Deville and Troost^: found the vapour
density of the chloride to correspond to ZrCl 4 , and therefore
suggested that the metal was tetravalent. This was supported by
Mendeleff when he drew up his Periodic Table in 1869, and
confirmed in 1873 when Mixter and Dane determined the specific
heat as 0*066 and the atomic weight, by the application of Dulong
and Petit's Rule, as 97.

Ferro-zirconium is made by alumino-thermal reduction in an
electric furnace, and is used in steel manufacture for de-oxidising,
desulphurising and denitrogenising purposes, as also for making
zirconium steel, armour plate and projectiles.

*LBLY and HAMBURGER, Z. anorg. Allg. Ghent., 1914, 37, 209.
IDE BOER and FAST, ibid., 1926, 153, i. MILLER, Industrial Chemist, 1950,26,435.
JDEVILLE and TROOST, Compt. rend., 1857, 45, 821, FRIEND, COLLEV and HAYES
/. Chem. Soc., 1930, p. 494,

230

THE TITANIUM GROUP

Zirconium metal is used in flashlight powders and ammunition
primers, and as a "getter" in valves and discharge tubes as it readily
absorbs gas when warmed.

Several hard non-ferrous alloys are now in use. Mention may be
made of cooperite^ a zirconium nickel alloy, non-corrosive and a^id
resistant. Being very hard it is useful for high-speed cutting tools.

Hafnium

For many years chemists suspected that ordinary zirconia contained
varying amounts of a second earth mixed with it. But, as with the
rare earths, chemists were floundering in the dark; the principle of
the atomic number had not been evolved and there was no clear
indication as to the possible number of elements that could exist.

In 1845 Svanberg* claimed to have found a new earth in zircons
which he called noria, the oxide of norium. The chloride, double
sulphate and oxalate of norium differed from those of zirconium
and the atomic weight of the metal was less. In 1853 Sjogren
believed he had found the same element in catapleiite, a complex
metasilicate of sodium, calcium and zirconium, and stated that
the density of noria (D = 5-5) was greater than that of zirconia
(D = 4*3). Both of these densities, however, are lower than that
of pure zirconia (D = 5*73) and several investigators who repeated
the experiments were unable to detect the presence of a second earth.

In 1864 Nylanderf reported the presence of two earths in
zirconia. Two years later A. H. ChurchJ described unusual bands
that he had observed in the absorption spectra of certain zircons,
notably those from Ceylon and Norway. He hazardeu uie sugges-
tion that they might be due to Svanberg's norium.

Unaware of this work H. C. Sorby in 1 869 published an account
of the absorption spectra of jargon from Ceylon and other zircons
from which he concluded that a new element was present for which
he suggested the extremely ugly name ofjargonium. On hearing of
this Church very properly directed attention to his earlier paper,
stated that he had been continuing the research and felt convinced
that ordinary zircons usually contained a new element. He
suggested the name nigrium||.

*SVANBERG, Ann. Phys., 1845, 65, 317.

fNYLANDER, Ada Univ. Lund. t 1864, n. Quoted by VENABLE, "Zirconium
md its Compounds" (N.Y., 1922), p. 16.
JA. H. CHURCH, Intellectual Observer, 1866, 9, 201.
H. C. SORBY, Chem. News, 1869, 19, 121, 181; 1869, 20, 7, 104.
IICHURCH, ibid., 1869, 19, 121.

231

THE CHEMICAL ELEMENTS

In 1901 Hofmann and Prandtl* claimed that a specimen of
zirconia extracted from euxenite contained the oxide of a metal
of high atomic weight. Euxenite is a very complex niobotantalate
of uranium, yttrium and the rare earth metals in which Nilson
h%d found scandia in 1879 (p. 172). But Hauser and Wirthf could
not confirm the presence of a new element.

It is easy to be wise after the event. Looking back with our
present knowledge of the existence of hafnium an invariable
associate (usually in small quantity) of zirconium, it appears quite
within die bounds of possibility that some of these investigators
did actually observe slight differences due to this element. But the
evidence of the existence of a new element was far from conclusive,
and we must leave it at that.

The ultimate discovery of hafnium is an outstanding tribute to
the value of modern scientific theory. When Moseley, in 1913
(p. 3) made it possible to ascertain by X-ray methods the serial
order of the elements it became obvious that an unknown element
should exist of atomic number 72, lying between the rare earth
element lutecium, No. 71, and tantalum, No. 73. The question
then arose as to whether or not this element would be the last
member of the rare earth series.

Langmuir, whose scheme for the arrangement of the electrons
round the atomic nucleus was based on Rydberg's formula,
predicted that element 72 would end the rare earth series.
UrbainJ had already in 1911 fractionated lutecium residues some
15,000 times in an endeavour to isolate No. 72 and obtained some
new lines in the spectrum which he took to indicate its existence;
but they were really fresh lutecium lines not observable with the
less pure specimens. He named the supposed element celtium.

According to the Bohr-Bury theory of 1921, however, the
number of electrons in the various shells round the nucleus are
given by 2# 2 , where n is the shell number. Accordingly the inner-
most or K-shell has 2 electrons, the second or L-shell has
2 x 2 2 = 8, and so on.

Arranging the rare-earth elements as shown in the table below,
it will be seen that the N-shell of lanthanum contains only 18

*HOFMANN and PRANDTL, Ber., 1901, 34, 1064.
f HAUSER and WIRTH, ibid., 1909, 42, 4443; 1910, 43, 1807.
JURBAIN, Compt. rend., 1911, 152, 141; 1922, 17, 1349.

BURY, /. Amer. Chem. Soc., 1921, 43, 1602. BOHR, "The Theory of Spectra
and Atomic Constitution", 1922.

232

THE TITANIUM GROUP

electrons although it is capable of holding 32. Now it is the outer-
most electrons that are mainly concerned with the chemical and
optical properties of atoms ; by filling up the N-shell, we can pass
from lanthanum to lutecium without appreciably altering the
chemical properties. But once we reach lutecium the N-shell is
full up and any further electrons can only be added to the O or*P
shells, with a corresponding change in chemical properties.
Element 72 therefore will have different properties from* the others
and can no longer be regarded as a rare-earth metal.

Shell K L M N O -P
Maximum No. of

electrons . . 2 8 18 32 50 72

57 Lanthanum ..2 8 18 18 8+1*2

58 Cerium ..2 8 18 18+1 8+12

70 Ytterbium ..2 8 18 18+13 8+1 2

71 Lutecium ..2 8 18 18+14 8+1 2

72 Hafnium ..2 8 18 i8+H 8 + ^2

Coster and Hevesy were thus encouraged to search amongst the
zirconium minerals for the elusive element and in 1923 announced
its presence as evidenced by its X-ray spectrum*. They called the
metal hafnium after Hafnia or Copenhagen. It was found to be
present in varying amounts in most zirconium minerals, being
about one-tenth as abundant as zirconium. Alvite (Zr, Hf, Th) SiO 4
was found to be particularly rich.

The metal was first isolated by Hevesy by reducing K 2 HfF 6
with sodium. As the atomic weight of hafnium is double that of
zirconium it now became obvious why different investigators had
obtained such varying results for the atomic weight of zirconium.
The two elements resemble each other as closely as do adjacent
members of the rare earth series and are as difficult to separate. For
most industrial purposes it is unnecessary to separate them.
Hafnium is about one-tenth as plentiful as zirconium in the earth's
crust, its amount being estimated at about 3*2 ppm. Van Liempt in
1925 recommended the use of the oxide, HfO 2 , with tungsten in
filament lamps, as it has a high melting point and low vapour
pressure, in order to reduce the tendency of tungsten to "off-set"
or crystallise. At present silica and thoria are used.

*COSTER and HEVESY, Nature, 1923, 111, 79, 182, 252. Chemistry and Industry,
1923, 42, 258, 929. Ghent. News, 1923, 127, 33, 353- Ber., 1923, 56, 1503. See also
HEVESY, "Das Element Hafnium" (Springer, Berlin, 1927).

233

THE CHEMICAL ELEMENTS

Thorium

Thorium is sometimes regarded as a rare earth element; but it is
wise to restrict the term to yttrium and the elements lying between
agd including lanthanum and lutecium for these are trivalent
aryi closely similar, whereas thorium is tetravalent and presents
many other contrasts. In many ways it resembles scandium, which
we have already seen to differ in several important ways from the
rare earth metals. Thus, like scandium, thorium yields an insoluble
fluoride, an acetyl-acetonate that sublimes without decomposition and
a basic -thiosulphate. The rare earth metals do none of these things.

In 1817 Berzelius* examined the Swedish mineral now known
as gadolinite and isolated from it what he believed to be a new
earth, the oxide of a metal which he called thorium after the
Scandinavian god Thor. Subsequently, however, he concluded that
his earth was a basic phosphate of yttrium, an element that had
already been discovered by Gadolin in 1794. Eleven years later,
however, in 1828 Berzelius examined a black mineral from the
island of L6v6n near Brevig in Norway and obtained from it a new
earth somewhat resembling his previous product, so he called it
thoria. The mineral is now known as thorite, ThSiO 4 , and is
isomorphous with zircon, ZrSiO 4 . Berzelius isolated the metal by
heating the hexafluo potassium double salt, K 2 ThF 6 , with metallic
potassium.

In 1851 Bergemannf announced the discovery of a new metal in
orangite, the gem variety of thorite, and named it donarium.
Subsequently, however, this was shown to be identical with thorium.
In 1862 BahrJ: thought he had discovered in a mineral from
Rftnsholm a new metal which he named wasium, but two years
later he himself showed that it was thorium. From experiments on
the fractional distillation of thorium chloride Baskerville concluded
in 1901 that two other elements were present, which he named
berzelium and carolinium. In this he was mistaken.

The radio properties of thorium are discussed later (p. 321).

The gasmantle industry

It was known more than a century ago that certain oxide earths
emit an intense light when heated in non-luminous flames such as

* BERZELIUS, Afhandl. Fys. Kem. och. Min., 1817, 5, 76. K. Svenska Vet.-Akad.
HandL t I, 1824, p. 315; 1829, p. i.

fBERGEMANN, Pogg. Annalen, 1852, 85, 558.
JBAHR, ibid., 1862, 119, 572; Annalen, 1864, 132, 227.
BASKERVILLE, /. Amer. Chem. Soc., 1901, 23, 761; 1904, 26, 922.

234

THE TITANIUM GROUP

we now obtain from a Bunsen burner. In 1829 it was known to
Berzelius that zirconia and thoria yielded a particularly brilliant
light in these circumstances. The earliest application was the
Drummond light or "lime-light" invented by Drummond in England
in 1826. A cylinder of quicklime was heated in an oxy hydrogen
flame and proved excellent for magic lanterns, for which it was
used for very many years, the lime being often replaced by zirconia
after 1867. I n 1846 mantles of platinum were used in tKe ordinary
gas flame; but they soon wore out and were, moreover, too
expensive.

In 1880 Dr Carl Auer, later von Welsbach, experimentecf with
cotton fabrics impregnated with nitrates of many metals yielding
upon ignition refractory oxides; these included zirconium* and
lanthanum, and his success encouraged him in 1884 to apply for
patents. In 1886 his experiments were extended to include thorium
nitrate. In efforts to obtain a maximum illumination thorium salts
were subjected to increasing purification and in 1891 the curious
discovery was made that the highly pure oxide gave a much less
intense light than the less pure. This was soon tracked down to
the catalytic activity of ceria, CeO 2 , addition of one per cent of
which to pure thoria increased by seven times the illuminating power
of the latter.

The main difficulty in commercialising the gas mantle lay in the
shortage of thorium which was only known to occur as the relatively
scarce mineral thorite or orangite^ ThSiO 4 , the price of which rose to
13 los od per Ib. avoirdupois. This was prohibitive so an
intensive search was made for fresh sources. Sands were soon found
in Carolina containing one per cent of monazite, which consists
essentially of thorium phosphate, Th 3 (PO 4 ) 2 , associated with the
phosphates of the rare earth metals. These were worked for a time
by the Welsbach Light Co. of New York. Deposits were also
found on the Pacific side of Idaho and a Company was formed in
1 906 to extract the monazite from the residues left after removing
the gold; the process was short-lived for a disastrous fire in 1910
ended the work .

In the meantime sands had been found in Brazil with a high
thorium content lying near the coast so that transport was easy. By
1910 the two above-mentioned American firms had been ousted
and the Brazilian sands, worked under German control, supplied
the world demand until 1913 when a formidable rival source was
found in the sands of Travancore, India. These were very rich in

235

THE CHEMICAL ELEMENTS

monazite, containing some 46 per cent with a thoria content of
from 8 to 10 per cent. At the outbreak of war in 1914, shipments
from Brazil fell off and the Travancore sands, under British control,
were shipped to Britain and America.

The fabric mantles are constructed of cotton, ramie fibre or
artificial silk, the last named being best but most expensive. The
fabrics are soaked with nitrate solution, dried, branded with a
didymium nitrate solution, shaped on wooden models and burned
off, the nitrates being converted to oxides. The fragile mantle is
now dipped in nitrocellulose and oil and dried. This renders it
sufficiently strong for transport. When burned off the usual
composition is 98 parts of ThO 2 , i of CeO 2 and I of some suitable
binder, such as CaO, A1 2 O 3 or MgO. Beryllium nitrate is added to
the impregnating solution to increase the strength of the finished
mantle when destined for use with high-pressure gas, as in light-
houses.

236

CHAPTER 18

THE VANADIUM GROUP

THE vanadium group comprises vanadium, niobium and tantalum.

Vanadium

In 1 80 1 a specimen of brown lead from Zimapan was examined by
Andres Manuel del Rio, a Spanish professor of mineralogy in the
Colegio de Mineria, Mexico City. Del Rio concluded tUat it
contained a new metal similar to chromium, to which he gave the
name erythronium, in recognition of the red colour acquired by its
salts when ignited. The mineral is known to-day as vanadinite,
PbCl 2 .3Pb3(VO 4 ) 2 , and the red colour obtained on ignition, for
example, of ammonium vanadate is due to formation of vanadium
pentoxide, V 2 O 5 .

Second thoughts are not always best. On further study of the
mineral, del Rio concluded that he was mistaken in assuming the
presence of a new element and that the brown lead was merely
basic lead chromate. In this he was supported by Collet Desc6tils,
and there the matter rested for many years,

But "truth will out". In 1830, Nils Gabriel Sefstrflm*, a
Swedish chemist, established the presence of a new element in an
unusually tenacious and ductile specimen of wrought iron prepared
from ore from the Taberg mine in Smaland. Upon dissolving the
iron in hydrochloric acid, a black insoluble powder was formed,
which contained an element that was neither chromium nor
uranium. To this he gave the name vanadium, in honour of
Vanadis, also known as the Scandinavian goddess Freia or Frigg,
the wife of Odin (p. 14), it being customary to name planets and
elements after heathen deities.

Now it so happened that Friedrich Wahlerf was, at this time,
interested in del Kio's brown lead and had found something new in
it when he was compelled, by temporary indisposition, due to
inhalation of hydrofluoric acid vapour, to set the problem on one
side. In 1831 he established the identity of Sefstrdm's vanadium

*SEFSTROM, Pogg. Annalen, 1831, 21, 43.
fWoHLER, ibid.. 1831. 22, i.

237

THE CHEMICAL ELEMENTS

with the erythronium of del Rio. He greatly blamed himself for
not having pursued his study of brown lead, although, as he after-
wards added, "Even if I had charmed her (*'.*., vanadium) out of
the lead mineral, I would have had only half the honour of discovery,
because of the earlier results of del Rio on erythronium. But
Sefstrftm, because he succeeded by an entirely different method,
keeps the honour unshared.

Like Stephen Hales, the worthy Vicar of Teddington, who, in
1728, allowed the discovery of oxygen to slip between his fingers
(p. 2i),' and Liebig, who had bromine on his shelves unhonoured
and unrecognised at the time that Balard discovered it in 1826 in
Montpellier brines (p. 49), W6hler had narrowly missed a great
discovery.

Berzeiius examined a number of derivatives of vanadium and
concluded that the element was allied to chromium and uranium.
Berzelius, however, had been handling the oxide, VO, or the nitride,
VN, when he thought he was dealing with the free metal. The same
kind of error occurred with uranium (p. 3 1 2). Roscoe, however,
corrected this error in the course of his classical researches during
1868 to 1870. He isolated the metal by reducing the dichloride,
VC1 2 at bright red heat in a current of hydrogen, every precaution
being taken to prevent the entry of moisture and oxygen into the
apparatus. The product was 95-8 per cent pure metal.

Rammelsberg in 1856 had shown that vanadinite and pyro-
morphite are isomorphous. Roscoe pointed out that if Mitscherlich's
Law of Isomorphism applied, the two minerals ought to possess
analogous structures. This could only be the case if vanadium had
the same valency as phosphorus. In that case vanadium would be
pentavalent like nitrogen and phosphorus, not hexavalent like
chromium and uranium. The two minerals would thus be
represented as follows

Vanadinite, 3Pb3(VO 4 ) 2 .PbCl 2
Pyromorphite, 3Pb 3 (PO 4 ) a .PbCl a

This was accepted by Mendel^eff who, when he drew up his
Periodic Table in 1869, placed vanadium in Group V along with
nitrogen and phosphorus.

Vanadium is not used commercially in the pure state. More than
90 per cent of it is marketed as ferro-vanadium and used in the
manufacture of steels; ferro-vanadium contains from 30 to 40 per
cent of vanadium. The metal enhances the toughness, tensile

238

THE VANADIUM GROUP

strength and elasticity of steel. Thus a good carbon steel containing
some i I per cent of carbon has an elastic limit of about 30 tons
per sq. in.; addition of 0-3 per cent vanadium increases this to 43
tons, whilst 0-6 per cent raises it to 65 tons. Vanadium steels are in
consequence used in the construction of piston rods, axles, bolt?,
gears, motor car and aeroplane parts, rock crushers, dredgers, and
in tools for punching, shearing and drawing. Vahadiufn is used
along with tungsten and molybdenum in the manufacture of high
speed tools. Chromium-vanadium steel is used for armour plate,
torpedo tubes, gun shields, etc. Vanadium is also added to casttiron.
It is used to a limited extent in non-ferrous alloys; thus copper-
vanadium and aluminium-vanadium alloys are used in aeroplane
construction; they contain up to about 0-5 per cent of vanadium.
Vanadium oxides are used to impart to glass an amber colour. The
pentoxide is used as a catalyst in the manufacture of sulphuric acid,
replacing the more expensive platinum catalyst used in oxidising
SO 2 to SO 3 .

The world production of vanadium averages some 3000 tons per
annum,

Niobium and tantalum

John Winthrop the Younger (1606 to 1676) was fond of
minerals and made a hobby of collecting them. In a spring near his
home in New London, Connecticut, he found a black rock, now
known as columbite. His grandson sent this to Sir Hans Sloane
(1660 to 1753) in London, who handed it over to the British
Museum. There it lay until 1801 when Charles Hatchett*
examined it. Hatchett was the son of a prosperous London coach-
builder in Long Acre, a well-known mineralogist and chemist, and
one of the Founders of the Animal Chemistry Club (1809) which
met alternately at the houses of Sir Everard Home and of Hatchett
himself. He was working on some chromium minerals in the
British Museum and concluded that this black mineral contained
a new element, which he called columbium; the mineral in con-
sequence was later called columbite, as mentioned above. It sub-
sequently transpired, however, that the columbium was not a simple
element, but a mixture of two. The discovery was made in this way.
In 1802 Anders Gustav Ekebergf found what he thought was
yet another new element in two minerals, one being tantalite from

* HATCHETT, Proc. Roy. Soc., 1802, 92, 49.
fEKEBERG, Ann. Chim., 1802, 43, 76.

239

THE CHEMICAL ELEMENTS

Kimito, Finland, and the other yttro-tantalite fiJDm Ytterby, Sweden.

To this element he gave the name tantalum
then the fashion to name new elements afte

partly because the name was particularly appi Dpriate in view of the
"jtantalising" difficulty he experienced in eff acting the dissolution
of the metal oxide in acid.

At firsjt, the impression gained ground

)artly because it was
heathen deities and

hat columbium and

tantalum were identical, but in 1 844 the famous German pharmacist
and mineralogist Heinrich Rose* followed up the observation that
many columbites and tantalites, together with the oxides produced
from them, showed marked differences in Density. He showed that
columbite from Bodenmais in Bavaria contained a new element in
addition to tantalum, to which he gave the name niobium^ since
Niobe was the daughter of Tantalus. Thus Hatchett's columbium
was a mixture of niobium and tantalum. Columbite may therefore
be written as (Fe,Mn)O. (Nb,Ta) 2 O 4 whilst tantalite is essentially
(Fe,Mn)O.Ta2O 4 . There is no definite line of demarcation between
the two minerals; they merge, like iron and copper pyrites, into one
another. If niobium is in excess the mineral is called columbite; if
tantalum, tantalite. In 1846 Rose thought he had obtained evidence
of the presence of yet another metal in columbite; this he called
pelofium^ but later concluded that it was merely niobium.
Nevertheless in 1925 Noddack and Tacke did discover at least one
new element in columbites and tantalites, namely rhenium (p. 250)
and believed they had obtained evidence of the existence of another
metallic element, No. 43, which they named masurium (p. 251).

In 1 903 von Bolton^: of Charlottenburg showed it was possible
to convert tantalum powder, the only form in which the metal had
then been obtained, into ductile filaments which rendered possible
its industrial application. The powder was pressed into rods,
melted in the electric arc, rolled and drawn.

In 1905 niobium and tantalum received commercial attention, as
possible material for electric lamps filaments to replace the fragile
carbon then in use. Niobium was soon found to be useless, but
tantalum with a melting point of 2850 C proved valuable, and was
extensively used during 1905 to 1911. In 1910 the National

*RosE, Pogg. Annalen, 1844, 63, 307, 693; 1846, 69, 118.

fGMELiN devoted a chapter to this * 'element" and its compounds in his
"Handbook of Chemistry". Translated by Watts (Cavendish Society) 1850,
Vol. 4, Chap. 173.

JVON BOLTON, Zeitsch. Elektrochem., 1905, 11, 45.

240

THE VANADIUM GROUP

Electric Lamp Association of the U.S.A. used 5 million feet of
tantalum wire weighing less than 100 Ib. Each i Ib. of wire yielded
some 20,000 lamps. After some 100 million lamps had been made
and used, tantalum was largely superseded by the more efficient
tungsten, melting only at 3382 C. Tantalum lamps are still .used,
however, when required to resist more than ordinary vibration, as
on railways. But only D.C. lamps are possible, - for with A.C.
tantalum undergoes progressive crystallisation.

Tantalum is extraordinarily resistant to acid attack and is being
used in ever-increasing amounts in the building up of chemical
plant. Its special field of usefulness appears to be in plant for
halogens, aqua regia and hydrochloric acid. For use in the manu-
facture of the last named a tantalum absorption tube 6 ft. 6 in. in
height and 6 in. in diameter has been described*. Tantalum dishes
can be used for evaporating aqua regia and they are resistant to
hydrofluoric acid. For the same reason tantalum can be used as
cathode in electrolytic analysis as the deposited metals, do not alloy
with it and gold and the platinum metals can be disso ved off with
aqua regia. In the U.S.A. tantalum is used in plant for concen-
trating acids and resisting the corrosive action of acid vapours;
tantalum nozzles are used in chlorinating water, and in dental and
surgical instruments, although for these latter stainless steels are
also in demand. The metal is biologically "acceptable" and is used
in wire for repairing bones and in plates for skull injuries; tantalum
"wool" and gauze are used in replacing muscular tissue and as
bridges for the overgrowth of new tissue.

Tantalum tends to oxidise above 1 50 C and cannot therefore be
used for crucibles except in a reducing atmosphere and it cannot
be used, either, in place of platinum as anode owing to oxidation. It
is useful as a "getter" for traces of unwanted gases.

Tantalum is a white metal similar to platinum but being much
less expensive is sometimes used as a substitute in jewellery; it
takes an iridescent oxide film which is attractive. It yields a very
hard and dense (D = 1 3-96) carbide, TaC, which is used in dies.

Niobium, now also known as columbium, enjoys a much more
restricted use in industry. It finds application in the refining of the
grain of aluminium alloys; it is present in certain stainless
chromium steels and weldable high-speed steels.

* HUNTER, Ind. Eng. Chem. t 1938, 30, 1214.

241

CHAPTER 19

THE CHROMIUM GROUP

THE chrqjnium group comprises chromium, molybdenum and
tungsten.

Chrornfum

In a letter to Buffon in 1762 Lehmann described a new mineral
fron\ the Berezov mine near Ekaterinburg, now of tragic memory.
From its ruddy colour it was known as Siberian red lead, but is
now called crocoite^ Greek krokos saffron, PbCrO 4 . A specimen
reaching Paris was analysed by Vauquelin and Macquart in 1789,
who found it to contain lead, iron and alumina. Bindheim of
Moscow, however, believed that several other elements were also
present, including the then newly discovered molybdenum.
Accordingly Vauquelin*' re-examined the mineral in 1797. On
boiling the powdered specimen with potassium carbonate solution
he obtained an insoluble residue of lead carbonate with a yellow
solution (of potassium chromate) which gave a red precipitate with
mercury chloride (mercuric chromate) and a yellow one with lead
nitrate. He rightly concluded that the yellow solution contained
the potassium salt of a new acid. The following year Vauquelin
obtained the metal itself; he decomposed the mineral with acid,
reduced the liberated oxide, CrO 3 , with charcoal and obtained a
mass of interwoven metallic needles, weighing about one-third as
much as the original oxide.

Fourcroy and Hatiy suggested chromium as a suitable name for
the element in recognition of the various colours shown by its
derivatives, Greek khroma colour. The same year Vauquelin
detected chromium in the spinel ruby while Taessert showed it to
be an essential constituent of chrome iron ore or chromite,
FeO.Cr 2 O 3 now the main source of chromium compounds.
The colour of the ruby is now usually attributed to its chromium
content and artificial rubies are manufactured by fusing pure
alumina with a little oxide of chromium, to "colour" it, in an

VAUQUELIN, Ann. Chim. Phys. t 1798, 25, 21, 194; Crell's Annalen, 1798, i,
183, 276.

242

THE CHROMIUM GROUP

oxyhydrogen flame. It should be mentioned that, about this time,
Klaproth* independently discovered chromium in crocoite.

Chromium is now used to a considerable extent in plating. It
yields a pleasing, non-tarnishing coat, which is greatly appreciated
domestically and in other realms. Hard deposits can now fye
obtained, so they are used on cycle wheel rims, and for "making
up" after wastage. Its most important use is in the production of
ferro-chrome an alloy with iron containing 43 to 80 per cent of
chromium. This is used largely in the manufacture of special irons
and steels. Stainless stee! y for example, contains 13 to 14 p<er, cent
of chromium and is very resistant to atmospheric corrosion and
attack by vinegar and other vegetable acids. It is used in cutlery, etc.
A chromium steel containing, say, i to 1-5 of carbon and 2-5 to 4
of chromium is intensely hard and is useful for burglar-proof safes,
railway couplings, etc. Chrome vanadium steels find application in
axle shafts and locomotive wheels; chrome nickel steels containing
2 to 3 per cent Cr and some nickel are used for armour plate, whilst
high-speed tools are manufactured from chrome tungsten and
chrome molybdenum steels. Staybrite steel may contain about 18
per cent Cr and 8 of Ni.

Amongst the non-ferrous alloys of chromium, nichrome, cochrome^
stellite and magnet steels (p. 245) may be mentioned.

Molybdenum

This word, derived from the Greek molybdos, lead, was used rather
widely in the eighteenth century to designate graphite and sub-
stances resembling it in appearance, such as the mineral known
to-day as molybdenite , MoS 2 , and some compounds of antimony. The
distinction between graphite and molybdenite was established by
Scheele in 1778, and he found it necessary in the opening words of
his thesis to make clear what the precise nature of his material
happened to be.

"I do not mean", he wrote, under the title Experiments with
Lead-Ore: Molybd<ena, "the ordinary lead ore that is met with in
the apothecaries shops, for this is very different from that concern-
ing which I now wish to communicate my experiments to the Royal
Academy. I mean here that which in Cronstedt's Mineralogy is
.called Molybd<ena membranacea nitens, with which Quist and others
probably made their experiments."

*See ROSCOE and SCHORLEMMER, "Treatise on Chemistry" (Macmillan, 1907)
Vol. 2, p. 995.

243

THE CHEMICAL ELEMENTS

Scheele observed that although nitric acid is without appreciable
effect on graphite, in contact with molybdenite it yields sulphuric
acid and a white insoluble residue. This he called terra molybdana^
and regarded it as an acid, whence molybdic acid.

*- "Earth of molybdsena is of an acid nature. Its solution reddens
litmus; soap solution becomes white and liver of sulphur is
precipitatsd."

Bergman suggested that it might be the oxide of a hitherto
unknown metal. Scheele desired to effect its reduction and, having
no suitable furnace of his own, induced his friend Peter Jacob
Hjelm* to undertake the work. Incidentally it may be mentioned
that shortly after, namely, in 1782, Hjelm was appointed Assay
Master of the Royal Mint at Stockholm. A paste of the powdered
residue was made with linseed oil, heated in a closed crucible as
strongly as possible, and, on cooling, metallic molybdenum
remained, albeit impure. Some years later, namely, 1817, Berzeliusf
obtained a pure metal by reduction of the oxide in hydrogen.

Molybdenum has a fairly wide industrial application. Ferro-
molybdenum is manufactured as an intermediary in steel production
as it enhances the tensile strength, toughness and fineness of grain.
Molybdenum steel, since about 1917, has been used for making
high-speed tools (associated with tungsten), rifle barrels, rollers,
in high-pressure work, and in the motor industry in place of nickel
steel. It contains up to 0-5 per cent Mo. Some of the alloy steels are
exceptionally resistant to acid and are useful in making chemical
plant steels with 3 to 4 per cent. Molybdenum and I to 1*5 of
carbon are used for permanent magnets. An alloy of iron, copper
and molybdenum, known as toncan, is very resistant to corrosion.

The pure metal, reduced in hydrogen, is softer than tungsten
and more ductile so it is used as a fine wire or filament for screens
for radio valves; thicker wire for winding electric furnaces; hemi-
spherical cups and sheets for X-ray and vacuum tube work.

Tungsten

There were two dense minerals, now known as scheelite^ CaWO 4 ,
and wolframite^ FeWO 4 , which, in the eighteenth century, were
regarded as varieties of tin ore, for tin-stone is a very dense mineral
(D = 7). Scheelite was then known as tungsten^ which is Swedish
for "heavy stone" and in 1781 Scheele wrote a short paper on its

* HJELM, Crell's Annalen, 1790, i, 39; 1791, i, 179, etc.
fBERZELius, Schweigger's /., 1817, 22, 51.

244

THE CHROMIUM GROUP

examination. Scheelite was, of course, later named after Scheele
himself. Wolframite was so called because it caused loss in tin
smelting, just as antimony was known as the wolf by the early
alchemists because it devoured the base metals in refining gold;
it can be separated magnetically from tin stone which is npt
magnetic.

"The constituents of this variety of stone", wrote Scheele "seem
probably to be still unknown to chemists. Cronstedt enumerates it
amongst the ferruginous varieties of stone, under the name of
Ferrum calciforme^ terra quodam incognita intime mixtum. That which
I used for my experiments is pearl coloured and taken from the iron
mine of Bitsberg; and as I made many experiments upon it and
have ascertained its constituents, I take the liberty of presenting
the following to the Royal Academy. "

Scheele then proceeded to give an account of his experiments
from which he concluded that scheelite is a compound of lime and
"tungstic acid .

In 1782 Bergman found the same acid in wolframite. The follow-
ing year, 1783, two Spanish brothers, Don Fausto d'Elhuyar and
Don Juan Jos, extended Scheele's observations and also showed
that wolframite likewise contains "tungstic acid". This they
proceeded to reduce by ignition with pulverised charcoal in a
crucible and were rewarded by finding metallic globules of tungsten
in the residue, some of which were as large as a pin's head. In 1 847
Oxland patented a method for manufacturing sodium tungstate,
tungstic acid and metallic tungsten from cassiterite. In 1857 he
took out a second patent for manufacturing iron-tungsten alloys,
the basis of modern tool steel production.

