Acta Physica Slovaca, vol.53, no.3, pp.253-258, 2003 (SCI-Expanded)
After introducing the quaternions and its algebra, the equations of the linear acoustics are defined. The local conservation equation for energy of the linear acoustics using quaternions and a quaternionic first-order Lagrangian description is then formulated. Using the variational principle, the local conservation equation for the energy is derived from the quaternionic gauge transformation. The purpose is to provide an alternative for the usual derivations.