[en] Major advances in our continuing program to determine, interpret, and correlate the basic chemical and physical properties of the transuranium elements are summarized for the period April 1, 1978, through March 31, 1979. The tri- and tetrafluorides of ²⁴³Am, ²⁴⁸Cm, ²⁴⁹Bk, and ²⁴⁹Cf were synthesized and characterized by absorption spectroscopy and X-ray powder diffraction. Efforts to prepare EsF₄ and EsF₂ have been unsuccessful. Studies of the consequences of radioactive decay have focused on the influence of the cover gas on the chemical and structural states of the decay products. Reflectance spectroscopy demonstrated that U₂F₉ consists only of U(IV) and U(V) species. The UO₂²⁺/U⁴⁺ and Eu³⁺/Eu²⁺ couples were studied by cyclic voltammetry and potential-step electrolysis combined with absorption spectroscopy. The results demonstrated both generation and simultaneous spectral identification of the electroactive species. UV-visible spectroscopy, potentiometric titration, and solvent extraction methods were employed to study the extent of interaction between lanthanide(III) ions and [2-2-2] cryptand in aqueous solutions. Problems of slow complexation kinetics, hydrolysis of Ln(III) ions, and/or cryptand solubility causing a pH change precluded the determination of complex stability constants. Studies of the adsorption of Am³⁺ onto crushed dolomite and apatite indicated that cation exchange has little influence of AM³⁺ retention by these minerals. Am³⁺ adsorption correlated well with the aqueous/anion concentration, CO₃^2- or PO₄^3-, respectively, coming from the minerals themselves. The second derivative flux-sensing coils in our SQUID magnetometer have been redesigned to overcome their breaking with repeated thermal cycling, with concomitant improvement in their stability and sensitivity