Some 90 per cent of the world's production of tungsten is
absorbed in the manufacture of steel. The old Mushet steel of 1859
contained tungsten. Ferro-tungsten is largely made for this
purpose. Some 2 to 8 per cent of tungsten increases the hardness,
toughness and tensile strength of steel, and the alloy is much used
in armour plate, projectiles, etc; 15 per cent of tungsten enables
steel to retain its hardness at a high temperature and renders it
valuable for high-speed tool production.

The alloy known as stellite retains its hardness at high tempera-
tures. It comprises Co 55, Cr 33 to 35, W 10 and C 1*5 to 2 and
stellite bits are often used in rock boring instead of diamonds. It is
used cast as it is too difficult to work. Magnet steels contain iron
alloyed with the above four elements. A typical steel suitable for

245

THE CHEMICAL ELEMENTS

good, permanent magnets, contains Co 35, Cr 6'O, W 4-0 and C
Q'75, the remainder being iron.

Prior to the European War of 1914 to 1918, wolframite was
mostly sent to Germany, and in August 1914 we had barely a four
months* stock of metallic tungsten in the country. A Government
inquiry was instituted, works were erected, arrangements were
made with the Dominions to furnish us with ore, and in the course
of a single year we were producing 98-5 per cent tungsten, fully
I per cent better than the best that Germany had ever sent to
Sheffield. That illustrates very graphically what can be done when
necessity arises. On account of its resistance to acids, tungsten is
recommended as a platinum substitute in laboratory practice.
Tungsten crucibles, lined with an alloy of Pt-Ir, are used for high-
temperature work.

Tungsten has an unusually high melting point, 3382 C. This,
indeed, is higher than that of any other known element. Its vapour
pressure is extremely low and the metal finds useful application for
electric wiring for furnaces, targets of X-ray tubes, contacts,
arcing points, thermionic valves, wiring for electric furnaces and
also for thermocouples in a reducing atmosphere; thus a W-Mo
couple can be used up to 2000 C,

Owing to its high electrical efficiency tungsten has since 1911
almost completely ousted tantalum for ordinary lamp filaments,
except when lamps are required to resist unusual vibration (p. 241).
Usually the wire is mechanically drawn through a die at 2000 C.
A rod the thickness and length (7 inches) of an ordinary pencil
will give 100 miles of filament; fewer than two tons of metal are
required to supply filaments for 100 million electric bulbs.

As a matter of historical interest, it should be mentioned that
Edison was not the inventor of the filament lamp, although this has
been frequently urged. Actually, in 1860, Sir Joseph Swan obtained
a glow in a carbon filament in vacuo and by 1878 he had perfected
his filament lamps and placed them on show in this country. At this
time Edison's lamp was only in the laboratory stage. This is not to
minimise in the slightest Edison's work. But fact is fact.

What is reputed to be the largest molybdenum and tungsten
works in Europe was recently opened in Kabardino-Balkaria in the
heart of the Caucasian mountains. The plant lies at the foot of
Mount Tyrny-Auz. Prospecting began in 1934 and at a height of
9850 ft ores of both metals were found, together with rich beds of

246

THE CHROMIUM GROUP

gold, tin, antimony, arsenic, copper and lead. Meteorological
difficulties are immense, fierce blizzards rage, and the extraction of
the ores presents many problems. But, persevera, per severa^
per se vera.

247

CHAPTER 20

THE MANGANESE GROUP

THE manganese group comprises manganese, masurium and
rhenium.

Manganese

The dioxide was known to the ancients, but until the close of the
eighteenth century was confused with oxide of iron. Pliny, for
example, distinguished two lodestones, one of which was magnetic,
namely, FegO 4 , whereas the other was not and is usually thought to
have been manganese dioxide. This mineral was used in Roman
times for decolorising glass, whence the name pyrolusite from Greek
pyr y fire and luo, I wash. Excess manganese gives a violet glass;
amethystine glass has been found at Memphis, Egypt, as well as in
Roman specimens. Such glass, resembling port-wine in colour, was
regarded as protecting the drinker from becoming drunk and would
naturally be popular; indeed the word amethyst is derived from
the Greek #, not and methein, to be drunk. Cleopatra's famous
amethyst ring was believed, in accordance with the doctrine of
signatures (p. 293), to protect its fair wearer from becoming intoxi-
cated should she be tempted to indulge too freely in Eastern wines.
The amethyst is quartz tinted with manganese, presumably as
silicate. Other names for pyrolusite were manganese and magnesia
nigra (p. 151).

In 1740 J. H. Pott expressed the view that pyrolusite contained
a metal unknown to science.

Scheele during 1771 to 1774 spent much time examining the
mineral under the name of manganese and was led to the discovery
of chlorine by acting on it with marine acid air (p. 46). He pointed
out that although the mineral contained a little iron, silica and lime
there was also "some of a new species of earth, which so far as I
know, is as yet unknown." This was a barium compound;
he further observed that the mineral as a whole behaved like a calx
or oxide. His friend Johann Gottlieb Gahn, who had in 1769
recognised phosphorus as a constituent of bones (p. 77), ignited
an oil paste of pyrolusite and charcoal and obtained a button of
metallic manganese in 1774.

248

THE MANGANESE GROUP

For a considerable time the position to be given to manganese in
the Periodic Table was a matter of dispute. Mendeleff in 1871
put it in Group vn immediately beneath fluorine and between
chromium and iron in the first long horizontal series. But as no
other metal was known to belong to Group vn, it was sometimes
bracketed with iron in Group vin. Those who supported its
position in Group vn pointed to the isomorphism of ootassium
perchlorate and permanganate. The determination of its atomic
number by Moseley's X-ray method confirmed this view and it was
further shown that vacancies occurred in the list of atomic numbers
that would lead one to expect the existence of two more elements
in Group vn, namely, numbers 43 and 75, lying between molyb-
denum and ruthenium in the second long horizontal period* and
between tungsten and osmium in the fourth long period respectively.
Mendeteeff's original scheme was thus supported.

Manganese by itself is seldom, if ever, used commercially.
Alloys with iron rich in manganese are extremely important.
Ferro-manganese contains upwards of 20 per cent of the latter
metal, whilst spiegel irons range from fco downwards. They are
used in steel manufacture. Small quantities of ferro-manganese are
added to the steel before teeming into ingots to de-oxidise and
desulphurise. Almost all of the manganese enters the slag, leaving
perhaps 0-4 per cent as sulphide disseminated throughout the steel.
Steels containing about one per cent of alloyed manganese are
commonly used for rails and structures. Those containing some
1 2 to 1 5 per cent manganese are very hard and tough and are used
for tramway points and crossings and numerous other purposes
where high resistance to shock and wear is essential.

Many alloys with non-ferrous metals are well known, such as
manganese bronze, manganin, cupro-manganese, Hensler's alloy,
and manganese German silver.

Elements 43 and 75

Amongst the claims to the discovery of elements that might have
been No. 43, the eka-manganese of Mendel^efF, the following may
be mentioned

Ilmenium, by Hermann, 1846, in ilmenite and also accom-
panying niobium and tantalum in various minerals; it was
closely allied to them in its general characteristics and to it he
ascribed an atomic weight of 104-6. Several years later he
relinquished his claims, but brought them forward again in

249

THE CHEMICAL ELEMENTS

1877, together with the announcement that a second element,
which he called neptunium, occurred in tantalite from Haddam,
Connecticut, belonging to the same series presumably
referring to element 75. Owing to the minute quantities of
the supposed elements obtainable and the lack of modern
X-ray methods of identifying them, no confirmation appeared
possible.

Nipponium, by Ogawa, 1908, in molybdenite and thorianite,
with an atomic weight of approximately 100. Nippon is the
Japanese name for Japan.

In addition to Hermann's neptunium mentioned above there
are three claims to elements that might have been No. 75, the
dvi-manganese of Mendel^eff

Ruthenium, by Osann in 1828, from platinum ores. This
is not to be confused with the element now recognised by that
name, discovered by Claus in 1845.

Uralium, by Guyard in 1869, again from platinum ores; it
had a density of 20-25 and an atomic weight of 1 87 ; these are
in general accord with those of rhenium D = 21-04 an d
At. Wt. 186-31. But in its chemical and other physical
properties there was less similarity.

Davy urn, by Sergius Kern* of St Petersburg, in 1877, in
residues obtained from platinum ores after removal of the
noble metals. He named it, as he says, in honour of Sir
Humphry Davy. The density was 9-385, very low for
rhenium (21-0). The atomic weight could not be determined
with accuracy as the quantity of the material available was too
small but a preliminary investigation suggested a value of
about 154; that of rhenium is 186-3. ^ * s of special interest
to note that the solution of its chloride gave a red precipitate
when heated with potassium thiocyanate a reaction that is
also given by rhenium. In 1899 Malletf confirmed Kern's
reactions and it would appear quite possible that Kern's
material did actually contain a little rhenium.

Rhenium

Three young chemists, Walter Noddack, Ida Tacke and BergJ,

*KERN, Chem. News, 1877, 36, 4, 114; 1878, 37, 65. Nature, 1878, 17, 245.
f MALLET, Amer. Chem. /., 1898, 20, 766. FRIEND and DRUCE, Nature, 1950,
165, 819.

JNODDACK and COWORKERS, Naturwissenschaften, 1925, 13, 567.

250

THE MANGANESE GROUP

working in Nernst's laboratory, claimed in 1925 to have discovered
two new elements. This was not a so-called "chance" discovery,
but, like that of hafnium (p. 232), the result of a direct search in likely
quarters. It was considered that the congeners of manganese should
be found, if they exist at all, in platinum ores and certain othpr
minerals such as molybdenite, niobite, and tantalite. After removing
most of the known elements, residues were obtaineft and submitted
to X-ray analysis with the result that the lines calculated for
elements 43 and 75 were found, thus indicating the existence of
the two elements in question. Element 75 was called rheniuni a
very appropriate name for Germans to give it in honour of their
national river the Rhine; but the choice of masurium for element 43
was a stupid psychological blunder, which no civilised scientist
should make. It commemorates the crushing defeat inflicted on the
Russians by the Germans in the Masurian district during the
Great War of 1914 to 1918, and thus tends to perpetuate racial
hatred in a realm where such should be forgotten in noble attempts
to serve mankind.

Simultaneously Loring and Druce* were examining pyrolusite
and crude manganese compounds for indications of a trans-
uranian element, No. 93. In the course of the work evidence was
obtained of the presence of dvi-manganese, No. 75. This was
supported by X-ray analysis in collaboration wtth Messrs Adam
Hilger in the latter's research laboratory in London and confirmed
by Heyrovsky and Dolejsekf.

Pure rhenium and rhenium compounds are now quite well known
and are obtainable by purchase. As yet they have no industrial
applications. The most important source of rhenium appears to be
molybdenite, MoS 2) particularly Norwegian and Japanese ores.

Does element No. 43 exist in nature ?

The existence of a stable isotope of this element seems unlikely on
theoretical grounds, and the claim of Noddack and Tacke to have
detected its presence in the minerals they examined has not been
substantiated.

In 1937 a molybdenum target that had been bombarded for
many months with deuterons in a cyclotron showed radio-activity

*LORING and DRUCE, Chem. News, 1925, 131, 273, 337. See also DRUCE,
"Rhenium" (C.U.P. 1948).

fHEYROVSKY and DOLEJSEK, Nature, 1925, 116, 782.

251

THE CHEMICAL ELEMENTS

characteristic of isotopes of element 43, for which the name technetium
or technicunt) Tc, has been suggested*,

*See SEGRE and his co-workers, /. Chem. Physics, 1937, 5, 712; 1939, 7, 155.
Physical Review, 1937, 52, 1252; 1938, 54, 772; 1939, 56, 753. EMELEUS, Nature,
1949, 163, 624.

252

CHAPTER 21

THE IRON GROUP

THE iron group comprises iron, cobalt and nickeL

Iron

Iron, like copper, occurs native in many parts of the world and has
in consequence been known to man from very early times.* Unlike
gold and silver it is not particularly prepossessing in appearance
and its contribution towards the growth or civilisation has lain in its
industrial applications rather than in its artistic merits, although
many primitive peoples have used iron for personal adornment,
and as late as the nineteenth century steel jewellery was fashionable
in Britain (see Plate 3).

The metallurgical discovery of iron, like that of copper, was a
truly epoch-making advance. Using the term iron in its broadest
sense to include cast and wrought irons and steels, we are still in the
iron age.

It is generally accepted that most native irqn is of meteoric
origin, but in certain cases there can be no doubt as to its terrestrial
source. Iron has been found in the coal measures of Missouri at
depths of 30 feet and more below undisturbed strata, which
precludes a meteoric source; it is extremely unlikely that iron
meteorites of Carboniferous age (c. 3 X io 8 years) would have
survived in metallic form. Furthermore, the metal was soft and free
from nickel, whereas the meteoric metal is nickeliferous. Probably
it was formed by reduction in situ.

Meteorites

Meteoric iron was known to primitive man and both worshipped
and used by him during the stone age. Numerous meteorites have
been found in different parts of the world; they vary greatly both
in size and in composition. The largest known is the Hoba West
meteorite which lies where it was found at Grootfontein, S. W.
Africa. It is a roughly rectangular mass, 3 X 3 X I cu. metres,

*A detailed account of the history of iron is given in the Author's "Iron in
Antiquity" (Griffin, 1926).

253

THE CHEMICAL ELEMENTS

weighing approximately 60 tons. Allowance for iron in the rocks
immediately surrounding the meteorite suggests that its original
weight was over 80 tons. Its nickel content of 16 per cent is un-
usually high, and it is a particularly hard and malleable specimen.
T^o natives required two full days, and a great supply of hack-saw
blades, to cut a surface only 8 cm. X 1 3 cm.*

The second largest known is the Ahnighito meteorite brought
by Peary from Western Greenland in 1895; ^ weighs 36*5 tons
and now reposes in the Hayden Planetarium, New York. In
Febniary 1947 an enormous meteorite fell in Russiaf, in Eastern
Siberia, and the noise of its fall was heard 200 km. away. It was
probably the largest that has struck the earth within historic times
and f may indeed have been a minor planet. A preliminary estimate
of its mass is about 1000 tons and its temperature due to friction
with the air was probably about 5000 C. On striking the earth it
broke up into thousands of fragments. Had it fallen in a populous
district like London the damage would have been irretrievable. On
the other hand, by way of contrast, the famous Rowton meteorite of
1876 (p. 256) weighed only 7 lb. (3109 grams).

In former days a fall of stones or "thunderbolts from the sky
was regarded as heralding events of prodigious importance, and
ancient literature contains many references to such phenomena.
One of the earliest is that recorded in Holy Writ, in Joshua x. II,
early in the fourteenth century B.C., where we are told that "the
Lord cast down great stones from heaven" upon the enemy of the
Hebrews, more being killed by the stones than by the sword.
Diana of the Ephesians (Acts xix. 35) "the image which fell
down from Jupiter " was undoubtedly a meteorite.

Livy (59 to 1 8 B.C.) tells of a shower of stones that fell on Mount
Albanus about 652 B.C. The Senate were so impressed that a nine-
day solemn festival was decreed.

An interesting legend enshrouds a large black meteoric stone
found in ancient Phrygia and taken to the shrine of the Mother Goddess
Cybele to be worshipped as her image. It remained there for many
generations. In 216 B.C., however, Hannibal, the Carthaginian
general, defeated the Romans at Cannae and threatened Rome
herself. The Sybelline books were consulted by the anxious
Romans and appeals were made to the oracles by the City Fathers
who were informed that Rome might yet be saved if Cybele could

*WATSON, "Between the Planets" (Churchill, London, 1945).
^Nature , 1949, 163, 92.

254

THE IRON GROUP

be brought within her walls. An imposing embassy was sent to
Phrygia to ask for the sacred image; naturally the king refused;
but an earthquake conveniently shook the royal palaQe and the
goddess herself spoke from her shrine stating that it was the will
of the gods that she should repair to Rome and save the city. What
king could resist so clear a command ! The sacred pines were hewed
by a thousand axes, a new vessel was built, fit for a divine passenger,
and the image was duly taken to Rome, reaching tnere about
204 B.C. The ancient city was never taken; Hannibal left Italy
for ever in 202 B.C. Thus were the oracles confirmed.

The behaviour of uncivilised races in analogous circumstances
in modern times is closely similar*.

Built into the north-east corner of the Kaaba at Mecca is a very
dark reddish-brown stone, believed to be a meteorite. It has been
venerated by the Arabs for generations. When Mohammed
captured Mecca, A.D. 630, he entered the sacred enclosure and
with habitual iconoclasm destroyed the 360 idols within; but,
strangely enough, he spared the stone; he even saluted it with his
staff and kissed it. To-day that stone is the most sacred jewel of
Islam. Towards it each devout Moslem is bidden to turn as he
prays five times a day. It is called The Right Hand of God on Earth
and is reputed to have dropped from Paradise when Adam was
created. In the day of judgment it will be endQwed with speech
and will witness in favour of all who have touched it with sincere
hearts; but woe to the unbeliever!

So rigidly obeyed is the injunction to Moslems to turn towards
Mecca when making their devotions, that the Emir Abdullah,
ruler of Transjordania, when on a flight over the Mediterranean
towards this country in 1 946, carried with him a compass so that he
might know which way to turn at the hour of prayer even if his plane
were lost in the clouds. There is something beautiful in such sincerity.

Meteorites may be roughly divided into three groups according
to their composition, namely siderites, siderolites and aerolites^. The
first named include those which consist mainly of iron (Greek
sideroSy iron), whilst the last consist almost wholly of stone, that is,
silicates with interspersed particles of nickeliferous iron etc. (Greek
aer air; lithos, stone). The siderolites are intermediate between the

*H. A. NEWTON, Nature, 1897, 56, 355.

fL. FLETCHER, "An Introduction to the Study of Meteorites" (British
Museum, 1908). Unfortunately the word siderite is also used to denote a natural
carbonate of iron, namely chalybite or spathic iron ore.

255

THE CHEMICAL ELEMENTS

two. Some authorities connect the Greek word sideros with the
Latin sidus a star, regarding this as an indication that meteoric iron was
known and that it was recognised as the metal dropped from the sky.

It is interesting that most ancient folk designated iron by words
indicative of celestial origin, but it does not necessarily follow that
a meteoric origin was envisaged. Thus the natives of the West
Indies, discovered by Columbus in 1492, were familiar with gold
and copper but not with iron. The brass and iron introduced by
the Spaniards intrigued them greatly; they called them turey^ a
gift jfr/Dm heaven. There was no question of meteoric origin; the
natives may however have regarded their white visitors as gods
until they knew them better.

Analyses of numerous siderites indicate that the iron is in-
variably alloyed with varying amounts of nickel. The specimen
from Rowton in Shropshire contains nearly nine per cent of nickel;
it may be seen in the Natural History Museum, South Kensington,
and is of special interest as its fall in 1876 is the first to be recorded
by an eye-witness in Great Britain. Other siderites have been
found to contain up to 6p per cent of nickel and as this metal tends
to render iron more resistant to corrosion, it has helped to preserve
the specimens from disintegration. On the other hand, a few
meteorites have been observed to corrode rapidly upon exposure
to the atmosphere, and this has been traced to the presence of small
amounts of Lawrencite or ferrous chloride, FeCl 2) a salt which
readily hydrolyses in moist air yielding free acid and stimulating
corrosion; a three-ton specimen from Cranbourne, Australia, is
now kept in a nitrogen-filled case for this reason*. Most iron
meteorites contain a proportion of troilite (FeS) which also is readily
erodible. Large specimens, after some years of atmospheric attack, are
frequently deeply pitted owing to the dissolution of this constituent.

The lodestone

The richest ore of iron is magnetite or the lodestone, FegO 4 .
According to an ancient legend a shepherd, Magnes by name, was
crossing the slopes of Mt. Ida in Asia Minor, taking his flocks to
pasture, when he felt his shoes fall to pieces, the nails having been
drawn from the soles as he trod the magnetic soil. The mineral thus
came to be known as Magnes' stone or magnetite.

It is always painful to destroy a pretty legend; let us do it gently \
More probably the word magnetite is derived from Magnesia, a

*WATSON, Opus cit.
256

THE IRON GROUP

town in Lydia, destroyed by earthquake during the reign of
Tiberius (A.D. 14 to 37).

In course of time the mineral was found to occur in other parts
of the world, specimens possessing extra powerful magnetic
properties being discovered in Siberia and the Hartz mountains.

The first iron miners in Greece appear to have been roving bands
of Phrygians who, because of their skill in metallu?gy, came to be
regarded with awe. In due course tradition traced them Back to the
Idean Dactyls or "Fingers" of the Earth Goddess, Rhea. These
miners settled in Samothrace where the ore was plentiful, and
exhibited to the wondering populace the magnetic properties of
the lodestone by suspending from it rings of iron as in chains.
They also demonstrated that the stone could impart its t>wn
magnetic properties to iron. The Samothracian rings were for long
regarded as mysterious and were repeatedly mentioned by early
authors from the time of Plato (427 to 344 B.C.) onwards.
Lucretius* writing in the first century B.C. refers to the lodestone
as still an object of wonder. "This stone men wonder at", he writes,
"as it often produces a chain of rings hanging down from it. Thus
you may see sometimes five or more suspended in succession . . .
each in turn experiencing the binding power of the stone."

Some 600 years later St Augustine, who came as a missionary
to Britain, A.D. 597, at the instance of Pope Gregry i, was thrilled
by a similar sightf. "When I first saw it I was thunderstruck", he
wrote, "for I saw an iron ring attracted and suspended by the stone;
and then, as if it had communicated its own property to the iron it
attracted, this ring was put near another and lifted it up and, as the
first ring clung to the magnet, so did the second ring to the first.
A third and fourth were similarly added, so that there hung from
the stone a kind of chain of rings with their hoops connected, not
interlinking, but attached together by their outer surface. Who
would not be amazed at this virtue of the stone . , .? Yet far more
astonishing is what I heard about the stone from my brother in the
episcopate, Severus, Bishop of Milevis. He told me that Bathan-
arius, once Count of Africa, when the Bishop was dining with him
produced a magnet and held it under a silver plate on which he
placed a bit of iron ; then as he moved his hand with the magnet

*LUCRETIUS, "De Rerum Natura". Translated by Munro (Routledge, 1886),
Book 6. Lucretius was born 95 B.C. and is believed to have committed suicide 51 B.C.

fP. BENJAMIN, 'The Intellectual Rise in Electricity" (Longmans, 1895),
p. 87. Quoted from Dod's translation of "De Civitate Dei".

257

THE CHEMICAL ELEMENTS

beneath the plate, the iron upon the plate moved about accordingly.
The intervening silver was not affected at all, but precisely as the
magnet was moved backward and forward below it, no matter how
quickly, so was the iron attracted above. I have related what I
Qiyself have witnessed. I have related what I was told by one
whom I trust as I trust my own eyes."

During the' later centuries the power of the lodestone grew
apace. Mountains of it beneath the sea could draw the very nails
out of the ships sailing above them so that they fell to pieces even
in calm weather. Similarly their presence would disturb the compass
and lead the mariner astray.

Being magnetic the mineral also possesses polarity, and an elon-
gated specimen, when freely suspended, will place itself in a direction
pointing to the magnetic north and south, whence the name lode-
stone, lode meaning direction.

The knowledge that the stone attracts iron presupposes a
knowledge of the metal. But we can conceive the possibility that
the polarity of the stone was known to man long before this. It is
possible that it had been observed by man in the bronze age, and
that the compass had already been invented before iron was
intentionally reduced from its ores.

The power of the stone to transmit its properties to iron is
clearly described* in a fourteenth century MS. believed to contain
the writings of one who styled himself William the Clerk, a monk
of the twelfth century; an intriguing translation into English
verse* runs as follows

"Who would of his course be sure,
When the clouds the sky obscure,
He an iron needle must
In the cork wood firmly thrust.
Lest the iron virtue lack
Rub it with the lodestone black,
In a cup with flowing brim,
Let the cork on water swim.
When at length the tremor ends,
Note the way the needle tends ;
Though its place no eye can see
There the polar star will be."

To-day, all this and much more is taken^for granted.

*By P. BENJAMIN, Opus cit. t p. 151.
258

THE IRON GROUP

Iron and primitive man

Whilst still in the stone age, man used both native copper and iron.
The quantity of native iron known to science is much les% than that
of native copper and the chance that man would come across it was
proportionately small. It has been estimated that some 246 tons of
meteoric iron* are known to science, and in prehistpric times there
were all the accumulations of previous ages for man to djraw upon.
As only about one per cent of the native metal is brittle and unsuit-
able for cold-working there would be sufficient malleable metal
available to supply man with an appreciable number of implefarents.
The Otumpa meteorite, discovered in the Argentine about 1783,
and weighing more than half a ton, shows at least six places from
which portions have been removed. The Descubridora meteorite
(Mexico), already known in 1780, has a gap in which is wedged a
broken copper chisel left by some primitive workman.

The metallurgical skill acquired by men of the bronze age
paved the way for the discovery and rapid utilisation of iron in such
areas as possessed suitable ores near the surface. Reduction of
oxide or carbonate ores takes place quite easily in a primitive
furnace; the metal does not melt, its melting point, 1535 C, being
far too high to be reached in an ordinary fire. It is obtained as a
spongy mass, more or less admixed with impurities but often very
free from carbon and hence very soft. It could rea&ily be hammered
into shape, but would not retain a sharp cutting edge and would
thus be useless as a sword. The introduction of a little carbon into
the metal, however, would render it hard and capable of receiving
a temper. The early worker would soon learn to test his product in
some simple practical way and to work up those portions that gave
promise of being suitable.

Unable to understand why his furnace sometimes yielded him
good material and sometimes poor, the superstitious workman
would tend to lay the blame on his gods. Thus in Japan, until
recently, it was the custom of the armourers, when making the
famous Samurai blades, to put on the cap and robes worn by
nobles of the Mikado's court, close the doors of the workshop, and
labour in secrecy and gloomf. A tasselled cord of straw, such as is
hung before the shrines of the native gods of Japan, would be
suspended between two bamboo poles in the forge ; which would

*ZIMMER, /. Iron and Steel Inst., 1916, No. u, 306.

fLoRD REDESDALE, "Tales of Old Japan" (Macmillan, 1910), p. 38.

259

THE CHEMICAL ELEMENTS

for the time being function as a holy altar. The gods thus appeased,
the work should be brought to a successful issue.

Once man had learned to produce good steel, its superiority over
bronze for military purposes would be rapidly appreciated, and the
conservative soldier proverbially slow to adopt new methods
would be compelled by dire necessity to throw aside his bronze
sword and shield and betake to himself weapons of steel (p. 275).

Iron in Egypt

Iron appears to have been known and prized by the pre-dynastic
Egyptians some 4000 B.C., that is, if we are correct in assuming
that the beads found in the graves, and now completely oxidised to
rusfc, were originally specimens of the metal. But another explanation
is possible, namely that the original beads were iron pyrites or
marcasite, the latter being particularly liable to corrosion. This is by
no means impossible, for the various forms of iron pyrites have
long been admired for their golden colour*.

Iron did not come into general use in Egypt before about 1350
B.C. The period ranging from the earliest use of the metal down to
this later date is aptly termed by Sir Flinders Petrie the Sporadic
Iron Age. Considerable interest centres round the iron objects
found by Howard Carter^ in the tomb of Tutankhamen, the boy
king who ruled over Egypt circa 1360 to 1354 B.C. Nineteen
objects were found, including a dagger the blade of which was still
bright though flecked with rust spots. It now reposes in the
museum in Cairo.

By the time of Rameses n, circa 1300 B.C., iron was being used
by the Mediterranean nations in fashioning weapons of war, and
a letter is extant indicating that Rameses applied to the Hittite
king for a supply of the metal ; whether he received it or not we do
not know, but iron gradually became more plentiful and the armies
of Rameses in a century later appear to have been equipped with
iron weapons, for these are painted blue on the monuments.

An interesting light is thrown upon the conditions prevailing in
the time of Rameses n by the Egyptian Papyrus Anastasi 1$,
popularly known as "The Travels of a Mohar". It is a collection

of letters written by a professor of literature at the Court of
.' " , , , i \ . . -

*See LUCAS, "Ancient Egyptian Materials" (Arnold, 1926), p. 97. WAIN-
WRIGHT, Revue Archeologique, 1912, No. i, 255.

f Ho WARD CARTER, "The Tomb of Tutankhamen" (Cassell, 1927), Volume 2.

JToLKOwsKi, "The Gateway of Palestine" (Routledge, 1924), p. 21. From
SAYCE, "Patriarchal Palestine" 1895, pp. 212-224.

260

THE IRON GROUP

Rameses n, giving a satirical account of the journeyings of a royal
messenger. It appears that at Jaffa his arms were stolen from his
side and the armour stripped from his unguarded chajiot as he
slept in a garden. In modern newspaper parlance this would be
described as an "impudent theft' ' and it is noteworthy that the
Mohar's prestige as envoy of the great Rameses was not sufficient
to protect him from such indignity. The letters profteed '

"Thou comest into Joppa; thou findest the garden in full
bloom in its time. Thou penetratest in order to eat. Thou
findest that the maid who keepest the garden is fair. Sht does
whatever thou wantest of her. Thou art recognised, thou art
brought to trial and owest thy preservation to being a
Mohar. Thy girdle of the finest stuff thou payest as the price
of a worthless rag. Thou sleepest every evening with a rug of
fur over thee. Thou sleepest deep sleep for thou art weary. A
thief steals thy sword and thy bow from thy side; thy quiver
dt^i thy armour are cut off in the darkness, thy pair of horses
run away . . . Thy chariot is broken to pieces . . . The iron-
workers enter into the smithy; they rummage in the workshops
of the carpenters; the handicrafts men and saddlers are at
hand; they do whatever thou requirest. They put together
thy chariot ; they put aside the parts of it that are made useless ;
thy spokes are fashioned quite new; thy wtteels are put on;
they put the straps on the axles and on the hinder part; they
splice thy yoke, they put on the box of thy chariot; the work-
men in iron forge the (?) ; they put the ring that is wanting on
thy whip and they replace the lashes upon it."

A truly human document.

It appears that even at this early date workmen could be found
in Jaffa skilful in repairing chariots and familiar with the art of
forging iron.

The earliest general group of iron tools in Egypt was found at
Thebes and belonged to the time of the Assyrian invasion by
Ashur-banipal, 666 B.C.

Iron in Holy Writ

The word iron occurs more than 60 times in the Old Testament.
The first reference occurs in Numbers xxxv. 1 6, where the Lord lays
down the law to be observed by the Hebrews when they entered the
Promised Land. If a man smite another "with an instrument of

261

THE CHEMICAL ELEMENTS

iron, so that he die, he is a murderer; the murderer shall surely be
put to death/' The next time iron is mentioned is in connection
with Og, the giant king of Bashan, a city of the Amorites. Og died
about 1400 B.C. and his bier or sarcophagus, was of iron (Deuf. iii.
1,1), "nine cubits was the length thereof, and four cubits the
breadth of it, after the cubit of a man." As a cubit was roughly
equivalent t to 20-6 inches, the bier would measure 15 by 7 feet.
Such large dimensions were no doubt worthy of note, but it is
doubtful if they would have found their way into Holy Writ had
it not been for the unusual fact that the bier was made of iron. Both
in the Authorised and Revised Versions of the Bible the word bier
is incorrectly rendered bed. Beds as we know them were not then in
use. 'The account may, however, be a later addition to the MS. and
it would be unwise to conclude from this alone that iron was in
general use at that early date*.

The early Hebrews did not use war chariots and we are toldf
that in consequence they found themselves at considerable dis-
advantage when fighting the Canaanites who possessed large
numbers of chariots plate'd or studded with iron.

The oldest specimens of iron hitherto found in Palestine are
two wedge-shaped lumps discovered at the bottom of the sloping
part of the water-passage at GezerJ. The passage had been sealed
up prior to 1250 B.C., so that the pieces of metal evidently date back
to a time many years anterior to that at which iron came into general
use in the country.

