An Encyclopedia of the History of Technology part 11 ppsx

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Haug & Co, who found the business so profitable that they began to consider
the prospect of further co-operation with the English Crown. A preliminary
survey of Britain’s mineral resources by Daniel Hochstetter in 1563 revealed
favourable prospects, and in 1564 substantial deposits of silver-bearing copper
ore were found at Keswick in Cumbria.
In September 1564 the initial Patent for working copper ores in Britain was
granted jointly to Daniel Hochstetter and Thomas Thurland, Master of the
Savoy. The organization thus established, formally incorporated in 1568 as the
Company of Mines Royal, was the first joint stock company to be set up in
England for the manufacture of a commodity (copper) rather than for trading
purposes only. From the legal controversies stimulated by the grant of a Royal
monopoly for a ‘new method of manufacture’, patent law as we now know it
emerged, evolved and refined itself.
A sister metallurgical enterprise, established in 1565, was the Society of
Mineral and Battery Works. It was a specialist organization, concerned with
the manufacture of brass and wire, and owed its existence largely to the
enterprise of Sir William Humfrey, Assay Master of the Mint. Humfrey’s
partner in this venture, Christopher Schutz, an expert in brass manufacture,
was the manager of the calamine mining company of St Annenberg, Saxony.
‘Battery’ was the name originally applied to all sheet metal utensils which had
been formed into the shape required by beating with a hammer. By the
eighteenth century the term applied specifically to beaten hollow ware of brass
or copper. Before Humfrey, who was one of the original shareholders in the
Mines Royal Company, applied to Lord Cecil for the privilege of introducing
‘battery works’ into England all the brass required was imported from Europe.
A further object of the Mineral and Battery works was to introduce
improved methods of wire drawing into England, where the wool trade was
then rapidly expanding and large quantities of fine brass and iron wire, needed
for the manufacture of wool carding equipment, were imported from the

Continent.
The Society’s Patents, granted in September 1565, gave Schutz and Humfrey
the sole rights to mine calamine and to make brass in England. They were also
authorized to work mines and minerals in any of the English counties not
already under the jurisdiction of the Mines Royal Company. By June 1566
calamine deposits were discovered at Worle Hill in Somerset, at the western end
of the Mendips on land belonging to Sir Henry Wallop. Zinc ore from this
deposit contained less lead and was superior in quality and yield to that which
was currently imported from Aachen. A brass manufacturing site was sought
within easy reach of the Mendip hills. The partners eventually erected their
manufacturing plant along the Angiddy Brook at Tintern, where lead and
copper working had been carried out on a small scale since mediaeval times.
Schultz estimated initially that his works would produce 4ocwt (2032kg) of
iron wire and 20cwt (1016kg) of brass wire per week. This output was never
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achieved, and not until the end of 1567 was any brass at all produced at
Tintern. Although of the right colour, indicating that it contained the
appropriate amount of zinc, it lacked ductility and could not be drawn into
wire. An innovation introduced by Schultz had been the use of pit coal rather
than charcoal as fuel for the cementation furnaces, and it has been suggested
that the sulphurous fumes thus introduced embrittled the brass as they did
iron. In 1569, Humfrey and Schultz gave up their manufacturing endeavours
and leased the Tintern works to a man experienced in drawing iron wire.
Brass manufacture was in fact completely ignored until 1582 when a group
of merchants headed by Sir Richard Martyn bought the rights to mine
calamine and make brass for the sum of £50 per annum. The factory they set
up at Isleworth, west of London, made brass of excellent quality for a number
of years under the managership of a London goldsmith, John Brode. The
manufacturing operation became very profitable, and when Brode refused to

