  An ideal mixture of parahydrogen (with nuclear spin K=0) and orthohydrogen
(with K=1), in statistical weights 1/4 and 3/4, respectively, is used as a test
ground for the existence of non-extensivity in chemical physics. We report on a
new bound on the non extensivity parameter q - 1 that characterizes generalized
thermostatistics a la Tsallis. This bound is obtained on the basis of
laboratory measurements of the specific heat of hydrogen. Suggestions are
advanced for the performance of improved measurements.
