An Encyclopedia of the History of Technology part 25 potx

PART ONE: MATERIALS
222
Progress) patented the making of sulphuric acid by burning sulphur and
saltpetre in the necks of large glass globes containing a little water. That was
converted to sulphuric acid, concentrated by distilling it. The price fell from £2
to 2s a pound, but the fragile nature of glass limited the scale of the process.
Largescale manufacture only became possible when John Roebuck substituted
lead chambers’, consisting of sheets of lead mounted on wooden frames, lead
being both cheap and resistant to the acid. Roebuck, a student of chemistry at
Leyden and Edinburgh set up his lead-chamber process outside the latter in
secrecy, a condition that lasted as long as it usually does. Knowledge of the
process spread rapidly; France had its first lead-chamber factory at Rouen
around 1766. The process was improved and enlarged in scale; Roebuck’s
chambers had a capacity of 200ft
3
(5.66m
3
) but by 1860 Muspratt had
achieved one of 56,000ft
3
(1584.8m
3
). The rise in scale of course lowered the
price; by 1830 it was 2 1/2d a pound.
The first stage of the Leblanc process produced large quantities of
hydrochloric acid gas, both poisonous and destructive. Not for the first or last
time, the chemical industry made itself unpopular by its unfortunate
environmental effects. In this case, from 1836 the gas began to be absorbed by
a descending stream of water. The Alkali Act of 1863 required manufacturers
to absorb at least 95 per cent of the acid. Important as the Leblanc process
was, it had other drawbacks, principally the problem of disposing of the

unpleasant ‘galligu’ or residue after the soda had been extracted. This led to a
long search for an alternative and the gradual emergence of the ammonia-soda
process, which eventually achieved success at the hands of the Belgian brothers
Ernest and Alfred Solvay, with a patent in 1861 and satisfactory working four
years later. It was introduced into Britain in 1872 by Ludwig Mond, who set
up a works at Winnington in Cheshire in partnership with John Brunner
which was to become part of Imperial Chemical Industries.
Improvements were also made in the utilization of the hydrochloric acid
formed in the Leblanc process. Henry Deacon oxidized it to chlorine using a
catalyst (a substance that facilitates a reaction but can be removed unchanged
at the end of the reaction). Also, Walter Weldon introduced the successful
oxidation to chlorine using manganese dioxide, which enabled the output of
bleaching powder to be quadrupled, with a considerable reduction in price.
A new method of producing sulphuric acid had been suggested in 1831, by
oxidizing sulphur dioxide to the trioxide using a platinum catalyst, but the
platinum was found to be affected or ‘poisoned’ by the reaction and progress
came to a halt. There was then little incentive to solve the problem, until the
new organic chemical industry in the 1860s began to make demands for not
only more but stronger sulphuric acid. So far, the only source of oleum, a form
of strong sulphuric acid with an excess of sulphur trioxide, had been
Nordhausen in Saxony, where it had been produced in limited quantities since
the late seventeenth century. The contact process, as it came to be called, was
THE CHEMICAL AND ALLIED INDUSTRIES
223
revived and at the hands of the German Rudolf Messel became, from around
1870, a practical proposition. The Badische Anilin- und Soda-Fabrik (BASF)
was very active in pursuing research into this process. Various catalysts were
tried, but from 1915 BASF used vanadium pentoxide and potash, and this
became the most widely used material.
Explosives

