The flows driven by buoyancy due primarily to concentration gradients, | N | >> 1, can be sorted out in an identical way. In the interest of brevity, however, we report only the main conclusions of this second half of the scale analysis by drawing attention to the symmetry properties of the governing equations (4)-(7). These properties indicate that the scales of class 2 flows can be obtained from the scales of class 1 flows through the simple transformation.