agricultural chemist

SUBJECT AREA: Agricultural and food technology

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John Augustus Voelcker, as the son of Dr John Christopher Voelcker, grew up in an atmosphere of scientific agriculture and would have had contact with the leading agriculturists of the day. He was educated at University College School and then University College, London, where he obtained both a BA and a BSc Following in his father's footsteps, he studied for his PhD at Giessen University in Germany. At college he enjoyed athletics, an interest he was to pursue for the rest of his life. He decided to take up agricultural chemistry and was to succeed to all the public offices once held by his father, from whom he also took over the directorship of Woburn Farm. The experimental farm had been started in 1876 and was used to study the residual effects of chemicals in the soil. The results of these studies were used as the basis for compensation awards to tenant farmers giving up their farms. Voelcker broadened the range of studies to include trace elements in the soil, but by 1921 the Royal Agricultural Society of England had decided to give up the farm. This was a blow to Voelcker and occurred just before experiments elsewhere highlighted the importance of these elements to healthy plant growth. He continued the research at his own expense until the Rothampsted Experimental Station took over the farm in 1926. Aside from his achievements in Britain, Voelcker undertook a study tour of India in 1890, the report on which led to the appointment of an Agricultural Chemist, and the establishment of a scientific service for the Indian subcontinent.

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1) Engineering: agrochemist

2) Agriculture: agricultural chemist, fertilizer scientist

3) Advertising: plant nutritionist

SUBJECT AREA: Agricultural and food technology

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The son of a merchant in the city of his birth, John Christopher had delicate health and required private tuition to overcome the loss of his early years of schooling. At the age of 22 he went to study chemistry at Göttingen University and then worked for a short time for Liebig at Giessen. In 1847 he obtained a post as Analyst and Consulting Chemist at the Agricultural Chemistry Association of Scotland's Edinburgh office, and two years later he became Professor of Chemistry at the Royal Agricultural College in Cirencester, retaining this post until 1862. In 1855 he was appointed Chemist to the Bath and West Agricultural Society, and in that capacity organized lectures and field trials, and in 1857 he also became Consulting Chemist to the Royal Agricultural Society of England. Initially he studied the properties of farmyard manure and also the capacity of the soil to absorb ammonia, potash and sodium. As Consulting Chemist to farmers he analysed feedstuffs and manures; his assessments of artificial manures did much to force improvements in standards. During the 1860s he worked on milk and dairy products. He published the results of his work each year in the Journal of the Royal Agricultural Society of England. In 1877 he became involved in the field trials initiated and funded by the Duke of Bedford on his Woburn farm, and he continued his association with this venture until his death.

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See also: Voelcker, John Augustus

SUBJECT AREA: Agricultural and food technology, Chemical technology

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As the son of a pharmacist, Lei big early acquired an interest in chemistry. In 1822 he pursued his chemical studies in Paris under Joseph Louis Gay-Lussac (1778–1850), one of the leading chemists of the time. Three years later he became Professor of Chemistry in the small university of Giessen, near Frankfurt, where he remained for over thirty years. It was there that he established his celebrated laboratory for training in practical chemistry. The laboratory itself and the instruction given by Liebig were a model for the training of chemists throughout Europe and a steady stream of well-qualified chemists issued forth from Giessen. It was the supply of well-trained chemists that proved to be the basis for Germany's later success in industrial chemistry. The university now bears Liebig's name, and the laboratory has been preserved as a museum in the same state that it was in after the extensions of 1839. Liebig's many and important researches into chemical theory and organic chemistry lie outside the scope of this Dictionary. From 1840 he turned to the chemistry of living things. In agriculture, he stressed the importance of fertilizers containing potassium and phosphorus, although he underrated the role of nitrogen. Liebig thereby exerted a powerful influence on the movement to provide agriculture with a scientific basis.

