“It is essential for men of science to take an interest in the administration of their own affairs or else the professional civil servant will step in—and then the Lord help you.” – Ernest Rutherford
Rutherford was knighted in the 1914 New Years Honors list and took the knighting in stride and, as people wrote to congratulate him, repeatedly told them, “I am very glad to feel that my old students are pleased with this recognition of my labors in the past. I think you know that I do not lay much stress on such forms of decoration for they have obvious disadvantages in the case of a scientific man like myself.” Later that year, he and his wife set sail for Australia and New Zealand for a scientific meeting and a family reunion. The war in Europe broke out just before their ship reached Australia. During their stay in Australia, he gave several public talks and attended the British Association meeting. Their next stop was to New Zealand to visit family and friends. While in New Zealand, the island’s favorite son was showered with dinners, honors, speeches, and a parade through Christchurch with students pulling his car through the streets. The couple then journeyed to North America where he visited old colleagues at McGill and Columbia Universities. The war had been going on for over six months before the Rutherfords returned to England in January of 1915.
The outbreak of the war in Europe drew the young men into the services and virtually emptied his laboratory of students and assistants. Rutherford worked as a civilian for the British military on the development of sonar and antisubmarine research. His role in war research was not widely known until decades later when secret documents were released. The research led to the development of sonar (sound navigation and ranging), which is commonly used on submarines today.
Toward the end of World War I in 1917, Rutherford was able to get back to his research and continued the work that Marsden had started before he was called to the war. Using a radioactive source, he shot alpha particles through a cylinder into which he could introduce various gases. The introduction of oxygen into the chamber caused the number of scintillations on the zinc sulfide screen to drop off, indicating the oxygen absorbed some of the alpha particles. When hydrogen was introduced into the chamber, noticeable brighter scintillations were produced. This effect was explained because the nucleus of the hydrogen atom consisted of single protons, and these were knocked forward by the alpha particles. The protons from the hydrogen gas that were launched forward produced a bright scintillation on the screen. When nitrogen was introduced into the cylinder, the alpha particle scintillations were reduced in number, and occasional scintillations of the hydrogen type appeared. Alpha particles (helium nuclei) were “hitting” nitrogen nuclei and driving out a positive charged hydrogen atom. Rutherford gave the new particle a name: the “proton.” The process had, in effect, changed some of the nitrogen atoms into hydrogen and oxygen atoms. In late 1917, Rutherford wrote to Bohr, “I have got, I think, results that will ultimately have great importance. I am detecting and counting the lighter atoms set in motion by alpha particles, and the results, I think, throw a great deal of light on the character and distribution of forces near the nucleus.” Then he wrote what would be an historic statement, “I am trying to break up the atom by this method…Best wishes for a happy Christmas.” Rutherford published his results in 1919 in the Philosophical Magazine under the title, “Collision of Alpha Particles with Light Atoms.”
Rutherford had accomplished what alchemists had been trying to accomplish for centuries; that was, convert one element to another, or transmutation. Alchemists, of which Sir Isaac Newton was one, sought among other things to convert base metals into gold. He had demonstrated the first “nuclear reaction” although it was a very inefficient process with only one in 300,000 nitrogen atoms being converted to oxygen. He continued his work on transmutation and by 1924 he had managed to knock protons out of the nuclei of most of the lighter elements.