Another important branch of the chemical industry was the manufacture of
explosives (see Chapter 21). Until the middle of the nineteenth century, the only
important explosive was gunpowder, but in the 1840s two other substances were
noted. Schönbein found that the action of nitric acid on cellulose produced an
inflammable and explosive substance and with John Hall at Faversham began to
make gun-cotton, so called because cotton was the source of cellulose. In the
same year nitroglycerine was discovered, formed by the action of nitric acid on
glycerine, a product of soap manufacture. But these two substances were found
to be too explosive to make or use. Alfred Nobel, however, showed that
nitroglycerine could be made by absorbing it on kieselguhr, a kind of clay; in this
form it was called dynamite. It was found that it would explode violently when
touched off by a mercury fulminate detonator. In 1875, Nobel invented blasting
gelatine, consisting of nitroglycerine with a small quantity of collodion cotton.
The first application of these materials was in blasting in mines and quarries;
their use in munitions became important in the 1880s.
Fertilizers
A less destructive application of the chemical industry was the manufacture of
fertilizers. Apart from carbon, hydrogen and oxygen, there are three elements
needed in relatively large quantities for plant nutrition: nitrogen, phosphorus and
potassium. Until the end of the nineteenth century, the most important source of
nitrogen was natural organic materials, but mineral sources were also important.
Of these, by far the most significant were the sodium nitrate deposits in Chile,
providing some 70 per cent of the world supply. By the 1960s this figure had
shrunk to 1–2 per cent. The reason for the decline was the successful tapping of
the richest source of nitrogen of all: the air we breathe. The ‘fixation’, or
chemical combination, of nitrogen was known to be chemically feasible by the
end of the eighteenth century and from around 1900 several processes had been
developed on an industrial scale. But by far the most important of these was that
worked out by Fritz Haber. It consisted of the synthesis of ammonia from its two
constituent elements, nitrogen and hydrogen. The reaction had been studied

spasmodically for many years but it was Haber who transformed it into an
PART ONE: MATERIALS
224
industrial proposition. High pressures were at first avoided, but Haber found
during his researches from 1907 to 1910 that a pressure of 200 atmospheres
produced the highest yield. At that stage BASF once again entered the scene and
engaged in research to find the most suitable catalyst. In 1913 the first full-scale
plant for the synthesis of ammonia by the Haber process was built at Oppau,
with a second at Leuna, near Leipzig three years later. By 1918, the process
contributed half of Germany’s output of nitrogen compounds. Hostilities with
Germany hindered the spread of knowledge of the process and it was only in the
1920s that manufacturing plants were set up in other leading industrial countries.
Progress was then rapid and by 1950 fourfifths of nitrogen fixation was by this
process. The catalyst most widely used from 1930 was finely divided iron mixed
with various oxides. Nitrogen fixation became important not only for the
production of ammonium sulphate and nitrate fertilizers but for the manufacture
of nitric acid, much in demand before and during the wars for making
explosives.
As to phosphorus, the main source until around 1900 was ground bones or
bone meal, but in the last decades of the nineteenth century large deposits of
calcium phosphate were discovered in northern Africa and, later, other major
producers were the USA, USSR and the Pacific island of Nauru. The calcium
phospate is converted to ‘superphosphate’ by treatment with sulphuric acid,
first achieved on a large scale from 1834 by John Bennet Lawes at Rothamsted
in Hertfordshire. ‘Triple superphosphate’, or monocalcium phosphate
produced by treating the mineral form with phosphoric acid, attained equal
importance with the ‘super’ variety in the USA in the 1960s.
Potassium fertilizers (potash), mainly potassium chloride, have been applied
as they were mined, the Stassfurt region in Saxony being the leading source for
some 130 years.

Electrolysis
An entirely new way of producing chemicals arose towards the end of the last
century. Electricity had been used to decompose substances, for example by Sir
Humphry Davy in 1807 in obtaining sodium metal for the first time, but it was
not until cheap supplies of electricity were available that electrolytic methods of
preparing chemicals became commercially viable. In 1890 an American
working in Britain, Hamilton Castner, developed a method of producing
sodium by electrolysis of molten caustic soda, for use in the making of
aluminium. At the moment of success, an electrolytic method of preparing
aluminium was achieved by Hall and Héroult (see pp. 107–9), rendering the
sodium superfluous. But relief was at hand. The ‘gold rushes’ of the 1890s
dramatically increased the demand for sodium, in the form of its cyanide, used
in the purification of gold and silver.
THE CHEMICAL AND ALLIED INDUSTRIES
225
Castner then worked out a cell for making high-purity caustic soda, by
electrolysis of brine over a mercury cathode and carbon anodes. The sodium
released formed an amalgam with the mercury which, by rocking, came into
contact with water in a central compartment; there, it reacted with the water to
form caustic soda. An Austrian chemist, Carl Kellner, was working along
similar lines and to avoid unpleasant patent litigation, the two came to an
arrangement, with the result that the cell is known as the Castner-Kellner cell.
The Castner cell was later modified, particularly by J.C.Downs’s patent of
1924, defining the electrolysis of molten sodium chloride with graphite anode
and surrounding iron gauze cathode, and using calcium chloride to lower the
melting point of the electrolyte. This was a more efficient process electrically,
although until 1959 both cells were in use, to provide cheap sodium. Other
heavy chemicals were made by electrolytic methods from around 1900, such as
sodium chlorate, much used as a herbicide.
FURTHER READING

