One of his central achievements was the use of radioactivity measurements as a quantitative tool that can replace classical methods like weighing or volumetric measurements. An application, impressive due to its simplicity, is described later on in the lecture. How would you determine the blood volume in a person’s body – quickly and easily? And without doing any harm? De Hevesy suggests to draw a small portion of the patient’s blood, enrich it with a known amount of radioactive phosphorous 32 and to re-inject it. After a short while, blood is drawn from the patient yet again and its radioactivity is measured. From the reduction of the radioactivity (i.e. the dilution factor), the patient’s blood volume may be calculated. Despite the obvious disadvantages of injecting radioactive material into the human body, similar methods are still used today.
How do you come up with such Nobel Prize worthy ideas? In the case of de Hevesy, there is a nice anecdote* suggesting that the troubles of everyday life may play their part. After he obtained his doctorate degree at the University of Freiburg, de Hevesy moved to the laboratory of Ernest Rutherford in Manchester (1911), where he witnessed great discoveries in the field of nuclear physics. The workgroup regularly had lunch at a nearby guesthouse. Unfortunately, the food was of miserable taste, which led the students to the suspicion that the hosts scraped the leftovers off the plates to use them for the next day’s meals. To convict the culprits, de Hevesy mixed a small amount of radioactive material, which he had obtained when trying to separate radium-D from lead, into his leftover food. And indeed, next day’s hash was slightly radioactive! Not to be repeated in your local canteen!
Until his death in 1966, de Hevesy remained a close friend of Lindau meetings. With a few exceptions, he visited every meeting in the years to come, even those dedicated to physics and medicine.
* Retold according to Chem. Unserer Zeit 3, 87 (1969).