A new type of instrument has been designed and built to make Fourier transform nuclear‐magnetic‐resonance (NMR) spectroscopic measurements at temperatures to at least 1200 °C, with a resolution of about 1 ppm. A sample is rapidly and repeatedly shuttled between the furnace and the radio frequency (rf) coil of the NMR probe (both located within a high field superconducting magnet), spending most of the time in the furnace. During each cycle, a series of rf pulses may be given and a single free‐induction decay sampled. The rf coil is located outside of the furnace and is maintained at room temperature despite its close proximity to the sample. Electronic stability and coil ‘‘filling factor’’ are thus both optimized. The sample temperature drops below that of the furnace when cycling begins, but rapidly approaches a nearly constant value with only small fluctuations. 99% BN has been successfully used as a sample container in experiments on27Al,29Si, and23Na in molten silicates in the system Na2O–Al2O3–SiO2.