provide the Society with details of his manufacturing processes, they revoked
his licence and drove him into bankruptcy. In 1605, Brode appealed against
the decisions of the Society to the House of Lords, claiming that he was ‘the
first here in England that co-mixed copper and calamine and brought it to
perfection to abide the hammer and be beaten into plates, kettles and pans by
hammers driven by water’. This was probably perfectly true.
After this failure brass sheet and battery ware was imported from Europe so
cheaply that few British brass-making enterprises managed to survive. Since
the death of Daniel Hochstetter in 1581 the mining activities of the Mines
Royal Company at Keswick had steadily declined. After the Civil War the
industry declined very rapidly indeed, since Parliament refused either to
reduce the duty on imported copper or to protect English manufacturers
against the importation of cheap imported brassware. After 1650 hundreds of
tonnes of high grade zinc ore were shipped to the Meuse valley and other
European brass-making centres to be turned into brassware, subsequently to be
sold in English markets at prices well below that of the domestic product.
When the Society of Mineral and Battery Works became aware of the extent
and profitability of this illicit commerce they did not attempt to restrict it,
finding it more expedient to impose royalties, of the order of five shillings on
each ton of the ore exported. By the 1680s it had become very evident that the
privileges granted to the Mines Royal Company and to the Society of Mineral
and Battery Works had been exercised in a repressive manner to the detriment
of the non-ferrous industry. The Crown monopoly on metallurgical mining
rights was finally abolished in 1689 when the Mines Royal Act was passed.
Further legislation passed in 1693 enabled manufacturers to participate freely
in metallurgical activities.
The British non-ferrous metal industry began to revive in the 1670s, when
development work by Sir Clement Clarke at his lead works at Stockley Vale in
Bristol led to the use of coal-fired reverberatory furnaces firstly for refining
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lead, and then in 1687 to the refining of copper. John Carter, a protégé of
Clarke, subsequently went into partnership with a group of London merchants
headed by William Dockwra to establish in 1692 the Copper Works of Upper
Redbrook, north of Tintern on the River Wye, where deposits of copper ore
had recently been discovered.
Dockwra had in 1691 become the proprietor of a brass works at Esher in
Surrey which had initially been set up in 1649 by Jacob Mummer, a German
immigrant. At Esher, brass made by the cementation process was cast into
stone moulds to produce flat ingots weighing seventy punds. These were then
rolled to sheet, slit, drawn to wire and finally made into pins. The copper for
the Easher brass works came from Upper Redbrook, then being profitably
managed by John Carter. A rival copper refinery, the English Copper
Company, was established soon afterwards at Lower Redbrook, only a short
distance downstream. In its early days, copper refining operations at Lower
Redbrook were controlled by Gabriel Wayne, who, like John Carter, had
formerly been employed by Sir Clement Clarke. Wayne, however, soon
perceived the limited opportunities for expansion along the River Wye, and in
1696 he set up a new copper refinery at Conham, on the banks of the River
Avon two miles to the east of Bristol, where the water was still navigable. His
business associate in this enterprise was the merchant Abraham Elton. The
improved reverberatory furnaces built at Conham owed much to the earlier
Clarke developments and to the practical lessons learned at Lower Redbrook.
The sulphide copper ores used at Conham were shipped directly ip the
Avon from Cornwall and also from North Molton in Devon. After the ores
had been roasted at Conham they were melted with lime in a reverberatory
furnance to remove silicious impurities. The iron and sulphur remaining in the
purified matte thus attained was then gradually removed by reverberatory
melting under oxidizing conditions until crude copper in metallic form began
to separate from the melt.

At that time Bristol was a very logical centre for metallurgical activity, since
it also offered a port from which metal products could be exported to all parts
of the world, and locally mined coal was available at prices very much lower
than eleswhere in the country. The decision to produce brass at Bristol was
made in 1700 by Abraham Darby, Edward Lloyd and several other
businessmen who were all Quakers of Bristol. Copper was being locally
produced on a large scale by three competing refineries, and William
Dockwras’s works at Esher was the only brass-making establishment in
England worthy of note. Darby was a manufacturer of malt mills, while
Edward Lloyd was a cidermaker, and both these activities involved the
extensive use of brass fittings and components.
Around 1703, it appears, Darby went to Holland, hired some Dutch or Low
Country workers and set up the Brass Works at Baptist Mills. This was
situated on the River Frome about 2.5km north-east of the point where this
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tributary emerges into the Avon. Darby’s immigrant workers seem to have
been skilled in casting large thin slabs of brass into flat granite moulds and in
the manufacture of hollow ware and other brass utensils by standard battery
procedures. In the early days at Bristol the ingots were beaten into sheet by
hammering and in this respect the activities at Baptist Mills were technically
behind those at Esher where brass had been rolled into sheet for a considerable
time. The Bristol enterprise flourished, however, and by 1708 an additional
mill had been set up on the River Avon at Keynsham.
In 1707, Darby had begun to appreciate the potentialities of cast iron. He
withdrew from the brass company in 1708 and acquired an established blast
furnace at Coalbrookdale, where in 1709 he demonstrated for the first time,
the feasibility of making iron of high quality by using coke rather than charcoal
as fuel for the blast furnace (see p. 153ff). The indications are, therefore, that
Darby was the man responsible for the use of coke rather than charcoal in the