The Philistines who entered Palestine from the Mediterranean
about the same time as the Hebrews from the desert, were a
cultured, non-semitic race, familiar with iron. They wisely retained
the monopoly of working the metal, refusing to teach the Hebrews
lest they should equip their armies with iron swords (i Sam. xiii.
19-22). In consequence the Hebrews had no smiths of their own
and only Saul and Jonathan possessed iron swords. The petty
skirmishes between the Hebrews and the Philistines are easily
understood when one has visited the country and traversed the
bleak and barren heights occupied by the Hebrews and compared
them with the fertile maritime plains below owned by the Philis-
tines. It was the have-nots versus the haves.

*RIDGEWAY, "The Early Age of Greece" (C.U.P., 1901), Volume i, p. 617.

f Joshua xvii. 16. Judges i. 19.

JMACALISTER, Palestine Exploration Fund, Quarterly Statement, 1908, p. i.

THE IRON GROUP

As Macalister* quaintly puts it "the promise of a land flowing
with milk and honey was not made to a crowd of beef-fed excur-
sionists, coming from cultivated and developed lands of the
modern west, but to tribes of half starved wanderers, fighting their
way from oasis to oasis over sterile sands/' Hence, if the barren
heights of Judah seemed to flow with milk and honey, how much
more so would the maritime plain. *

The break up of the Philistine domination removed the embargo
on iron, and when David ascended the throne about 1000 B.C. the
use of iron had become more general. By the time of Amosi|" 760
B.C.), the herdman of Tekoa in Southern Judah, iron was in general
use among the Hebrews, and the later Hebrew writers were
evidently familiar with smelting furnaces:):.

In 1925, when in Jerusalem, a dragoman informed the Author
of a curious belief which he stated to be prevalent amongst the
Jews, namely that if the crevices in the ancient wall at the famous
Wailing Place are completely filled with iron nails, Jerusalem will
once again be restored to the Jews. The authorities have very
properly stopped the practice of plugging the walls with nails
which had become a nuisance. A host of questions instantly
suggests itself to the inquiring mind. Would copper nails be
equally effective? If not, wherein lies the virtue of the iron?

There are but few references to iron in the New Testament. It
is generally conceded, however, that the nails used in the crucifixion
of Christ were of iron, and tradition says that these were subse-
quently welded into an iron band to which six golden plaques were
affixed thus making the Corona Ferrea or the Crown of Lombardy.
Tradition says that this crown was given by Pope Gregory the
Great to Queen Theodelinda, who died A.D. 638, and it is known
to have been used at many coronations since that of Henry of
Luxemburg in 1311, who is the first who is known with certainty
to have worn it. In 1805 wh en Napoleon was crowned King of
Italy in Milan cathedral he placed the crown upon his own head
voicing the traditional formula "God gave it to me; woe to him
who touches it." History adds pathetically that Josephine was
present at the ceremony, but only as a spectator||. The crown

*MACALISTER, "A History of Civilisation in Palestine" (C.U.P., 1921), p. 29.
fAmos may have witnessed the total eclipse of the Sun in Palestine in 763 B.C.
(Amos viii. 9).

I Jeremiah xi. 4. Written about 600 B.C.

JONES, W., "Crowns and Coronations", p. 23 (1883, Chatto & Windus).

||GEER, "Napoleon and his Family" (Allen and Unwin, 1928), p. 206.

263

THE CHEMICAL ELEMENTS

followed the remains of King Victor Emmanuel to the Pantheon at
Rome in 1878.

And what of the spear that pierced the Master's side so deeply
that "forthwith came there out blood and water" John xix. 34?
Traditions are unanimous that the spear-head was made of iron,
but very different tales are told of its subsequent history. According
to one story the spear-head was carefully preserved after the
crucifixion and was ultimately blended into the huge sword Joyeuse
of Charlemagne (742 to 814).

According to another legend the spear-head was found by Peter
Bartholomew during the First Crusade in 1098. Antioch had fallen,
but the crusaders who had taken it were themselves besieged in
turrt by the Turks. One night St Andrew appeared to Peter in a
vision and showed him where the relic lay. "Behold" said he "the
spear which pierced the side of Him who saved the world." On
awaking, Peter communicated his vision to the authorities ; digging
was undertaken and the spear-head found a piece of rusted iron.
This was regarded by the crusaders as a sign that God was with
them. Under BohemuncJ they sallied forth from Antioch with the
spear-head bound to a standard; the Turks were routed. The spear-
head was later encased in silver and given to the Byzantine
emperor*.

Iron in India

It is claimed that iron was worked in India at a very early date,
possibly some 2000 B.C. if early records are to be believed. This is
quite conceivable. But the imagination of the Easterns is apt to run
riot, and early traditions must be scrutinised with the utmost care.

Herodotusf states that the Indian troops in the army of Xerxes,
King of Babylon 485 to 455 B.C., used arrows pointed with iron.

Several large masses of iron are to be seen in India made many
centuries ago by welding together small blooms, obtained by the
direct process and weighing several pounds each. That such huge
masses could be constructed is a remarkable tribute to the skill of
the early Indian metallurgists. The most famous of these are the
Delhi Pillar, the Dhar PillarJ and the iron beams from the Black

*H. LAMB, "The Crusades" (London, 1930), Chapters 25 and 26. See also
BESANT and PALMER, "Jerusalem" (London, 1908), Chapter 6.

f"The History of Herodotus", translated by G. Rawlinson, Book 7, Chapter 65.

JV. A. SMITH, /. Royal Asiatic Society, 1898, p. 143. /. Iron Steel Institute, 1912,
i, 158. GRAVES, ibid., p. 187.

264

PLATE 2

[Facing p. 264

The Iron Pillar at Delhi

Height 22 feet, Upper Diameter 121 inches, Lower Diameter 16 inches, Weight 6 tons
(Reproduced by permission of the late Sir Robert Hadfield, F.R.S.)

THE IRON GROUP

Pagoda at Konarak* in the Madras Presidency. It will suffice to
give a brief account of the first of these, namely the Delhi Pillar,
which dates back to about A.D. 300. According to Brahmin
tradition it was erected after the stars had indicated the auspicious
moment, and was embedded so deep in the earth that it pierced the
head of the serpent god Schesnag, who supports the earth. The
priests told the Rajah that this ensured that his 'kingdom would
last for all time. But the Rajah could not be satisfied lihtil he had
confirmed what the priests told him. He dug the pillar up again
and sure enough the end was covered with blood. On replacement
the serpent refused to be caught and the pillar now merely rested
in the soil without supernatural support. This of course was nothing
like so secure a foundation and after a few generations the Rajah's
kingdom was supplanted by another. The pillar is not now on its
original site; it was placed in its present position in A.D. 1052 as an
adjunct to a group of temples from the materials of which the
Mahommedans later constructed the mosquef. Analysis^ shows
the metal to be an excellent type of wrought iron, somewhat high
in phosphorus but low in sulphur, showing that the fuel used in its
manufacture and subsequent treatment was very pure it would
most probably be charcoal. The pillar has resisted corrosion
extremely well and it has been argued that this ancient metal is of
better quality than that produced to-day. But the* ancient custom of
anointing the pillar with butter at certain religious festivals may
have had something to do with this. The total height of the pillar
is 23 feet 8 inches, of which only 20 inches lie beneath the ground.
The upper diameter is roughly one foot, the lower 1 6 inches, the
total weight being estimated at about 6 tons. The pillar is illus-
trated in Plate 2.

Legend hath it that Delhi owes its name to this pillar, the priests
giving it that name from dhili loose or unstable. A Hindoo Judge
has informed the Author that there is no connection between the
two words. The word Delhi most probably means "Heart's
Delight".

Iron in the Far East

In China the bronze age probably began about the time of the
Emperor Ta-yii, that is, Yii the Great, circa 2200 B.C., and drew to

* FRIEND and THORNEYCROFT, /. Iron Steel Institute, 1924, n, 313. GRAVES,
loc. cit.

fV. A. SMITH, "Early History of India 11 (Clarendon Press, 1924).
JHADFIELD, /. Iron Steel Institute, 1912, i, 156. T. TURNER, ibid. p. 184.

265

THE CHEMICAL ELEMENTS

a close about 500 to 600 B.C. For religious purposes bronze
remained the favoured metal and the art of casting in bronze
continued f.o improve, attaining its zenith in the magnificent and
gigantic castings of the Northern Wei (386 to 535) and T'ang
(6 ( i8 to 907) Dynasties.

During the reign of the Emperor Chuang-Wang, 696 to 682
B.C., iron had crime into general use, a tax on iron needles, knives
and agricultural implements being instituted. This proved so
profitable that later governments continued the tax and did all they
could, to increase the production of iron articles. But in the original
tax no mention was made of swords or arms. This suggests that
the metal was not as yet sufficiently reliable for military purposes.
Som6 300 years later the King of Ch'u is stated to have been
interested in the production of iron swords possessing magical
properties, which suggests that the Chinese had learned to
carburise their iron and convert it into steel sufficiently hard and
reliable to warrant the confidence of the soldier*; it was usual to
attribute magical properties to swords that were specially efficient
(see p. 276).

Japan has long been famous for her swords. The Samurai, a man
belonging to the military class and entitled to bear arms, set much
store by his sword, which was his constant companion and allyf.
The price of the sword was high, particularly if made by a famous
craftsman, the blade alone costing several hundred pounds. The
swords were handed down from father to son as valued heirlooms,
and the swordsmith, regarded as following a most honourable
profession, was of gentle blood.

"The trenchant blade of the Japanese sword is notorious",
wrote Lord Redesdale. "It is said that the best blades will, in the
hands of an expert swordsman, cut through the dead bodies of
three men, laid one upon the other, at a blow." The swords of the
Shogun were wont to be tested on the corpses of executed
criminals; it is said that the public headsman was entrusted with
this duty and that for a "nose-medicine" or bribe he would
substitute the sword of a private individual for that of his lord, and
that the executioner earned many a fee from those who wished to
see how their swords would cut off a head.

The blades of MuramasaJ were reputed to be unlucky; and the

*F. HIRTH, "The Ancient History of China" (New York, 1908), pp. 203, 235.
fLoRD REDESDALE, "Tales of Old Japan" (Macmillan, 1910), pp. 38, 61 and 93.
%

266

THE IRON GROUP

superstitious regard them as hungering after men's lives. The
Suk^sada was an ancient and famous family of swordsmiths whose
blades fetched very high prices. *

Iron and the Greeks

The Greeks and the Cretans appear to have been amongst the first
European peoples to use iron; the Grecian iron age began about
1400 B.C., although for most of the Celtic and Teutonic^peoples it
did not commence until some 900 years later.

Homer, who lived about 880 B.C., was very familiar with the
metal. The Homeric Age, however, as depicted in the "Iliad'* and
"Odyssey", was much earlier, being in the main coeval with the
Third Late Minoan Period of Crete, that is about 1400 to 1*200
B.C., and represents a transition period, during which iron and
bronze weapons and implements were used side by side. In the
Homeric age iron, though not regarded as a precious metal like
gold, ranked amongst the treasures of the wealthy, and was used,
amongst other things, in ransoming prisoners and as a prize in
sporting contests. Thus Achilles awarded^ a heavy lump of iron to
him who could hurl it the greatest distance. The swords and defen-
sive armour of the Homeric Heroes were made of bronze, as this
metal could be relied upon to resist reasonable force. Goliath of
Gath was similarly armed. Heavy implements nuch as axes and
plough shares, however, were frequently made of iron, as a solid
block of metal would be less liable to deformation than the fine
cutting edge of a sword. Thus we read of

Great Areithous, known from shore to shore

By the huge, knotted iron mace he bore*.

The Greeks in Homer's time possessed a certain knowledge of
tempering. This is hinted at in the Odyssey, in the story of the
blinding of the one-eyed giant, Polyphemus, by Ulysses, who
plunged a fiery stake into his orbj".

As when the smith an hatchet or large axe
Temp'ring with skill, plunges the hissing blade
Deep in cold water (whence the strength of steel)
So hissed his eye around the olive wood.

Herodotus, in his famous History, written about 450 B.C., makes
numerous references to iron. It is curious that he refers to the metal

* "Iliad", Pope's translation, vn.

f "Odyssey", Cowper's translation, ix.

267

THE CHEMICAL ELEMENTS

as having been "discovered to the hurt of man". The same idea runs
through Homer and Virgil, whilst the Roman admiral Pliny
moralises a,t length in the same strain. Even Mahomet, early in the
seventh century, held a similar view; he is reported in the Koran as
saying

And we haye sent down iron. Dire evil resideth in it, as well as
advantage to mankind.

Iron and the Romans

( o

The Romans were skilled metallurgists and it is evident that
already before the Christian era they were familiar not only with
iron* but with the tempering of steel. Virgil in his "Aeneid",
written about 36 B.C. describes a smithy in full blast*

A flood of molten silver, brass and gold,
And deadly steel in the large furnace rolled;
Of this, their artful hands a shield prepare,
Alone sufficient to sustain the war.
Seven orbs within a spacious round they close,
One stirs the fire, and one the bellows blows,
The hissing steel is in the smithy drowned.

Ovidf, writing some 40 years later than Virgil, refers to the
same metallurgical process in his description of the mythical fight
between the Thessalian chiefs and the centaurs half man, half
horse. After the wedding of the beautiful Hippodame with
Pirithotts, the nuptial song was in full strain and the great hall
smoked with fires. As the maiden entered, her surpassing beauty
inflamed the wild centaurs, excited by the wine that had been
flowing freely, and the hall was straightway in an uproar. Eurytus,
the wildest of the centaurs, seized the bride, but Theseus rushed to
the rescue, hurling an antique vessel full in the centaur's face, so
that he fell, never to rise again. The centaur Rhoetus with a blazing
torch struck Charaxus, whose hair caught fire and burned like a
dry field of grain. The "blood, scorching in the wound, gave forth
a horrid sizzling sound, such as a bar of iron, glowing red in the fire,

*VIRGIL, "The Aeneid". Dryden's translation (Routledge, 1884), Book vm.
The last line has been italicised by the present Author. Virgil was born 76 B.C.,
and was at work on the "Aeneid" when about forty years of age.

fP. OVIDIUS NASO, born at Sulmo, 43 B.C. and died A.D. 17. See OVID
"Metamorphoses". Translation by Miller (Putnam, 1916), Book xn. The work
was completed by Ovid in A.D. 7.

268

THE IRON GROUP

gives when the smith takes it out in his bent pincers and plunges it into
a tub of water"

Pliny has much to say in reference to iron. One passage* is of
special interest

It is a remarkable fact that, when the ore is fused, the meCal
becomes liquefied like water, and afterwards acquires a
spongy, brittle texture.

This can only mean one thing, namely, that the Romans
occasionally made small quantities of cast iron, possibly by
the accidental overheating of their furnaces by extra draught.
If so, the above passage is the earliest reference to cast iron in
existence.

Like earlier writers (p. 268), Pliny laments the fatal uses to which
iron is put, for "it is with iron also that wars, murders, and rob-
beries are effected.' 1 But as a punishment for its evil propensities,
iron is cursed with a tendency to rust. "Nature," he writes, "in
conformity with her usual benevolence, has limited the power of
iron by inflicting upon it the punishment of rust." Pliny knew also
that some kinds of iron are more prone to rust than others. "There
is in existence", he says, "at the city of Zeugma, upon the Euphrates,
an iron chain by means of which Alexander the Great constructed
a bridge across the river, the links of which that have been replaced
having been attacked with rust, while the original links are totally
exempt from it." This is the earliest recorded report on the
relative corrodibilities of different specimens of ironf.

One cannot help smiling at the unconscious betrayal that human
nature alters but little with passage of time. In Pliny's day, as in
ours, the modern metal was inferior to the old. We are reminded
of the man who complained that Punch's jokes are not now as good
as they used to be; to whom Punch pithily replied "They never
were".

As a sort of atonement, however, iron is accredited by Pliny
with certain beneficial virtues. "For if a circle is traced with
iron ... it will preserve both infant and adult from all noxious
influences ; if nails, too, that have been extracted from a tomb, are
driven into the threshold of a door, they will prevent nightmare."
And so on.

*PLINY, "Natural History", translated by Bostock and Riley (Bohn, 1857),
Book 34, Chapter 41.
\Ibid. , Chapter 43.

269

THE CHEMICAL ELEMENTS

Iron in Pre-Roman Britain

Iron was known to the British at least a couple of centuries before
Julius Ca&ar visited our shores in 55 B.C. one of the few dates
we all remember. None of the earliest furnaces have been discovered
but it is thought probable that the first iron furnace of the Britons
was similar to those used so successfully in the extraction of tin ; it
would thus be a simple low hearth resembling the Catalan furnace
of the Pyrennees which has been in use there from very remote
times down to the present*.

At* the time of the Roman conquest iron was in common use
amongst the Britons. The wheels of their war chariots had iron
tyrec, and fragments of these have been found in the remains of
chariot burials in various parts of the country. The wooden parts of
the chariots have long since mouldered away. Some of the chariots,
like modern motor cars, were fitted with iron mirrors to prevent the
charioteer from being attacked unawares in the rear. Although
Boadicea is represented on the Thames Embankment as riding in a
scythed chariot, there is no evidence that such scythes were ever
attached to British chariots, although they were used on the
Continent.

Although coins were known, having been introduced from Gaul
some 200 B.C. the British also used bars of iron as currency.
Numbers of these bars have been found in various parts of the
southern half of England, including the Isle of Wight, and were
first recognised as such by Reginald A. Smith of the British
Museum|. The bars somewhat resemble unfinished swords, a rude
handle being formed at one end by folding over the edges. They
are, however, of different sizes and weights, multiples or sub-
multiples of about 309 grams or 4,770 grains. In the National
Museum of Wales at Cardiff there lies a bronze weight, found near
Neath in Glamorganshire amongst late Celtic relics, the weight of
which approximates to the above. A similar weight, in basalt, once
lay in the Mainz Museum; it weighs 4767 grains, and like the
Neath specimen it bears the mark i. These weights correspond to
half an Attic commercial mina of the period 160 B.C. Evidently in
their trade with the Continent the British used similar standard

*R. A. SMITH, "A Guide to the Antiquities of the Early Iron Age" (British
Museum, 1925), p. 2.

fR. A. SMITH, Archceological /., 1913, 19, (2), 421. Proc. Soc. Antiq., 1915, 21.
69. FRIEND, Trans. Worcestershire Nat. Club. 1919. BULLEID, "The Lake Villages
of Somerset" (Folk Press, 1924), p. 44.

270

THE IRON GROUP

weights. It is a thousand pities that we ever departed from this
very sensible custom.

Various iron relics have been found in Wookey Hold, a cave in
the Mendips some two miles from Wells in Somerset. A rocky
path by the side of the Paper Mills leads up the hill to the famous
cavern. The narrow entrance opens into a large cave some 80 feet
in height carved out by nature in the limestone. The cave was
inhabited in pre-Roman times as well as during me Roman
occupation; it has been thoroughly explored by Balch* and his
collaborators who found within it numerous implements irf stone,
bronze, iron and bone. The iron objects exceeded 60 in number
and of particular interest are those dating from pre-Roman times.
Amongst these was an iron dagger, now known as the Goatherd's
dagger, for it probably belonged to the person whose skeleton was
found near by, together with the remains of some goats. Judging
from the size of the bones the goatherd was only about 5 feet in
height, and may well have been a woman. As Balch suggests, it is
just possible that this lonely occupant of the cave gave rise to the
legendary Witch of Wookey, who was /'laid'' by a pious monk
from the hard-by Abbey of Glastonbury. The ballad runs as
follows

In anciente days tradition showes
A base and wicked elfe arose
The Witch of Wokey hight;

In due course, however, a monk from Glastonbury came to
exorcise the witch.

He chaunted out his godlie booke,
He crost the water, blest the brooke,
Then paternoster done
The horrid hag he sprinkled o'er;
When lo! where stood a hag before,
Now stood a ghastlie stone.

The first chamber entered by the curious visitor, and described
above is known as the "Kitchen", and a lump of stalagmite is
pointed out as the remains of the witch, a warning for all time to the
godless, A strong imagination, assisted by the weirdness of the
surroundings, enables the superstitious to detect a human profile
in that shapeless mass of rock.

*H. E. BALCH, "Wookey Hole" (Oxford, 1914).

271

THE CHEMICAL ELEMENTS

The cave was not always thus deserted. At times its walls
echoed to the shouts of the hunter and the laughter of happy
children. The hammer of the worker was also heard at intervals, ror
a piece of unworked iron weighing more than 6 Ib. was found
near the door of the cave, indicating that it was usual to work up
iron objects at the cave itself. Other pre-Roman iron relics included
two Celtic saws, a bill-hook and sickle, a latch-lifter, awls showing
remains of wooden handles and a currency bar. One of the saws had
a handle of cleft antler, and the teeth of both were set in opposite
directions alternately as with modern saws. The sickle indicates
that the cave dwellers grew grain upon the land surrounding their
home; a sickle of similar shape was used in Saxon times. The
purpose of the latch-lifter was to lift a concealed latch in a palisade.
It would appear therefore that the cave entrance was at times
protected. An ox shoe had holes for nails just like a modern horse
shoe.

Numerous iron objects have been found also amongst the
remains of the Glastonbury Lake village which was probably
inhabited from about 100 B.C. to 50 A.D, These include bill-hooks
and latch-lifters similar to those found at Wookey.

The Mabinogion

Several referencee to iron occur in that curious collection of ancient
Welsh literature known as the "Mabinogion"*. In the story of
"Kulhwch and Olwen" we are introduced to the giant, Yspad-
daden, father of Olwen whom Kulhwch wishes to marry. The
name Olwen means white footprints, and the girl was so named
because four white clover blossoms would spring up in her foot-
prints wherever she walked. Kulhwch and his companions duly
called upon the giant and stated their errand. 'Come here to-
morrow, and I will give you some answer* said the giant. The
young men rose and went their way, but as they left Yspaddaden
"seized one of three poisoned j/o^-spears which were to hand, and
hurled it after them; but Bedwyr caught it, and hurled it back,
piercing the giant's thigh. 'A cursed savage son-in-law' roared
the giant '. . . Like bite of gadflies has this poisoned iron pained
me. Accursed be the smith who fashioned it and the anvil it was
fashioned on, so painful it is'."

The stone spear, it will be observed, becomes one of iron when
it is flung back. The episode was twice repeated ; at the end of the

See the translation by Ellis and Lloyd (Clarendon Press, 1929).
272

THE IRON GROUP

second visit the giant hurled his second stone spear after the young
men but received it back as an iron one in the middle of his chest so
that it came out in the small of his back. After the thir$ visit the
last of the three stone spears was flung back at the giant, the iron
entering his eye.

This is not a mere idle tale. It represents the passage from th'e
stone age to that of metals. The younger genei*ation won the
victory by using the more modern weapons. *

Numerous Welsh stories tell of the dire result of allowing iron
to come into contact with fairies*.

These stories have their modern counterpart in the belief that the
gift of a knife or any cutting instrument will sever the bonds of
friendship. Hence on receiving a present of this character ft is
usual for the recipient to give the donor a farthing or half-penny;
the "gift" is then not a gift; it has been purchased.

The Manx saw displays much wisdom

Where folks believe in witches, witches are;

And where they don't, the de'il a witch is there!

Iron in Roman Britain

With the advent of the Romans, the iron industry of our island was
enormously stimulated; both Gloucestershire and Sussex became
important centres. Large quantities of slag, known as cinders, were
left in various places, and at one time were in demand for the repair
of roads. That the word cinder is not modern is evident from its
appearance on early documents, as also from the names of many
early sites, such as Cinderford, Cinderhill, etc. In A.D. 120 the
Emperor Hadrian founded an arms factory at Bath, where iron
from the Forest of Dean was worked. From among the remains of
ancient Roman towns many interesting iron relics have been taken.
Mention may be made of an iron ring or ferrule unearthed during
excavation on the site of Uriconium. The ring had been made by
bending over on to itself a strip of sheet iron and "brazing" or,
more correctly, "copper soldering" the ends together with some
copper alloy. This appears to be the only duly authenticated sample
of the kind actually done by the Romans")". The specimen cannot be

*T. GWYNN JONES, "Welsh Folklore and Folkcustom" (Methuen, 1930), p. 66.

See also MCPHERSON, "Primitive Beliefs in the N.E. of Scotland" (Longmans,
1929), p. 102.

t FRIEND and THORNEYCROFT, /. Inst. Metals, 1928, 39, 61. FRIEND, Nature,
1925, 116, 749-

273

THE CHEMICAL ELEMENTS

dated very closely, but as Uriconium was destroyed about A.D. 380
it cannot be younger than this. It is now in the possession of the
Birmingham City Museum. (See Plate 3 ).

Iron and Post-Roman Britain

With the coming of the Saxons we are beginning to escape from
antiquity. The, Saxons were, of course, quite familiar with iron,
although references to it in the " Saxon Chronicle* ' are scanty. We
do know, however, that, owing to shortage of weapons, some of the
troops under Harold at the battle of Hastings were armed with
ston6 hammers. The Normans required considerable quantities of
iron for their armour. The metal was always made by the direct
process.

In Anglo-Saxon times the smith was regarded as a person of
great importance. In the royal court of Wales the smith sat in the
great hall with the King and Queen, next to the chaplain, and was
entitled to a draught of every kind of liquor that was brought into
the hall. His duties were numerous, and the smith had to be
proficient in all manner of ways. He was expected to make horse-
shoes and the nails to fix them, as well as all sorts of military
weapons including the forging of mail coats and armour for both
knight and horse.

As the various uses to which iron could be put steadily increased,
the smiths began to sort themselves out and specialise in certain
types of work, some concentrating on horse-shoes and nails, others
on swords and knives and so on. During the reign of Edward in
(1327 to 1377), the pots, spits and frying-pans of the royal kitchen
were classed amongst the king's treasures.

In Scotland likewise the smith was held in high esteem and a
story is told of one of his craft who committed a crime for which he
was found guilty and sentenced to death. But the chief of the clan
could not dispense with his services and offered to hang two
weavers instead!*

In the fifteenth century cannon were made by hooping wrought
iron bars together; Mons Meg, in Edinburgh, made in 1455, is a
noted example.

William Shakespeare in his various works makes reference to
iron some 48 times and to steel 64 times. In his boyhood days the
forge and smithy of Richard Horneby stood close to where he
lived, and would be frequently visited by the youthful poet. They

*W. JONES, 'Treasures of the Earth" (Warne), p. 167.
274

PLATE 3

[Facing />. 214

A Roman ferrdle

The ferrule, here reproduced
actual size, was found f ai
Uriconium. The bottom view
shows a copper join at A and
a weld at B. (See page 273.)*

A nineteenth century
steel brooch

Steel jewellery was popular

in the nineteenth century.

(See page 291.)

THE IRON GROUP

adjoined a tailor's shop (now the Birthplace Ticket Office) which
lay next door to Shakespeare's residence, in Stratford on Avon. In
Shakespeare we find the expression "true as steel" ("Troilus and
Cressida", act I, scene 3), The expression had also been used by
Chaucer on several occasions; in the "Canterbury Tales" (c. 1388)
the host uses it to describe his wife, and in the "Parlement of Foules'
(1382) the royal eagle is described as "wys and worth/, secree, trewe
as stel". The expression is first known in English literature from a
MS. of c. 1300, which runs "Oure love is also trewe as stel". It is
likely that from about Chaucer's time onwards the expression was a
common enough compliment; a few centuries earlier, however, in
Viking times, it would surely have been thought an insult (see
p. 276).

For many centuries Sussex and Gloucestershire were most
important centres of the iron industry. As the practice of metallurgy
improved so did the size of the furnaces. At one time the Forest of
Dean could boast the largest furnace in England; this was in 1724,
the furnace measuring 2 8 feet in height. The ore was first dried by
exposure to air and then calcined in heaps in the open using wood
fuel; later this calcining took place in kilns. The ore was then
smelted with charcoal in stout-walled furnaces built in the form of
square, truncated pyramids which, by the advent of the seventeenth
century measured some 22 feet square at the base, Inside they were
approximately egg-shaped ending in a rectangular hearth of
considerable depth. The blast was produced with bellows which,
in 1323, were worked by water power for the first time, though of
course hand bellows continued to be used for many years*.

Iron for swords

The soldier is naturally conservative. No doubt this is largely due
to the natural working of the law of self preservation. The bronze
age warrior was slow to discard his trusty sword and shield of bronze
in favour of new-fangled iron weap 3ns, just as the hero of Waterloo
preferred the musket long after the superiority of the rifle had been
demonstrated to less prejudiced minds. We cannot altogether
wonder at it, for in the early days of its manufacture iron was a
somewhat uncertain metal, and, when a man's life depended upon
the trustworthiness of his sword, the proved weapon, even if
antiquated, might well be preferred to the more modern one if the
slightest doubt existed as to its reliability.

*RHYS JENKINS, The Engineer, 1921, 131, 116, 502, 546.

975

THE CHEMICAL ELEMENTS

Polybius, for example, tells us that the defeat of the Kelts by
the Romans at the battle of Addua, near Milan, 223 B.C., was
largely attributable to the fact that the long iron swords of the
Kelts were "easily bent and would only give one downward
cut with any effect, but that after this the edges got so turned
and the blade so bent, that, unless they had time to straighten
them with the foot against the ground, they could not deliver a
second blow/'

The same kind of difficulty faced the warriors in Iceland more
than c. millenium later. In the Viking sagas, covering the period
A.D. 800 to 1 100 (approximately), we constantly read of the failure
of the iron swords to "bite". In The Story of the Ere-dwellers*, for
example, we are given details of a family squabble which ended
in an appeal to arms. "So then befell a great battle", we are told,
"and Steinthor was at the head of his own folk, and smote on
either hand of him; but the fair- wrought sword bit not whenas
it smote armour, and oft he must straighten it under his foot."
Such, then, was the state of affairs as late as the eleventh century
of our era !

The early metallurgist, to whom chemical analysis and micro-
graphical examination were unknown, was unable to explain the
uncertainty of his iron. When, by chance, a good piece of metal was
obtained, it was often given a supernatural origin. Thus the
sacred sword of Attila (A.D. 395 to 453) was believed to have been
found by a shepherd, inverted in the ground, and was handed to
that "Scourge of God" as a token of Heaven's approval. It is
interesting to note that the name Atli, Etzel or Attila, in the Hun
language, is believed to have signified the metal ironf. The divine
origin of Arthur's Excalibur is beautifully portrayed by Tennyson
in The Passing of Arthur. One can sympathise with bold Sir
Bedivere who hesitated to consign so beautiful a weapon to the
misty waters of the mere.

When a sword had once been proved to be reliable, its value was
priceless. Upon the death of its owner it was not usually buried in
the warrior's grave, but was appropriated by his conqueror or by
his next of kin for future use. Thus the weapons became christened
with suggestive names and developed a sort of pedigree. Numerous
examples are quoted in the Icelandic Sagas, and similar tales are
associated with the famous swords of the Japanese Samurai.

"Translated by Morris and Magnusson (Quaritch, 1892), p. 120.

fBRiON, "Attila, The Scourge of God", translated by Ward (Cassell, 1929).

276

THE IRON GROUP

Cast iron

At first the iron was always produced by direct reduction although
even in Roman times it would appear that cast iron was sometimes
produced by accident through overheating of the furnaces (p. 269) ;
but this would be regarded as unfortunate as in those days there was
no use for this brittle product. As the size of the furnaces increased,
however, the iron remained for a longer time in contact with the
fuel and the temperature tended to rise, ultimately reaching that at
which carbon and iron combine, yielding cast iron. This accidental
production of cast iron became increasingly frequent until ulti-
mately it became, designedly, the only product, as it is to-day. We
do not know when cast iron first became important metallurgically.
It is recorded that in 1340 a blast furnace designed as such was
erected near Namur in Belgium and there were blast furnaces in
England before 1490; in 1497 one Simon Ballard cast large
quantities of iron shot in Ashdown Forest in Sussex. But of course
cast iron was known in England much earlier than this, certainly
by 1350 in Sussex.

It is held that the introduction of the blast furnace proper, as
apart from the ordinary furnace really intended to produce wrought
iron direct, led to Sussex becoming the premier iron producing
district in England; the forests yielded ample fuel and the streams
provided the necessary mechanical power.

