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Justus von Liebig Edit Profile

chemist

The German chemist Baron Justus von Liebig was one of the pioneers in the field of organic chemistry and introduced the science of agricultural chemistry. Liebig, who received many honors during the course of his life, stands out as perhaps the most influential of the many German chemists of his age.

Background

Justus von Liebig was born at Darmstadt, Landgraviate of Hesse-Darmstadt, Holy Roman Empire (now Germany) according to his baptismal certificate, on the 12th of May 1803 (4th of May, according to his mother).

His father, a drysalter and dealer in colours, used sometimes to make experiments in the hope of finding improved processes for the production of his wares, and thus his son early acquired familiarity with practical chemistry.

Education

Having determined to make chemistry his profession, at the age of fifteen he entered the shop of an apothecary at Appenheim, near Darmstadt; -but he soon found how great is the difference between practical pharmacy and scientific chemistry, and the explosions and other incidents that accompanied his private efforts to increase his chemical knowledge disposed his master to view without regret his departure at the end of ten months.

He next entered the university of Bonn, but migrated to Erlangen when the professor of chemistry, K. W. G. Kastner (1783 - 1857), was appointed in 1821 to the chair of physics and chemistry at the latter university.

Indeed, as he himself said afterwards, it was a wretched time for chemistry in Germany.

No laboratories were accessible to ordinary students, who had to content themselves with what the universities could give in the lecture- room and the library, and though both at Bonn and Erlangen Liebig endeavoured to make up for the deficiencies of the official instruction by founding a student, physical and chemical society for the discussion of new discoveries and speculations, he felt that he could never become a chemist in his own country.

Therefore, having graduated as Ph. D. in 1822, he left Erlangen where he subsequently complained that the contagion of the "greatest philosopher and metaphysician of the century" (Schelling), in a period "rich in words and ideas, but poor in true knowledge and genuine studies, " had cost him two precious years of his life-and by the liberality of Louis I, grand-duke of Hesse-Darmstadt, was enabled to go to Paris.

By the help of L. J. Thenard he gained admission to the private laboratory of H. F. Gaultier de Claubry (1792-1873), professor of chemistry at the Ecole de Pharmacie, and soon afterwards, by the influence of A. von Humboldt, to that of Gay-Lussac, where in 1824 he concluded his investigations on the composition of the fulminates. It was on Humboldt's advice that he determined to become a teacher of chemistry, but difficulties stood in his way.

He studied and graduated at the university of Giessen, and it was only through the influence of Humboldt that the authorities forgave him for straying to the foreign university of Erlangen.

After examination his Erlangen degree was recognized, and in 1824 he was appointed extraordinary professor of chemistry at Giessen, becoming ordinary professor two years later.

Career

Liebig's first care was to persuade the Darmstadt government to provide a chemical laboratory in which the students might obtain a proper practical training.

This laboratory, unique of its kind at the time, in conjunction with Liebig's unrivalled gifts as a teacher, soon rendered Giessen the most famous chemical school in the world; men flocked from every country to enjoy its advantages, and many of the most accomplished chemists of the 19th century had to thank it for their early training.

He remained at Giessen for twenty-eight years, until in 1852 he accepted the invitation of the Bavarian government to the ordinary chair of chemistry at Munich university, and this office he held, although he was offered the chair at Berlin in 1865, until his death, which occurred at Munich on the 10th of April 1873.

His first research was on the fulminates of mercury and silver, and his study of these bodies led him to the discovery of the isomerism of cyanic and fulminic acids, for the composition of fulminic acid as found by him was the same as that of cyanic acid, as found by F. Wohler, and it became necessary to admit them to be two bodies which differed in properties, though of the same percentage composition.

In 1832 he published, jointly with Wohler, one of the most famous papers in the history of chemistry, that on the oil of bitter almonds (benzaldehyde), wherein it was shown that the radicle benzoyl might be regarded as forming an unchanging constituent of a long series of compounds obtained from oil of bitter almonds, throughout which it behaved like an element.

Berzelius hailed this discovery as marking the dawn of a new era in organic chemistry, and proposed for benzoyl the names "Proin" or "Orthrin" (from irpcoi and dpOpus).

A continuation of their work on bitter almond oil by Liebig and Wohler, who remained firm friends for the rest of their lives, resulted in the elucidation of the mode of formation of that substance and in the discovery of the ferment emulsin as well as the recognition of the first glucoside, amygdalin, while another and not less important and far-reaching inquiry in which they collaborated was that on uric acid, published in 1837.

About 1832 he began his investigations into the constitution of ether and alcohol and their derivatives.

These on the one hand resulted in the enunciation of his ethyl theory, by the light of which he looked upon those substances as compounds of the radicle ethyl (C2H6), in opposition to the view of J. Be A. Dumas, who regarded them as hydrates of olefiant gas (ethylene); on the other they yielded chloroform, chloral and aldehyde, as well as other compounds of less general interest, and also the method of forming mirrors by depositing silver from a slightly ammoniacal solution by acet aldehyde.

In 1837 with Dumas he published a note on the constitution of organic acids, and in the following year an elaborate paper on the same subject appeared under his own name alone; by this work T. Graham's doctrine of polybasicity was extended to the organic acids.

Liebig also did much to further the hydrogen theory of acids.

These and other studies in pure chemistry mainly occupied his attention until about 1838, but the last thirty-five years of his life were devoted more particularly to the chemistry of the processes of life, both animal and vegetable.

In animal physiology he set himself to trace out the operation of determinate chemical and physical laws in the maintenance of life and health. To this end he examined such immediate vital products as blood, bile and urine; he analysed the juices of flesh, establishing the composition of creatin and investigating its decomposition products, creatinin and sarcosin; he classified the various articles of food in accordance with the special function performed by each in the animal economy, and expounded the philosophy of cooking; and in opposition to many of the medical opinions of his time taught that the heat of the body is the result of the processes of combustion and oxidation performed within the organism.

A secondary result of this line of study was the preparation of his food for infants and of his extract of meat.

His first publication on this subject was Die Chemie in ihrer Anwendung auf Agricultur und Physiologie in 1840, which was at once translated into English by Lyon Playfair.

Rejecting the old notion that plants derive their nourishment from humus, he taught that they get Carbon and nitrogen from the carbon dioxide and ammonia present in the atmosphere, these compounds being returned by them to the atmosphere by the processes of putrefaction and fermentation- which latter he regarded as essentially chemical in nature-while their potash, soda, lime, sulphur, phosphorus, ike. , come from the soil.

Achievements

  • Apart from Liebig's labours for the improvement of chemical teaching, the influence of his experimental researches and of his contributions to chemical thought was felt in every branch of the science.

    In regard to methods and apparatus, mention should be made of his improvements in the technique of organic analysis, his plan for determining the natural alkaloids and for ascertaining the molecular weights of organic bases by means of their chloro-platinates, his process for determining the quantity of urea in a solution-the first step towards the introduction of precise chemical methods into practical medicine-and his invention of the simple form of condenser known in every laboratory.

    He discovered the isomerism of cyanic and fulminic acids and described an improved method for the manufacture of potassium cyanide, an agent which has since proved of enormous value in metallurgy and the arts.

    He proved that the radicle benzoyl might be regarded as forming an unchanging constituent of a long series of compounds obtained from oil of bitter almonds, throughout which it behaved like an element.

Personality

Quotes from others about the person

  • “"No other man of learning, in his passage through the centuries, has ever left a more valuable legacy to mankind. " (A. W. Hofmann)”

Connections

friend:
Friedrich Wohler