FeSe has a superconducting ordering temperature Tc = 9K. Superconductivity coexists with nematic order which is manifest most clearly by an orthorhombic distortion which sets in at Ts = 90K. Substitution of S for Se has a relatively minor effect on Tc but strongly suppresses Ts, such that Ts = 0 at 17% substitution. This point has been identified as a nematic quantum critical point, where strong nematic fluctuations are observed. The proposed experiment aims to test whether nematic fluctuations couple to magnetic fluctuations, which are widely believed to be involved in the pairing mechanism in the iron-based superconductors. We shall do this by comparing the powder-averaged magnetic fluctuation spectrum in a sample at the quantum critical composition with that in a sample with x = 0, which has no nematic fluctuations but strong magnetic fluctuations.