brass works at Baptist Mills, to avoid sulphurous contamination of the metal
from raw coal, and that he introduced the practice of turning the coal into coke
by roasting it in the brass furnace itself during the preliminary stages of brass
making. Between 1710 and 1712 over 400 cartloads of coal per week were used
by the Bristol Brass Works.
In September 1709, as the Company for Brass and Battery Work at Bristol,
they combined with their former competitors, the proprietors of the Brass Wire
Works at Esher, to form the Societies of Bristol and Esher for making Brass,
Battery and Brass Wire. Compared to the Bristol establishment, the works at
Esher were small, and here the production of wire was concentrated. Brass
sheet and battery ware were produced at Bristol. By 1712, Baptist Mills were
producing 255 tonnes of brass a year, well in excess of the 210 tonnes then
being imported from Europe. Between 410 tonnes and 540 tonnes per year of
copper were then being produced in Bristol by two large copper refineries,
both situated on the River Avon. The site at Crew’s Hole, half a mile
downstream from the Conham works, had been established by the Bristol
Brass Company to ensure their own requirements of copper which increased
greatly after their amalgamation with Esher.
In the early 1720s, Henric Kahlmeter of the Swedish Board of Mines visited
England and reported that the two copper refineries at Bristol and those at
Upper and Lower Redbrook were the ‘most considerable’ of those he had
seen. By that time the four companies were working as a loose form of trade
association to run a group of copper mines in Cornwall and Devon. By
working together and refusing to buy copper ore until prices fell the group was
able to obtain its supplies from primary producers at very low terms.
The brass works at Bristol were then being managed by Nehemiah
Champion, a man of considerable technical ability. In 1723 he applied for
and obtained Patent No. 454 which was concerned with the preparation of
copper used for the manufacture of brass by the calamine process.
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86
Champion’s leap forward was to use granulated copper rather than broken
fragments. By this approach, which greatly improved the surface-to-volume
ratio of the copper, the uptake of zinc during cementation increased from 28
to 33 per cent, approaching the level which is now known to be the
theoretical maximum possible by cementation. Since copper was the most
expensive component of the alloy, Champion’s approach gave him an
important commercial advantage over his competitors, and helped to ensure
the prosperity and growth of his works.
The calamine brass process
The brass cementation process used at Baptist Mills did not differ
significantly in principle from that used by the Romans. Fairly
comprehensive details of the brass-making processes used during the
sixteenth century were given in 1574 by Lazarus Ercker, a native of
Annaberg in the Saxon Erzgebirge, and Chief Superintendent of Mines in the
Holy Roman Empire. The cementation process he describes differs from that
of Theophilus and Pliny in that alum and salt were added to the copper/
charcoal/calamine mixture charged into the crucible. After smelting in eight
small pots, the brass was transferred to a large crucible and cast into ingot
moulds of large flat ‘Britannish Stone’. It is interesting to recall that small
quantities of salt were found in the zinc retorts of Zarwar (see p. 77).
The Swedish brass-making techniques described by Swedenborg in 1734
were virtually identical to those outlined 160 years previously by Ercker, with
the exception that neither salt nor alum were added to the charge. The copper
and calamine were still melted in eight small crucibles, the combined contents
of which were then cast into sandstone ingot moulds.
In 1720, Kahlmeter reported that the thirty-six brass-making furnaces in
operation at Baptist Mills were grouped into six separate brass houses, which
were worked as required to produce 305 tonnes of brass per year. As in
Ercker’s and Swedenborg’s descriptions, cementation was effected in eight

