Expert on molecules who shunned the establishment

FEW CHEMISTS were as famous and controversial as Linus Pauling. His fame among his fellow scientists stemmed from his ground-breaking work on chemical bonding and molecular structure.

His wider fame was due to his opposition to nuclear testing in the 1950s, and then from his advocacy in the 1970s of the alleged benefits of vitamin C in not only warding off colds, but also preventing cancer. Had he been proved right, Pauling might have won three Nobel prizes. As it was he had to content himself with only two: the chemistry prize in 1954 and the peace prize in 1962.

Pauling's greatest achievement was his insight into the nature of the formation and construction of molecules.

He devised the first scale of so-called electronegativity, which measures the strength of attraction between atoms and the electrons that bind them together. His textbook, The Nature of the Chemical Bond, which was first published in 1939, is still worth reading.

Pauling saw that chemistry was the key to understanding the function of biological molecules, such as antibodies, haemoglobin and proteins. He discovered that proteins can be coiled into a springlike helix, and he came near to proving the structure of DNA.

Although no official reason was given for awarding the peace prize to Pauling, it is generally accepted that it was for his work in alerting the world to the dangers of testing nuclear weapons in the atmosphere. His book No More War] (1958), and the petition he presented to the United Nations, signed by 11,021 scientists from around the world, were instrumental in bringing about the Test Ban Treaty.

Although Pauling was awarded a Presidential Medal for Merit, he was never an establishment scientist. Indeed when he became president of the American Chemical Society in 1949 he used his inaugural address to advocate a National Health Service for the United States - a speech that caused uproar.

The 1950s were stormy years for Pauling, and the US government even refused him a passport. In 1960 he risked jail after refusing to reveal to a Congress subcommittee who had helped him to collect signatures for his anti-nuclear petition. By the end of the Sixties he was working at Stanford University, where he began his work on vitamin C and wrote the best-seller Vitamin C and the Common Cold.

Though he strongly defended his beliefs, the weight of scientific evidence was against him.

Dr John Emsley is science writer in residence at Imperial College, London.