About 40 years ago, the scientific community washeatedly debating the reported discovery of a newform of water called polywater. The report statedthat if a sample of water was confined in a quartzcapillary tube (a very small-diameter tube of a spe-cial high-purity glass), some liquid water condensedin another part of the tube. The recondensed waterhad some peculiar properties, including a high boil-ing point (more than 150 °C), a low freezing point(below ), and a density greater than that ofordinary water.

At first, this discovery was largely overlooked,probably because it was not published in anywidely read journals. Only after the scientists whomade the discovery described their experimentsand presented an interpretation of their results at aninternational meeting did other scientists begin totake note. The experiments yielded similar resultswhen repeated by many laboratories and thusmet the first criterion of a valid scientific result: Itmust be reproducible. There was no dispute, then,about the facts—but their interpretation sparkedactive debate.

The properties of the recondensed water could be explained in one of two ways,and each explanation was consistent with the observations. One explanation was thatthe water contained impurities that had dissolved during the preparation of the watersample. The other was that the water was of a form in which simple water molecules(each consisting of two hydrogen atoms and one oxygen atom) aggregate into largeclusters. Such “super” molecules are known as polymers.

In one critical experiment, researchers subjected recondensed water to very carefulexamination by a method known as spectroscopy. The method is designed to revealthe structure of a substance at the molecular level. The spectroscopic data suggestedthat the recondensed water was a pure substance, not a solution. Further, the datasuggested a polymer-like structure for the water. Hence the name polywater wascoined. The publication of these results in 1969 created a sensation, both among scien-tists and in the popular press.

Those who firmly believed that polywater existed employed the reasoning ofSherlock Holmes, a fictional but ardent follower of the scientific method: “When youhave eliminated the impossible, whatever remains, however improbable, must be thetruth.” The trouble was that the impossible had not been eliminated. Within a year orso, new reports pointed to dissolved impurities in polywater. At about the same time,new spectroscopic data indicated that the results interpreted as being due to polywatercould not be due to any form of water. They were now attributed to impurities in thewater. Finally, in 1973, the scientists who had made the original observations reportedthat they could not produce polywater in capillary tubes that had been freed of allimpurities. And so ended this brief but fascinating chapter in the history of science.

The polywater story may seem to reveal a failure of science, but actually it repre-sents a great success of the scientific method. A novel idea was thoroughly examinedby many scientists by using a variety of techniques. Hypotheses were proposed,experiments were conducted, and the experimental results were discussed openly.After all of this, the scientific community reached a consensus: Polywater is an impureform of water. A crucial aspect of the scientific method was also revealed: the self-correcting nature of science. Science may veer off course at times, but eventually it getsback on the right track.

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▲ The melting behavior of polywater–water mixtures. Two polywater–water mixtures at The sample at the left has just begun to melt. At both samples will have completely melted. Pure water, bycontrast, does not melt until the temperature reaches 0 °C.(S.B. Brummer, Tyco Laboratories, Inc.)

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The Scientific Method at Work: Polywater

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