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SUBJECT AREA: Agricultural and food technology

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Joseph Gilbert was the son of a congregational minister. His schooling was interrupted by the loss of an eye as the result of a shooting accident, but despite this setback he entered Glasgow University to study analytical chemistry, and then went to University College, London, where he was a fellow student of John Bennet Lawes. During his studies he visited Giessen, Germany, and worked in the laboratory of Justus von Liebig. In 1843, at the age of 26, he was hired as an assistant by Lawes, who was 29 at that time; an unbroken friendship and collaboration existed between the two until Lawes died in 1900. They began a series of experiments on grain production and grew plots under different applications of nitrogen, with control plots that received none at all. Much of the work at Rothampsted was on the nitrogen requirements of plants and how this element became available to them. The grain grown in these experiments was analyzed to determine whether nitrogen input affected grain quality. Gilbert was a methodical worker who by the time of his death had collected together some 50,000 carefully stored and recorded samples.

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SUBJECT AREA: Agricultural and food technology

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Muller was educated in Basle and his interest in chemistry was stimulated when he started work as a laboratory assistant in the chemical factory of Dreyfus \& Co. After further laboratory work, he entered the University of Basle in 1919, achieving his doctorate in 1925. The same year, he entered the dye works of J.R.Geigy AG as a research chemist. He spent the rest of his career there, rising to the position of Deputy Head of Pest Control Research. From 1935 he began the search for an insecticide that was fast acting and persistent, but harmless to plants and warmblooded animals. In 1940 he patented the use of a compound known since 1873, dichlorodiphenyltrichloroethane, or DDT. It could be easily and cheaply manufactured and was highly effective. Muller obtained a Swiss patent for DDT in 1940 and it went into commercial production two years later. One useful application of DDT at the end of the Second World War was in killing lice to prevent typhus epidemics. It was widely used and an important factor in farmers' postwar success in raising food production, but after twenty years or so, some species of insects were found to have developed resistance to its action, thus limiting its effectiveness. Worse, it was found to be harmful to other animals, which gave rise to anxieties about its persistence in the food chain. By the 1970s its use was banned or strictly limited in developed countries. Nevertheless, in its earlier career it had conferred undoubted benefits and was highly valued, as reflected by the award of a Nobel Prize in Medicine or Physiology in 1948.

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SUBJECT AREA: Agricultural and food technology, Chemical technology

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Sustained by the family tanning business in Dole, near the Swiss border, Pasteur's school career was undistinguished, sufficing to gain him entry into the teacher-training college in Paris, the Ecole Normale, There the chemical lectures by the great organic chemist J.B.A.Dumas (1800–84) fired Pasteur's enthusiasm for chemistry which never left him. Pasteur's first research, carried out at the Ecole, was into tartaric acid and resulted in the discovery of its two optically active forms resulting from dissymmetrical forms of their molecules. This led to the development of stereochemistry. Next, an interest in alcoholic fermentation, first as Professor of Chemistry at Lille University in 1854 and then back at the Ecole from 1857, led him to deny the possibility of spontaneous generation of animal life. Doubt had previously been cast on this, but it was Pasteur's classic research that finally established that the putrefaction of broth or the fermentation of sugar could not occur spontaneously in sterile conditions, and could only be caused by airborne micro-organisms. As a result, he introduced pasteurization or brief, moderate heating to kill pathogens in milk, wine and other foods. The suppuration of wounds was regarded as a similar process, leading Lister to apply Pasteur's principles to revolutionize surgery. In 1860, Pasteur himself decided to turn to medical research. His first study again had important industrial implications, for the silk industry was badly affected by diseases of the silkworm. After prolonged and careful investigation, Pasteur found ways of dealing with the two main infections. In 1868, however, he had a stroke, which prevented him from active carrying out experimentation and restricted him to directing research, which actually was more congenial to him. Success with disease in larger animals came slowly. In 1879 he observed that a chicken treated with a weakened culture of chicken-cholera bacillus would not develop symptoms of the disease when treated with an active culture. He compared this result with Jenner's vaccination against smallpox and decided to search for a vaccine against the cattle disease anthrax. In May 1881 he staged a demonstration which clearly showed the success of his new vaccine. Pasteur's next success, finding a vaccine which could protect against and treat rabies, made him world famous, especially after a person was cured in 1885. In recognition of his work, the Pasteur Institute was set up in Paris by public subscription and opened in 1888. Pasteur's genius transcended the boundaries between science, medicine and technology, and his achievements have had significant consequences for all three fields.

