March 24 marks the passing of Willem Hendrik Keesom. Keesom was a Dutch physicist who was the first to solidify helium.
Helium behaves in strange ways as it gets colder. Helium turns to a liquid like any other element, but it doesn’t do so until -269 °C or 4.2 K. Heike Kamerlingh Onnes, another Dutch physicist invented the refrigeration technique necessary to achieve these low temperatures and the first to produce liquid helium. He opened his cryogenics laboratory to other scientists who wished to investigate low temperatures. His low-temperature work would earn him the 1913 Nobel Prize in Physics.
Keesom began working in Onnes’ laboratory in Leiden and continued this work by trying to reach even lower temperatures and solidifying helium. During his attempts, he found liquid helium underwent a startling change at 2.17 K. The specific heat rises sharply, the density drops and some of the liquid’s viscosity drops to zero. This point is known as the lambda point after the Greek letter. The graph of specific heat vs temperature resembles the letter lambda: λ. The liquid helium with zero viscosity is known as a ‘superfluid’.
Keesom kept trying to lower the temperature further to get solid helium, but could not reach it in normal atmospheric pressure. He had to ramp up the pressure of the liquid to 25 atmospheres before he finally produced solid helium.
As a student, Keesom produced the first mathematical representation of dipole-dipole interactions between molecules. These interactions are caused by electrostatic attraction or repulsion between the charged ends of polar molecules. Today these interactions are known in some texts as Keesom interactions.
Notable Science History Events for March 24
2002 – César Milstein died.
1956 – Willem Hendrik Keesom died.
1917 – John Cowdery Kendrew was born.
Kendrew was a British biochemist who shares the 1962 Nobel Prize in Chemistry with Max Perutz for their investigations into the structures of globular proteins. He determined the three-dimensional structure of myoglobin, the protein that stores oxygen in muscle cells. When a muscle is being used, it requires more oxygen and myoglobin releases any stored oxygen to keep the cell functioning.
1903 – Adolf Butenandt was born.
1889 – Frans Cornelis Donders died.
Donders was the Dutch physician who pioneered ophthalmology by discovering the cause of near and farsightedness and astigmatisms. He introduced the use of prismatic and cylindrical lenses to correct astigmatisms.
Donders is also credited with one of the first recorded experiments in cognitive psychology. He measured people’s reaction times to two types of stimulus. The first was a simple reaction time where the subject pressed a button when they saw a light appear. The second was a choice reaction time test. The subject would be asked to press either a right or left button depending on if a left or right light was lit. He found the simple choice reaction times were much faster than the choice reaction times.
1884 – Peter Debye was born.
1864 – Karl Ernst Klaus died.
1835 – Josef Stefan was born.
Stefan was an Austrian physicist best known for his contributions to thermodynamics. He related the amount of energy given off by a black body to the fourth power of the body’s temperature. This work was later refined with his student, Ludwig Boltzmann to relate the radiant energy of a body to its absolute temperature. He was then able to derive a value for the temperature of the Sun that was only 80 K from the currently accepted value of 5780 K.
1711 – William Brownrigg was born.
Brownrigg was an English physician and scientist who identified platinum as an element. He received samples from a relative in Jamaica and identified the unique nature of the metal.
He also investigated the various gases involved with coal mining. His laboratory had pipes running from a nearby coal mine so he could collect his gases without actually going down into the mine itself. He was interested in the composition of two gases known as firedamp and blackdamp. Firedamp is known as methane today and blackdamp is simply air with little or no oxygen. The term damp is a mining term originating from the German word for vapors or fumes: dampf.
1494 – Georg Pawer (Georgius Agricola) was born.
Agricola was a German doctor and natural philosopher who is considered to be the founder of mineralogy as a scientific discipline. He wrote extensively on everything that was currently known about mining techniques, rock formations, fossils, and minerals.