Chandler, D. and Lacey, A.D. The rise of the gas industry in Britain (Gas Council, London,
1949)
Clark, J.A. The chronological history of the petroleum and natural gas industries (Clark Book Co,
Houston, Texas, 1963)
Douglas, R.W. and Frank, S. A history of glassmaking (G.T.Foulis, Henley-on-Thames,
1972)
Haber, L.F. The chemical industry during the nineteenth century (Clarendon Press, Oxford,
1958)
—— The chemical industry 1900–1930 (Clarendon Press, Oxford, 1971)
Hardie, D.W.F. and Pratt, J.D. A history of the modern British chemical industry (Pergamon
Press, Oxford, 1966)
Kaufman, M. The first century of plastics (Plastics Institute, London, 1963)
Longstaff, M. Unlocking the atom: a hundred years of nuclear energy (Frederick Muller,
London, 1980)
Nef, J.U. The rise of the British coal industry (Routledge, London, 1932)
Russell, C.A. Coal: the basis of nineteenth century technology (Open University Press,
Bletchley, 1973)
—— ‘Industrial chemistry’ in Recent developments in the history of chemistry (Royal Society of
Chemistry, London, 1985)
Singer, C. et al (eds.) A history of technology, 7 vols., each with chapters on industrial
chemistry (Clarendon Press, Oxford, 1954–78)
Taylor, F.S. A history of industrial chemistry (Heinemann, London, 1957)
Warren, K. Chemical foundations: the alkali industry in Britain to 1920 (Clarendon Press,
Oxford, 1980)
Williams, T.I. The chemical industry past and present (Penguin Books, Harmondsworth,
1953)
—— A history of the British gas industry (Oxford University Press, Oxford, 1981)


PART TWO

POWER AND
ENGINEERING



229
4

WATER, WIND AND
ANIMAL POWER

J.KENNETH MAJOR
The three main forms of natural power have a long history of development, and
since classical times the development of water and wind power has been
interrelated. The use of all three forms has not ceased, for water and wind power
are gradually coming back into use as alternatives to the fossil fuels—oil and coal —
and to nuclear fission. The need to develop rural communities in the Third World
has brought about a rediscovery of the primitive uses of water, wind and animal
power which can remain within the competence of the rural craftsmen.
WAT E R P OW E R
The ancient world
The first confirmed attempts to harness water to provide power occurred in the
Fertile Crescent and the countries that border the eastern Mediterranean, in
the centuries before the birth of Christ. The harnessing of these natural forms
of power grew out of the difficulties of grinding grain by hand or raising water
for irrigation laboriously by the bucketful. Slaves were not cheap, and the
milling of enough flour by hand became increasingly expensive. At first the
grain was ground by being rubbed between two stones known as querns. The
grain would rest on a stone with a concave upper face and would be rubbed

with a large smooth pebble. The next stage was to shape a bottom quern and
to have a top stone which matched it and which could be pushed from side to
side over the grain. By making both upper and lower stones circular, and by
fixing a handle in the upper stone, a rotary motion was imparted to the hand
quern. From that it is a short step to mounting the quern on a frame and
having a long handle to rotate the upper millstone.
PART TWO: POWER AND ENGINEERING
230
The first attempt to power millstones with water resulted in a form of
watermill which we now call the Greek or Norse mill (see Glossary). In this
the two millstones—derived from rotary hand-processing—were mounted over a
stream with a high rate of fall. The lower millstone was pierced and mounted
firmly in the mill, and the upper (runner) millstone was carried on a rotating
spindle which passed through the lower millstone. This spindle was driven by
a horizontal waterwheel which was turned by the thrust of water on its blades,
paddles or spoon-shaped buckets. The stream was arranged, possibly by
damming, to give a head of water, and this head produced a jet of water which
hit and turned the paddles of the horizontal waterwheel. The horizontal
watermill was a machine, albeit primitive, which ground grain faster than it
could be ground by hand, and soon improvements began which further
increased the speed of grinding.
The Romans adopted the Greek mill and made the hand mill more profitable
by turning it into a horse-driven mill. Roman Europe became a civilization in
which the countryside supported a growing number of larger towns. The use of
slaves or servants to grind the grain for the family became too expensive, and
there was a real need to increase the production of meal from the millstones. The
often-quoted example of the range of ass-driven hourglass mills in Pompeii (see
p. 262) shows how a town bakery was able to produce large quantities of meal
for sale or for a baker’s shop. The Romans are thought to have been the
inventors of the vertical waterwheel. In this system a waterwheel is turned in a

