Industrial revolution
Watt’s rotary steam engine was being perfected just at the same
moment that iron-working improved and textile inventions were becoming more
powerful, greater in size, sizeable and in need of better, cheaper, and more
reliable power sources. The new steam engine could be harnessed to all these
new inventions. In 1782, the year after Watt perfected the rotary steam engine,
there were only two cotton mill factories in Manchester. Twenty years later
there were more than 50.
INNOVATION AND INDUSTRIALIZATION
The textile industry, in
particular, was transformed by industrialization. Before mechanization and
factories, textiles were made mainly in people’s homes (giving rise to the term
cottage industry), with merchants often providing the raw materials and basic
equipment, and then picking up the finished product. Workers set their own
schedules under this system, which proved difficult for merchants to regulate
and resulted in numerous inefficiencies. In the 1700s, a series of innovations
led to ever-increasing productivity, while requiring less human energy. For
example, around 1764, Englishman James Hargreaves (1722-1778) invented the
spinning jenny (“jenny” was an early abbreviation of the word “engine”), a
machine that enabled an individual to produce multiple spools of threads
simultaneously. By the time of Hargreaves’ death, there were over 20,000
spinning jennys in use across Britain. The spinning jenny was improved upon by
British inventor Samuel Compton’s (1753-1827) spinning mule, as well as later
machines. Another key innovation in textiles, the power loom, which mechanized
the process of weaving cloth, was developed in the 1780s by English inventor
Edmund Cartwright (1743-1823).
Developments in the iron industry
also played a central role in the Industrial Revolution. In the early 18th
century, Englishman Abraham Darby (1678-1717) discovered a cheaper, easier
method to produce cast iron, using a coke-fueled (as opposed to charcoal-fired)
furnace. In the 1850s, British engineer Henry Bessemer (1813-1898) developed
the first inexpensive process for mass-producing steel. Both iron and steel
became essential materials, used to make everything from appliances, tools and
machines, to ships, buildings and infrastructure.
The steam engine was also
integral to industrialization. In 1712, Englishman Thomas Newcomen (1664-1729)
developed the first practical steam engine (which was used primarily to pump
water out of mines). By the 1770s, Scottish inventor James Watt (1736-1819) had
improved on Newcomen’s work, and the steam engine went on to power machinery,
locomotives and ships during the Industrial Revolution.
Chemicals for Textiles
Output of wool and cotton cloth grew
substantially in the late 18th and early 19th centuries as a result of the
mechanisation of the textile industry and the needs of the expanding
population.
In the earlier days the cleansing and
bleaching of cloth was achieved by the processes of bucking (soaking in alkali
for a week), souring (soaking in buttermilk for a week), and crofting (exposing
the cloth for several weeks to sunshine and rain in bleachfields on
south-facing slopes).
In the late 18th
century sulphuric acid for souring, and chemical bleaching (initially using 4
chlorine in caustic alkali and, later, bleaching powder) came to be used; the
use of chemicals speeded up the whole process considerably and reduced the
amount of working capital tied up in unfinished goods. (‘Bleachfield’ on the
University of York campus was a crofting site and by about 1850 a bleachworks
stood there).
In addition to the direct use of alkali more
was needed for the manufacture of soap (production of which, mainly for textile
use, rose from about 1500 tons in 1785 to over 50000 tons in 1830). Still more
alkali was needed for glass manufacture, production of which for windows in
housing increased as a further consequence of the population explosion.
The Leblanc Process
The process was a
messy batch process. Salt was treated with sulphuric acid; the resulting ‘salt
cake’ (sodium sulphate) was mixed with limestone and coal (or, better, coke)
and roasted to produce ‘black ash’ – an impure mixture of sodium carbonate and
calcium sulphide: 2NaCl + H2SO4 J Na2SO4 + 2HCl Na2SO4 + CaCO3 + 2C J Na2CO3 +
CaS + 2CO2 The sodium carbonate was extracted with water and the solution was
evaporated to dryness in open pans; if necessary for higher purity (e.g. for
glass manufacture), the product was recrystallised. The operation of the
Leblanc process was environmentally noxious. In the early days the acid fumes
from the initial stage was vented to the atmosphere, and the smelly residual
wet sludge from the black ash extraction stage was dumped. The emission of HCl
fumes was a nuisance to neighbours in spite of the palliative use of tall
chimneys (as high as 145 m at St Rollox), and litigation was frequent. Gossage
introduced scrubbing towers in 1836 and they were increasingly used to absorb
the descending water streams. Their use became general after the passing of the
1863 Alkali Act which made the absorption of at least 95% of the acid fume
obligatory; the Act also set up an Alkali Inspectorate to enforce the measure.
