Landau andLifshitz (1959) (1) have mentioned the following result:It two (or more)successive shock waves take a gas from state 1to state 2and from there to state 3,the transition from state 1to state 3can not, in general, be effected by the passages of any one shock wave. The object of this note is to obtain conditions for the transition from state 1 to state 3 to be effected by the passage of any one shock wave.