At first cast iron was used exclusively for casting purposes and
several Sussex church yards are graced with cast iron tomb stones.
Cast iron cannon balls are said to have been made at Memingen in
1388, whilst in 1412 cannon were cast at Lille as the earlier bronze
cannon were found too weak to stand the increasingly larger
charges the army desired to use. The first cast iron cannon produced
in Britain were made at Buxted near Crowborough in Sussex in
1543. According to local legend

Master Huggett and his man John
They did cast the first cannon.

Cast iron guns were used by the Spaniards in their ships at the
time of the attempted invasion of Britain in 1588. After a thorough
trouncing at the hands of the Royal Navy under Drake, the
surviving ships of the Spanish Armada, afraid to return through the
English Channel, straggled home round the north of Scotland in
pitiable plight. The weather was stormy and most of the vessels,
probably already damaged, either foundered at sea or were broken

277

THE CHEMICAL ELEMENTS

to pieces on the rocks. In 1740 cast iron guns were raised from
The Florida, one of the Spanish ships that had sunk off the coast of
Mull an4 had thus lain in the sea for 1 52 years. On scraping away
the corroded surface they became too hot to touch. Wilkinson*
states that "the inhabitants of Mull, and all who witnessed the
phenomenon, were greatly astonished (as may naturally be
supposed) ; and being themselves unable to solve the mystery, they
applied tc the surgeon of the ship, as being the most scientific man
present; he was, however, as much at a loss to account for such
unusual appearances as themselves, but said that although they had
been buried in the sea nearly 200 years, yet, as they went down in the
heat of action, he supposed they had not had sufficient time to cooll"

Actually of course, the iron had undergone oxidation to ferrous
oxide which, on coming into contact with the oxygen of the air,
rapidly oxidised to ferric oxide, with evolution of heat, the reaction
being strongly exothermic.

About this time, also, guns were made of wrought iron bars
hooped together, a good example being afforded by Mons Meg in
Edinburgh, made in 1455 (p. 274). The Mary Rose was fitted with
this type of gun ; she was a British vessel which sank off Portsmouth
in an engagement with the French in 1545. In 1836 her guns were
raised after having lain in the water for nearly 300 years.
Wilkinson describes them as "formed of iron bars hooped with
iron rings, and they were all loaded"; the cannon balls were of
cast iron, originally 8 inches in diameter and weighing 70 Ib.

In 1822 some cast iron cannon were fished up off Holyhead|;
they had belonged to a pirate vessel sunk there a century or so
earlier and had oxidised through their whole mass. When raised
from the water they were quite soft and could be cut with a knife.
On exposure to air they hardened and were used along with other
truly metal ones to fire salutes when King George iv passed through
Holyhead somewhat later en route for Dublin. It was noticed that
these old cannon made more noise than any others when fired; it
was a marvel they didn't burst.

The fuel problem

Rich though Sussex was in wood its stocks began to show signs of
depletion owing to the large amount of charcoal required to keep

*WILKINSON, "On the Extra-ordinary Effect produced on Cast Iron by the
Action of Sea-water" (London, 1841).

fRENNiE, Min. Proc. Inst. Civil Engineers, 1845, 4, 323.

278

THE IRON GROUP

her furnaces ablaze. The shortage of fuel was equally acute elsewhere
in Britain and in the first year of Queen Elizabeth's reign (1558)
and again in 1584 Acts were passed for the preservation of timber.
But iron was badly needed. Attempts were made by Simon
Sturtevant, Dodo (Dud) Dudley and others in the seventeenth
century to use "Pit-coale, sea-coal e, etc, and with the same Fuell
to Melt and Fine Imperfect Mettals and Refine perfect Mettals"
as we read on the title page of Dud Dudley's "Metalluji Martis",
dated 1665. To Simon was granted the first patent in 161 1.

Dud Dudley, a natural son of Edward, Lord Dudley, was born
in 1599 near Birmingham and as a young man studied at Baliol
College, Oxford; in 1619 he was called home to take charge of
several iron works belonging his father. In his own words

Wood and Charcole, growing then scant, and Pit-coles, in
great quantities abounding near the Furnace, did induce me
to alter my Furnace, and to attempt by my new Invention, the
making of Iron with Pit-cole, assuring myself in my Invention,
the loss to me could not be greater than others, nor so great,
although my success should prove fruitless ; But I found such
success at first tryal animated me, for at my tryal or blast, I
made Iron to profit with Pit-cole and found Facere est addere
Inventioni.

Dudley took a prominent part in the Civil War as a Royalist and
in 1642 he was busy making cast iron cannon at his foundries for
use by the King's troops. He died in 1684 at the ripe age of 85,
and in the church of St Helen's at Worcester a large monument
was erected on the South Wall to his memory.

Dudley's persevering efforts met with a given measure of success,
but it was not sufficient to induce others to follow in his footsteps.
In the Forest of Dean, charcoal furnaces some 30 feet high
were in use and Henry Powle*, writing in 1677, states that,
although various attempts had been made to substitute coal for
charcoal all had proved abortive. The problem of smelting iron
with coal was not really solved until 1735 when Abraham Darby
the younger, at Colebrooke Dale, Shropshire, first coked his coal
and then reduced his calcined ore; by 1750 coke-fired furnaces
were becoming serious rivals of the charcoal ones and eventually
superseded them. The Colebrooke Dale Works were very pro-
gressive; they appear to have been the first to use a steam engine

*POWLE, Phil. Trans., 1676, 12, No. 137, p. 931.

279

THE CHEMICAL ELEMENTS

and they were the first to erect a cast iron bridge, about 1785, over
the Severn. By 1790, 81 of the 106 furnaces in the country were
coke fed. ,

The iron industry had reached its zenith in Sussex round
1650 and employed some 50,000 men; it then began to decline,
but it was not until 1809 that the last Sussex forge was
extinguished. Writing of this Lady Nevill stated, "Ashburn-
ham was closed in 1809, the immediate cause of it being the
failure of the foundrymen, through intoxication, to mix chalk
with the ore, by reason of which it ceased to flow, and the
blasting finally ended."

Meanwhile, however, the iron industry had spread to many
other centres. In 1740 England and Wales together possessed 59
furnaces the total annual yield of metal being 17,350 tons; this
looks small in comparison with the modern output of the order of
15 million tons of steel.

The essential difference between steel and wrought iron is that
the former contains more carbon, which is combined with the iron
to form a carbide known to the metallurgist as cementite.

It was already known to the Romans that certain ores yielded
what we call steel. The iron ores of Noricum were celebrated for
this; but the real "eason was unknown. Both Biringuiccio in 1540
and Agricola (p. 50) in 1561 described the making of steel by
keeping lumps of wrought iron for several hours immersed in
molten cast iron. The process of "cementing" by keeping iron at
red heat in charcoal whereby the carbon is absorbed converting the
metal into steel, was described by Reaumur (p. 226) in 1722, but
it was even then an ancient process. In 1750 Benjamin Huntsman
improved it by melting wrought iron with a definite amount of
charcoal in fire-clay crucibles, thus paving the way for the pre-
eminence of Sheffield in the steel industry. With this "cement"
steel tools, shears, razors, springs, etc, were produced, although
the chemistry of the process long remained ill-understood. Be it
said, however, that long before Benjamin Huntsman saw the
light, Sheffield was already famous for her steel. Peter Bates,
writing in 1590, gave the schoolmaster sound advice regarding
the making of quill pens. "First then be the choice of your
pen-knife. A right Sheffield knife is best." The poll tax records
of King Richard n (1379) show that the making of knives
was an important Sheffield industry even in those days. The

280

THE IRON GROUP

miller in Chaucer's Reve's tale (circa 1388) bore a Sheffield
knife*

Ther was no man, for peril, dorste hym touchc;

A Sheffeld thwitel baar he in his hose.

The idea of obtaining wrought iron from cast iron by oxidation
of the impurities in the latter was put into practice by T. and G.
Granage in 1776, more successfully by Henry Cort in 1784, and
still more successfully by Rogers in 1 8 1 6. The cast iron was heated
in a furnace lined by Cort with siliceous material, by Rogers with
iron oxide; such a furnace came to be known as spuddling furnace ;
the iron oxide yields up its oxygen to the cast iron converting its
:arbon into gaseous carbon monoxide which escapes, other
impurities being oxidised such as silicon to silica and entering the
>lag. The carbon monoxide burns with a blue flame as it meets the
ur, yielding the puddlers* candles, as they are called. The escape of
:he gas causes the appearance of boiling, and the workmen refer
:o this as the boil. The metal is now pasty, for the melting point of
ivrought iron is much higher than that of pig iron ; it is removed
Tom the furnace, squeezed whilst hot to force out the still molten
slag, and rolled to give the product a fibrous structure. This
: ormed a second outlet for the cast iron which had hitherto been
ased mainly for castings.

It would appear that if the oxygen of iron oxide could effect the
purification of cast iron, so might atmospheric oxygen. Accordingly
n 1852 Kelly patented a process for forcing air through molten
Dig iron. In 1856 Henry Bessemer patented a "converter" for this
Durpose and later bought up Kelly's patent. In this converter air
s blown through the molten pig iron, and when the impurities
lave been sufficiently oxidised, an alloy of iron and manganese,
:ontaining also some carbon, is added to carburise the metal and
:onvert it into steel. The manganese helps to remove the sulphur.
The liquid steel is then cast into ingots.

Bessemerf was born in 1813 and showed great promise at an
sarly age. When only about twenty years of age he invented the

*"The Canterbury Tales". The quotation comes from "The Works of Chaucer",
*lobe edition (Macmillan, London, 1910). The word "thwitel" (A.S. thwitan, to
;ut) survives in the modern word "whittle". The citizens of Sheffield, rightly
>roud of this Chaucerian reference, have recently installed in their cathedral a
tained-glass window depicting a scene from "The Canterbury Tales". It was
lesigned and painted by Mr Christopher Webb.

fE. J. LANGE, Memoirs of the Manchester Literary and Philosophical Society,
*9i3 57, No. 17.

281

THE CHEMICAL ELEMENTS

method of dating stamps by perforation; this was designed to
prevent the transfer of Government stamps from old deeds to new
ones, a practice which he had been informed caused the Stamp
Office an annual loss of revenue of some 100,000. Not having
patented his invention, the grateful Government appropriated
it without offering any reward until a twinge of conscience
some 45 years" later led them to make a tardy amend by bestow-
ing upon che now wealthy and celebrated inventor the honour of
knighthood.

In 1854 Bessemer invented a rotating projectile for guns but
the War Office, with characteristic aloofness, refused to have
anything to do with it; Louis Napoleon, later Napoleon n, saw the
value or the invention, being himself an authority on artillery, and
offered to finance the necessary experiments. A chance remark by
Commandant Mini6 the inventor of the rifle of that name
that the new projectile would require a better gun than one of cast
iron led Bessemer to consider the possibility of improving the then
known methods of steel production. This led to his invention of
the process already descnbed, an account of which was presented
to the British Association at their Cheltenham Meeting in 1856
under the title "The Manufacture of Malleable Iron and Steel
without Fuel". Sir Henry lived to the ripe age of 85, passing in
1898 at his residence in Denmark Hill, London.

It so happens that many ores of iron contain phosphorus which,
if left in the steel, would render it brittle and unsuitable for most
purposes. In 1878 Thomas and Gilchrist showed that by lining the
furnace with a basic material such as dolomite (calcium magnesium
carbonate) the phosphorus could be made to enter the lining as
metallic phosphate. Two birds could thus be killed with one stone.
The steel was rendered free from phosphorus and the basic lining
became valuable a^ a fertiliser in virtue of its phosphate content.
In this manner arose the familiar basic Bessemer and open hearth
processes. The latter, developed in England by Sir William
Siemens, has now superseded the basic Bessemer process in most
countries. The industry is an enormous one, world production
of ingots and castings being of the order of 140 million tons
annually.

Uses of iron

According to an ancient Chinese proverb the nation that holds the
iron of the world may rule the world. Needless to say uranium and

THE IRON GROUP

atomic forces had not then been visualised. Kipling put the case in

a nutshell

Gold is for the mistress, silver for the maid,
Copper for the craftsman cunning at his trade.
"Good" said the Baron, sitting in his hall,
"But iron, cold iron, is master of them all."

Iron is so intimately bound up with every phase of modern
civilisation that we cannot hope to do more than mention a few of
its more important uses.

Ships

Probably the earliest recorded suggestion that iron might be made
to float on water occurs in Holy Writ, 2 Kings vi. 6, where we are
told that, whilst a beam was being felled, the iron head of an axe
wielded by one worker flew off into the Jordan ; whereupon Elisha
caused it "to swim" evidently by prodding it in some way with a
piece of wood sufficiently large to bring it to the surface. This was
about 840 B.C. Another reference of interest but much more recent
occurs in the sixteenth century prophecy of Mother Shipton
(p. 125) who said that

Iron in the water shall float
As easy as a wooden boat.

The earliest use of iron in ships, apart from such minor com-
modities as nails, etc, appears to have been for naval purposes.
According to a work published at Stuttgart in 1866, one Samuel
Kieshel visited Stockholm in 1586 and was specially interested in
the warships he saw lying in the sea approach to the city. The
largest was named The Great Dragon and Kieshel describes it as a
strong and stable vessel with several decks. He further adds "I
have been told that the space between both the ship's boards has
been filled with iron so that the shots rebounded and could not
easily go through the vessel or inflict damage to it." If this was
really the case Sweden must be credited with having possessed the
first iron-clads in the world.

In Britain an iron canal boat was launched in 1788, and the
first iron sea-going vessel, the Aaron Mawby, was built in 1821.
Round 1835 th e use of armour plate was proposed; at first the
ships were built of wood and cased with metal ; later the wood was
discarded and the vessels built entirely of steel.

On i yth October 1855 the first iron-clad ships went into action

283

THE CHEMICAL ELEMENTS

in the Black Sea, in the shape of three primitive floating batteries
protected with iron armour, against the Russian fortifications at
Kinburn which were destroyed in a few hours. This sounded the
doom of Britain's wooden walls, for but a few months previously a
cpmbined attack by the British and French fleets of wooden
battleships had been driven off by fire from the forts at Sebastopol
and badly knocked about.

The armed cruiser Triomphante*, built for the French Navy in
1877, illustrates the gradual transition from the wooden battleships
of Nelson's time to the modern all-steel vessels. She was built of
wood with an armour belt nearly six inches thick whilst her
batteries were protected with iron armour nearly 5 inches thick.
She played an important part in the operations in the Min River
during the China War or 1884.

Bridges

There are, however, other ways of crossing water than by boat, and
many millions of tons of iron in its various forms have been used in
the construction of tunnels and of bridges. The first cast iron
bridge in the world appears to have been that over the Severn near
Colebrooke Dale about 1785. To-day steel is more commonly used,
although the year before last (1949) saw the opening of a bridge of
aluminium-alloy (p. 164).

The Forth Bridge, designed by Sir Benjamin Baker and opened
in 1890, is perhaps the most impressive in existence. For centuries
the traveller wishing to cross the Forth at its junction with the sea
had been dependent on ferry-boats, and many a one had been over-
taken by a gale which prevented his ever reaching the other side.
In 1805 it was proposed *o construct a double tunnel, some 15 feet
wide, under the bed of the Forth, one tunnel for the 'comers' and
one for the 'goers' as was quaintly explained; but nothing came of
it.

In 1873 ^e Forth Bridge Company was formed with the object
of building a bridge designed by Sir Thomas Bouch, but the
collapse of the ill-fated Tay Bridge in 1 879 shook public confidence
and the scheme was abandoned. In 1882 an Act of Parliament
authorised the construction of a bridge designed by Mr (later Sir)
Benjamin Baker, based on the principle of the cantilever, full
advantage being taken of the island of Inchgarvie, a peak of
whinstone rock in the middle of the Forth. Some 50,000 tons of

*See The Engineer, 1890, 49, 648.
284

THE IRON GROUP

steel were required and the total cost of the bridge approximated
to ,3,200,000. In order to protect it from corrosion the bridge is
continuously painted by "steeplejack painters" as they are called
from the dangerous nature of their work. These men are always at
work; it takes them some three years to paint the bridge from end
to end, and when the job has been completed it is necessary to
begin over again. It is estimated that the total surface to be painted
amounts to about 135 acres of steel, and during the process trains
pass over every few minutes.

Nails and horseshoes

It is remarkable what a wealth of legend and romance has
collected round iron nails and horseshoes. Reference has already
been made to the legends surrounding the nails used at the Cruci-
fixion of our Lord (p. 263). The earliest type of nail was undoubtedly
the wooden peg, which in later years became known as a "tre-nail",
that is a nail of wood (tree). Such pegs are used to-day alongside
their metal fraternity, and were very frequent in the pegged joints
of medieval half-timber work. The discovery of metals paved the
way for a metal nail industry and legend states that the Argos
which carried Jason and his crew to the Black Sea in search of the
Golden Fleece was built of oak and pine joined with bronze nails.
The greater strength of iron, once man had learned to produce it in
good quality, gave the iron nail the premier position as a means of
fastening woodwork, although nails of copper, brass and bronze
are still frequently used, sometimes because they are more
ornamental in the circumstances and sometimes, too, because they
are less susceptible to corrosion.

The smooth wire nail, so commonly used to-day, readily enters
wood with the minimum danger to splitting, but for the same reason
it may easily come out of the wood again. This led to the invention
of a threaded nail or screw. It seems impossible to discover when
screws were first used; it cannot have been later than the fourth
century for, in the literature of that period an account is given of
the chasing of screws by hand. At first they were known as "screw-
nails". The screw cutting lathe was known to one Jacques Besson
in 1548, but Maudsley was the first to make really accurate screws
in 1800 to 1810-

Until about 1750 all nails were hand-made and the smith who
forged them was called a "nayler", a word that survives in the
modern surname Naylor which, however, is not quite so common

285

THE CHEMICAL ELEMENTS

as Smith. Leland, when he visited Birmingham in 1 538, recorded that
"there be many Smithes in the Towne . . . and a grate many Naylors."

In medieval records nails are mentioned under various interesting
and curious names, the meanings or origins of which are not always
patent. For example "strokhede nayles" are referred to in the
Windsor Castle records of 1534. The entry runs: "i 1 1 c of vstrok
hede nayles tinned for the new Dore in the colege garden wall,
price Vjs", The reference to tinning shows that our tin-tacks are
not mere modern luxuries. The fact that these nails were intended
for doors suggests that they were stud nails, partly constructive
and partly decorative, as was common enough in those days. The
"five stroke" perhaps refers to the labour involved in making the
nail head as these were formed with a "nayle tulle" (nail tool) or
matrix in which the head was shaped by hammering. Perhaps the
number five also indicated the size of the head, for in other MSS.
the prefix vn is sometimes used; if all were of the same size there
would be less point in quoting the stroke number. "Strake nails"
were used for fixing the strakes or iron plates of cartwheels before
the iron band or tyre became common. In the "penny" nail, the
prefix stands for pounder and refers to the weight in pounds per
thousand. The derogatory expression "Not worth a tenpenny
nail" thus meant that the article in question was not even equal in
value to a nail, 1000 of which weighed only 10 Ib.

"Tyngyl nailles" or "chingil nayles" were made to replace the
old wooden "tylepynnes" or oak pegs used for fixing roor shingles
before the introduction of nibbed tiles, the nibs keeping them in
position on the laths. Other kinds of nails were known in medieval
times as spykynges, goletts, haxnailles, sharplinges, flywings or
sparabilis (sparrow bills), and traversnailles. Several of these names
are difficult to unravel, but the reader will without difficulty
recognise the modern forms of brods, takkets and bordnayles.

Animals sometimes take a fancy to nails, and a curious case was
recorded in 1938 of a pigeon which built its nest of six-inch nails.
Workmen engaged on the erection of scaffolding in front of the
Birmingham Art Gallery, were perplexed by the disappearance of
their nails during their lunch hour. No boys or other persons
appeared to be involved, so a watch was set. It was soon found that
tne thief was a pigeon whose mate had ensconced herself on top
of one of the columns supporting the fagade of the Art Gallery.
Waiting until the coast was clear, the bird made innumerable
flights, bringing back each time a new "stick" for the nest.

286

THE IRON GROUP

Its efforts must have involved a considerable tax on its strength,
for the watchers saw the bird labouring for breath after every flight,
*Nor was the avian labourer helped by the tendency of the nails to
roll over the edge of the column head; nearly 2 Ib. of nails were
afterwards picked up, having been lost by the birds in this way.
Eventually, however, the nest was complete, and two eggs were
duly laid therein.

Iron nails have frequently been used in the past both for purposes
of medicine and necromancy. A favourite remedy for toothache
consisted in hammering a nail into a tree and as the iron rusted so
would the toothache disappear. This was much less drastic than
having the tooth extracted. Warts have been a nuisance for
centuries, though it is difficult to understand why such should have
been the case as so many infallible remedies have been prescribed
from time to time. The mere touching of a wart by a wise man will
effect its disappearance provided an iron nail is offered as a reward
for the service; but lack of men sufficiently wise may nowadays
make this cure somewhat difficult to effect. A simpler remedy hails
from the Weald of Kent, namely rub the warts with a piece of raw
steak and then bury the latter. As the meat rots so will the wart
disappear.

The arabs believed that the soul of a murdered man should be
nailed down by driving a nail into the ground where the murder was
committed, otherwise the ghost would rise*.

Once each year, namely in October, the Corporation of London
and the Sheriffs of Middlesex pay a curious rental to the King for
two pieces of land. London's imposing Law Courts are built on
one of these plots, the site of an ancient jousting ground; the other
plot lies somewhere in Shropshire, but nobody appears to know
exactly where.

On the annual rent day the King's Remembrancer goes into the
city to represent the Sovereign. He sits in full wig and gown on the
bench, with the City Clerk and other leading officials of the
Corporation at the table below him. First of all the warrant from the
Sheriff and City Remembrancer demanding the payment of the
rent for the piece of land in the Strand is read out, calling upon
the "tenants and occupiers of a certain tenement called The Forge
in the Parish of St Clement Dane's, in the County of Middlesex,
to come forth and do their service."

*C. J. S. THOMPSON, "The Mysteries and Secrets of Magic" (London, 1927),
p. 90.

287

THE CHEMICAL ELEMENTS

The site had been granted in 1235 by Henry in to a farrier, one
Walter le Brun, for repairing the armour of a Knight Templar
wounded, in a tournament, on condition that he annually paid six
horseshoes and 6 1 nails as rent, and in course of time it passed into
the hands of the city with the same liability.

The Secondary having recited the warrant and stated the facts,
the City Solicitor solemnly hands up to the King's Remembrancer
the six horseshoes and the 6 1 nails, counting them one by one in a
stern voice. This little account being settled, the Secondary next
proceeds to recite the authority for paying his Majesty the sum of
one billhook and one hatchet for the piece of land in Shropshire
which the Corporation has held from the Crown for more than
700 years. But this time the representative of the Sovereign must
be assured that the billhook and hatchet are good sharp implements.

So, before the rent is paid, the City Solicitor places a small
chopping block on the table. A clerk hands him a bundle of sticks.
Then, having chopped some with the billhook and some with the
hatchet, he presents both tools to the King's Remembrancer, who
formally accepts them as payment of the Shropshire rent. A written
acknowledgment follows later. Actually the Crown only gets the
billhook and hatchet each year. The horseshoes and nails are kept
to serve as hardy ceremonial annuals.

Who has not heard of Horse-Shoe Corner in Lancaster City
where John of Gaunt's horse is said to have cast a shoe, about 1380,
on a visit the Duke never actually paid? A horseshoe lies embedded
in the middle of the road to perpetuate the legend; it has to be
replaced every few years, however, for modern traffic wears it
away.

Oakham in Rutland is the tiniest county town in Britain; it
possesses an ancient castle; nailed to a wall in which is a remarkable
collection of horseshoes. Rutland has exacted by traditional right,
accorded to the Ferrers family centuries ago, one horseshoe from
every member of the Royal Family and every peer who has crossed
its border. The collection contains, amongst others, horseshoes
presented by Queen Victoria and by her son, King Edward vn.

Horseshoes are generally regarded as bringers of good luck ; but
the owner should be careful to hang his specimens with the two ends
upwards, otherwise there is a danger that his luck may run out.
The shoe nailed to the mast of the Victory at Trafalgar in 1805
was wrong way up. What wonder that Nelson paid the penalty!
When, as late as April 1930, the Duchess of Bedford set out on her

288

THE IRON GROUP

return flight by aeroplane from South Africa to England, a lady
well-wisher handed her a be-ribboned horseshoe for luck; the
plane, called The Spider, was thus enabled to make a perfect ascent
From the Maitland Aerodrome, Cape Town, and the crowd raised
a hearty cheer as the Duchess waved her farewell to them.

In northern Scotland it was believed that if a horseshoe were
nailed over the stable door, no witch or warlock would dare to
enter and steal a horse no matter how badly the animal wis required
to take them to their conventions.

During their excavations at Wookey Hole, Balch (p. 271) and
his collaborators found the shoe of an ox which had apparently
been used by the cave-dwellers for burden or draught. It is "of
interest to note that the early workman made the holes for the iiails
in exactly the same form as the farrier of to-day uses for his horse-
shoes"*. Evidently the long lapse of time has failed to improve
upon the positions of the nails.

Alloys of iron

This chapter could hardly be regarded a3 complete without some
reference, however brief, to the numerous alloys of iron and steel
that play such an important part in modern civilisation. One of
the best known and most popular of these is stainless steel^ an alloy
containing some 13 per cent of chromium. This beautiful metal
has saved the housewife much arduous toil, because it does not rust
when exposed to air and water, even in the presence of organic
acids like vinegar or the juice of oranges and lemons. Many of us
can well remember the unsavoury appearance of the table knife
after a meal including lamb and mint-sauce; but that fortunately is
a thing of the past. One day a steel manufacturer, a friend of the
author, had a lump of his own stainless steel worked up into table
knives and proudly exhibited them one evening at dinner, inviting
his guests to try them. Beef and pickles were on the menu and, to
the manufacturer's disgust, his stainless steel rusted. Confident
that his steel was all right he had the pickles analysed; they con-
tained sulphuric acid! Stainless steel is not immune to attack from
mineral acids ; sea water will also effect its corrosion ; such corrosion,
however, is invariably localised resulting in deep pitting. The
actual loss in weight may be small, but if a tube or a tank, for
example, is pitted through, that is, perforated, it may be much

*BALCH, Opus cit., p. 87.

289

THE CHEMICAL ELEMENTS

more seriously damaged than if it had lost ten times as much metal
through corrosion distributed equally over its entire surface.

Another interesting alloy, known as invar (p. 297) contains some
35 per cent of nickel and is particularly valuable for certain
purposes such as clock pendulums, because of its negligible
expansion with rise of temperature. An alloy containing 40 per
cent of nickel expands by a similar amount as glass and may there-
fore be sealed into glass instead of the more expensive platinum
which at one time had to be used ; for this reason the alloy is known
*& platinite (p. 297).

Steels containing both chromium and tungsten are known as high
speed tool steels and retain their temper at high temperatures at
red^heat, indeed, when ordinary carbon steels would soften and be
useless. Alloys containing small amounts of chromium and vana-
dium are very hard and strong; they find application in springs,
locomotive wheels, axle-shafts and the like. Manganese steels are
also very hard and are used at tramway points and elsewhere
where great resistance to wear and tear is essential. Various high
tensile steels are now used in large quantities in the construction of
fast-going steamers and ocean liners. The hull of the magnificent
French liner Normandie, for example, was stated to include some
5000 tons of high tensile steel. Unfortunately she was a war loss,
being burnt out In New York harbour.

Important alloys of iron with other metals are also discussed in
connection with those metals.

Iron for adornment

Iron beads were possibly used by pre-dynastic Egyptians some
4000 B.C. although the evidence is not unassailable (p. 260).
Remains of iron finger rings have been found in Palestine dating
back some 1000 B.C.

Pliny*, in a lengthy discourse on rings, states that at the time of
the Second Punic War (218 to 201 B.C.) rings were in very general
use. These were mostly of gold, but Pliny is careful to add that
"not even in those days did all the senators possess gold rings,
seeing that, in the memory of our grandsires, many personages who
had even filled the praetorship wore rings of iron to the end of their
lives." In Pliny's own day iron was a much more common com-
modity, and when slaves wore rings of iron they were allowed to

"PLINY, "Natural History". Translated by Bostock and Riley (Bohn, 1857),
Book 33, Chapter 6.

290

THE IRON GROUP

encase them with gold. Apparently, however, slaves were not
allowed to wear pure gold rings, the use of which was confined to
the free.

The wedding rings of the Romans were generally of iron;
probably this originated in another Roman custom, namely, the
bestowal of a ring as an earnest upon the conclusion of a bargain*.
In Rome it was at one time customary to give a ne-vly made bride
a ring of pure gold and to send at the same time an iron ring to her
parents as a remembrance of modesty and domestic frugality.

It is not impossible that the modern use of iron or steel finger
rings to "cure* rheumatism is a relic of those times when iron was
supposed to ward off attacks of the evil one.

In modern times steel has been used even in this country for
jewellery for the production of which both Birmingham and Wolver-
hampton were at onetime famous (Plate 3,opp. p. 274). Missen referred
to the good quality of the Birmingham ware in 1690, and in the
succeeding century Boulton and Watt were engaged in its manufac-
ture. Thackeray tells us that when King George iv (1820 to 1830)
made his first appearance at a Court Ball "his hat was ornamented
with two rows of steel beads, five thousand in number, with a button
and loop of the same metal, and cocked in a new military style."

With the introduction of numerous alloys resembling gold, steel
jewellery gradually became less popular. But primitive races still
love to adorn themselves with iron rings and bangles. Kaffir
bangles, for example, are made of malleable iron in the shape of
a horseshoe, so that African chiefs, no matter how fat they may be,
can get them on their arms and legs. When they have got them on
the ends are forced together; they are nickel-plated, so that they
scintillate in the African sun.

Cobalt

Certain natural arsenides of cobalt were known, many centuries
ago, to be associated with silver ores in Saxony, although their
chemical composition was not understood. They were probably
what are to-day called smaltite, CoAs2, and f04////i, CoAsS, but were
then recognised under the general name kobold, from the Greek
kobalos, a subterranean gnome or malicious sprite, the word being
akin to our "goblin". The miners were a superstitious folk (p. 18)
and, as the mineral was believed to be poisonous, its presence in
the mines was attributed to the malice of the little devils inhabiting

*WILLIAM JONES, "Finger Ring Lore" (London, 1877), p. 303.

291

THE CHEMICAL ELEMENTS

the underworld, from whose pestilential machinations it was
customary to pray for deliverance on the Sabbath in the churches.
Goethe mentioned these kobolds or sprites in " Faust",

Up to 1540 the mineral was regarded as useless, but Scheurer
then found that it would impart a beautiful blue colour to glass
'a discovery that gave it a commercial value; he sold his secret to
England, and 'from that time on till the present cobalt compounds
have been used in the European glass industry. One great advantage
lies in the fact that the colour is but little affected by the composition
of the glass, O' i per cent of the metal being ample to produce an
intense blue colour, whilst a pale blue tint results even with o-oi
of cobalt.

Cobalt compounds had been used in very early times for colour-
ing glass, though of course nothing was then known of their real
composition. Thus, cobalt blue glass or "fine lapis of Babylon"
figured in the tribute sent by the ancient city of Assur in Assyria,
some 1480 B.C. to Thothmes i, the Egyptian king, after his conquest
of Syria and Palestine. Metallic cobalt was present (0*54 per cent)
in the nickel-bronze coin of the Bactrian king Euthydemos, 235
B.C., but its inclusion was undoubtedly a matter of accident and not
one of design.

In 1735 the c balt ore used by the glass maker was examined by
Georg Brandt, P. Swede, born at Riddarhytta in Vestmanland in
1694, and not to be confused with Hennig Brand, the Hamburg
merchant, who obtained phosphorus from urine in 1669 (p. 76).
Brandt isolated a new metal from the mineral in impure form in
1742 and called it cobalt. That it was really a new metal was
confirmed by Bergman in 1790 and by Tassaert in 1799. The real
study of the chemistry of cobalt compounds began with the re-
searches of Thenard in 1 802 and of Proust in 1 806.