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SUBJECT AREA: Chemical technology

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As well as receiving a formal education in law and literature, Lavoisier studied science under some of the leading figures of the day. This proved to be an ideal formation of the man in whom "man of science" and "public servant" were so intimately combined. His early work towards the first geological map of France and on the water supply of Paris helped to win him election to the Royal Academy of Sciences in 1768 at the youthful age of 25. In the same year he used some of his private income to buy a part-share in the "tax farm", a private company which leased from the Government the right to collect certain indirect taxes.

In 1772 Lavoisier began his researches into the related phenomena of combustion, respiration and the calcination or oxidation of metals. This culminated in the early 1780s in the overthrow of the prevailing theory, based on an imponderable combustion principle called "phlogiston", and the substitution of the modern explanation of these processes. At the same time, understanding of the nature of acids, bases and salts was placed on a sounder footing. More important, Lavoisier defined a chemical element in its modern sense and showed how it should be applied by drawing up the first modern list of the chemical elements. With the revolution in chemistry initiated by Lavoisier, chemists could begin to understand correctly the fundamental processes of their science. This understanding was the foundationo of the astonishing advance in scientific and industrial chemistry that has taken place since then. As an academician, Lavoisier was paid by the Government to carry out investigations into a wide variety of practical questions with a chemical bias, such as the manufacture of starch and the distillation of phosphorus. In 1775 Louis XVI ordered the setting up of the Gunpowder Commission to improve the supply and quality of gunpowder, deficiencies in which had hampered France's war efforts. Lavoisier was a member of the Commission and, as usual, took the leading part, drawing up its report and supervising its implementation. As a result, the industry became profitable, output increased so that France could even export powder, and the range of the powder increased by two-thirds. This was a material factor in France's war effort in the Revolution and the Napoleonic wars.

As if his chemical researches and official duties were not enough, Lavoisier began to apply his scientific principles to agriculture when he purchased an estate at Frechines, near Blois. After ten years' work on his experimental farm there, Lavoisier was able to describe his results in the memoir "Results of some agricultural experiments and reflections on their relation to political economy" (Paris, 1788), which holds historic importance in agriculture and economics. In spite of his services to the nation and to humanity, his association with the tax farm was to have tragic consequences: during the reign of terror in 1794 the Revolutionaries consigned to the guillotine all the tax farmers, including Lavoisier.

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SUBJECT AREA: Agricultural and food technology

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The son of a schoolmaster. Mouriés became a chemist's assistant in his home town at the age of 16. He then spent a period of training in Aix-enProvence, and in 1838 he moved to Paris, where he became Assistant to the Resident Pharmacist at the Hotel Dieu Hospital. He stayed there until 1846 but never sat his final exams. His main success during this period was with the drug Copahin, which was used against syphilis; he invented an oral formulation of the drug by treating it with nitric acid. In the 1840s he took out various patents relating to tanning and to sugar extraction, and in the 1850s he turned his attention to food research. He developed a health chocolate with his calcium phosphate protein, and also developed a method that made it possible to gain 14 per cent more white bread from a given quantity of wheat. He lectured on this process in Berlin and Brussels and was awarded two gold medals. After 1862 he concentrated his research on fats. His margarine process was based on the cold saponification of milk in fat emulsions and was patented in both France and Britain in 1869. These experiments were carried out at the Ferme Impériale de La Faisanderie in Vincennes, the personal property of the Emperor, and it is therefore likely that they were State-funded. He sold his knowledge to the Dutch firm Jurgens in 1871, and between 1873 and 1874 he also sold his British, American and Prussian rights. His final patent, in 1875, was for canned meat.

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