Some substances with 3 smectic and in part also 1 nematic modification have been prepared. The relations of miscibility of their liquid crystalline modifications in binary systems have been investigated by means of a hot-stage microscope. By the use of our rule of selective miscibility and the observation of the textures the smectic modifications could be arranged into the groups smectic A, C and B. The so far investigated properties of these liquid crystalline modifications point to structures of the same kind for all modifications of the same group.