A few years ago almost the only commercial uses of cobalt lay
in its compounds; but two important fields have suggested them-
selves, namely, electroplating and coinage on account of its hardness
and resistance to oxidation. Several alloys of cobalt are now marketed
such as stellite (p. 245), used for stainless cutlery, surgical instru-
ments, and some parts of motor cars. It is an alloy of cobalt,
chromium, and a little tungsten. Cochrome y analogous to nichrome,
contains cobalt and chromium, and is used for the windings of
electric fires and furnaces; it is extremely resistant to atmospheric
corrosion, even at elevated temperatures. A 35 per cent cobalt steel
is used in loud-speaker magnets and for short bar magnets, a high

292

THE IRON GROUP

magnetism being possible with this alloy. An alloy containing
75 F C > 35 Co, 2 Cr, 5 W and 0-90 was until comparatively
recently the most highly magnetic material known. It has now been
superseded by Ni-Fe-Al alloys, some of which also contain cobalt.
Cobalt is the best binder for tungsten carbides and similar
excessively hard materials welded on to steel for cutting purposes.

Nickel

The early history of nickel is closely interwoven with the "Doctrine
of Signatures' 1 to which reference was made when dealing with the
search for gold in gold-coloured urine, which search led to the
discovery of phosphorus in 1669 (p. 76). According to this doctrine
Nature has implanted her signature upon all things, great and small,
animate and inanimate. This enables the observant; and initiated to
ascertain to what good ends Nature's gifts may be properly used.
Thus, a plant with leaves curiously spotted reminds one of the
lungs ; this is Nature's way of indicating, to those endowed with
eyes to see, that an infusion of this plant would prove a remedy for
lung trouble whence its name lung wort or, as the botanist has
it, pulmonaria. Colas, writing in 1657, says, of the "Heart trefoil",
that it is so called "not only because the leaf is triangular like the
heart of a man, but also because each leafe doth contain the perfect
icon (image) of an heart, and that in its proper colour. It defendeth
the heart against the noisome vapour of the spleen."

In a similar manner minerals were held to indicate by their
shapes, colours, or some other outstanding physical properties, the
specific uses to which they are specially adapted. Thus yellow
arsenic sulphide, like urine, was supposed by virtue of its colour,
to contain gold whence its name orpiment or auri pigmentum, the
pigment of gold (p. 81).

Few minerals resemble copper in appearance; one of the best
known and most important or these was known to German miners
and was used to colour glass green. Although repeatedly worked for
copper, that metal could never be extracted from it; the doctrine
of signatures had broken down. Not that Nature herself was at
fault; it was the Devil who had deliberately tinted the mineral in
order to mislead the poor miner. So the mineral was called Kupfer-
nickel, that is false copper, -pseudo copper, or, more literally, Old
Nick's copper.

' The term Old Nick is sometimes regarded as a perverted form
of St Nicholas, the patron saint of children, thieves, and fishermen.

293

THE CHEMICAL ELEMENTS

The reference to fishermen might be due to its connection with the
Anglo-Saxon Nicor y a water sprite. Anyhow, Old Nick was a
disreputable fellow, and Saxe referred to his bad behaviour when
he wrote

Don't swear by the Styx

It's one of Old Nick's

Most abominable tricks

To get men into a terrible fix.

In 1751 Axel Frederick Cronstedt, the Swedish mineralogist,
who introduced the blowpipe into analysis, turned his attention to
kupfer nickel or niccolite, as we generally term it to-day. Cronstedt
was regarded by his illustrious compatriot, Berzelius, as "the
founder of the chemical system of mineralogy". He observed that,
although the mineral dissolved in acid yielding a green solution,
no copper was deposited on metallic iron placed within it. This
surprised him for he was familiar with the old alchemical trick of
converting iron into copper with the aid of copper sulphate solution.
He therefore calcined a portion of the green deposit on the surface
of some weathered niccolite, reduced the resulting oxide with
charcoal and obtained a whitish metal, that certainly was not copper.
For this new element he suggested the very appropriate name of
nickel.

At first chemists were disinclined to accept the view that nickel
was a new element. Cronstedt's specimen was impure and many
believed that it was merely a more or less unholy mixture of cobalt,
arsenic, iron, and possibly copper. But in 1775 Torbern Bergman,
Cronstedt's famous Swedish contemporary, confirmed the existence
of nickel, of which he prepared a fairly pure sample, and showed
that no alloy of copper, iron, cobalt, and arsenic would behave like
it.

"Natural" alloys of nickel have long been used by man, being
reduced by reduction of naturally occurring mixed ores, the
introduction of the nickel being at first purely accidental. Thus
ancient bronze implements from pre-iron age civilisation have been
found to contain from 2 to 4 per cent of nickel. Reference has
already been made to the coin of the Bactrian king*, Euthydemos
u, dating back to 235 B.C., analysis of which showed copper 77*6,
nickel 20-0, with cobalt 0-54, and iron i-o. It has been conjectured
that the alloy was originally obtained in ingot form from China

*CHARLBTON, /. Roy. Soc. Arts, 1894, 42, 496.
294

THE IRON GROUP

possibly carried by camel trade to the Mediterranean, for it is
known that nickel-copper alloys were made from nickeliferous
copper ores in very early times in Yunan and Szechuan. These
alloys were known as Pei-tung, that is, white copper, or Pack-long,
incorrectly rendered as Pack-fong. They contained copper, nickel
and zinc and were used for gongs and other musical instruments.
As soon as refined nickel became commercially available the
Chinese alloys were made in England and Germany, the latter
country making one in particular, called Argentan^ which became a
popular substitute for silver whence the general term "German
silver" (see table, p. 297).

Nickel coins*

In 1850 the Swiss Federal Government decided to use German
silver as the basis of their coinage, on the ground that it was hard
and durable, and was thus resistant to abrasion and difficult to
counterfeit. The first attempts were not very successful as it was
desired to make the coins worth their face value, and accordingly
some 5 to 1 5 per cent of silver was added, according to the value of
the coin. They were intensely hard, the coining dies broke, and the
impression obtained on the coin itself was shallow. Similar diffi-
culties were encountered with our own coinage after World War I
(1914 to 1918), as already explained (p. 1 18) and we ought not to
have fallen into the same error. After experimenting with several
alloys, the Swiss, in 1881, decided to use pure nickel the first
time in history that the pure metal had been used for coins. It
could not have been used much earlier because it was only in 1879
that Fleitmann showed the brittleness of commercial nickel could
be removed by addition of a small amount of magnesium; it thus
became possible now to roll the metal. This, Fleitmann did; he also
rolled sheets of nickel both upon iron and steel much as silver was
rolled on copper in the manufacture of Sheffield Plate. He thus
became the pioneer in the development of nickel-clad steel.

In 1855 the Belgians decided to reform their low currency coins
and, after experimenting with a number of alloys, were the first to
employ one containing copper 75 and nickel 25. In 1857 the U.S.A.
replaced their cumbrous copper cent pieces by an alloy of copper 8 8
and nickel 22, the latter metal then costing $2 per pound and was
admittedly added to raise the intrinsic value of the coins. Later, in

*See Report of the Royal Ontario Nickel Commission, Toronto, 1917.

295

THE CHEMICAL ELEMENTS

1865, ^ e U.S.A. adopted the Belgian alloy, and Germany followed
suit in 1873. We in Britainare now replacing our silver coins with
a copper-nickel alloy (p. 106).

It is estimated that up to the end of 1912 some 900 million pure
nickel coins had been issued in the old and new worlds, together
with some 4500 million coins of nickel bronze*. It is easy to dis-
tinguish between the two, since nickel coins are readily attracted
by a magnet, whereas the alloys are not.

Miscellaneous alloys

As nickel and copper mix in all proportions yielding uniform solid
solutions, the nickel increasing both the hardness and electrical
resistance of the alloys, mixtures of many different compositions
are marketed bearing special names.

Cupronickels contain from 1 5 to 20 per cent of nickel, the remainder
being copper. They can be cold- worked; for example they can be
cold-rolled from I inch down to 0-05 inch without annealing being
necessary. They have been extensively used for bullet jackets. The
25 Ni, 75 Cu alloy used in coinage has already been mentioned. A
30 Ni, 70 Cu alloy is uded for condenser tubes. Another useful
alloy, sometimes known as constantan^ has 40 Ni and 60 Cu.
Owing to its high electrical resistance and low resistance tempera-
ture coefficient it is used for standard electrical resistances.

In 1905 Ambrose Monell, President of the International
Nickel Company, suggested smelting mixed copper and nickel ores
together to produce a natural alloy containing small quantities of a
few other elements as well. The registered trade name of this alloy
is monel metal and it contains from 60 to 72 per cent Ni, the
remainder being copper with iron up to 6*5 per cent and small
quantities of Mn, Si and Al. The U.S. Government Specification,
issued in July 1910 for the rolled metal, was 60 Ni, 36 Cu, 3-5 Fe
and 0-5 Al, but no lead. The alloy looks like nickel, is non-magnetic
and resistant to corrosion; it retains its high tensile strength at
elevated temperatures. It is used for locomotive fireboxes, propellers,
turbine blades, laundry fittings, kitchen ware, etc. One recent use
is for aircraft fittings where steel, being magnetic, might influence
the instruments.

Numerous other nickel alloys are now marketed, including
many grades of nickel-silver^ which are essentially ternary alloys of
copper, nickel, and zinc.

* Bulletin Imperial Institute, 1916, 14, 228.
296

THE IRON GROUP

The manufacture of nickel silver in Europe was begun in Berlin
in 1824 and the fancy names given are legion. Different grades are
recognised in the trade, the first three in the accompanving table
are three of many recognised in the trade in Birmingham and
Sheffield. Nickel-silver to which a little tungsten has been added is
known as platinoid. Argozoil contains, in addition to the three usual
elements about 2 per cent each of lead and tin, whilst manganin has
up to 12 per cent of manganese. Nichrome has many interesting
features; it has a high electrical resistance and is used for electrical
heating appliances; it is also very resistant to acid attack and is thus
suitable, amongst other uses, for pickling baskets.

Ni Cu Zn Miscellaneous

White Metal

24

54

22

Arguzoid

20-5

48-5

31

Electrum

26

5''5

22-5

Argentan

20

55

2 5

Hgnda Metal

3 J *5

Fe6 3 -

5> c 5

Nichrome

60

Fei5,

Cr 14

Platinoid

H

60

24

W I to 2

Alloys of nickel and iron are also of great economic importance.
Ordinary nickel steel, containing some 3 to 5 per cent of nickel, is
hard and tough, and is suitable for naval armour, burglar-proof
safes, and for parts of machinery that are subject to special wear and
tear. A 3-5 nickel steel was used in Segrave's Golden Arrow.

Steels with 7 to 35 per cent Ni, often with a little Cr are heat and
corrosion resistant; they are used in chemical apparatus, domestic
and marine fittings, turbine blades and in the food industry. A 1 3
per cent nickel steel is extremely hard and can hardly be cut or
drilled. With 24 per cent of Ni magnetic power is lost and with 24
to 32 of Ni the alloy offers a high resistance to the passage of an
electric current, for which reason it finds application in heating
coils. With 36 of Ni the alloy, known as invar ', has an extremely
low coefficient of expansion with rise of temperature. Platinite, with
46 of nickel expands comparably with glass and may thus replace
the more expensive platinum for sealing into glass ware. Permalloy
is used in cables, yielding a more rapid service in virtue of its high
permeability.

297

THE CHEMICAL ELEMENTS

Towards the close of the 8o's of last century, Samuel J, Ritchie,
who was interested in the Sudbury nickel ores, wrote to Krupps
suggesting the use of an alloy of nickel and iron for ordnance.
Krupps without hesitation rejected the idea as absurd. Meanwhile,
however, the French had developed chrome steel projectiles that
Were making havoc with the naval armour plate, and the problem
arose as to how this was to be countered.

In 1889 James Riley* of Glasgow drew attention to the various
special properties of nickel steels. This interested, amongst others,
the American Naval Authorities, who, in 1891, purchased plain
steel plates from British and French manufacturers and nickel
steel plates from Le Creusot works of Schneider in France. On
testing these, the last named proved much more resistant to
projectile attack than the others. The results attracted world wide
attention and the introduction of alloy steels for naval armour plate
dates from this time.

Honda metal^ a ternary alloy prepared by Professor Honda of
Japan, has a lower thermal coefficient of expansion even than
silica. Its composition is given in the table on p. 297.

Nickel added in small amount to cast iron increases its strength
and resistance to corrosion ; it also enhances the ease of casting and
machining. Such alloys are used in Diesel engines, valves, pumps,
etc.

Nickel plating

Already in 1839 Jordan was depositing copper electrolytically from
sulphate solutions and establishing the art of electrotyping. In 1842
Boetger had pointed out that dense, lustrous deposits of nickel
could be obtained electrolytically in similar manner from solutions
of nickel salts but it was not until about 1870 that the art of nickel
plating was developed for, prior to that date, there was a difficulty
in obtaining suitable nickel anodes at reasonable cost. Once that
difficulty had been solved the nickel plating industry rapidly
progressed and many hundreds of tons or nickel are used annually
in this country for this purpose alone. It yields a hard coat, takes a
good polish and does not readily tarnish; it looks well and is ornate.
One can always detect nickel plate by moistening with a drop of
acid, absorbing the drop on filter paper, adding ammonium
hydroxide, then acetic acid and dimethyl glyoxime. The character-
istic red colour of the nickel derivative is developed.

*RILEY, /. Iron Steel Inst. t 1889, 1, 45.
298

THE IRON GROU P

Nickel is used in the manufacture of cooking utensils and table
"crockery" or "silver"; for this it is particularly useful, as it is
remarkably resistant to corrosion and will withstand rough usage,
such as that encountered in hotels, cafs, and restaurants. In a finely
divided condition nickel is used as a catalyst for many reactions;
for example, the "hardening" of oils is an important industry,
unsaturated liquid oils being "hardened" or rendeied solid by the
absorption of hydrogen with the aid of a nickel catalyst.

Occurrence

Nickel is much more plentiful in the Earth's crust than lead and tin
as indicated in the table on p. 7. The world production of nickel
is normally of the order of 100,000 tons annually.

For a time the world was combed for supplies of nickel ores and
ores containing as little as i per cent nickel were profitably worked.
For many years the pyrrhotite-chalcopyrite deposits of Norway
were the main source of nickel, the industry reaching its height
during 1870 to 1877.

In 1774 Captain Cook discovered New Caledonia, an island in the
S. Pacific Ocean and once used as a French convict station. In 1865
Gamier found a nickel ore there near the capital Noumeia. It is a
silicate, (Ni, Mg)SiO 3 .Aq. and exists in two varieties; one is light
green and is known as garnierite, the other is dark green and called
noumeite. In 1874 it was proved present in large quantity and by
1875 some 300 tons had been exported; the export rate increased
until New Caledonia's output exceeded that of Norway, and the
island became the chief producer of nickel ; it maintained its lead
until 1905.

An area of fewer than 1000 sq, miles in the Sudbury District of
Ontario now entered the scene. Already in 1856 a Government
Surveyor had reported the presence of ores there, but it was not
until 1883, when the Canadian Pacific Railway was being extended
westward from Sudbury, that the discovery assumed industrial
importance. The first attraction was copper ; later the nickel content
was noted and a nickel industry developed, which by 1905
succeeded in swamping that of New Caledonia. It is likely to
maintain its foremost position long into the future as the area
contains many millions of tons of ore.

299

CHAPTER 22

THE PLATINUM METALS

THIS group comprises platinum, ruthenium, rhodium, palladium,
osmium arid iridium.

Platinum

Platinum was the first of the so-called platinum metals to be dis-
covered, and its history reads like a Jules Verne novel. Platinum
occurs in nature, sometimes in a fairly pure state, but more usually
alloyed with its congeners in the eighth vertical group of the
Periodic Table. Generally, it appears as grains or scales, but
occasionally irregular lumps or nuggets have been found, ranging
in weight from anything up to some 20 Ib. The largest nugget ever
found weighed 21 Ib. Troy, or 7837 grams, and was deposited in
the Demidoff Museum a f Leningrad. Platinum does not appear to
have been used or prized by primitive man to any extent, certainly
not like gold; possibly because its appearance is far less attractive.
In 1901 Berthelot stated, however, that a Theban (Egypt) casket of
about 700 B.C., covered with inscriptions, had a portion of one of
its characters made of an alloy of platinum. It was too small for
a complete analysis, but from its behaviour towards aqua regia it
was thought to be native metal, possibly from the alluvial deposits
of Nubia or the upper regions of the Nile Valley.

It is said that in 1557 Scaliger referred to a metal, found in
Mexico and Colombia, that could not be melted in existing Spanish
furnaces. This is usually regarded as a reference to platinum, which
is found in these regions. In 1741, Charles Wood, a metallurgist,
sent his relative, Dr Brownrigg, a specimen of a new metal which
he had found in Cartagena, Colombia. Nine years later this was
handed over to the Royal Society. "I take the freedom to inclose to
you," wrote Dr Brownrigg, on 5th December 1750, "an account
of a semi-metal called Platina di Pinto; which, so far as I know, hath
not been taken notice of by any writer on minerals/'

The story now returns to South America. In 1735, ^on Antonio
de Ulloa was one of two officers selected by the French and Spanish
Governments to take charge of a scientific expedition to Peru.
Whilst out there, Ulloa came across native platinum and included

300

THE PLATINUM METALS

an account of it in his log. On his return to Europe in 1 744 on a
French ship, the latter was captured by the British. Ulloa was treated
with the greatest courtesy by the British naval officers and given a
safe passage, with his records, to England. We were hot at war
with Spain at the time. The Admiralty returned his papers and his
log was published in 1748. The Spaniards called platinum platina
del Pinto, that is, "little silver of the R. Pinto". At the time the
metal had no commercial value and was frequently used by the
Spaniards to adulterate South American gold. So the Spanish
Government closed the mines and ordered the metal to be thrown
into the sea. The British frequently referred to it as "frog gold",
and as late as 1874 its market value was a mere 253. per oz. Troy.
Platinum was found in the Urals in 1819 and five years later (i 824)
Russia began to export the metal. For very many years that was the
main source of the commercial product. At the present time,
platinum is being obtained in ever-increasing quantity during the
refining of nickel by the International Nickel Co. of Canada. Prior
to 1929 the nickel produced by this company contained traces of
platinum metals originally present in the ores used, but in that year
electrolytic refining of nickel was introduced whereby the platinum
metals were obtained in a rich anode sludge. Owing to the large
tonnage of the nickeliferous ores worked over six million tons
in 1937 the actual amounts of the recovered platinum metals
are appreciable. There is one part of the metal in two million parts
of ore, which is approximately the same as of radium in pitchblende.

Platinum was difficult to work; but William Hyde Wollaston,
who began as a medical practitioner at Bury St Edmunds, famous
for his researches in metallurgy, mineralogy and optics, found that
the metal becomes malleable when the spongy form is strongly
compressed. It then may be annealed and hammered. His discovery
brought him a fortune of some 30,000, so he was able to "retire"
in 1800 at the age of 34 and devote himself to scientific pursuits.
We shall meet him again presently. Incidentally, it may be men-
tioned that Wollaston drew gossamer threads of platinum by
enclosing in silver, extending, and removing the silver with acid.
These threads he made red hot with an electric current from a
voltaic cell constructed in a tailor's thimble! We may thus regard
Wollaston as the inventor of the first electric glow lamp,

Thomas Cock manufactured platinum by Wollaston's process,
and^ Wollaston was associated with him for some time. In 1805,
platinum crucibles could be bought for 173. 6d. per oz., and wire

301

THE CHEMICAL ELEMENTS

at 1 6s. per oz. Cock was a relative of Percival Norton Johnson, who
began a metallurgical business in Hatton Garden in 1817. A few
years later he was joined by George Matthey, and thus was founded
the world-famous firm of Johnson, Matthey & Co. Ltd. which is
"still going strong".

Brownrigg referred to platinum as a semi-metal, and the interest
of chemists w?s rapidly engaged. One has only to refer to early
issues of certain well-known scientific journals to realise what an
immense amount of research was carried out by famous
chemists at the close of the eighteenth and beginning of the
nineteenth century. Such names as Berzelius, Berthollet, Bonsdorff,
Descotils, Pelletier, Tennant, Klaus, Osann, Vauquelin, and others,
constantly recur. It was not long before it was realised that native
platinum was far from the pure metal and contained elements,
alloyed with it in varying proportions, that were entirely new to
science. In those days there was no rule to guide chemists as to the
greatest possible number of elements such as we possess to-day in
the Atomic number the product of the brilliant work of Moseley
in 1913. There thus appeared to lie before each and every invest-
igator the possibility mac he might discover a new element. Alas
that such a possibility should be so remote to-day 1

Palladium and rhodium

In 1803 Wollaston* dissolved crude platinum in aqua regia, and,
after evaporating off the excess acid, obtained a yellow precipitate
by the dropwise addition of mercuric cyanide solution. It was a
lucky experiment, for only one of the platinum metals is precipitable
in this way. On ignition of the precipitated cyanide a white metal
remained which Wollaston called palladium in honour of the minor
planet Pallas, discovered the previous year by Olbers.

Wollaston's discovery succeeded in raising the usual crop of
sceptics, as witness such titles as "Reward of Twenty Pounds for
the Artificial Production of Palladium" and "Enquiry concerning
the Nature of a Metallic Substance lately sold in London as a New
Metal, under the Title of Palladium", which appeared in
Nicholson's famous Journal in 1804.

Following up his discovery of palladium, Wollaston dissolved
some native platinum in aqua regia, removed platinum as ammon-
ium hexachlorplatinate and palladium as cyanide. Evaporation of
the filtrate with acid effected the decomposition of excess of the

WOLLASTON, Phil. Trans., 1804, p. 419; 1805, p. 316.
902

THE PLATINUM METALS

mercury cyanide and a dark red double chloride of sodium and a
new metal remained. To this new metal Wollaston gave the name
rhodium from the Greek rhodon rose, because of the beautiful rose
colour of aqueous solutions of its salts. The double salt, probably
Na 3 RhCl 6 i8H 2 O, was reduced in hydrogen, the sodium chloride
leached away, and rhodium obtained as a powder.

Iridium and osmium

But Wollaston was not the only chemist who was tackling the
mysteries of native platinum. In the same year (i 803) the Wensley-
dale Yorkshireman, Smithson Tennant*, a pupil of Black at
Edinburgh, also dissolved the metal in dilute aqua regia. Despite
his happy-go-lucky temperament he did happen to ponder over
the insoluble black residue which had hitherto been regarded as
merely graphite, and which we now know to have been osmiridium.
He found that by alternate action of acid and alkali it was possible
to effect its separation into two distinct metals. One of these he
named indium, from the Greek iris rainbow, because it yielded
salts of various colours green, red, violet. The other, on heating,
yielded a volatile oxide which he at first called ptene, from the
Greek ptenos, winged; but he was persuaded against that very
awkward term and called it osmium, from the Greek osme a smell,
in recognition of the unpleasant odour of the volatile tetroxide,
OsO 4 , produced when the metal is heated in air. The vapour is very
penetrating, intensely poisonous, producing temporary blindness
and other unpleasant symptoms. Osmium thus reminds us of the
halogen (p. 49) which Baiard first called muride but accepted its
alteration to bromine from the Greek brbmos a stench.

Poor Tennant came to an untimely end shortly after his election
to the Chair of Chemistry in Cambridge. Ever fond of horseflesh,
he was riding over a drawbridge at Boulogne, when the bridge
moved and he fell into the ditch, with his horse on top of him.
When extricated he was fast dying.

In 1922 the extraction of gold by the amalgamation process was
discarded on the Rand in favour of the cyanide process and a
preliminary concentration on blankets and corduroy introduced.
This recovers the osmiridium together with coarse gold particles
that are not readily dissolved in the subsequent cyaniding. This is
comparable with tne sheep-skin method of the ancients used in the
recovery of gold from river gravels, which is generally believed to

*TBNNANT, Phil. Trans., 1804, p. 411.

THE CHEMICAL ELEMENTS

have given rise to the legend of the golden fleece. The Rand gold
mines are now the main source of osmiridium ; only small quantities
are present, amounting to about I oz. in 1200 tons or roughly i
part in 30 million,

Ruthenium

Ruthenium was the last of the platinum metals to be discovered and
for it we are indebted to the Russian chemist Karl Karlovich Klaus*,
It owes its name to Osann who, in 1828, thought he had obtained
three new metals from crude metal from the Urals; he christened
them pluranium, polinium, and ruthenium^ the last named being
derived from Ruthenia, a name of Russia. The first two supposed
elements, however, were not new elements but the existence of one
new element in Osann's "ruthenium" was confirmed by Klaus, who
retained for it the name ruthenium. In 1842 Klaus obtained 20 Ib.
of platinum residues from the laboratory of the Russian Govern-
ment Mint in what was then known as St Petersburg. He
separated osmiridium by its insolubility in aqua regia, fused with
potassium hydroxide and nitrate, and extracted the melt with
water, thereby obtaining an orange-coloured solution of potassium
osmate, K 2 OsO 4 , and ruthenate, K 2 RuO 4 . Addition of nitric acid
effected the precipitation of osmium di-oxide and ruthenium oxide
from which the , osmium was separated by distillation with aqua
regia ; addition of ammonium chloi ide to the residue yielded what
was supposed to be ammonium hexachlorruthenate, (NH 4 )RuCl 6 ,
but was most probably the nitrosyl derivative, K 2 RuCl 5 .NO, from
which the new metal was obtained by ignition.

Uses of the platinum metals

Although ruthenium appears to have no industrial applications all
the other platinum metals are used to a considerable extent.

A good deal of platinum is used in jewellery, often alloyed with
iridium to increase its hardness. It is valued as a setting for diamonds
the brilliance of which is developed by the white colour of the metal.

Platinum is largely used in the chemical industry as a catalyst
in various processes. Every chemist thinks immediately of the
"contact" process of the sulphuric acid industry and the classic
researches of Knietsch in 1901. A healthy stimulus to the investiga-
tion of platinum catalysts was afforded by the placing on the market

*KLAUS, Annalen, 1845, 56, 257; 1846, 59, 234. Pogg. Annalen, 1845, 64, 192;
65, 200. OSANN, ibid., 1828, 14, 329; 1845, 64, 197.

304

THE PLATINUM METALS

of a vanadium catalyst; but the palm still goes to the former as they
give an efficient conversion of SO 2 to SO 8 over a wide range of
SO 2 -concentration in the initial gases. Platinised asbestos is a
favourite, but platinised silica gel was introduced into factory use
in 1926, and possesses an undoubted advantage in being immune
to arsenical poisoning.

Platinum is unusually ductile; it can be drawn into wire of
diameter 0*00005 inch; one ounce of metal could thus be drawn
out for several hundred miles. Its coefficient of linear expansion
from o to 1 00 C is 0-0000089, which is closely similar to that for
ordinary glass; for this reason platinum wire is used in the con-
struction of electrical and other apparatus in which it is necessary
to pass wire through glass and leave a perfectly air-tight and
hermetically sealed joint.

World production of platinum in 1938 was 460,000 oz. Troy
and two years later it is believed to have exceeded 600,000 oz.

Rhodio-platinum, an alloy containing 10 of rhodium, is widely,
used, in the form of gauze, in the catalytic oxidation of ammonia to
nitric acid a process that has largely supplanted natural nitrates
as a source of nitric acid. Its conversion ratio is higher than with
platinum alone. Thermocouples of platinum and rhodio-platinum,
that can be immersed direct in molten steel in open hearth furnaces,
have recently been designed; the junction is encased in a silica
sheath, covered by a steel tube; the latter melts, but the silica
sheath lasts for several immersions. Rhodio-platinum, as also alloys
of platinum and gold (30 : 70) and platinum, gold and palladium
(20 : 70 : 10) are used in making spinnerets for the production of
rayon.

As rhodium is very resistant to tarnish and remains white even
in concentrated solutions of alkali sulphides, it is now in demand
for electroplating. Although a very costly metal, exceedingly thin
coats suffice so that the process is not too expensive. It is claimed
that a coat, o-oooi in. in thickness, on silver can withstand boiling
aqua regia for 30 minutes without appreciable damage. A new
secret process for rendering silver untarnishable, known as rhodan-
ising, can be applied to old and new silver alike (1936).

Rhodium-plated reflectors, on account of their resistance to heat
and oxidation, are particularly suited for searchlight and cinema
projectors. Rhodium black has been used for producing a black
colour in the decoration of pottery.

On account of its hardness ana extreme incorrodibility iridium

305

THE CHEMICAL ELEMENTS

is used for pivots, surgical tools, etc. Alloyed with platinum it is
used in electrical contacts used under severe conditions as, for
example, in aircraft ; in constructing chemical apparatus, a classical
instance Being the U-tube and electrodes used by Moissan in 1886
for the isolation of fluorine from the electrolysis of potassium
hydrogen fluoride. An alloy containing 10 of iridium and 90 of
platinum was used in preparing the International Prototype Metre
and the corresponding Kilogram (pp. 307, 309).

Iridium black like rhodium black has been used in producing
black colours in the decoration of porcelain.

F6r crucibles an alloy of platinum and rhodium, with 3 to 5 per
cent of the latter, is recommended for high temperature work.
Iridium stiffens platinum but increases its volatility above 900 C
whereas rhodium not only stiffens the platinum but also reduces its
volatility. Iridio-platinum is used successfully in sparking-plug
electrodes of aero-engines, best all-round results being obtained
with 20 per cent iridium.

Osmium is used in the fountain pen industry being the most
important component of "iridium" tips. Alloys of extreme hardness
containing osmium are finding increasing application. It has been
used in the filaments of electric lamps on account of its infusibility
which closely approaches that of tungsten ; its melting point being
2700 C (tungsten, melting point 3382 C). Osmium is also used
in electroplating as, for example, for searchlight reflectors.

Palladium is now being used more in industry than hitherto,
often as a substitute for platinum. Sometimes medals are struck in
it. Alloyed with gold it is used as a substitute for platinum. Gold
with 20 per cent palladium is completely white and is sometimes
used in expensive jewellery under the name "white gold".

On account of its resistance to corrosion it has been used for
astronomical and dental purposes.

Standards of length and mass

The original standard metre and kilogram were constructed by
Borda in platinum. The metre owes its origin to the French
Republic of 1795. ^ was decided that the metre should be a
physical constant and, as a convenient length, one ten-millionth
(io~ 7 ) of the Earth's quadrant was selected, or more precisely
that of the distance between the N. Pole and the Equator measured
over the surface of the Earth along the meridian passing through
Paris. It was thought that by this means if ever the standard were

306

THE PLATINUM METALS

lost it could be replaced. The actual measurements were carried out
by Delambre and Mechain between Barcelona and Dunkirk, and
Borda was entrusted with the task of constructing the standard
metre.

It was soon realised, however, that, if the metre were defined as
above, every time a more accurate determination was made all the
copies in general use would require altering, which would be
almost fatal to scientific progress beside causing a great deal of
inconvenience to trade. The metre was therefore converted into a
purely arbitrary unit like the British yard and was defined as the
distance between the ends of Borda's platinum rod.

According to more recent measurements the mean meridian
quadrant measures 10,002,100 metres.

The International Prototype Metre is a copy of the original Borda
standard or Metre des Archives \ it is made of an alloy of Pt 90 and
Ir 10 per cent, this alloy being hard, durable, very resistant to
corrosion and possessed of a low thermal coefficient of expansion.
The metre is here the distance between the centres of two lines
engraved upon the standard, when measured at o C.

Platinum-iridium copies of this metre, called the National
Prototype Metres^ were made at the same time and distributed
about 1889 to various Governments, the British copy being housed
at the Standards Department of the Board of Trade.

In ancient times in Britain three barley corns were taken as the
measure of one inch. The earliest recorded standard of length in
Britain was the gird or yard^ decreed by the Saxon King Edgar
(959 to 975); it was kept at Winchester and is believed to have
represented two cubits, the cubit being the average length of the
fore-arm and one of the earliest known standards of length recorded
in ancient history.

From time to time new standards were prepared approximating
very closely to the old ones, the last standard being housed, down
to 1834, in the House of Commons. It was destroyed, however, in
the fire of 1834, when the Houses were burned down, the fine old
Westminster Hall fortunately escaping.

