G. Meissner and H. Mais using a rigid model have shown that chemical random disorder might give rise to a considerable change of the critical behavior of the specific heat of uniaxial ferroelectrics. Therefore authors investigated TGS, which was deuterated to an amount of about 50%, and compared with its specific heat near T//c with the corresponding behavior of other uniaxial ferroelectrics, e. g. pure and fully deuterated TGS. All results can be described within the frame of classical theories.