small crucibles of Stourbridge clay, which were inserted into each circular
furnace and emptied twice every twenty-four hours. The calamine used by
Champion was carefully calcined to convert it from the carbonate to the oxide
and was then ground into a fine powder before being incorporated into the
cementation charge. Apart from the use of water granulated copper, the main
technical innovation introduced by Champion appears to have been in the way
the cementation furnaces were arranged in groups of six under large brick
covers similar to those used in the glass industry. This formation, which
provided improved draught and ventilation, was commonly adapted when
brass making moved from Bristol to Birmingham towards the end of the
eighteenth century.
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William Champion and his zinc metal process
Nehemiah Champion’s youngest son, William, visited most of the industrial
centres of Europe before returning to Bristol in 1730 at the age of twenty.
Metallic zinc was then being imported from the Far East at prices around £260
a ton, too costly for the manufacture of battery brass, although it was in great
demand for manufacturing those brasses of low zinc content and attractive
golden colour used for making cheap jewellery. It was also used for making
brazing alloys containing 40 per cent or more of zinc which could not be
obtained by cementation. William Champion’s immediate objective on
returning from Europe was to produce metallic zinc from English calamine at a
price low enough to allow it to be used for routine brass manufacture.
His early work soon showed that zinc oxide could only be reduced by
carbon at very high temperatures, so that the zinc obtained left the reaction
zone in vapour form and oxidized to a blue powder as soon as it made contact
with air. The essence of his reduction process, which required six years of
‘great expense, study and application’ before success was achieved, was to
condense the vapour rapidly to metal in the complete absence of air. To do this

he used a vertical retort and, as can be seen from Figure 1.7(b), the equipment
he evolved is remarkably similar in its geometry and general arrangement to
the vertical zinc retorts used at Zawar in the fourteenth and fifteenth centuries.
An iron tube led from the base of the reaction crucible to a cold chamber
below the floor, its end being sealed by immersion in a bowl of water. This
ensured that the zinc vapour did not encounter significantly oxidizing
conditions before it condensed and settled as granules below the water surface.
The reaction crucibles, approximately 1m high, and Qocm in diameter, were
arranged in groups of six in each furnace. The distillation process took about
seventy hours, during which time around 400kg (882lbs) of zinc were obtained
from the six retorts.
William Champion encountered some opposition from his colleagues, and
he was dismissed from his old firm in 1746. Between 1738 and 1746 he built a
new factory for zinc manufacture at Baber’s Tower in Bristol, where he was
able to produce 205 tonnes (200 tons) of metallic zinc. This, he found, was
virtually unsaleable, since the merchants who imported zinc from the Far East
dropped their prices and seemed quite prepared to lose £25 per ingot ton in
their efforts to drive him out of business. Moreover the city fathers of Bristol
had complained about the fumes emitted by his Baber’s Tower factory which
he was forced to demolish. He then built a new large works at Warmley, five
miles to the east of Kingswood. In complete contrast to the fragmented
operations of the old Bristol Company, the Warmley plant was intended to be
completely integrated, co-ordinated facilities for copper smelting, zinc
distillation and brass manufacture being arranged on the new site. In 1748 the
factory at Warmley was in full production. Copper ore was brought from
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Cornwall, refined on the site and granulated in water for the manufacture of
brass by cementation according to the original patent of William’s father
Nehemiah. For the manufacture of ingot moulds, William seems to have

departed from tradition in using granite slabs rather than sandstone.
The zinc distillation process was carried out at Warmley under conditions
of great secrecy, and it was not until 1766 that the processes involved were
described by Dr Watson in his Chemical Essays. The Warmley plant grew
rapidly, and further capital was raised in 1761 for the erection of 17 new
copper refining furnaces. In 1765 the Warmley Company began to
manufacture brass pins on a large scale. By 1767, when the fortunes of the
Warmley plant were at their peak, the pin-making operation, which was
probably undertaken in the old Clock Tower building was in full operation,
and the works at Warmley housed two large rotative steam engines.
Figure 1.7 (a): Methods of zinc production.
Zinc production by the process of Tyryakpatnayantra, or ‘distillation by
descending’ is described in the thirteenth-century Hindu alchemical work, Ras
Ratnasammuchchaya. This recommends that the retort should be charged with
ingredients such as lac, treacle, white mustard, cherry plum, resins, borax, salt
and zinc ore.
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Following petitions by his competitors to the Lords Committee of the Privy
Seal, Champion’s application for a Charter of Incorporation was rejected in
March 1768. This decision destroyed the Warmley Company, since it made it
impossible to raise the capital required for continued operation by the issue of
transferable shares. Following an unauthorized attempt to withdraw some part
of his share capital from the company, Champion was dismissed by his fellow
directors in April 1768. He was declared bankrupt in March 1769, when the
works at Warmley were offered for sale. These were eventually acquired by the
Bristol Brass Company but never extensively used.
Figure 1.7 (b): Methods of zinc production.
When William Champion introduced his version of this process in Bristol in
1738 his crucibles were charged merely with a mixture of calcined calamine and