By 1845 a new standard had been prepared by taking the mean
length of the most authoritative measures constituting the best
primary approach to the lost standard, no official duplicates or
copies ever having been made or recognised. The new Imperial
yard was defined as the distance between two fine lines cut in gold
plugs let into a bronze bar, measurements being made at 62 F.

307

THE CHEMICAL ELEMENTS

The composition of the alloy was Cu : Sn : Zn as 16 : 2-5 : i.
Four official copies were made and housed in different places, the
standard being kept at the Standards Department of the Board of
Trade in accordance with the Weights and Measures Act of 1878.

Copper alloys are now known to be unsuited for standard lengths
knd in 1902 an iridio-platinum (10 : 90) copy was made.

The metre *vas recognised by the British Parliament in 1897,
and the legal equivalents established by Order in Council of May
1898 are

i metre = 1*0936 143 yards
I yard = 0*914399 metre

Both the metre and yard have now been measured in terms of the
wavelength of the red cadmium spectral line, A rt in vacuo with the
following results

i metre = 1,552,734-44*,
i yard = 1,419,818-24*,

It would thus be possible to replace the standards with great
accuracy in the event of loss or destruction of the standards them-
selves and their copies.

Ordinary cadmium consists of several isotopes and ideal mono-
chromatic light is obtainable from a single isotope only. Even greater
accuracy may therefore be expected when light from one single
isotope is available. Cadmium is difficult to separate into isotopes
but, by the bombardment of metallic gold with neutrons in an
atomic pile, one of the isotopes of mercury (At. wt. 198) has been
prepared. Thus

Au (197) + n -+ Hg (198) + e

an electron e being evolved, which is an inversion of the alchemists'
dream of transmutation, Hg (198) gives a pure monochromatic
green light and in time this should be available for standard length
measurements. Preliminary measurements of this line indicate
(1950) the metre to equal 1,831,249-2* in standard air. On the
Continent the krypton isotope 84 is being similarly studied.

The metric standard of mass is the kilogram, a lump of platinum
prepared by Borda to represent the mass of a cubic decimetre of
water at the temperature of its maximum density, namely 4 C.
It is called the Kilogram des Archives.

This kilogram was prepared at the close of the eighteenth
century with the very greatest care, but during succeeding years
methods of measurement became increasingly refined and by 1872

308

THE PLATINUM METALS

it was realised that the experimental error in the determination was
greater than was permissible for accurate work. So instead of
defining the kilogram as the mass of 1000 cc. of water it was
decided to make the mass of that particular lump of platinum the
arbitrary unit. The International Prototype Kilogram is the mass of a
cylinder of iridio-platinum (10 : 90), similar in composition to the
alloy used for the metre and for the same reasons: it is an exact
copy of the original Borda standard. Copies of this have been
prepared and distributed to various Governments as National
Prototype Kilograms. The British copy is kept at the Standards
Office.

Ever since Saxon times the unit of weight in Britain has been the
pound) but that pound has varied considerably in value from time to
time. In 1533 Henry vm instituted the pound Troy as the legal
unit. This had been introduced from the French city of Troyes
towards the close of the reign of Edward in (d. 1377) and was
apparently widely known and used even before it became official.
The standard Troy pound appears to have been renewed from
time to time and that used from 1758 onwards was destroyed in
the fire at the House of Commons in 1834, having been housed
there along with the standard yard.

A commission was accordingly appointed to consider the
whole question of standard weights and measures; it was
decided to construct a Troy Ib. in platinum as close in
weight as possible to the lost standard by averaging reliable
copies. The difference between the two must have been extremely
small.

As the old Troy Ib. was equivalent to 5760 grains the new grain
was defined as one 576oth of the new standard Troy Ib.

At this time the Troy Ib. was less popular among business men
than the heavier Avoirdupois pound which had been in use more
or less from the time of Edward in. It was equivalent to 7000
grains. Advantage was accordingly taken to change the legal
standard from Troy to Avoirdupois and a cylinder of platinum was
prepared equal in weight to exactly i Ib. Troy X 7000 -f- 5760.
A pound weight was thus obtained equivalent to 7000 of the new
grains. By Act of Parliament (1878) the weight in vacuo of this
cylinder became the standard pound from which all other weights
and all measures having reference to weight were to be derived.
The cylinder was marked "P.S. 1844 i Ib." The letters P.S.
mean Parliamentary Standard,

309

THE CHEMICAL ELEMENTS

The connection between the kilogram and pound is defined
legally (1898) as

i kilogram = 2-2046223 pounds
i pound = 0-45359243 kilogram

Thus, both the kilogram and the pound are purely arbitrary units.

310

CHAPTER 23

THE RADIOELEMENTS AND THE
ACTINIDE SERIES

THESE include elements of atomic numbers 84 upwardr. Elements
of higher At. No. than uranium are frequently termed transuranic^
and six of these are now known. When they were studied it was
observed that they bore a closer resemblance to uranium than to
the elements of Group VIII the platinum metals. It appeared,
therefore, that these elements formed part of a new series resem-
bling the rare earth elements, Nos. 57 to 71. This suggested that
the electronic arrangements might be analogous, the O shell now
filling up in a similar manner to the N shell in the former.
Actinium thus resembles lanthanum, thorium resembles cerium,
and so on. It was therefore proposed by Seaborg that the rare earth
elements be termed the lanthanide series, and the radioelements
from actinium onwards the actinide series.

The electronic arrangement is shown in the following table, in
the final column of which are given the symbols of the correspond-
ing rare earth metals. Elements 97 and 98 (p. 327) have not yet
been (1950) officially recognised and are not included in the table.

Shell K
Maximum No. of 2

L M

8 18

N
32

O

5

P

72

Q

9 8

electrons

89

Actinium

2

8 8

32

18

8 +

i

2

La

90

Thorium

2

8

32

18 H

- i

8 +

i

2

Ce

9i

Protactinium

2

8

32

18 -

- 2

8 +

i

2

Pr

92

Uranium

2

8

8

32

18 -

- 3

8 +

i

2

Nd

93

Neptunium

2

8

8

32

18 -

- 4

8 +

i

2

(6 1)

94

Plutonium

2

8

32

18 -

u S

8 +

i

2

Sm

95

Americium

2

8

8

32

18 -

- 6

8 +

i

2

Eu

96

Curium

2

8 8

32

18 -

h 7

8 +

i

2

Gd

Uranium

In 1789 Klaproth was investigating a mineral which, from its
black, shining appearance, was known as pitch-blende. It was thought

311

THE CHEMICAL ELEMENTS

to be an ore of zinc and iron, but since, on dissolution in nitric acid
and neutralising with caustic potash, a precipitate is obtained
soluble in excess of the latter reagent, Klaproth rightly conjectured
that he wks dealing with a new element. To this he gave the name
uranium in recognition of Herschel's discovery of the new planet
Uranus in 1781. It constitutes about 4 ppm of the earth's crust.

By igniting a paste of the oxide with oil and charcoal, Klaproth
obtained a black, metallic-like powder which he regarded as
uranium itself. In 1841, however, Peligot showed that it was an
oxide. He analysed the chloride, UC1 4 , and his results added up to
no per cent. This impossible result was due to the fact that the
"uranium" he had weighed was not really the element but the very
stable oxide, UO 2 , which was not reducible either with hydrogen
or carbon. He therefore reduced the chloride with metallic
potassium in a closed platinum crucible and, after removing the
potassium chloride by leaching with water, was rewarded by finding
a residue of metallic uranium, the properties of which were different
from those of the oxide hitherto regarded as the element.

More than a century passed between the recognition of the
presence of a new element in pitch-blende by Klaproth in 1789,
and the discovery that this element possesses extraordinary physical
properties, the examination of which led to revolutionary ideas on
the structure of natter.

It came about in this wise. In 1896, Antoine Henri Becquerel
was studying the fluorescence shown by uranic salts such as
potassium uranyl sulphate, K 2 SO4.UO 2 SO4.2H 2 O, and made the
interesting observation that these would affect a wrapped photo-
graphic plate, even in the dark. This appeared to rule out the
possibility of fluorescence being the cause, and further support
came from the activity of uranous salts, which similarly affected the
photographic plate, although they were not fluorescent. It appeared,
therefore, that an entirely new type of radiation was being emitted,
capable of passing through black paper and affecting a photo-
graphic plate.

The scientific world, at this time, was all agog with Rdntgen's
discovery of 1 895 of a new set of rays, the so-called X or Rdntgen
rays, emanating from the glass walls of tubes where bombardment
by cathode rays occurs. The time was therefore ripe for Becquerel's
results and scientists were not slow to turn them to good account.

Shortly before this Marie Sklodowska, daughter of a science
master in Warsaw, had gone to the Sorbonne in Paris and worked

312

THE RADIOELEMENTS AND THE ACTINIDE SERIES

in the laboratory of Pierre Curie. With the wilfulness of her species,
she neglected Punch's advice to those about to be married and,
in 1895, changed her name to Curie. This, as afterwards transpired,
was a distinct advantage for scientific nomenclature. The two were
happy though poor; Pierre swept the floor and Marie cooked the
meals. She still found time for science. Interested in Becquerel's
discovery, Mme Curie began to test all sorts of substances for
"rays" and was not long in discovering that thorium compounds
were also active.

It was soon realised that this radioactivity is an atomic property
with an intensity directly proportional to the concentration of the
element yielding it and entirely independent of the state of chemical
combination of that element. Not only do the rays affect a photo-
graphic plate, but they induce ionisation in air and thus assist the
discharge of an electroscope. Hence a radioelement can be detected
electroscopically no matter what chemical process it undergoes.
This enormously simplifies the method of detection which is both
rapid and delicate.

Radium

Mme Curie noticed that certain pitch-blendes show greater activity
than corresponds to their uranium content, and concluded that
this was due to the presence of an unknown element, much more
active than uranium itself, but present in such minute quantities
that it had escaped detection by the ordinary methods of analysis.
Upon request the Austrian Government very generously placed a
ton of pitch-blende residues from their state "Dollar Mine" at
Joachimstal, at the disposal of Mme Curie. This, with the collabor-
ation of her husband, she fractionated according to accepted
qualitative methods of analysis, each precipitate being tested
electroscopically for radioactivity and rejected when inert. In this
way the radio precipitates were concentrated, and two radio-
substances eventually separated in 1898. One of these was
precipitated with bismuth and was named polonium, in honour of
Poland, Mme Curie's native land; the other was precipitated
with the barium and was christened radium, because of its great
activity*.

For many years radium was only known in the form of its salts.
These were purified by fractionation ; for four years Mme Curie

*Full references are given to this early work in FRIEND'S "Textbook of
Inorganic Chemistry", Vol. Ill, Part I, by M. S. BURR (Griffin, 1925).

313

THE CHEMICAL ELEMENTS

carried on this dangerous task and in 1903 presented her results
to the Paris Faculty of Science with a view to her doctorate. Poor
Pierre's hands were crippled by the activity of the rays, whereas
Marie escaped injury a striking tribute to the knightly chivalry
of her husband, who evidently bore the brunt of the exposure. The
happy pair leaped into fame; the same year, the Nobel Prize was
shared between them and pecuniary embarrassments were now at
an end. Pierre's fame was short-lived. In 1906 he went out one
day to lunch with some friends ; Marie waited in vain for his return ;
he had been run over and mortally injured by a dray*.

This cruel blow did not prevent Mme Curie from carrying on
her research. She learned to cultivate a sublimely detached attitude
towards things in general, as her maid once discovered to her
consternation. She had entered the laboratory exclaiming,
" Madame, madame, I have swallowed a pin!" Madame attempted
to soothe her, saying, "There, there, don't cry, there's a good girl;
here is another pin for you."

To perpetuate the name of Curie, the quantity of emanation in
equilibrium with one gram of radium was termed a curie. This is an
inconveniently large amount and the milli-micro curie is frequently
used as a practical unit. It is the quantity of emanation in equi-
librium with one millionth of a milligram of radium. Since one-
fiftieth of this can be detected with a sensitive electroscope, this
method of detecting the presence of radio-elements is extra-
ordinarily sensitive more so even than the spectroscope. The
above definition of the curie has now been superseded. In July
1950 the Joint Commission on Standards, Units and Constants of
Radioactivity defined the curie as the quantity of any radioactive
nuclide in which the number of disintegrations per second is
3-700 X io 10 .

The radium content of the Earth's crust is estimated as
1-4 X io- 12 per centf.

In 1904 an amalgam of radium was obtained by Coding who
electrolysed a solution of radium bromide in methyl alcohol using
a silver anode and an amalgamated zinc cathode. It was not until
1910 that Mme Curie and Debierne isolated the pure metal by

*EvE CURIE, "Madame Curie". Translated by V. Sheean (New York, 1943).
fG. BERG, "Das Vorkommen der Chemischen Elemente auf der Erde" (Berlin,
1932), p. 113.

JCoEHN, Ber., 1904, 37, 811.

CURIE and DEBIERNE, Compt. rend., 1910, 151, 523.

314

THE RADIOELEMENTS AND THE ACTINIDE SERIES

distillation of the amalgam in a current of hydrogen. The same
year Ebler* obtained it by thermal decomposition of the azide,
Ra(N 8 ) 2 .

Radium is a brilliant white metal, melting at 700 D C, and
manifesting luminescence, thereby differing from the other
alkaline earth metals.

Radium is continuously disintegrating; the process is sub-
atomic and can neither be accelerated nor retarded by any means at
our disposal. Radium is a member of the Uranium series and may
be found in all minerals containing this latter element. The scheme
in Fig. 8 shows the various stages of the disintegration of uranium,

U, -J^ UX, -^ X U -^- lo -2L*. Ra -~+ Rn -^ RaA

238 234 \,, X234 230 226 222 218

VIA 1VA ^X&V V V1 A 1VA 11A V1B

RaG -
206
IVB

Uranium
.lead

Fig. 8 The uranium series

The arrows are marked to indicate whethei the disintegration takes place

by a- or /^-emission

the ultimate product being radium G or uranium lead (p. 324). The
atomic weights are given beneath the symbols and the vertical
groups in the Periodic Table to which the elements belong.

It is customary to express the stability of a radioelement in
terms of its half-life, by which is meant the time that would be
required for one half of a given mass of the element to undergo
natural disintegration. Thus the period of half-life or half-change
of radium is 1600 years. If therefore we have to-day a gram of
radium, in 1600 years there will be only half a gram left, and in a
further 1600 years the amount will have fallen to 0-25 gm. and
so on.

During the disintegration of radium, as indeed of uranium,
many new transitional elements are formed, some of purely

*EBLBR, Ber. t 1910, 43, 2613.

315

THE CHEMICAL ELEMENTS

ephemeral existence, like radium C, whose period of half-life is
estimated at icr e second, and brevium, 1-14 minutes, whereas
radium D has a life of some 16 years. Polonium is the penultimate
disintegration product of radium, and is also called radium F\ its
period of half-life is 136-5 days; when it loses an a -particle it is
converted into radium G or uranium lead. In its chemical properties
polonium resembles tellurium and early preparations were sold as
radio-tellurium. Old radon tubes are a useful source.

Radium itself has no commercial applications. Its compounds
are used mainly for medical purposes and as a source of radon;
these absorb some 85 per cent of the world's output: 10 per cent
is used for rendering dials of instruments and other objects lumin-
ous, the remaining 5 per cent being used for scientific and
miscellaneous purposes*. One mg of radium emits 22-2 X io 8
a-particles per min. Its half-life is 1610 years.

Atomic energy

Decomposition of a radioelement, whether natural or induced by
bombardment is invariably accompanied by liberation of energy.
When, for example, a radium salt is confined in a thick lead vessel
almost all the evolved energy is converted into heat, some 25 gm-
calories per hour being produced per gram of radium. For this
heat to serve any useful economic purpose we should require
Vastly greater quantities of radium than we could ever hope to obtain.

The position is even worse with uranium, U(238), the half-life
period of which is 4,500 million years. During that period a gram
of the metal would, it is true, evolve an enormous amount of
energy, equivalent to 3 x io 12 gm-calories. This could raise
30,000 tons of water from freezing to boiling point, or afford hot
baths for more than one million people a matter of supreme
indifference to those politicians who do not bathe.

But this energy is evolved over so long a period that the quantity
available at any one moment is too small to be of economic value.
It has been calculated that io million tons of uranium would be
required beneath the boilers of the Queen Mary (81,235 tons) to
propel that noble vessel across the Atlantic at full speed. This it
could continue to do for many million years without renewal.

But that is of no use to us. No ship could possibly carry so vast
a load of fuel; and even if it could the radioactivity would be so

*See JENNINGS and Russ, "Radon" (Murray, 1948).
316

THE RADIOELEMENTS AND THE ACTINIDE SERIES

intense that no human freight could accompany it. If, however, we
could hurry up the rate of disintegration, something economically
useful might be achieved. If, for example, we could induce
uranium to reduce its period of half-life from 4,500 million years
to six months, its energy would be liberated some 9000 million
times as rapidly and a matter of 2 Ib, would suffice to take the Queen
Mary across the Atlantic at full speed; refuelling after each journey
would require less than I oz. of uranium. This would enormously
reduce the fuel space and increase that for cargo. At present this
cannot be done. No means has yet been discovered of acceleiating
the natural decomposition of uranium or indeed of any other radio-
element for economic use in this way.

We can often hasten a chemical reaction with rise of temperature.
On the average it is found that if the temperature is raised by
i o C the rate of reaction is doubled. By raising the temperature
through 1 00 C therefore, the reaction would, if it followed
the rule, proceed 2 10 or 1000 times as rapidly; raised through
1000 C its rate would be roughly io 30 or one pentillion times
as rapid. Experiments were accordingly tried with uranium, but
no influence whatever was observed by raising its temperature to
2500 C.

There is no doubt, however, that if we could obtain a sufficiently
high temperature the rate of dibintegration would be increased. In
the interior of the sun, for example, which approximates to 20
million C, matter as we know it cannot exist; even atoms are
disrupted.

But although we cannot accelerate the natural radio-
decomposition of uranium, we can effect an entirely different type
of decomposition by bombarding its nucleus with suitable projectiles
moving with appropriate speeds. A useful projectile is the neutron,
which is a minute mass of neutral matter entirely devoid of
electrical charges. On account of its neutrality and small size, its
diameter being io~ 12 cm, it possesses unique penetrating power.
It can pass through the planetary space surrounding the nucleus
of an atom without disturbing the electrons. Its existence, first
suggested as possible by Lord Rutherford in 1920, was confirmed
by Chad wick in 1932.

The results obtained by the bombardment of uranium with
neutrons depend both on the isotopic form of uranium used and
the speed or the neutrons.

317

THE CHEMICAL ELEMENTS

Isotopy of uranium

Ordinary uranium is a mixture of three isotopes, all of which are
radioactive. Thus

Per cent Emission Half-life

Isotope in natural (years)

metal

U(238) 99' 2 94* " 4'56 X io 9

11(255) 0-70 a 7-1 X io 8

U(234) 0-006 a 2-7 X I O 5

*By difference

Although identical in their chemical behaviour these isotopes
respond differently towards neutron bombardment. At speeds
between those of fast and thermal (relatively slow), neutrons are
captured by 11(238) without fission, producing a very active isotope
11(239), which loses an electron producing a new element
neptunium, Np, which in turn loses an electron yielding plutonium^

239 p Emits* 235 ff
94 Pu - - U

(Intermediate)
Half life 4-56 x lo'yrs. 23 muts 2-3 days 2-4xl0 4 yr* 7-1 x I0*yr s -

(a) Formation of transuranic elements, Np and Pu, and U(235)

(Thermal) Critical energy (Fast)

for stability
exceeded

(b) Fission of U(235) after thermal-neutron capture
Fig. 9 Neutron bombardment of uranium

Pu, which is radioactive, ejecting a-particles and yielding U(235);
this decay is relatively slow. The scheme may be written as in Fig. 9(0).
Thermal neutrons have relatively little action on 11(238) but
can effect the fission of 11(235). This is illustrated in Fig. 9^).
Krypton and barium are not always formed; many different
elements have been identified. The fission is accompanied by the
liberation of an enormous amount of energy, and this is the
principle of the atomic bomb. It will be noticed that these artificial
disintegrations yield very different products from the natural
processes as shown on p. 315.

318

THE RADIOELEMENTS AND THE ACTINIDE SERIES

The uranium bomb

The high speed neutrons liberated by fission of U(235) mostly
escape or are neutralised by foreign bodies during natural dis-
integration. As, however, usually one to three secondary high speed
neutrons are liberated for each fruitful collision it is clear that, if
sufficient of these could be slowed down to thermal velocities and
themselves allowed to combine fruitfully with further U(2J5) atoms,
the process might be made continuous or chain-wise. This is shown
diagrammatically in Fig. 10.

Kr atom

o

o

\ I

o

Energy

Thermal
neutron U(235)

dtom

excess energy -

a* s,t.*~ t b * sloved to

bet atom t hermaL

for further disruptions
Fig. 10 The initiation of a chain reaction

Owing to the rapidity with which fission occurs (about icr 12
second) when once the neutron has been absorbed, if one could
ensure that even only a few more of the evolved neutrons than those
absorbed in producing them could collide fruitfully, the number of
collisions would increase with terrific speed leading to an explosion
of unprecedented violence.

Let us consider how this can be done.

(i) It is first necessary to increase the proportion of U(235) in
the metal ; in Nature it constitutes less than one per cent.
As 11(235) is merely an isotope of 11(238) and hence
possesses identical chemical properties, its separation
presents unusual difficulties. One of the ways in which the
difficulty has been overcome lies in the fractional thermal
diffusion of the fluorides U(238)F 6 and U(235)F 6 , there
being only one form of fluorine. The process is lengthy.
(ii) A neutron liberated in the middle of a mass of uranium has
little chance of escape; one produced near the surface has
obviously a better chance. Hence the average opportunity

319

THE CHEMICAL ELEMENTS

for a neutron to escape without fruitful collision is propor-
tional to the surface area of the generating material, whereas
the chance of capture is a volume effect. For spherical masses
the area is oc r 2 but the volume is oc r 8 ; hence the larger the
lumps the less the chance of escape. There is thus a critical
size for a mass of U(235) below which rapid disintegration
will not occur, but above which, owing to neutrons
normally present in consequence of natural decay, rapid
disintegration will occur spontaneously. What that critical
mass may be has not been disclosed; it probably lies
between 20 and 40 Ib.

(iii) To effect a maximum fission capture the high speed
secondary neutrons must be slowed down. This can be
effected with the aid of moderators. These must be of such a
kind as will function without actually capturing the
neutrons. Graphite is largely used.

(iv) Finally both the uranium and the moderator must be as
free as possible from impurities,

/. A'

E

Fig. 11 The atomic bomb

Having prepared the material the next step is to construct the bomb.
This presents great mechanical difficulties which, however, have
been solved to a certain extent.

The principle consists in assembling lumps of U(235), suitably
moderated and of size well below the critical so that they remain
stable, apart from natural radio-disintegration. When an explosion
is required these lumps must be made to coalesce mechanically
with great rapidity and completeness when spontaneous dis-
integration will immediately occur. An arrangement like that
shown in Fig. 1 1 might be expected to fulfil the above conditions.
A, A' are two lumps of 11(235) in a steel tube. When the explosive
charge E is fired, A' rapidly coalesces with A; the combined mass
is above the critical size and disintegration occurs immediately.

A trial bomb based on the above principles was fired in New
Mexico on i6th July 1945. It was mounted on a tall steel tower.
As detonation occurred there was an intense flash and a huge dome
of fire ascended heavenwards. The temperatures attained were of

320

THE RADIOELEMENTS AND THE ACTINIDE SERIES

the order of those attained in the centre of the sun ; the steel tower
disappeared and in its place was a shallow crater surfaced with
fused grains of sand. The Frontispiece shows photographs taken at
two different intervals after detonation.

President Truman has stated that the bomb which devastated
Hiroshima on 6th August 1945, was equivalent in its explosive
power to more than 20,000 tons of T.N.T. It has been estimated
that the total cost involved in the production of this type of bomb
was of the order of ^700 million.

The atomic pile

The uranium bomb is of relatively little economic value; its energy
is liberated as much too rapidly as that of uranium is liberated too
slowly in natural radio disintegration. If the liberation of that
energy could be controlled at will, it would be of unprecedented
value to the human race. For example, it has been calculated that,
assuming 100 per cent efficiency, i Ib. of 11(235) would suffice to
keep an 18,000 h.p. engine running for 100 years. Even a mere
10 per cent efficiency would be of inestimable value. But there are
enormous difficulties that have not yet been surmounted, although
scientists have now been tackling the problems for several years.

The nearest approach as yet to the solution lies in the atomic pile.
This usually comprises rods of uranium surrounded by some
suitable moderator such as graphite. The so-called GLEEP pile
at Harwell commenced operations in 1947; the larger BEPO or
British Experimental Pile, with O for euphony, began operations
in July 1948. It is air-cooled, the warmed air being used to warm
the buildings. Its moderator consists of several hundred tons of

traphite, the ratio of carbon to uranium being about i o to I . The
rst French atomic pile began work in December 1948.

At present, owing to the extreme susceptibility of uranium to
corrosion it is not possible to use the evolved heat for steam raising
purposes. But the pile has many other uses including the production
of new elements, such as plutonium; the manufacture of radio-
compounds for greenhouses, etc, or as tracers for engineering,
chemical and medical purposes; and for research into the produc-
tion of complex substances.

Thorium

In 1898 both Mme Curie and Gerhardt Carl Schmidt, professor
of physics at the University of Mtinster, independently discovered

321

THE CHEMICAL ELEMENTS

the radioactivity of thorium, observing it to be less active photo-
graphically than uranium, but equally active electroscopically, this
latter indicating an equal ionising power. The interested reader
may easily demonstrate the photographic activity of thorium
compounds by laying a gas mantle on a wrapped photographic
plate and leaving it undisturbed for two or three weeks. Upon
developing th^ plate an image of the mantle is obtained.

The changes undergone by thorium during its spontaneous
disintegration to lead are indicated in Fig. 12, which gives the type
of "particle" evolved, the recognised symbol for the product, its
atomic weight and the vertical group in the Periodic Table to
which it belongs.

Th -*- MsTh, -- M$Th M -* RdTh. -*- ThX - Thn -^- ThA
232 228 228 228 224 220 216

1VA 11A 111A 1VA 11A V1B

v'r.ra ^

ThC 1
208

1B ^ THC -*- TUB
IV B v , 212 212

Thorium ^V ty VB 1VB

212
V1B

Fig. 12 The thorium series

The first product of disintegration is mesothorium I, discovered
by Hahn in 1907. It is isotopic with radium and is used as a
substitute for certain radium preparations. As large quantities of
thorium minerals are now worked up in connection with the gas-
mantle industry, and mesothorium is a by-product, it has assumed
commercial importance. It is separated from thorium in monazite
being precipitated along with barium as sulphate. Thorium X y
discovered by Rutherford and Soddy in 1902, is another isotope of
radium. Radiothorium, RdTh, is an active isotope of thorium and
cannot be separated from it directly; it has to be obtained from
mesothorium I by disintegration if required free from isotopes.

The final product is thorium D or thorium lead. Several isotopes of
thorium are known. Fast neutrons can cause fission with Th(232)
as with U(238) and Np(237)

Actinium

Actinium was discovered in pitch-blende by Andr Debierne in
1899, a friend of the Curie family and later associated with Mme
Curie in the isolation of metallic radium in 1910. He found

322

THE RADIOELEMENTS AND THE ACTINIDE SERIES

actinium was precipitated along with the rare earths in fraction-
ating pitch-blende; in 1902 it was re-discovered by Geisel who
named it emanium. It resembles the rare earth metals, particularly
lanthanum, and when the double magnesium nitrates of acuniferous
earths of the cerium group are fractionated, it concentrates in the
neodymium and samarium fractions.

Actinium is a member of a third radioactive seres, known as
the actinium series, which originates in actino-uranium> an isotope of
uranium I with a half-life period of 4 X io 8 years. It occurs in all
uranium minerals in a constant ratio to UI whatever the age.

Until last year (1950) compounds of actinium have not been
obtained in anything like a state of purity. This is partly because of

p a _L*. Ac * ~ RdAc - AcX -^ - Acn -^ AcA - AcB

230 226 226 222 218 214 210

VA 111A 1VA HA V1B 1VB

206
111B

Fig. 13 The actinium series

rarity, only 0-15 mg of actinium occurring per ton of pitch-blende;
also it is invariably associated with rare earth elements, usually
those of the lanthanum end, from which it is extremely difficult to
separate. Of the known isotopes, only Ac(227) has a sufficiently
long life for macro-separation. Hagemann* has succeeded in
synthesising actinium bromide by neutron irradiation of radium
bromide; thus

Ra(226) + n -> Ra(227) -> Ac(227) + p

Although the metal was not isolated, micro quantities of pure
AcgC^, AcF 3 , AcCl 3 , etc. were obtained and shown to be iso-
morphous with the corresponding lanthanum and cerium derivatives.
The immediate parent of actinium is protactinium or eka-
tantalum, discovered independently by Hahn and by Soddy in
1917; it occupies the position between thorium and uranium left
vacant by Mendel^eff in his Periodic Table of 1869. ^ l ses an
a-particle yielding actinium. At one time the actinium series was
regarded as a branch of the uranium series. In old minerals the

*HAGEMANN and co-workers, /. Amer. Chem. Soc. t 1950, 72, 768, 771.

323

THE CHEMICAL ELEMENTS

U/Ac ratio was found to be constant, but the amount of actinium
present was nevertheless less than would be expected if it were a
direct disintegration product of uranium. This was the reason for
assuming it to lie in a separate chain. By the Group Displacement
Law protactinium should belong to Group v and thus resemble
tantalum. It was this consideration that led to its discovery.

The changes undergone by protactinium during its spontaneous
disintegration to actinium lead are indicated in Fig. 1 3, which gives
the type of radiation evolved, the recognised symbol for the product,
its atomic weight and the vertical group in the Periodic Table to
which it belongs.

Atomic weight of lead

Three isotopes of lead are the end products of the three natural
disintegration series just considered. As these are inactive they
accumulate in their radioactive mineral sources.

If the lead present in a pure uranium mineral has resulted from
the disintegration of uranium atoms only, its atomic weight should
approximate to that of uranium less 8 a-particles, that is, to
238-14 8 X 4-002, or 206-12. Actinium lead will be the same.
But lead from a thorium mineral should have an atomic weight
equal to that of thorium less 6 a-particles, that is 232-12 6 X
4-002, or 208-1 T . Hence the atomic weight of lead may be expected
to vary with its source.

Experiment has shown this to be the case. Ceylonese thorite was
found to contain 0-39 per cent of lead oxide presumably derived
from thorium by natural disintegration during past ages. The
atomic weight of the lead was found by Soddy and Hyman in 1914
to be 208-4.

On the other hand several investigators have obtained a value of
approximately 206-0 for lead extracted from pure uranium minerals.
Mention may be made of the value 206-06 obtained by
Hftnigschmidt and Horovitz in 1915 for lead from a sample of
Norwegian broggerite, a variety of uraninite from Norway; and
206-00 found by Baxter in 1 933 for lead from Katanga pitch-blende.
The atomic weight of ordinary lead is 207-22.

Radon

In 1900 Rutherford* observed that thorium compounds impart a
temporary activity to the surrounding air, this activity being

* RUTHERFORD, Phil. Mag., 1900, (5), 49, i.
324

THE RADIOELEMENTS AND THE ACTINIDE SERIES

retained for a short time after the removal of the thorium compound,
but rapidly diminishing in strength, its half-life being less than one
minute. He showed that the emanation was a gas that could be
condensed at or about the temperature of liquid air. The gas is now
known as thoron\ it is chemically inert, belonging to Group O and
is one of the isotopes occupying the place of element 86.

Rutherford sought for a similar gaseous emanation from radium
compounds, but the quantity of these at his disposal was too small.
Within a few months, however, Dorn* detected the presence of the
gas and three years later Debiernef found that actinium behaved
likewise. The three emanations are now known as thoron of half-life
54 sees., radon 3-825 days, and acfinon.^'9 sees.