vertical plane about a horizontal shaft and the millstones are driven from this by
means of gear wheels. About 25 BC Vitruvius wrote De Architecture, and in the
tenth book he describes the vertical waterwheel and its gear drive to the
millstones. The earliest form of mill in which a single pair of millstones is driven
by a waterwheel is therefore known as the Vitruvian mill.
Many examples of the Vitruvian mill have come to light in archaeological
excavations. The most famous of all the Roman Vitruvian mills is the group at
Barbegal near Arles, in the Bouches-du-Rhône department of France. Here an
aqueduct and channel delivered water to a chamber at the top of a steep slope.
The water descended in two parallel streams, and between the streams there
were the mill buildings. There were sixteen overshot waterwheels in two rows
of eight, the water from one wheel driving the next one below it. This example
from c. AD 300 shows a sophistication in millwrighting design which typifies
the Roman approach to many of their problems of engineering and
architecture. There are representations of vertical waterwheels in Byzantine art
and in the Roman catacombs. By Hadrian’s Wall in 1903, Dr Gerald Simpson
excavated a Roman watermill which dates from c. AD 250. Lord Wilson of
High Wray prepared drawings of this which were published in Watermills and
Military Works on Hadrian’s Wall in 1976. Similar and more important
excavations, carried out in Rome in the 1970s by Schiøler and Wikander, show
how universal the spread of the Vitruvian mill was in the Roman period.
WATER, WIND AND ANIMAL POWER
231
Further archaeological evidence confirms the presence of Roman watermills in
Saalburg, near Bad Homburg in Germany, and Silchester, Hampshire.
The Romans and their colonials were among the first people to dig mines for
metals. In some of these deep mines there was a need to install mechanical water-
raising devices and in the mines at Rio Tinto in south-west Spain a substantial
water-lifting wheel has been found. While this is not strictly a waterdriven wheel it
is analogous. The large rim carries a series of wooden boxes which have side

openings at the upper ends. The wheel is turned by men pulling on the spokes and
the boxes lift the water so that it empties out at high level into a trough which leads
it away from the wheel. This wheel is one form of water-raising device and its
derivatives still exist in parts of Europe and the Near East. The best-known
examples are those at Hama in Syria, where waterdriven wheels carry containers
on the rim which raise the water to the top of the wheel where it empties out into
irrigation channels. The biggest of these is 19.8m (65ft 6in) in diameter.
Mediaeval and Renaissance Europe
As a result of archaeological excavation, the Dark Ages are now producing
examples of water-powered devices, and more attention is being paid to these
examples. At Tamworth in Staffordshire the excavation of a watermill shows
evidence of a well-designed mill of the Saxon period. These excavations
revealed that the mill had been powered by two horizontal waterwheels housed
in wooden structures.
The mediaeval period gives us our first real insight into the growth of water
power in Europe. In England, the Domesday survey of 1086 gives a record of
the number of mills in England—some 5000. While all the counties in the
country were not surveyed, those that were show a surprising number of mills
in relation to the manors, villages and estates. It must not be taken for granted
that all the mills were water driven: hand mills may be indicated by the low
level of their rents. Similarly, it must not be assumed that the mills were
separate buildings, just that there was more than one waterwheel. The
documents, cartularies, leases and grants of land give a greater insight into the
way in which the use of water power was developing. All over Europe the
abbeys, manors and towns were building watermills, and while most of these
were corn mills, there is evidence of the construction of fulling mills, iron mills
and saw mills. For example, the most famous drawings of a saw mill were
made by Villard de Honnecourt in 1235. A mill built to his drawings was
erected as a monument to him at Honnecourt sur Escaut, France. In this mill
the waterwheel rotated as an undershot or stream wheel, and by means of

cams the reciprocal motion was given to the saw blades. Although it cannot be
assumed that this was the first saw mill, it is the first positive document
showing the mechanism to have survived.