charcoal.
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90
The decline and fall of Bristol brass
The demise of the Warmley Company was soon followed by that of the ‘Old
Bristol Company’, which had been largely responsible for its failure and
destruction. The four brass companies which had prevented William
Champion from obtaining his Charter of Incorporation were led by the Brass
Battery, Wire and Copper Company of Bristol as it was then known. The
others were John Freeman and Copper Company of Bristol, Thomas Patten
and Coy of Warrington, and Charles Roe and Copper Company at
Macclesfield. Brass manufacture represented only a small part of the total
activities of John Freeman and Company. Together with the Bristol Brass
Company, however, Thomas Patten and Charles Roe produced most of the
brass used in Great Britain.
Bristol had, in fact, begun to lose its predominance as the centre of copper
and brass production in 1763. In the autumn of that year, Charles Roe of the
Macclesfield Copper Company first sensed the possibilities of the copper ore
deposits of Parys Mountain in Anglesey, and leased part of it from Sir Nicholas
Bayly. Extensive bodies of rich ore were found in 1768 and rapidly exploited.
The remainder of the Parys Mountain complex was soon being worked by the
Warrington Copper Company under Thomas Patten, and the Parys Mine
Company which in 1780 opened its own smelting works at Ravenshead in
Lancashire.
Thomas Williams, the solicitor who led the Parys Mine Company was a
man of energy and vision who recognized soon after he joined the industry
that the Anglesey copper ore, being abundant, close to the surface and easily
worked, could be sold very cheaply at prices which would make the Cornish
Figure 1.7 (c): Methods of zinc production.
The horizontal zinc retort process, introduced by the Abbé Dony in 1807, was far

simpler and more economical to operate. Most of the zinc produced in Europe
and the United States between 1820 and 1940 was made in this way.
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mines unviable. By that time the old Bristol Company had relinquished its
earlier control of the copper mines in Devon and Cornwall and bought the
copper ore needed by its smelting works on the open market. With Parys
Mountain copper, Thomas Williams became the major producer and found
himself able to control the copper market. Bristol was forced to increase the
price of brass, a move which antagonized many customers and had particularly
unfortunate consequences in the Birmingham area.
Birmingham began to emerge as a centre of brass fabrication at the
beginning of the eighteenth century, and the vast quantity of brassware it
exported to the Continent was discussed by Daniel Defoe as early as 1728.
Much of the brass worked on there was initially imported from Europe,
although by the middle of the century it was all obtained either from Bristol or
from Thomas Patten at Cheadle in North Staffordshire. A small brass-making
factory was established at Coleshill Street in Birmingham in 1740 by the
Turner family. By 1780, Birmingham consumed about 1000 tonnes per annum
of brass, most of which came from Bristol. By then, however, the Birmingham
fabricators were beginning to resent the high price of the brass they bought
from Bristol and the attitude of Brass Battery, Wire and Copper Company
(derisively referred to as the ‘OC’, or ‘Old Company’) which protected its
monopoly by controlling brass prices in such a way that any new brass
manufacturers in the Birmingham area were soon forced out of business.
A public attack on the brass manufacturers cartel, which was headed by the
Old Company, was mounted in the autumn of 1780, when, according to Aris’s
Gazette, the Birmingham fabricators ‘boldly stood forth the Champions of
Industry, and in Defiance of Oppression, ventured to erect Works and risque
their Fortunes therein’. The result of this campaign was the formation of the

Birmingham Metal Company, set up in April 1781, initially under the aegis of
Matthew Boulton, although he shortly afterwards resigned from the
committee. The first action of this company was to negotiate with Thomas
Williams for a regular supply of copper on very advantageous terms.
Bristol, therefore, rapidly lost its hold on the Birmingham market and its
fortunes dwindled. In 1784 the lease Charles Roe had taken at Parys Mountain
expired and Thomas Williams then assumed control of the whole copper
mining complex of Anglesey. The Bristol Brass Company had encountered
serious difficulties during 1786 and the joint proprietors resolved in December
of that year that the business should be dissolved and terminated. The firm at
that time was owned and managed largely by the Harford family, and in
February 1787 the firm was sold for £16,000 to ten Bristol merchants, six of
whom were Harfords.
Relationships between the Cornish and Anglesey mining concerns had,
meanwhile, stabilized. Thomas Williams had been requested by the Cornish
Metal Company to market their vast stocks of unsold copper, a task which he
accomplished by 1790 without any reduction in copper prices. He also