Of these radon alone is of medical importance, the other two
isotopes being too short lived. The medical usef of radon in the
U.K. began in 1914. Radon capsules are used in the treatment of
deafness where due to blocking of the Eustachian tube. This
occurs with airmen when flying at great heights or when changing
their altitudes rapidly, as for example, during dive-bombing. As
radon is soluble in. petroleum jelly a radio-ointment is prepared
that has been used in the treatment of necrosis and radiation
injuries. Radon "seeds" and "needles" are also used. The seeds are
short lengths of capillary glass tubing filled with radon which may
be inserted into growths such as, for example, orcur in cancer of
the tongue. Needles are generally larger. Being a chemically inert
gas, radon readily diffuses into most tissues and is used in
biological research. It is also used as a tracer element in the study
of gas flow.

Trans -uranium elements

Neptunium was the first of these to be synthesised ; it was obtained
in traces by bombardment of 0(238) with neutrons (see Fig. 9(0),
p. 318). Its chemical properties are not in general like those
of rhenium or the other elements of Group vn. It yields no
volatile oxide corresponding to Re 2 O 7 . It functions with valencies
3, 4, 5 and 6 and in its higher stages of oxidation it tends
to resemble uranium. Several isotopes are known including 237,
238 and 239. It was named after the planet Neptune discovered
in 1846.

*DORN, Abh. Naturforsch. Ges. Halle-a-S., 1900.

JDEBIERNE, Compt. rend., 1903, 136, 446, 671; 1904, 138, 411; 1904, 139, 538.

{JENNINGS and Russ, Opus cit.

McMiLLAN and co-workers, Physical Review, 1939, 55, 519; 1940, 57, 1185.

325

THE CHEMICAL ELEMENTS

Plutonium was synthesised by Seaborg in 1940. It has been
detected both in pitch-blende, UO 2 .2UO 8 , and in carnotite,
K 2 (VO 2 ) 2 (VO 4 ) 2 .8H 2 O, to the extent of about i in lo 14 . Probably
the naturkl element is the isotope 239 formed by non-fission absorp-
tion by U(238) of some of the neutrons always present, possibly
resulting from spontaneous fission of 11(238). Although it has a
longer life thaa radium, namely 2-1 X io 4 years (as against 1600)
each mg emits 160 million a-particles per minute so that it is
dangerous to handle. It functions with valencies of 3, 4, 5 and 6
and generally resembles neptunium and uranium, being more
stable than the former in its lower stages of oxidation. Several
isotopes are known including 236, 238 and 239. Slow neutrons
cause fission with 239?u as with 2351!.

Emits ft

237... Emits oc 241 .
93 NP + 95

I

96 - 9 4 5 2Am

Fig. 14 The transuranic elements

Production of plutonium was begun in Chicago in 1 942 in an
atomic pile. The bomb that devastated Nagasaki in Japan on 9th
August 1945 contained plutonium.

The name plutonium was suggested for barium by E. D. Clarke,
Professor of Mineralogy at Cambridge, 1808-1822, and was used
in this sense by Thomas Thomson in his "System of Chemistry"
in 1817.

In 1945 the synthesis of elements 95 and 96 was announced.
No. 95 corresponds to europium in the lanthanide series (p. 177)
and was hence appropriately named americium. No. 96 corresponds
to gadolinium, named after the Finnish mineralogist Gadolin. It
was therefore felt that it was the turn of the Curies to be honoured,
and the new element was named curium. Several isotopes of the
two elements are known.

Both elements are dangerous to handle. Am(24i) with a half-life
of 500 years evolves 7x10 a-particles per minute per mg, and
Cm(242) with a half-life of 5 months evolves io 18 . The relation
between these elements and plutonium is illustrated in Fig. 14.

THE RADIOELEMENTS AND THE ACTINIDE SERIES

Neptunium, plutonium and americium metals have been
isolated by reduction of their fluorides with barium at 1200 C.
Like uranium they are base metals and do not resemble the
platinum group. The metal curium has not yet been described.

From the Radiation Laboratory of the University of California*
comes news of the syntheses of two more elements, Nos. 97 and 98.

No. 97 has been obtained, by irradiation of amerHum (96) with
helium ions accelerated in the cyclotron, as a nuclide of half-life
4'6 hours and probable atomic weight 243. It decays by electron
capture. For it, the name berkelium, Bk, has been suggested.

No. 98 has been similarly synthesised by irradiation of curium
(96); its half-life is only 45 min. and its atomic weight probably
244, The name californium^ Cf, has been suggested.

"Office of Public Information, University of California; released iyth March
1950. See also PANETH, Nature. 1950, 165, 748.

327

NAME INDEX

AARON, 128

Abdul, 63

Abdullah, 255

Abednego, 221

Aboutig, 132, 133

Abraham, 103, 111

Achan, 129

Achilles, 104, 267

Agatharchides, 133

Agricola, 50, 68, 87, 156, 162

Agrippina, 136

Ahmed Shah, 65

Ahrens, 165

Al Idrisi, 215

Al Khazini, 194

Albright, 78, 79

Alexander Gt, 55, 269

Alfonso VIII, 217

Alfred, Gt, 192

Algarotus, 85

AUgood, 205, 206

Allison, 52

Amen, 30

Amenemhat II, 131

Amenhetep I, 199

II, 131

Ammarwaru, 56

Ammon, 30

Amos, 263

Ampere, 51

Amundsen, 204

Analtis, 134

Anaxagoras 1

Andrew, St, 264

Andrews, 26

Antoinette, Marie, 63

Appert, 208, 209

Aquinas, 215

Archimedes, 134

Areithous, 267

Arfvedson, 145

Argon, Prince, 41

Aristarchus, 12

Aristotle, 1, 81, 203, 214
Arrhenius, Lt, 179
Arthur, King, 276
Ashurbanipal, 261
Aston, 36, 173
Atli, 276
Attila, 276
Augustine, St, 257
Augustus, 99, 134
Autolycus, 130
Azazel, 10

BAADE, 93
Babbitt, 212
Babington, 151
Bacchus, 130
Bacon, Francis, 83
, John, 19
, Roger, 72, 82, 106
Baddeley, 192
Bahr, 234
Bailey, 200, 216
Baker, B., 284
, H. B., 74
Balard, 49, 238, 303
Balch, 271, 288
Ball, 56

Ballard, A., 192
, Simon, 277
Bannister, 58, 131
Barba, 23, 87
Baron, 68

Bartholomew, P., 264
Barwell, 135
Bates, Peter, 280
Bathanarius, 257
Baume', 84
Baxter, 324
Beaulieu, 63
Becher, 69
Becquerel, 312
Bede, 192

329

NAME INDEX

Bedford, Duchess, 288

Bedivere, Sir, 276

Benjamin, 112

Benjamin, P., 257, 258

Bennett, 74

Berg, 250, 314

Bergemann, 234

Bergman, 74, 77, 244, 245, 292,

294

Berlin, 172 179, 181
Berquem, 59
Berthelot, 82, 300
BertUollet, 46, 68, 77, 150
Berzelius, 46, 58, 68, 73, 74, 143,

145, 151, 155, 183, 184, 229,

230, 234, 235, 238, 244, 294
Bessemer, 281, 282
Besson, 285
Biggs, 59
Bindheim, 242
Biot, 35
Bird, 208
Birge, 36

Biringuiccio, 105, 280
Black, 28, 33, 143, 151, 303
Bleakney, 37
Boadicea, 270
Boer, de, 230
Boerhave, 227
Boetger, 298
Bohemund, 264
Bohr, 232

Boisbaudran, 173, 181-184
Bolsover, 116
Bolton, 222
, von, 240
Bonaparte, L., 175
Bonhoeffer, 32
Booth, 208
Borda, 306-309
Bostock and Riley, 104, 112, 120,

200, 215, 269, 290
Botha, 62
Bottger, 79
Bouch, 284
Boulton, 33, 291
Boyle, 2, 21, 61, 77, 86, 142, 156,

222 224
Brand, 76, 77, 292

Brandes, 145
Brandt, 76, 82, 192
Brashear, 117
Brauner, 74, 75, 183
Brion, 276
Briscoe, 41
Brodie, 26
Bromehead, 201
Brown, "Capt.", 124
Brownrigg, 300
Brim, Le, 288
Budge, 110, 131
Buffon, 242
Bulleid, 270
Bunsen, 42, 146-148
Burke, 116
Burr, 313
Bury, 232
Bussy, 152, 154

CJESAR, J., 201, 202, 270
Cain, Tubal, 10, 94, 99
Camden, 16
Cannizzaro, 169
Caractacus, 201
Carlisle, 143
Carnarvon, Lord, 132
Caro, 30
Carter, 132, 260
Casciorolus, 76, 149
Cassivelaunus, 199, 201
Castro, de, 160, 161
Cavallo, 26, 33
Cavendish, 24, 29, 31-33
Caxton, 197
Celsius, 226
Ceres, 95, 182
Chadwick, 317
Chaloner, 162
Champion, 157
Chancel, 77
Chancourtois, 169
Chaptal, 28, 162
Charaxus, 268
Charlemagne, 264
Charles, 34

I, 211

II, 77, 205, 206

330

NAME INDEX

Charles XI, 77

the Bold, 61, 66, 161

Charleton, 294

Chartres, de, 86

Chattaway, 46

Chaucer, 15, 130, 275, 281

Chfel, 77

Christ, 263

Ch'u, 266

Chuang Wang, 266

Church, 231

Cicero, 141

Clarke, E. D., 152, 326

Clarke, F. W., 7

Claudius, 136

Claus, 250

Clayton, 78

Cl&nent, 48, 49

Cleopatra, 248

Cleve, 42, 172, 181, 182

Cock, Thomas, 301, 302

Cockcroft, 2

Coehn, 314

Coit, 216

Cohen, 226, 227

Cohen de Meester, 226, 227

Colas, 293

Colbert, 205

Coles, Cowper, 158

Colley, 230

Columbus, 256

Cook, Capt., 299

Cook, M., 92

Cooke, 169

Coolidge, 48

Combes, 155

Copernicus, 14

Cort, Henry, 281

Coster, 233

Courtois, 48

Cowper, 267

Crawford, 150

Crawfurd, 157

Cronstedt, 149, 243, 294

Crookes, 42, 166, 167

Crusoe, 216

Cublai Khan, 136, 219

Cullinan, T., 61, 62

Curie, L, 2

Curie, Eve, 314
, Mme, 321, 322
Curies, the, 313, 314, 326
Cybele, 254

DAEDALUS, 92

D'Albe, Fournier, 166

Dalton, 168

D'Andrada, 145

Damiens, 51

Dana, 89

Dane, 230

Daniel, 221

Darby, Abraham, 279

D'Arlandes, 34

David, 94, 128, 129, 188, 263

Davy, Humphry, 2, 47, 49, 51, 57,

68, 69, 72, 83, 102, 143, 145,

151, 152 220, 230, 250
J, 143
Dawes, 30

Debierne, 314, 322, 325
Defoe, 193, 216
Delafontaine, 180, 181
Delambre, 307
D'Elhuyar, Don, 245
Demarcay, 18b, 184
Demetrius, 112
Dent, 115
Descotils, 237
Desormes, 48, 49
Deville, 69, 163, 230
Dewar, 43
Diana, 112,254
Diocletian, 99
Diodorus, 133, 134
Dioscorides, 81, 83, 149
Dodo, 279

Doebereiner, 46, 168
Dolejek, 251
Donkin, 209
Dorn, 43, 325
Dover, 216
Downs, 138
Drake, 277
Druce, 250, 251
Drummond, 235
Dryden, 268

331

NAME INDEX

Dudley, Dud, 279
Dumas, 167, 168
Durand, 209

Dyche, 198

r

EASTMAN, 165
Ebler, 315
Edgar, King, 307
Edison, 246
Edward I, 211

Ill, 97, 203, 274, 309

IV, 197

VII, 62, 288
Ekeberg, 179
Elisha, 283
Elizabeth, Princess, 67

, Queen, 97, 150, 194, 279
, H.M. Queen, 154
Ellis, 272
Ellis, G. E., 143
Elton, 200
Emeteus, 252
Emerson, 100
Emmanuel, Victor, 264
Empedocles, 1
Enoch, 10
Erman, 68 ,
Etzel, 276
Eurytus, 268
Euthydemos, 292, 294
Excalibur, 276
Ezekiel, 83, 112

FAHRENHEIT, 223-227
Fala, 63
Faraday, 20
Fast, 230

Ferdinand II, 221-223
Ferrers family, 288
Fink, 93
Fleitmann, 295
Fletcher, 255
Flower, 205
Ford, Wm., 125
Fourcroy, 68, 150, 242
Franchot, 30
Frank, 30
Frankland, Percy, 27

Frankland, Edward, 42

Fraunhofer, 146

Freia, 237

Friend, 81, 91, 96, 151, 190, 221,

230, 250, 265, 270, 273, 313
Frigg, 237

GADOLIN, 172, 179, 234, 326

Gahn, 72, 73, 77, 150, 248

Galileo, 14, 222

Galvani, 101

Garces, 218

Garland, 131

Gamier, 299

Gaunt, John of, 288

Gay-Lussac, 35, 49, 51, 68, 69

Geber, 15, 16, 143

Geer, 263

Gegania, 95

Geisel, 323

Geoftroy, 87, 99

George IV., 278, 291

Giauque, 25, 36

Gibril, 10

Gilchrist, 282

Gladstone, 114

Glauber, 85

Gmelin, G. C., 145

Gmelin, L., 49, 146, 230, 240

Godfrey, 77

Goliath, 188, 267

Goldschmidt, 175

Gore, 51

Gowland, 90, 95, 100, 131, 133,

191, 199

Granage, T. and G., 281
Grandison, 194
Graves, 130, 264
Green, 34
Gregor, 228

Gregory, Pope, 257, 263
Grew, 150
Gutenberg, 197
Guthalac, St, 193
Guyard, 250

HABER, 29
Hadfield, 70, 265

332

NAME INDEX

Hadrian, 193, 273
Hagemann, 323
Hahn, 322, 323
Haldane, 44
Hale, 43
Hales, 21, 238
Hall, C., 163
, H. R., 91
- J-, 209
Halley, 222, 224, 225
Hamburger, 230
Hanbury, 206
Hanckewitz, 77
Hannay, 58
Hannibal, 254, 255
Hanstein, 135
Harold, 274
Harris, 183
Harvey, 21
Hatchett, 239, 240
Hauser, 232
Haiiy, 154, 242
Hayes, 230
Heine, de, 209
Heisenberg, 32
Hellot, 87
Hellriegel, 30
Helmont, van, 20
Hendrie, 100
Henckel, 156
Henry II, 118

Ill, 137, 288

Ill (of France), 66

IV, 18

VI, 18,81, 160

VII, 105

VIII, 97, 98, 161, 193,309

(of Luxemburg), 263
Hensler, 249
Hercules, 219
Hermann, 249, 250
Herodotus, 264, 267
H6roult, 163
Herschel, 12, 312
Hesiod, 130, 187, 199
Hevesy, 233
Heyrovsky, 251
Hildebrand, 42
Hilger, 251

HOI, Mary, 111

Hippodame, 268

Hirth, 266

Hisinger, 143, 182, 184

Hjelm, 244 ^

Hofimeister, 93

Hofmann, 232

Holmberg, 181

Homberg, 68, 76, 156

Home, 239

Homer, 10, 11, 71, 137, 187, 199,

268

Honigschmidt, 324
Honda, 298
Hooke, 21, 224
Hope, R, 63
, H. P., 63
Hopkins, 175, 183, 184
Horovitz, 324
Horus, 132
Huggins, 43
Huggett, 277
Hulubei, 148
Hunter, 229, 241
Hunstsman, 280
Huram, 94
Hyman, 324

ICARUS, 92, 93

JAMES, C., 180

I, 98, 109, 162

11,66
Janssen, 42
Jason, 285
Jehoram, 83
Jehu, 83

Jenkins, 160, 275
Jennings, 316, 325
Jeremiah, 83
Jezebel, 83
Joab, 129

Joan of Arc, 81
Job, 94, 187
John, King, 203
Johnson, 302
Johnston, 25, 36
Joliot, 2

333

NAME INDEX

Jonathan, 262
Jones, H. L., 133
, S., 78
, T. G., 273

, W., 90; 121, 196, ?63, 274, 291
Jonker, 64
Tordan, 298
Jorden, 98
Jos<, Don, 245
Joseph, 112, 127
Josephine, 263
Josephus, 128
Joshua, 129

Jupiter, the god, 14, 30, 203, 218,
254

KAMA, 65

Kaplan, 65

Keesom, 41, 43

Kekute, 165

Kelly, 281

Kelvin, 226

Kepler, 14

Kern, 250

Kerr, 122

Kheta-sar, 110

Kieshel, 283

Kipling, 283

Kirchhoff, 42, 146, 147

Kirchmaier, 77

Kirwan, 150

Kitaibel, 74

Klaproth, 73, 74, 182, 228, 229,

243, 311, 312
Klaus, 304
Knietsch, 304
Koster, 197
Krafft, 77
Kroll, 45, 230
Krupp, 298
Kulhwch, 272
Kunckel, 77, 140, 156

LAMB, 264
Lamy, 166, 167
Lange, 281
Langmuir, 29, 232
Lavallidre, de, 63

334

Lavoisier, 2, 24, 28, 46, 57, 68, 71,

77, 150, 151
Lebeau, 51
Leczincka, 66
Leland, 286
Legrange, 24
Lehmann, 242
Lely, 230
Lentulus, 112, 133
Leurechon, 221
Levesons, the, 207
Lewis, A. C., 17
Libavius, 83, 162
Liebig, 49, 116,238
Liempt, van, 233
Lincoln, 208
Little, 179
Livy, 133, 254
Lloyd, 272
Lockyer, 42
Lonsdale, 58
Loring, 251
Louis, H., 189, 191

XIV, 62, 63, 205

XV, 66

XVI, 63
Lowig, 49
Lucas, 142, 260
Lucretius, 257
Lundstrom Bros., 79
Lyndon, 115

MACALISTER, 99, 129, 262, 263

Maccabaeus, 111

Mackenzie, 53

Macquart, 242

Madanapala, 156

Magnes, 256

Magnus, Albertus, 13, 16, 82, 215

Magntisson, 276

Mahomet, 268

Mallard, 155

Mallet, 250

Manget, 17

Marggraff, 143, 149, 162

Marignac, 26, 172, 180

Marina, Princess, 121

Mariotte, 224

NAME INDEX

Marline, 223, 224
Marum, van, 26
Mary, Princess, 121
Matthey, 302
Matthiessen, 146
Maudsley, 285
Mawe, 56, 57
McKie, 22
McLean, Ed., 63

, Evelyn, 63, 64

McMillan, 325

McPherson, 273

M<chain, 307

Mendeteeff, 4, 155, 167, 169, 171-

173, 230, 238, 250, 323
Menzel, 36
Merlin, 190
Merret, 18, 19, 61
Meshach, 221
Meyer, Kirstine, 225
, Lothar, 169, 171
, Thyra, 225
Midas, 130
Miers, 42
Miller, 268
, G. L., 45
Mini6, 282
Missen, 291
Mitchell, 102
Mixter, 230
Mohammed, 255
Moissan, 51, 58, 306
Monceau, Duhamel de, 142
Monell, 296
Montespan, de, 63
Montfaucon, 189
Montgolfier Bros., 33
Moore, 43

Morgan, Pierpoint, 148
Morris, 276
Morveau, de, 68, 150
Mosander, 179, 180, 181, 183, 184
Moseley, 3, 183, 232, 249, 302
Moses, 41, 112, 127, 128, 187
Moult, G. and R, 150
Muller, 73, 74
Munro, 257
Mushet, 245
Myddleton, 108

NAAMAN, 130
Nadir Shah, 65
Nagarjuna, 100, 114
Napoleon I, 35, 66, 144, 145, 208,
263

II, 282

Ill, 163
Nasmyth, 208
Nebuchadnezzar, 221
Nelson, 284, 288
Nero, 134

Nevill, Lady, 280

Newlands, 169

Newton, H. A., 255

, Isaac, 14, 16, 57, 222-225

Nicholas, St, 293

Nicholson, 143, 149, 302

Nick, Old, 293, 294

Nicor, 294

Nilson, 155, 165, 172, 181, 229

Niobe, 240

Noddack, 240, 250, 251

North, 198

Nylander, 231

ODIN, 14, 237

Odling, 26
Oersted, 162
Og, 262
Ogawa, 250
Gibers, 302
Oldfather, 134
Olwen, 272
Onnes, 43
Oppenheimer, 64
Osann, 250, 304
Otter, 152
Ovid, 71, 268
Oxland, 245

PALMER, Smythe, 12, 88

Paneth, 327

Papish, 148

Paracelsus, 17, 24, 82, 85, 156

Pardon, 198

Paris, 143, 144

Parry, 209

Partington, 22, 50, 110,214

Pasteur, 27, 208

Paul II, 161

335

NAME INDEX

Paul, St, 94

Paulinus, 113

Payne, 207

Pearson, 144

Peligot, 3f2

Pemberton, 101

Pendray, 117

Pepi I, 105

Percy, 108, 156

, Mile, 148

Petrie, 82, 260

Pettersson, 155, 165, 229

Piazai, 182

Pinson, 208

Pisani, 147

Pit*, 66

Pius II, 160, 161

Plato, 15, 257

Plattner, 147, 174

Pliny, 18, 53, 55, 71, 72, 81, 84,
94,95, 104, 112, 113, 120, 128,
134-138, 142, 149, 188, 189,
200, 205, 215, 216, 218, 219,
248, 268, 269, 290

Polo, 41, 55, 56, 136, 219

Polybius, 276

Polyphemus, 267

Pontin, 151

Pope, 267

Poppaea, 134

Pott, 248

Powle, 279

Prandtl, 232

Priestley, 21, 22, 24, 28, 32, 219

Priscus, 136

Proust, 292

Psammetik I, 105

Punch, 269

Pythias, 201

QUIST, 243

RAMA Sita, 62

RamesesII, 110, 133, 136, 260,

261

Ill, 260
Rammelsberg, 238
Ramsay, 33, 41-43, 171
Rand, 213

336

Ray, 156, 216

Rayleigh, 28, 29, 41

Reaumur, 205, 226, 280

Redesdale, Lord, 218, 259, 266

Reich, 165

Reinach, 111

Rekh-my-Re, 93

Remy-Gennete, 148

Renaldini, 225

Rennie, 278

Rey, Jean, 24

Rhea, 257

Rhodes, 57

Rhoetus, 268

Richard II, 280

Ill, 129

Richmond, 204

Richter, 165, 174

Rickard, 134, 187

Ridgeway, 11, 262

Riley, 298

Rio, del, 237

Ritchey, 117

Ritchie, S. J., 298

Rive, de la, 26

Robert, 34

Robinson, 126

Rodwell, 216

Roebuck, 78

Roemer, 224-227

Rogers, 281

Rolla, 183

Rontgen, 3, 48, 312

Roscoe, 238, 243

Rose, H., 180, 240

, T. K., 126

Ross, Capt., 209, 219

, E. D., 131

Rossi, 229

Rozier, de, 32, 34

Rumford, 143

Russ, 316, 325

Rutherford, Daniel, 28

, Lord, 2, 317, 322, 324

Rydberg, 232

Ryton Bros., 207

SAGE, 133
Sagredo, 223

NAME INDEX

Saizec, de, 82

Salcedo, 109

Samarski, von, 148, 179

Sanci, 66

Sandwich, Earl, 23

Santorio, 222

Sarah, 111

Saul, 262

Sayce, 260

Scaliger, 300

Scheele, 21, 22, 28, 30, 46, 51, 53,

69, 149, 150, 182, 228, 243-245,

248

Schesnag, 265
Scheurer, 292
Schmidt, 321
Schneider, 298
Schonbein, 26
Schorlemmer, 243
Schroeder, 82
Schrotter, 78
Schwarz, 72
Scott, Capt., 204
, Walter, 28
Seaborg, 178,311,326
Sefstrom, 72
Segrave, 297
Segre, 252
Selkirk, 216
Selwood, 37
Seti I, 133
Setterberg, 148
Severus, 257
Shadrach, 221
Shakespeare, 274
Sheean, 314
Shenstone, 49
Shipton, Mother, 125, 283
Siemens, 282
Simon, 68
Siva, 156, 216
Sjogren, 231
Sloane, 239
Smith, B., 124
, C. C., 209
, E. A., 116, 140
, L., 180
, R. A., 96, 270
, V. A., 264, 265

Smith, W., 73
Smithson, 158
Smythe, 204
Soddy, 43, 322-324
Solomon, 94, 112, 128 >
Sorby, 231
Soret, 26

Spencer, L. J., 58, 62
, Wm., 59
Spenser, 198
Squeers, Mrs, 72
Stahl, 22, 23, 142
Steinthor, 276
Stephen, 206
Stow, 118

Strabo, 81, 112, 133,
Stromeyer, 158
Strutt, 28, 29
Sturtevant, Simon, 279
Suter, 122
Svanberg, 231
Swan, 246
Swanhardt, 50
Swift, Dean, 113
Sylvester, 16

TACHENIUS, 69

Tacitus, 202

Tacke, 240, 250, 251

Taessert, 242

Tait, 26

Tantalus, 240

Tassaert, 292

Tavernier, 62, 65

Taylor, 37

, A. S., 209, 210

-,J., 116

Telephus, 104

Tennant, 2, 57, 303

Tennyson, 276

Thackeray, 291

Thenard, 51, 68, 69, 292

Theodelinda, 263

Theophilus, 100

Theophrastus, 214

Theseus, 268

Thomas, 282

Thompson, 287

Thomson, Thomas, 152, 326

337

NAME INDEX

Thor, 14, 234

Thorneycroft, 91, 190, 265, 273

Thothmes I, 292

III, 110,131

Tiberius, 257

Timothy, 94

Titania, 95

Titus, 192

iblkowski, 260

Tomlinson, 79

Travers, 43

Trevethick, ?13

Troost, 230

Trum?n, 321

Tubal, 10

Tut, 132

Tutankhamen, 132, 260

Twyman, 117

Tyler, 201

Tylor, 11

ULLOA, de, 300, 301
Ulysses, 267

Urbain, 179, 180, 181, 232
Urey, 37

VALLANCE, 157

Valentine, BasU, 84, 85

Vanadis, 237

Vauquelin, 154, 162, 179, 242

Venable, 231

Vernatt, 98

Verne, Jules, 300

Vernon, 104

Vespasian, 192

Vickers, 212

Victoria, Queen, 65, 106, 119, 288

Vinci, da, 21, 28

Virgil, 268

Volta, 101, 102, 143

WAINWRIGHT, 260
Waite, 85
Wakeling, 132
Walker, 8
Walton, 2
Ward, 276
Washington, 175
Watson, 254, 256

Watt, 32, 213, 291
Watts, H., 240

Wm., 196, 197
Webb, 152

- C., 281

Webster, 163

Weeks, Miss, 36

Weintraub, 69

Wellington, 209

Welsbach, 6, 173, 174, 180, 183.

184, 235
Wheelock, 191
Whiston, 128
Whitby, 104
Wilkins, 205
Wilkinson, 278
William!, 118

the Clerk, 258
William and Mary, 194
Wilson, 79

Windle, 193

Winkler, 165, 174

Winston, 164, 165

Wintrop, 239

Wirth, 232

Withering, 150

Woden, 14

Wohler, 154, 162, 237, 238

Wollaston, 301-303

Wolsey, 193

Wood, Charles, 300

WooUey, 92

Wren, 103, 194, 195

Wynter, 193

Wyrouboff, 74

XENOPHON, 188
Xerxes, 264

YARRANTON, 206
Yntema, 183
Yohe, May, 63
Yost, 178
Yspaddaden, 272
Yu the Great, 265

ZlLLAH, 10

Zimmer, 259
Zosimus, 82

338

SUBJECT INDEX

AARON Mawby, 283
Aaron's rod, 111
Actinide series, 178, 311

, electronic systems, 311
Actinium, 311, 322-4

, electron system, 311

lead, 323, 324

series, 323

, synthesis from radium, 323

Actinon, 325

Actino-uranium, 323

Addua, battle of, 276

Aerolites, 255

Aeron, 41

Affinity, 16, 215

Agincourt, 195

Air, dephlogisticated, 22

, marine acid, 46

, electrified, 26

, eminently pure, 24

, empyreal, 22

, fire, 22

, fixed, 142

, foul, 28

-, inflammable, 32

, life and, 21

, marine acid, 46

, phlogisticated, 28

thermometer, 221
, weight of, 6
Al'Ubaid, 91, 103
Alabamine, 52
Alchemists, 12

, Indian, 100, 114

symbols, 61
Alcohol, 83, 84

of Mars, 83

of sulphur, 83
Aldebarania, 180
Alkali, caustic, 143
, fixed, 142

metals, 142-148
, mild, 143

Alkali, mineral, 142

, vegetable, 142

Alkaline earths, 14&-153

Allom foyle, 160

Allotropy, 58

Alpha particles from radium, 316

Alum, Roman, 160

rock, 161

shale, 162

, Tolfa, 160, 161

trade, 160
Alumina, lime and, 162
Aluminium, 160-164
, abundance of, 7

alloys, 163, 164

bridge, 164

bronzes, 164

cooking utensils, 163
, corrosion, 164

, eka-, 171, 173

in gold, 138

, isolation, 162, 163
, uses, 163, 164

wire, 164
Alunite, 161
Alvite, 233

Amalgams, 151, 215, 303
Americium, 6, 311, 326
, electron system, 311
Amethystine glass, 248
Ammon, 30
Ammonal, 164
Ammonia, 30, 31
Andalusia, 112, 133, 187, 199
Ankh, 13

Anti-monakhos, 84
Antimonium, 83, 84
Antimony, 82-87, 93

, butter of, 85

cups, 86

in lead, 195

in type metal, 197

on copper, 93

339

SUBJECT INDEX

Antimony pills, 86
, regulus of, 86
, symbol, 86
Apothecaries' bottles, 14
Aqua suhs, 202
Arbor Diana, 114

Jovis, 203

Saturni, 194
Arcturus, 187
Argentan, 297
Argentum, 114

vtvum, 215
Argon, 41-44
, discovery, 41
, uses, 44
A*-guzoid, 297
Argyrodite, 174
Arsenic, 81, 82
, symbol, 82

transmuted to tin, 15, 19,
199

, white, 81, 82
Arsenicum album, 82
Arsenikon, 81
As, the, 95
Astatine, 52
Atmosphere. See Air
Atomic bomb, 32o

clock, 30, 31

disintegration, 315

energy, 316, 317

fission, 2, 318

number, 3

piles, 55, 321

weights, 5

Auri pigmentum, 81, 293
Aurum album, 74

paradoxicum, 74

problematicum, 74
Australia, discovery of, 125
Azote, 28

BABEL, 16
Babbitt's metal, 212
Bahn-metall, 153
Balloons, 33-36
, military, 35, 36
Barium, 151-153

Barium as plutonium, 152, 326
, electron system, 177
Barote, 150
Baryta, 150
Barytes, 150
Bastard metal, 82
Bath, Roman, 191
Bearing metal, bronze, 107

, cadmium, 159, 166

Beer, canned, 210
Bell metal, 107, 108
Bells, 107, 108
Bellyeter, 107
Bendigo Creek, 123
B.E.P.O., 321
Berkelium, 6, 327
Bermannus, 50
Beryl, 154
, caesium, 148
Beryllerde, 154
Beryllia, 181
Beryllium, 154, 155

in copper, 105

nitrate, 236
Berzelium, 234
Bewdley iron works, 206
Bible, Latin, 197

, Treacle, 86
Big neck, 49
Billiter street, 107
Birkeland Eyde process, 29
Birmingham mayoral chain, 59
Bismuth, 87, 88

turning to silver, 15
Black lead, 53

Blast furnace, 277
Bleu jaune, 50
Blonde. H.M.S., 209
Blue John, 50

powder, 157
Boadicea's chariot, 270
Bog iron ore, 19
Bomb, hydrogen, 38-40
, plutonium, 326

