SCIENCE NOW AND THEN, Friedrich Wohler, 1800-1882, CHEMIST. James Williams looks at the work of Friedrich Wohler, whose findings revolutionised understanding of organic chemicals.
Though many modern drugs are synthetic reproductions of organic chemicals, 170 years ago most scientists believed that organic chemicals could only be produced by living tissue, a property they referred to as "vitalism".
Vitalism was a belief that living processes could not be explained by the rather ordinary laws of chemistry or physics. It had two main forms, one where a body was endowed with some of its vital properties, and another where the vitality came from within the living body. Friedrich Wohler's serendipitous discovery was one of the many challenges that laid to rest the doctrine of vitalism in the 19th century and signalled the end of the reign of Natural Theology.
Friedrich Wohler was born at Aschersheim and was educated initially in Frankfurt and then at the University of Marburg. He read medicine there but during his studies he decided that chemistry was the subject for him.
His interest in chemistry began as a young boy, when he fostered a love of geology, collecting rocks and minerals and conducting simple chemical experiments. At the age of 23 he left Marburg and took up a post to study chemistry at Stockholm. Two years later he took up teaching in Berlin.
Then, in 1828, he chanced upon a simple but startling discovery, that heating ammonium cyanate in a test tube resulted in the formation of urea, the main organic compound found in animal urine. That an organic chemical could be produced from inorganic chemicals posed a major challenge to vitalism. Although most chemists still believed in vitalism, it had been found by analysis that organic chemicals contained seemingly ordinary chemicals such as carbon and hydrogen.
In the early part of the 19th century, vitalism was linked to the study of Natural Theology, the study of the existence and attributes of God. Natural Theologists believed that the "force" of vitalism came from God. One of the last major series of scientific works published under the banner of Natural Theology was the Bridgewater Treatises (1830s), written by a number of eminent scientists of the day. Friedrich Wohler's discovery was a fundamental challenge to this belief.
The end of Natural Theology was not, however, a sudden one. It had a long existence, its initial importance lying in proving the existence of a Christian God. Creation needed a creator and, in Medieval times, that creator had to be a Christian God. With creation came order and science displayed order. Scientists began to formulate laws and those laws could only point to one thing, a creator.
Many famous publications, such as John Ray's Wisdom of God in the Creation and William Paley's Natural Theology culminating in the Bridgewater Treatise series, had long supported the stance that science was the physical manifestation of God's creation.
Wohler's work, entropy theory in heat and thermodynamics (predicting that the cosmos would undergo a heat death) and the DarwinWallace theory of evolution by natural selection challenged the idea that life and the universe was the product of design rather than random events. When the latter was published in 1856 it effectively sounded the death knell of Natural Theology.
After Wohler, other scientists then took up the challenge to try to synthesise organic compounds from basic inorganic chemicals. This was the basis of the splitting of chemistry into the now familiar organic and inorganic branches. In the 1820s, however, the process was not immediately recognised as the synthesis of an organic compound, rather as the rearrangement of atoms and an example of isomerism - the existence of two or more chemicals with the same molecular formulae but different physicalchemical attributes.
After the death of his first wife in 1832, Wohler accepted an invitation to work with Justus von Liebig (1803-1873) at the University of Giessen. Here they developed the theory of radicals and tried to explain many organic chemical reactions through the use of this theory.
When they studied the oil produced by bitter almonds, Wohler and Liebig found that no matter what chemical reaction the oil was put through, the basic atomic structure of the oil remained unchanged, the basic chemical of the oil was a radical.
During his time at Giessen Wohler remarried and, in 1836, became the professor of chemistry at the University of Gottingen. He remained there until his death in 1882. Wohler's contribution to science was threefold. He paved the way for the synthesis of organic compounds, an essential activity in the present day pharmaceutical industry; made a major contribution to the theory of radicals; and, above all, he was an inspirational teacher of chemistry who fostered a love of the subject in his many students.
James Williams is head of the science faculty at the Beacon School, Banstead, Surrey