The apparatus enables both thermal gravimetric analyses and differential thermal analyses to be carried out in inert or oxidizing atmospheres, but as completely independent operations. It is fully automatic and is built in three compact sections from readily available commercial units, with the exception of the specifically designed furnaces. A vacuum pump and all necessary gas supply controls are included. Differential thermal analyses may be carried out to a limiting temperature of 1150° C, and trace recording is accomplished by means of a d.c. amplifier and a 6 in. strip chart recorder, together with an automatic marker for reference temperature points. A wide range of sensitivities is available, the maximum being such that a 10 μV input will give full-scale deflection at the recorder. A simple recording thermo-balance with a sensitivity of 1 mg is used in thermal gravimetric analysis. Several choices of heating rate for both techniques are available, these being governed by two stepless programme controllers, operating through saturable reactors.