, uranium, 319-321
Boracic acid, 68
Bordnayles, 286
Bore, 69
Boric acid, 68

340

SUBJECT INDEX

Borith, 142

Boron, 68, 69

, eka-, 172, 173, 181

Bort, 59

Bow and arrow, 8

Brashear's process, 117

Brass, 99-101

, biblical, 9, 10, 94, 155

, Brindisi, 105

, calamine, 100

cannon, 97

cartridge, 101

coins, 99

, Corinthian, 128
, Emerson's, 100
, Indian, 100
, natural, 99

pins, 98

wire, 97
Brevium, 316
Brimstone. See Sulphur

and treacle, 72
, biblical, 9, 22, 71
, fire and, 22
Bridge, aluminium, 164
, cast-iron, 280

Forth, 284
, Tay, 284

, Zeugma, 269
Britannia metal, 212

silver, 118
Brods, 286
Bromine, 49, 50
Bromum solidificatum, 50
Bronze, 9, 10, 105-108

age, 9, 91

, aluminium, 164

cannon, 97

, Chinese, 105, 265

coins, 105, 106

, Egyptian, 93, 105, 199

gong, 96

, Japanese, 95

, Mesopotamian, 105

, natural, 91

, phosphor, 106

, silicon, 70

, uses, 105

weight, 270

Bronze, white, 213
Bronzo, 105
Brown lead, 237
Bruges belfry, 108
Bucher process, 30
Bullets, 195
Butter of antimony, 85
Buxted iron, 277

CABLE, Atlantic, 103
Cadmium, 158, 159

bearing metals, 159, 166

in copper, 104

in gold, 138

spectrum, 308
Caduceus, 13
Caesium, 146-148

beryl, 148
, eka-, 148
Caisson work, 44
Calamine, 97, 100, 158
Calcium, 149-153

, abundance, 7

cyanamide, 30

, electron system, 177
, uses, 153
Californium, 6, 327
Calx, 23

Cannon, brass, 97
, bronze, 97
, cast-iron, 277, 278
, wrought iron, 274, 278
Canterbury Tales, 275
Carat, 58, 136
Carbon, 53-67
, abundance, 7
, amorphous, 54
Carbonado, 58, 61
, Bahian, 62
Carborundum, 59
Carolinium, 234
Cassiopeia, 180
Cassiterides, 125, 200
Cassiteros, 199
Cast-iron, 277, 278

bridge, 280

cannon, 277, 278
, Roman, 269

341

SUBJECT INDEX -

Catalan furnace, 270
Celestine, 150
Centaurs, the, 268
Ceres (planet), 182
Ceria, 182-184
Cerium, 175, 176, 185, 233
, abundance, 176

alloys, 185

, electron system, 177. 233

group, 182-185
Chalcolithic age, 11
Charcoal, 8, 53

furnace, 279
Chemistry, 10
Chloride of lime, 2

separation of gold, 133
Chlorine, 46-48

, abundance, 7
, an element, 47
, as poison gas, 48
Chromite, 242
Chromium, 242, 243

plating, 243
Chrysocolla, 68
Cinnabar, 16, 215-219
Cinderford, 273
Cinderhill, 273 ,
Cire perdue, 92
Cleveite, 42

Clock, atomic, 30, 31
, water, 96, 201
Cobalt, 18, 291-293

glass, 292
Cochrome, 292
Codex Germanicus, 72
Coinage metals, 9, 89-141
Coins, aluminium, 164
, Belgian, 295

, brass, 99

, bronze, 105, 106

, Chinese, 111

, gold, 137

. nickel, 105, 106, 295, 296

, silver, 106

, Swiss, 295

, zinc, 157

Columbite, 239, 240

Columbium. 239-241

Combustion, 24

Condensed sunbeams, 13
Conversion factor, 25
Converter, Bessemer, 281
Coolgardie, 125
Cooperite, 231
Copper, 11, 12,89-112
, abundance, 7, 176
, alchemists and, 98, 99
, bible, 94
, British, 96-98
, cold worked, 104
, corrosion, 103, 104
, Egyptian, 92
, false, 293

Imgig, 91, 103

moss, 89
, native, 89

, Old Nick's, 293

, primitive metallurgy, 89. 90

, pseudo, 293

roofing, 103
, Roman, 94-96

soldering, 96, 273

springs, 99

' , Sumerian, 91
swords, 93

symbol, 13

tinning of, 205, 210, 211

uses, 101-106

- washerwoman's, 11
wet processes for, 99
wire, 97
Coracles, 201
Coral ore, 216
Cornet o museum, 140
Cornish ancestors, 201

tin miners, 203
Corona ferrea, 263
Counterfei, 156
Cretinism, 49
Critical temperature, 20
Crocoite, 242

Crown of Lombardy, 129
Crowns, golden, 129
Crucifixion nails, 263

spear, 264
Cupellation, 112-114
Cupronickels, 296
Curie, the, 314

342

Curium, 6, 311,326
, electron system, 311
Currency bars, 270, 272
Cutch, 138
Cyclonium, 185

DACTYLS, 257

Dartford iron works, 209

Davyum, 250

Days of week, 14

Dean, Forest of, 275, 279

Delhi pillar, 264, 265

Deuterium, 36-38

, uses, 38

Dhar pillar, 264

Diabolus metallorum, 203

Diamond, 55-67

, Alaskan, 61

, artificial, 58

, Arkansas, 61

, Austrian Yellow, 60, 61

, biblical, 9, 55

, black, 58, 61

, blue, 60, 62-64

, blue white, 60

, Brazilian, 56

, Bristol, 61

, Brunswick blue, 60

, Ceylon, 61

, Colenzo, 61

, Cornish, 61

, Cullinan, 61, 62

, De Beers, 62

, Derbyshire, 61

, Dresden, 60

, Excelsior, 62

, first water, 60

, Florentine, 61

, German, 61

, Golconda, 55, 56

, Great Mogul, 65

, Great White, 64

, green, 60

, Hannay's, 58

, Hope, 62-64

, Imperial, 64

, Indian, 55

, Jonker, 64

SUBJECT INDEX

Diamond, Kohinoor, 65, 66

, luminosity, 61

, Marmora, 61

, Matura, 61

, Moissan's, 58

, Mountahi of Light, 65

, pink, 67

, Pitt, 66

, red, 60

, Regent, 66

, Sanci, 66

, Saxony, 61

, Simili, 61

, Strass, 61

, structure, 59, 60

, Tennant, 61

, Tiffany Yellow, 61

, Tuscany, 61

, uses, 59

, Victoria, 64

Didymia, 183, 184

Didymium, 4

Doebereiner triads, 46, 168

Dona/ium, 234

Druids, 201

Drummond light, 235

Duralumin, 163, 164

Diirkheim, 147

Dvi-manganese, 250

Dysprosia, 181

Dysprosium, 182

, abundance, 176

, electron system, 177

Earth, an, 149
Earth goddess, 257
Earth, weight of the, 6
Earths, the rare, 175-185
Eber's papyrus, 199, 214
Egyptian screw, 134
Einstein's equation, 38, 39
Electron, 137, 152
Electrum, 134, 137, 297
Element, 1, 2, 4

No. 43, 249-252

No. 61, 184, 185

No. 75, 249-251

Elements, abundance of, 6, 7, 176

343

SUBJECT INDEX

Elements, Aristotelean, 1

, disintegration of, 2, 315-327

known to ancients, 9, 12
, radio, 311-327

, rare eaith, 4, 175-185

, transmutation, 2, i5-18, 221,

308

, transuranian, 311, 325-327
Emanium, 323
Emerald, 154
Energy, atomic, 316, 317
, mass and, 38, 39
Epsom springs, 150
Erbia, 179, 182
Erbium, abundance, 176
, electron system, 178
Ere-dwellers, the, 276
Erythronium, 237
Europia, 183, 184
Europium, abundance, 176
, electron system, 177
Euxenite, 172, 232
Excalibur, 276
Exodus, 111, 127
Eye, sensitivity, 147

FERRUM calciforme, 145
Festival of Britain, 196
Fine slapper, 115
Fire, 8, 10

air, 22

and brimstone, 22, 23

stone, 85
Fission, 2, 318
Fleurus, Battle of, 35
Flood, the. See Deluge
Florentium, 183
Fluon, 51
Fluorescence, 50
Fluorine, 50-52

, abundance, 7

oxide, 51
Fluorium, 51
Fluorspar, 50
Fosse Way, 202
Foul air, 28
Francium, 148
Franconium, 148
Frescoes, 8

Frog gold, 301

Fuel problem, 193, 194, 278-282

Furnaces, Catalan, 270

, charcoal, 279

, coke-fired, 279

, puddling, 281

Fury, H.M.S., 209

Fusible metals, 88, 159, 166, 212

GADOLINIA, 181, 182

Gadolinite, 172, 179, 180, 234

Gadolinium, abundance, 176

, electron system, 177

Galena, 108, 186, 188

, silver in, 108, 189

Gallium, 173

Galvanising, 157

Gas, 20

Gases, inert, 41-45

, permanent, 20-40

Gasmantle industry, 234-236

Geber's cooks, 16

Germanite, 174

Germanium, 173, 174

Gezer iron, 262

Gird, 307

G.L.E.E.P., 321

Gibberish, 16

Glucine, La, 154

Glucinum, 154

Goddess of levity, 33

Godless florin, 119

Goitre, 49

Golconda, 55, 56, 65

Gold, 120-141

, abundance, 7

, alchemist and, 136

alloys 137-138, 140

, amalgamation process, 215,

303

, Australian, 122-125
, biblical, 127-129
, Californian, 122
, Canadian, 125, 126

carat, 136

, chloride separation, 133

coins, 137

, colloidal, 140, 150

344

Gold, condensed sunbeams, 13
, corrosion resistance, 120, 140
' , cyanide process, 303
, Frog, 301

from base metals, 15-18
, Geber's, 16

in Bendigo Creek, 123
. central Africa, 215

dentistry, 140

Egypt, 131-133

_ Tibet, 126, 127

Transvaal, 126

Victoria, 122, 123

, Irish, 121, 122
, Japanese, 131

leaf, 138
, liquid, 140

mines, 121-127, 133, 134

of the Incas, 135

production, 141
, radio-active, 2
, rolled, 139, 140
, Roman, 133

, South African, 126

, Spanish, 133, 134

, tongue, 129

, transmutation, 15, 221, 308

, uses, 136-141

, vaporisation, 139

, Welsh, 121

, white, 138

writing tablets, 136
Golden fleece, 285, 304

penny, 137
Goldbeater, 128
Gollets, 286
Gong, bronze, 96
Grain, the, 309
Graphite, 53-55

as moderator, 321
, structure, 54
Growth of minerals, 18, 19
Gunmetal, 106
Gunpowder, 72, 106

HABER process, 29
Haematite, 19
Hafnia, 233

SUBJECT INDEX

Hafnium, 231-233

, electron system, 178, 233

Half-life, 315

Halogens, 46-52

Harpax, 72

Hastings, Battle of, 274

Haxnailles, 286

Heavy hydrogen. See Deuterium

spar, 149

water, 38
Helion, 43
Helium, 42-44

, applications, 44

from deuterium, 39

hydrogen, 39

radium, 43

uraninite, 42

Hensler's alloy, 249
Hiroshima, 321
Holme's signal, 80
Holmia, 181, 182
Holmium, abundance, 176
, electron system, 177
Holosphyrata, 134
Holyhead cannon, 278
Honda metal, 297, 298
Horseshoe Corner, 288
Horseshoes, 283-289
Hyacinth, 229
Hydrargyrum, 215
Hydrogen, 31-40

, abundance, 7
as phlogiston, 32

bomb, 38-40

, goddess of levity, 33
, heavy, 37

isotopes, 36, 37
, ortho, 32, 33
, para, 32, 33

, spin isomerism, 32
, uses, 37-40

ICARUS (planet), 93

Illinium, 183

, abundance, 176

, electron system, 177

Ilmenite, 249

Ilmenium, 249

345

SUBJECT INDEX

Imgig relief, 91, 103, 190
Imperial yard, 307
Incas, the, 135
Incoctilia, 205
Indian alchemists, 100, 114
Indium, 164-166

bearing alloys, 166
, valency, 166
Invar, 307

Iodine, 48, 49

Iridium, 303

, application, 306

Iritis* 139

Iron, 253-293

, abundance, 7

alloys, 289, 290

, bane of man, 268, 269
, biblical, 261-264

bridges, 284, 285
, cast, 269, 277-281
, Chinese, 265, 266
, Egyptian, 260, 261
, Far Eastern, 265-267

for adornment, 290, 291

from Gezer, 262
, Grecian, 267, 268
, Hebrew, 263

, Homeric, 267 <

horseshoes, 285-289

in Britain, 270-274
, Indian, 264, 265

industry, 279-282
, Japanese, 266, 267

, meteoric, 253-256, 259

nails, 283, 285-289
, native, 253

, Philistine, 262

, pre-Roman, 270-272

, primitive man and, 265

rings, 290

, Roman, 268, 269
, Saxon, 274

ships, 283, 284

swords, 275, 276

symbol, 13, 14

tinning of, 205

transmutation, 98

uses, 282, 283

virtues of, 269

Iron wedding rings, 291
, white, 210

JACINTH, 229

Jaffa, 261

Japan ware, 206

Jargon, 229

Jargonium, 231

Jaw disease, 78

Jazada, 156

Jericho, 129

Job, Book of, 187

Johannesburg, 126

Joppa, 261

Joyeuse, 264

Jupiter, 12-15, 203, 218, 224

KALTE Feuer, 77
Khem, 10
Kilogram, 309
Kimberley, 57, 60-62
Klondike rush, 126
Knockers, 18
Kobalds, 18
Kohl, 83, 84
Konarak, 265
Kopa, 12
Krypton, 43-45
Kupfer-nickel, 293

LANTHANA, 183, 184
Lanthanide series, 175-185, 311

, electron system, 177, 178,

233

Lanthanum, abundance, 176
, electron system, 177, 233
Lapis bononiensis, 76

of Babylon, 292
Larbasis, 84
Lawrencite, 256
Lead, 186-198

abundance, 7, 82

actinium, 323, 324

alchemists and, 194

atomic weight, 325

biblical, 187

black, 53

346

SUBJECT INDEX

Lead book, 189

bullets, 195
, brown, 237

, cupellation, 113
, debased silver, 187, 194
, Derbyshire, 192
, desilverising, 190
, Egyptian, 187, 188
.in Britain, 190-192
in bronze, 95
, isotopes, 324

mallets, 195

, Mediterranean, 188

, primitive metallurgy, 186

, Roman, 188, 191

roofing, 103, 194

shot, 196, 197

, silver in, 108, 189, 190
, swinging the, 195
, symbol, 13, 114
, thorium, 322

transmuted to silver, 15

tree, 114, 194

, uranium, 315, 316
, uses, 194-200

writing tablets, 187
Lepidolite, 147
Limelight, 235
Limpopo, 126
Linotype, 198
Lithium, 145, 146
Lodestone, 248, 256-258
Lucifers, 78

Luna, 114

Lunar caustic, 114

Lutetia, 180, 181

Lutecium, 180

, abundance, 176

, electron system, 178, 233

Lydenburg gold-field, 126

MABINOGION, 272, 273
Magnalium, 164
Magnes 1 stone, 256
Magnesia, 149, 152
- alba, 151

nigra, 151, 248
, town of, 256
Magnesium, 151-153

Magnesium, abundance, 7

Magnetite, 256

Magnium, 151

Manganese, 149, 248, 249

, eka-, 249

, ferro, 249

Manganin, 297

Manna, pot of, 111

Manx saw, 273

Marcasite, 87, 260

M armor metallicum, 1^9

Mars, 12-14

, regulus of, 86

Masurium, 240, 251

Match industry, 77

Matches, chemical, 77

, friction, 78

, oxymuriate, 77

, safety, 79

Mecca, 255

Menachanite, 228

Mendeleeff s system, 4, 74, 155

periodic table, 70

predictees, 168-174
Mercury, 9, 12-15, 214-221
, alchemists and, 215

, ancients and, 116

as medicine-, 216

as silver water, 215
, biblical, 116

corpse detector, 220

from gold, 221, 308

mining, 217
, native, 218

(planet), 12-15
, symbol, 16

thermometers, 223

transmutation, 2, 17
, uses, 219-221
Mesdemet, 88

Meso thorium, 322
Metal, 11
Metalloid, 68
Metalloids, the, 68-70
Metallum martis, 279
Metals, age of, 9
, bastard, 82
, dead, 24
, fusible, 88

347

SUBJECT INDEX

Meteorite, Ahnighito, 254

, Cranbourne, 256

, Descubridora, 259

, Hoba West, 253

, Mecca, 255

, Otumpa, 259

, Phrygian, 254

, Rowton, 254, 256

, Russian, 25*

Meteorites, 253-256

, biblical, 254

, Mt. Albanus, 254

, nickel in, 254

Mina, 111

Mine(s), Almaden, 217

, Clogan, 121

, Cornish tin, 18, 19, 201

, Crone-Bawn, 99

, De Beers, 57, 62

, discovery, 90

, Dollar, 313

, Gogerddan, 108

, Himmelfiirst, 173

, Idria, 218

, Jagersfontein, 62

, Kapsan, 90

, Kimberley, 57, 60-62

, Llandudno, 95

, mercury, 217

, Pierrefitte, 173

, Premier, 61, 64

, Salcedo, 199

, San Jos6, 109

, Taberg, 237

, Welsh, 18

Minerals, growth of, 18

Miners, 18, 291

, Cornish, 18, 203

, iron, 257

, Saxony, 291

, Tibetan, 19

Miners' parliament, 203

Minerva tavern, 115

Mining map, first, 133

Minium, 194, 216

Misch-metall, 185

Moderators, 320, 321

Mohar, travels of, 260 m

Moldavium, 148

Molybdaena, 243
Molybdenite, 53, 243
Molybdenum, 243, 244
Molybdos, 53, 188
Monarch of Moscow, 107
Monazite, 235
Monel metal, 296
Monksbane, 84
Mons Meg, 274, 278
Montgolfieres, 33
Moon, 13, 14
Morganite, 148
Mortar, 149
Mosandra, 180
Moseley number, 4
Mother of ore, 19
Mottled teeth, 51
Mull, 278

Murasama blades, 266
Muride, 49, 303
Museum sickness, 204
Mushet steel, 245

NAGASAKI, 326

Nails, 285-289

, chingil, 286

, crucifixion, 263, 285

, nest of, 286

, penny, 286

remedies, 287

rental, 287, 288

screw, 285

strake, 286

strokehede, 286

tre, 285

tyngyl, 286
Natron, 142
Natural alloys, 10, 294
Nayle tuUe, 286
Nayler, 285
Necrosis, 78
Neodymia, 183, 184
Neodymium, abundance, 176
, electron system, 177
Neon, 43-45
Neoytterbia, 180, 181
Neptune, 12, 325
Neptunium, 6, 250, 311, 318, 325
, electron system, 311

348

SUBJECT INDEX

New Caledonia, 299

Mexico, 320

River, 109
Niccolite, 294
Nichrome, 297
Nickel, 293-299

alloys, 296-298

as catalyst, 299

coins, 295, 296

in coins, 105, 106

meteorites, 254-256

natural alloys, 294
, occurrence, 299

plating, 298

silver, 296, 297

zirconium alloy, 231

Nigrium, 231

Niobium, 239-241

Nitre, 142

, Egyptian, 142

Nitrogen, 28-30, 41

, abundance, 7

, active, 2

, fixation, 29, 30

in air, 29

in blood, 44
, radio, 2
Nitron, 142
Noctiluca, 77
Nona, 231
Noricum, 280

)AKHAM Castle, 288

v ccupatpres, 191

)ctaves law, 168
Jg's bedstead, 262
Old Sarum, 202
Open hearth process, 282
Orpiment, 81, 82, 293
Osmium, 303
, uses, 306
Oxygen, 21-36
, abundance, 7
, discovery, 21
, isotopes, 25
, uses, 25
Oxymuriatic acid, 46
Ozone, 26-27

Ozone, structure, 27
water, 27

PACTOLUS E,, 130
Palladium, 302

in gold, 138
, uses, 305, 306
Pallas, 302
Paris, siege of, 36
Pearl ash, 142
Pelopium, 240
Penny, bun, 106
, English, 106
, golden, 137

, silver, 117, 137
Periodic law, 169

table, ideal, 4, 5, 171

, Mendeteeff's, 170

Permalloy, 297
Petalite, 145
Petroleum, 23
Pewter, 195,211,212
Pewterers, Guild, 211
Phillipia, 180

Philosopher's Stone, 17, 85
Philosophical star, 84
Phlogisticated air, 28
Phlogiston theory, 22-24
Phoenician traders, 200, 201
Phosphorus, 76-80

, abundance, 7
, Bolognian, 76
, Boyle's, 77
, English, 77
, ferro, 80
, Homberg's, 76

in bones, 77

in bronze, 106

in iron ores, 282

mirabilis, 77
, radio, 2

, red, 78, 80
, uses, 80
Phossy jaw, 78
Pigeon post, 36
Pins, 98

Pitchblende, 311-313
Planets, 12-15

349

SUBJECT INDEX

Platina del Pinto, 301

di Pinto, 300
Platinite, 297
Platinoid, 297
Platinum, 300-302

, a semi-metal, 300,^302

as catalyst, 304

gas mantles, 235

glow lamp, 501
, uses, 304, 305
Platyophttalmon ore, 83
Plumbago, 53
Plumbaria, 192
Plumbum album, 188

antimonii, 84

candidum, 188

nigrum, 188
Pluranium, 304
Pluto, 72

Plutonium, 6, 152, 311, 318, 326

bomb, 326

, electron system, 311
Poculum emeticum, 86
Polinium, 304
Polonium, 313, 316
Polluxite, 147, 148
Pontypool iron ware, 207

japan ware, 207

tin plate, 207
Portus Magnus, 203
Potassium, 144

, abundance, 7
Pound, the, 309, 310
, Troy, 309
Powder of Algaroth, 85
Praseodymia, 184
Praseodymium, 183
, abundance, 176
, electron system, 177
Predynastic graves, 132
Priestley's statue, 21
Procurator metallorum, 191
Prometheum, 185
Protactinium, 311, 323
, electron system, 311
Pt&ie, 303

Ptolemaic system, 14
Puddlers 1 candles, 281
Puddling furnace, 281

Pulvis angelicus, 85
Punic wars, 217
Pyrolusite, 46, 248

QUEEN Mary, 316, 317

of metals, 108
Quicksilver. See Mercury

RlOl, 35
Radioelements, 311-327

gold, 2

tellurium, 316

thorium, 322
Radium, 313-316

, abundance, 7, 314

amalgam, 314
-r- an element, 4

, conversion to Ac, 323

C, 316

D, 316

F, 316

G, 315

, half-life, 315
Radon, 43, 324, 325
, medical uses, 325

needles, 325

seeds, 325

Rare earths, 4, 175-185

, abundance, 176

, electron systems, 177, 178

233

Ratsbane, 81
Realgar, 81
Red lead, 194, 216
phosphorus, 78, 80

schorl, 228
Reduction, 24
Regulus of antimony, 86
Mars, 86

_ Venus, 87
Rhenium, 240, 250, 251
Rhodium, 302, 303

plating, 114, 305
Rifle, invention of, 282
Roads, Roman, 202
Rontgen rays, 3, 312
Rowton meteorite, 254, 256
Rubidium, 146-148

350

SUBJECT INDEX

Ruthenium, 250, 304
Rutile, 228

SAL anglicum, 150
sedativum, 68
Samaria, 183, 184
Samarium, abundance, 176
, electron system, 177
C^marskite, 179, 180
Samothracian rings, 257
Samurai blades, 259, 266
Sandarake, 81
Saturn, 12-15, 194
, scythe, 13, 194
Saturnine red, 194
Sauerstoff, 25
Saxon chronicle, 274
Scandia, 172, 182
Scandium, 172, 173
, atomic weight, 173
, electron system, 177
Scheelite, 244
Schorl rouge, 228
Scourge of God, 276
Screw nails, 285
Selenion, 73
Selenium, 72, 73
Serpek's process, 29
Sharplinges, 286
Sheffield plate, 116, 117

steel, 280

Shekel, Babylonian, 129

, Hebrew, 111, 129

Sherardising, 158

Shiner, 121

Ship halfpenny, 106

Ship, Aaron Mawby, 283

, Florida, 278

, Great Dragon, 283

, Mary Rose, 278

, Normandie, 290

, Queen Mary, 316, 317

, Triomphante, 284

Ships, iron, 283-284

Shoder, 138

Shot, lead, 196, 197

tower, 196
Siderites, 255
Siderolites, 255

Signatures, doctrine of, 76, 293
Signet star, 84
Silicon, 69, 70
, abundance, 7

bronze, 70

, eka-, 17, 174

steels, 70 *
Silver, 108-120
, abundance, 7

, alchemists and, 114
, biblical, 110-112
, Britannia, 118

coins, 106, 117-9

"cord", 112

corrosion resistance, 119
, cupellation, 113

, debased, 187, 194
, Egyptian, 110-H2
, electroplating, 139

in copper, 89

galena, 108

lead, 108, 189, 190

Peru, 90

, liquid, 214

mines, 108-110

mirrors, 116, 117

pennies, 117, 137

plate, 116, 117

, quick. See Mercury

, refining, 112

, Roman, 112, 113

, Saxon, 118, 137

, separation from gold, 133

solders, 120
, symbol, 13

treaty tablet, 110

tree, 114

, untarnishable, 166
, uses, 114, 115

water, 215

Silvering mirrors, 116, 117, 220
Slapper of ale, 115
Slough murder, 102, 103
Small people, 18
Smith, the, 274
Smithsonite, 158
Soap bubbles, 23
, Hebrew, 142
Sodium, 144

351

SUBJECT INDEX

Sodium, abundance, 7

Solder, 120, 212, 213

, decay, 204

Solomon's temple, 128

Soret's X, 182

South Wales tinplat;, 210

SparabilisJ, 286 < +

Speculum metal, 213

Spelter, 156

Spialter, 156

Spiauter, 156

Spider, the, 289

Spiegel iron, 249

Spin isomerism, 32

Spinel ruby, 242

Spinelising, 164

Sporadic iron age, 260

Spykynges, 286

Stagmum, 188

Stainless steel, 243

Stalloy, 70

Stamps, perforation, 282

Standard measures, 306-310

Stannary worker, 203

Stannum, 188

Steam hammer, 208

SteeU basic, 282

, cement, 280 r

, Chinese, 266

, cobalt, 245, 292, 293

, copper in, 107

, Homeric, 267

jewellery, 290

, magnet, 245, 292, 293

, manganese, 249

, nickel, 297

, nickel-clad, 295

, Roman, 268

, silicon, 70

, stainless, 243

, tempering, 267

, true as, 275

Stellite, 243, 245, 292

Sterilisation of food, 208-210

Sterling, 118

Stibi, 84

Stibium, 83

Stone ages, 8

Strontia, 150

Strontium, 151

, abundance, 7

, electron syscem, 177

Sudbury ores, 298, 299

Sulphur, 9, 22, 71, 72

, abundance, 7

candle, 72

- , disinfectant, 71, 72

, essence of fire, 22

mercury theory, 15

, symbol, 71

Sun, 12-14

, temperature, 39

Sussex; iron, 273, 277, 280

Swords, 259, 275, 276

, copper, 93

, Homeric, 267

, Japanese, 259, 266, 267

, Viking, 276

Symbols of alchemists, 13

TAKKET, 286
Talent, 111, 129
Tantalite, 239, 240
Tantalum, 239-241
, eka-, 323
, electron system, 178
Tantra Rasahridaya 1 14

Rasaratnakara, 100

Rasarnava, 156, 219
Tarshish, 112, 133, 187, 199
Technecium, 252
Technicum, 252
Telegraph, first, 102
Telluric screw, 169
Tellurium, 73-75

, atomic weight, 74

breath, 75

isotopes, 75
Temple, Solomon's, 128
, sun, 135
Teputzli, 11

Terbia, 179-182
Terbium, abundance, 176
, electron system, 177
Terra molybdana, 244

ponderosa, 150

vitrescibilis, 69
Terre du Beril, 154

352

SUBJECT INDEX

Terre ochroite, 182

Thallium, 166, 167

Theriac, 85

Theriaka, 86

Therion, 86

Thermit, 164

Thermometer, 221-227

, air, 223

, Centigrade, 226

, Fahrenheit, 226

, invention, 221

, linseed oil, 227

, mercury, 223

, Newton's, 225

, Reaumur's, 226

, Roemer's, 225

, spirit, 223

, water, 222

Thorite, 234, 235, 324

Thorium, 234, 311, 321, 322, 324

D, 322

, electron system, 311

lead, 322
, meso, 322

series, 322
, radio, 322

X, 322
Thoron, 325
Thulia, 181, 182
Thulium, abundance, 176
, electron system, 178
Thunderbolts, 254
Tibet, 126

Tin, 198-214
, abundance, 7, 176
, alchemists and, 203
, allotropy, 204

amalgam, 220

, biblical, 9, 10, 199
, British, 200-203

cans, 209, 210
, Chinese. 199
, Cornish, 18, 201
, cry of, 203

, debased silver, 198
, Egyptian, 199

foil, 211

from arsenic, 199

islands, 125, 200

Tin, Nigerian, 213

on copper, 205, 210, 211

pest, 204

plague, 204 '

plate, 205-210
, Roman,) 199

, sources, 213, 214

tree, 203
Tincal, 68
Tinken, 198
Tinker, 198
Tinned food, 209, 210
Tinsel, 198
Titanium, 228, 229
, abundance, 7

, cupro, 229

, ferro, 229

, mangano, 229

Transmutation, 2, 15-19

, a felony, 18

Transuranic elements, 311, 325-

327

Travancore sands, 235
Travorsnailles, 286
Treacle bible, 86
Trenail, 285
Triacleur, 86
Triads, 46, 16C; 169
Tritium, 37
Tungsten, 244-247
, ferro, 245

filaments, 246
Tungstic acid, 245
Turdetania, 133
Turey, 256
Turin candles, 78
Tylepynnes, 268
Type, lino, 198

metal, 197

ULCO, 153
Ur, 103
Uralium, 250
Uraninite, 42
Uranium, 311-313

bomb, 319

chloride, 312

, electron system, 311
, fission, 185

353

SUBJECT INDEX

Uranium, fluorescence, 312

G, 315

, half-life, 316
isotopes, 318

lead, (U5, 316

series, ,31 5
Uranus, 12, 312
Uriconium, 273

VALLEY of Kings, 132
Vanadinit?, 237
Vanadium, 237-239

alloys, 239
Vapour, 20
Varech, 48

V f enta belgarum, 202
Venus, 12-15
, looking glass, 98
, regulus of, 87
Verdigris, 104
Vermilion, 216-218
' , adulteration, 219
, antiseptic, 218
, Chinese, 219
, Hindoo, 219
Viking swords, 276
Virginium, 148
Voltaic battery, 1*)2, 143

pile, 102, 143

WARTS, cure for, 287
Wasium, 234
Waste wax process, 92
Water, composition, 32

clock, 96, 201

, decomposition, 143
, heavy, 38

of purification, 214

power hammers, 97
, silver, 215
Watts's folly, 197
Wedding rings, 137
Weld decay, 229
Whitby shales, 162
White arsenic,

bronze,

gold,

iron, 21C

metal,

White metals, 159, 166
Whittle, 281
Wire drawing, 97
Wirksworth, 192, 193
Wismat, 88
Witherite, 150
Woden, 14
Wolframite, 244-246
Wolverhampton Old Hall, 207
Wood's metal, 88, 159, 166
Wookey Hole, 81, 271

ox shoe, 289

witch, 271
Worcester tin plate, 206
Wotton hoard, 96

X-rays, 3, 312
Xenon, 43-45
, dizziness, 44

YARD, standard, 106, 306-308
Ytterbite, 179, 181
Ytterbia, 181
Ytterbium, 180
, abundance, 176
, electron system, 178, 233
Yttrium, abundance, 176
, electron system, 177

group, 179-182
Yttrotantalite, 240
Yukon R., 126

ZARNICK, 81
Zeugma bridge, 269
Zimapan, 251
Zinc, 155-158
, Chinese, 156

coins, 157

confused with bismuth, 156

dust, 157

fume, 157

in coins, 99, 100
,. Indian, 156
Zinkum, 156
Zircon, 229, 234
Zirconium, 229-231
, ferro, 230

nickel alloy, 231
Zirnuk, 81

354