Measurement of the Universal Gas ConstantRUsing a Spherical Acoustic Resonator

We report a new value for the universal gas constant R:8.314471±0.000014 J mol^-1 K^-1. The standard error of R has been reduced by a factor of 5, to 1.7 ppm. R was determined from the speed of sound in argon contained within a thick, spherical shell at the temperature of the triple point of water Tₜ. The volume of the shell was measured by our weighing the mercury required to fill it at Tₜ. The molar mass of the argon was determined relative to that of a standard with accurately known chemical and isotopic composition by use of speed-of-sound data.