 One of the main examples that Lange uses to present his interpretation of mass-energy equivalence is the heating of an ideal gas, which we have already considered above (see  Section 1.3).  He also considers examples involving reactions among sub-atomic particles that, for our purposes, are very similar in the relevant respects to the example we have discussed concerning the bombardment and subsequent decomposition of a \({^7}\Li\) nucleus. In both cases, Lange essentially adopts the minimal interpretation we discussed in  Section 1.3.  In the case of the ideal gas, as we have seen, when the gas sample is heated and its inertial mass concurrently increases, this increase in rest-mass is not a result of the gas somehow being suddenly (or gradually) composed of molecules that are themselves more massive. The rest-mass of any individual molecule does not change. It is also not a result of the gas suddenly (or gradually) containing more molecules. Instead, the increased kinetic energy of the molecules of the gas constitutes an increase to the rest energy of the gas sample which, through Einstein’s equation, manifests as an increase in the gas sample’s inertial mass. Lange summarizes this feature of the increase in the gas sample’s inertial mass by saying: