Imides and their derivatives; salts thereof (excl. saccharin, its salts, glutethimide "inn", 3,3',4,4',5,5',6,6'octabromon,n'ethylenediphthalimide, n,n'ethylenebis[4,5dibromohexahydro3,6 methanophthalimide], and inorganic or organic compounds of mercury)