Linus Pauling: Here we had A.A. Noyes who was determined that the new physics, the new discoveries
in physics that were being made, would be included, incorporated within the body of
physical chemistry. And Tolman, who Noyes had selected, and who was really an extraordinary
man -- Tolman worked on the theory of relativity in these early days. Tolman was himself
more active in this respect than Noyes who, whose training had been of the old-fashioned
sort. Mathematics was something of a strain for him except the simple mathematics
of thermodynamics.
And ah...but this wasn't true of Tolman. One of the early experiments that Tolman
carried out was to centrifuge a solution of cesium fluoride. His contention was that
if our ideas about electrolytes were right, and about nature as a whole, the cesium
ion ought to go out to the ends, they ought to fall in the pseudo-gravitational field
and the fluoride ions would not be forced out so strongly. And there should be produced
a potential difference from centrifugation. And he carried out this experiment. And
then he got to thinking about the mass of the electric conductor in metals and out
on the camps, about where, well, up against, about where the biology lab is now he
had a little building in which he jiggled a cylinder of metal and by making some sort
of electromagnetic operations on it was able to calculate what the, what it was that
carried the electric charge. If you move a piece of metal and then stop it suddenly
the electrons keep moving, a little current appears, which he measured. He was interested
in the heat capacity of hydrogen gas.
He and Professor Badger, Badger wasn't a professor then of course, and they tried
very hard to understand, to develop a quantum theory of the heat capacity of hydrogen.
They were unsuccessful in doing this. It wasn't until 1927 that David Dennison, the
father of the young Dennison who took his PhD degree here recently, uh, 1927 that
David Dennison realized that protons have a spin and that the molecules H2 in which
the proton spins are parallel and those in which they are antiparallel are meta-stable
transitions between the parallel and the antiparallel rotati...orientations of proton
spins are slow. And that what one was measuring, in measuring the heat capacity of
hydrogen gas, was not an equilibrium heat capacity but rather the heat capacity of
a frozen in non-equilibrium mixture at temperatures below room temperature with 25%
of the antiparallel spin, 75% of the parallel spin forms of hydrogen.