Initially the acid absorbate was often discharged to rivers but it came to be
recognised as a useful source of chlorine for absorption in lime (CaO) to make
bleaching powder, a product 5 introduced by Tennant in 1799. The chlorine
required for this purpose was released from the hydrochloric acid solution by
heating with the mineral pyrolusite (MnO2) 4HCl(aq) + MnO2 J Cl2 + MnCl2 + 2H2O
Partially successful efforts were made by Gossage as early as 1837 to
regenerate the scarce manganese dioxide by: 2MnCl2 + 2Ca(OH)2 + O2 J 2MnO2 +
2H2O + 2CaCl2 But it was not until the 1860s that the recovery process was
perfected by Weldon who used excess lime. Also in the 1860s the Deacon process
for catalytic oxidation of gaseous HCl and Cl2 (using CuCl2 catalyst) came into
use. Using these processes the manufacture of bleaching powder as an adjunct to
alkali manufacture became firmly established in the 1860s and bleachfields
disappeared. The dumping of the sulphide sludge was not only environmentally
offensive, it represented the total loss of sulphur from the sulphuric acid
produced by the lead chamber process which played a key role in the alkali
industry. However, effective recovery of sulphur from the sulphide waste lay in
the future. Originally the sulphur came from Sicily but in 1838 the price of
the raw material doubled owing to monopolistic behaviour; within a very short
time the mineral pyrite (FeS2) was substituted; it was roasted in air to
generate sulphur dioxide: 4FeS2 + 11O2 J 8SO2 + 2Fe2O3 And the iron oxide byproduct
was disposable to iron works. Another source of sulphur of importance later on
was ‘spent oxide’ from gasworks which could also be used in the pyrite burners.
The Ammonia-Soda Process
The process, essentially involving the
reaction of carbon dioxide with an ammonia-saturated solution of salt, was
first proposed by Fresnel (better known for his work on optics) in 1811.
Various attempts were made in Britain (Thom in Scotland 1836, Muspratt in the
1840s, Deacon 1856) to achieve a workable process but all were on a small scale
and none was really successful. The effective establishment of an economic,
large-scale process was achieved in Belgium in 1865 by Solvay who overcame the
engineering problems of gas handling and absorption. A licence for the
exclusive operation of the process in Britain was acquired in 1872 by Mond who,
with Brunner, started a works in Cheshire in 1874. In the meantime some variants
of the Solvay process were also established in England but were later taken
over and shut down by Brunner, Mond & Co. The full process comprised a
number of stages: CaCO3 J CaO + CO2 (1) CaO + 2NH4Cl J CaCl2 + 2NH3 + H2O (2)
2NH3 + 2H2O + 2CO2 J 2(NH4)HCO3 (3) 2(NH4)HCO3 + 2NaCl J 2NaHCO3 + 2NH4Cl (4)
2NaHCO3 J Na2CO3 + H2O + CO2 (5) giving the net reaction: CaCO3 + 2NaCl J
Na2CO3 + CaCl2 (6) Stages (3) and (4) were operated in a continuous cycle. In
principle, the ammonia was not consumed and only top-up quantities were
required; the only waste product was the calcium chloride which, being soluble,
could be discharged to drain. The ammonia-soda process prospered and production
of soda increased rapidly. Although more capital-intensive than the Leblanc
plants, it was less labour-intensive, more economical in use of raw materials,
and had no serious waste problems. It presented a serious economic challenge to
the Leblanc alkali industry and it was to be the soda process of the future. In
the 1870s the Solvay process was not only established in England but also in
the now unified Germany and the post-civil war USA, countries that had never
had Leblanc plants and had been significant export markets for Britain.
Consequently, British exports of alkali declined. For the Leblanc producers the
competition was intense. But the mostly small producers using the Leblanc
process (of whom there were now a fairly large number) fought back. For a while
they had the advantage that most of their plants were fully depreciated whereas
the large ammonia-soda plant had to bear heavy capital servicing 8 charges.
Also, of considerable importance, they had the very big advantage of being able
to sell the byproduct bleaching powder. They exploited this advantage further
by forming the Bleaching Powder Association in 1883 to operate a cartel (which
was quite legal in those days) to keep prices up. They also appreciated the
need for cost-saving and thoughts turned to sulphur recovery.
Dyestuffs
As noted earlier the synthetic dyestuffs
industry started in 1857 with the manufacture of aniline dyes by Perkin. In the
decades to follow, the range of synthetic dyes was extended considerably as
great advances were made in organic chemistry – incidentally Kekulé postulated
his ring structure of benzene in 1865, the year Hofmann returned to Germany.
One dye of importance was alizarin, obtained from the plant madder which was
very extensively used still in 1870; methods of alizarin synthesis were devised
in 1868/69 by Gräbe and Liebermann in Germany and by Perkin in England, and
commercial production started in both countries in the 1870s – on a larger
scale in Germany. It was from this time that the German industry expanded
rapidly with profits from alizarin manufacture an important source of finance
for dyestuffs research and development; this factor, together with the greater
availability of trained chemists in Germany compared with Britain, soon made
Germany pre-eminent in synthetic dyestuffs production (Switzerland also became
an important dyestuffs-producing country from the 1870s as a result of the
establishment there of émigré producers from France escaping patent
restrictions!). Thus Britain suffered a relative decline in the dyestuffs field
even though there was expansion of production here too – some of it by German
and Swiss firms. Britain actually became a net importer of synthetic dyes.
