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How Chemistry Changed the World
From: Cambridge University Press
| By:
Colin Russell |
EDITOR'S INTRODUCTION |
The influence of the science of chemistry on the course of history is rarely acknowledged. In fact, public perceptions of chemistry today are almost as ill-informed as they were when chemistry was identified with magic and alchemy. Yet, as Colin Russell of the UK's Open University maintains, without chemistry the Industrial Revolution--and with it the many social benefits still enjoyed today--would not have been possible. |
 he time when chemistry started to make a really large-scale impact on society may be identified as the middle of the eighteenth century. Until then there had been a continuous history of the extraction of metals, purification of alum and a few other common minerals, the manufacture of pigments and paints and the production of vinegar and of a handful of natural drugs purified by the art of the apothecary or druggist. How far they can readily be called 'chemicals' and how far the rudimentary theory behind their manufacture was properly called 'chemistry' must be a matter of debate. Just about the time when Europe was priding itself on its 'Enlightenment' and the French Revolution was imminent, some strange chemical production processes were being scaled up to such an extent that people could hardly avoid noticing them. |
 In the Midlands of England and in the Clyde valley in Scotland several entrepreneurs were beginning to make sulfuric acid on a considerable scale, by atmospheric oxidation of moist sulfur dioxide in large though fragile glass globes and later in vast air-cooled chambers made of the acid-resistant lead. At about this time Liebig made his famous remark that the consumption of sulfuric acid is a barometer of a nation's commercial prosperity. Much was needed for a new process for making soda, for which the vital raw material was sodium sulfate, made by the time-honoured reaction
H2SO4 + 2NaCl = Na2SO4 + 2HCl 
The soda was made by a process invented by Nicholas Leblanc and summarized by the equation
Na2SO4 + CaCO3 + 4C = Na2CO3 + CaS + 4CO |
The Industrial Revolution
Meanwhile something else was happening. Towards the end of the eighteenth century British society, though exempt from the political upheavals of revolutionary France, was to experience a convulsion no less dramatic and far-reaching. It was, in fact, shaken to its very foundations by what we now call the Industrial Revolution. Most obviously this was an explosion in the production of textiles made possible by the mechanization of such processes as spinning, carding and weaving. The new technology was powered at first by water-wheels and later by steam. There were unprecedented changes in demography with a rural society accepting urbanization on a huge scale. The movement of people, and still more of raw materials like coal and iron, called for vastly improved means of transport and the canals of the eighteenth century were followed by the railways of the nineteenth. These increased still further the pace of social transformation of early Victorian Britain. Less than 20 years elapsed between the opening of the Stockton and Darlington Railway in 1825 and the rise of the Railway Mania, in which speculation went wild in an attempt to cover the country in a network of railways, a pattern that was closely followed overseas. In addition to the rise of great industrial towns, especially in the north, there came about an increase in the mobility of individuals and families, the rise of the seaside holiday and the emergence of a new and militant working class. |
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| Antoine Lavoisier and his wife. | |
In all these revolutionary changes to society it has not been customary to regard chemistry as having made a significant contribution. Indeed, most elementary textbooks of modern British history do not even mention it and it is usually ignored in more advanced treatments of economic and social history. Yet the fact is that recent scholarship has demonstrated beyond doubt that chemistry was not merely an important, but even a critical, determinant in the rise of an industrial society. The eighteenth century saw the demise of the old phlogiston theory and its replacement by the modern (oxygen) theory of combustion. Paradoxically, one of the most famous casualties of the French Revolution, Antoine Lavoisier (who was guillotined in 1789), played a principal part in establishing what is now often called 'the chemical revolution'. However, certain other developments took place at this time, just as important and having a more obvious impact on society. These have also been termed a 'chemical revolution' and amply chronicled by Archie and Nan Clow in their classic book of that name. They involved the rise and rapid growth of the heavy chemical industry. At its heart lay the manufacture of soda, sulfuric acid and chlorine. |
As the rate of production of textiles soared, it became woefully evident that problems that had so far been minor irritants were now to threaten the success of the whole enterprise. These were the processes of washing and bleaching the fabrics. Hitherto they had been conducted in a manner so extravagant in its use of labour, land and time that the inefficiencies could be tolerated only on a very small scale. |
Textiles and techniques
Washing is needed at many stages of the production of textiles, particularly that from animal raw materials like wool. For this purpose soft soap (from potash) is less suitable than its sodium counterpart. This had been made from soda, which until the eighteenth century was usually produced by ignition of barilla, a form of sea-weed whose harvesting from the coasts of northern Britain was a long and labour-intensive operation. The discovery of an alternative source, by Nicholas Leblanc, came in the nick of time at the end of the century. It became possible to use this 'synthetic' soda to satisfy the huge demands of the textile manufacturers so that from 1800 to 1850 the production of hard soap in Britain rose from almost nothing to nearly 21 million tonnes per year. Use of such soap for personal hygiene was at first on a relatively minor scale, though eventually it doubtless contributed much to the health of the general population. Important early manufacturers included Pears of London (1789), Crosfield of Warrington (1815) and Gossage of Widnes (1857). |
 Fabrics needed not only to be clean. Most of them needed to be white, even if they were later coloured by dyestuffs. The bleaching of cloth by traditional means was to moisten it with sour milk, spread it out in the open air ('bleach fields') and leave it there for several months to be slowly bleached by whatever direct sunlight there might be. Again, at the end of the century, chemistry produced the first economic alternative. This was to use chlorine, a bleaching agent recognized by Berthollet that reduced the duration of the process from months to minutes and released for other purposes acres of land in the countryside around textile factories. A modification, introduced by Charles Tennant, was to make bleaching powder from the chlorine, thus allowing the material to be transported easily from its place of manufacture. |
It is thus apparent that chemistry played an absolutely critical role in the early phase of the Industrial Revolution. Some 60 years later synthetic dyes were introduced, thereby displacing such natural raw materials as madder, the indican plant, woad and so on and increasing still further the dependence of the textile industry on chemistry. Soda was also used to make glass (by fusion with sand). A series of fiscal measures to raise revenue from the more opulent owners of buildings led to the Window Taxes, the last of which was not repealed until 1845. So the chief outlet for soda-based glass was in clear glass bottles, but, as the nineteenth century advanced, the large northern mills were able to glaze their windows, thus allowing production to continue in all weathers. As the Clows observed: |
It is difficult to decide whether manufacture of glass for windows or for glass containers had the greater effect on the trend of western civilization. |
To make soda and chlorine one needed sulfuric acid on a large scale and, as we have seen, this was available at precisely the time when the Industrial Revolution was getting into full swing. From the 1840s it became needed additionally for the manufacture of superphosphate fertiliser, a calcium acid phosphate. The effect of this on agriculture was comparable to that of chlorine on the production of textiles. Above all, sulfuric acid, or its derivative hydrochloric acid, became necessary for the 'pickling' of iron before it was fabricated into a multitude of engineering artefacts and structures. This was essentially the removal of covering layers of oxide. |
Conclusion
Merely to take these three chemicals, it is not hard to grasp that the immense technical advances of the early nineteenth century would have been utterly impossible without them. As the century advanced the role of chemistry became ever more important and obvious. Yet it is truly remarkable that so many histories of this period make no mention of the fundamental fact that, had there been no prior Chemical Revolution, the Industrial Revolution could not have taken place and with it the ensuing social and political changes that have transformed our world. |
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