Lacking a means of identifying substances correctly, the early chemists could be so confused about them as sometimes to use the same name for different substances, such as ‘nitrum’, which could mean both sodium carbonate and potassium nitrate. On the other hand, different names could unwittingly be used for the same substance: ‘vitriolated tartar’ and ‘vitriolated nitre’ were both used at times for more or less impure potassium sulphate, apparently with no awareness that the substances so designated were essentially the same. Inability to identify materials made it impossible to evaluate them, that is, to determine how much of them was present. Finding out what and how much is the object of chemical analysis and not surprisingly it arose in connection with those materials that could be recognized, namely the metals, particularly gold and silver. The printed books on the assay of metals which began to appear early in the sixteenth century are evidence of a practical tradition in the quantitative evaluation of gold and silver. But for other materials it was hit or miss. The ironworker, for example, had no way of knowing whether he had extracted all the iron from a charge of ore. Very likely more than half would have been left in the refuse or slag, so that later workers often found it worth while to rework them. As for determining the quality of the product, if the customer was satisfied, that was enough; there was no other criterion.
Not understanding what was going on, the artisan found it difficult to regulate his processes and distinguish significant from irrelevant factors. Adding a new ingredient one day, or giving the mixture a good stir, might appear to have improved the result and the new procedure would have passed into timehonoured practice until somebody accidentally omitted it without adverse effect. Nobody would have known or even asked why the new procedure seemed to work. There was thus no understanding of the effects of temperature, pressure and all the other conditions that are now known to influence chemical changes. Temperature was in any case difficult to control. The mainly charcoal-fired furnaces were awkward to regulate and things could easily get out of hand, as illustrated by the explosive mishaps that befell the alchemists of Chaucer and Ben Jonson. The poor quality of many of the reaction vessels was also a hindrance and led to much waste. Considering all the handicaps, it is indeed remarkable that such a range of useful materials was produced with an acceptably high quality. It was all achieved by craftsmen relying on skill of eye and hand gained through years of practice and inherited from generations of work in the industries concerned.
All this was to change dramatically within a relatively short space of time. The idea of increasing natural knowledge gained from observation and applying it to industry or the useful arts developed during the seventeenth century. The Fellows of the Royal Society, from its foundation in 1662, took a considerable interest in industry and made some useful suggestions for improvements in chemical processes. One of the founder members, the Hon. Robert Boyle, sharply criticized the prevailing ideas in chemistry and urged that it shed its disreputable alchemical connection and apply the concepts of the new mechanical philosophy. This criticism lacked precision, however, and a further century was to elapse before a chemical theory was established which actually corresponded with reality, at the hands of Antoine-Laurent Lavoisier from around 1780. The processes involving oxygen, such as combustion, were correctly explained, the nature of acids, bases and salts was put on a sounder footing, and in particular a clear definition of a chemical element was not only stated but usefully applied to draw up the first list of elements in the modern sense. A beginning was made in chemical analysis and after 1800 great improvements were made in quantitative analysis. Soon after 1800 rules for the way in which elements combined to form compounds were first enunciated, and with the atomic theory of John Dalton, chemists could visualize and explain chemical reactions in terms of the ultimate particles forming the basis of all matter.
Early beneficiaries of the chemical revolution were the manufacturers of cheap sulphuric acid, caustic soda, and chlorine for the textile industry. Developments in the industry gathered pace, informed by discoveries on the theoretical side. The nineteenth century was the era of pure and applied chemistry. The pure chemist was concerned to advance chemical knowledge for its own sake, irrespective of its possible practical use. The applied chemist, meanwhile, was employed to improve the processes for producing commercially useful substances, seeking new exploitable materials and, above all, in chemical analysis to monitor processes and the quality of products. Too often the two kinds of chemist worked in isolation from each other, the former being blissfully unaware of the needs of industry and the latter prevented from carrying out research that did not show an obvious profit. This division of role has, however, become increasingly blurred with the growth from the beginning of this century of the great chemical firms: indeed, the terms ‘pure’ and ‘applied’ chemistry can be said to belong to a bygone age. Improved contacts between the universities and industry make the former’s research departments more aware of problems in industry, while much research in industry is in areas wider than those for which there is an immediate cash return. In addition, in most industrialized countries the state sponsors research and itself carries it out, in government laboratories, and without rigidly restricting its attention to problems of public concern. It is a melancholy fact that, in Britain, state, industry and the universities combined to deal with common needs never so effectively as in the two world wars. The production of the first atomic bomb is the prime example of such co-operation on an international scale.
By and large the chemical industry in the developed countries has been in the hands of private commercial firms and, however altruistic some of their activities may be at times, the ultimate reason for a process or product to be developed is that it will make a profit. It is worth noting that this profit is the source of funds for research by the state and the universities whether by direct sponsorship or indirectly through taxes. Because of the successful and systematic application of theoretical chemistry, first in inorganic then in organic chemistry and physical chemistry, especially the mechanism of reactions, the range of substances which the chemical industry has produced for man’s use, with ever-improving quality, has been truly remarkable. The comparison with several millennia of near stagnation makes the progress of the last two centuries all the more striking. In 1800 the chemical industry was important, but on a small scale, its products limited to metals, acids, alkalis, pigments, tan-stuffs, medicines and a few other chemicals, some made on a scale not much greater than in the laboratory.
Now the scale is vast, yet the industrial chemist exercises a precise control over the processes to yield an exactly predictable result. The source of this progress has been research. Sometimes progress has come by directing research to solving a particular problem, such as making a substance with certain required properties. But the more fruitful source has been to apply discoveries not made with a particular practical end in view. An example of the first is presented by Alfred Nobel and his intention to make nitro-glycerine a safe explosive. In the course of this he invented dynamite and blasting gelatine (see p. 223). But the more remarkable discoveries have been those that were not intended. Thus Perkin, while trying to synthesize quinine lighted on something quite unexpected, the first aniline dye, mauve—which led to a whole new industry. An example of the deliberate application of the results of pure research can be seen in the hydrogenation of oils to make fats like margarine, stemming from the study of the catalytic hydrogenation of unsaturated compounds in the presence of a metallic catalyst by Sabatier and his colleagues around 1900. Until then, the production of margarine, invented in 1869 by the French chemist Hippolyte Mège Mouriès, had been limited by the availability of raw materials, but the hydrogenation process enabled almost unlimited quantities of oils such as cottonseed oil to be converted into solid fats.
The Chemical Industry: Earlier Evolution
