"The electrical conductance of CoCl2 and CoBr2 from 10−4 to 10−1 mol/l over the temperature range 0–35°C is reported. The effects of water as trace impurity, and the halide common ion effect on conductance are examined. The properties of these solutes are also examined using spectrophotometry and transport numbers. Crystalline “solvated” compounds, of empirical formulae [CoX2(CH3CN)3]x can be separated from the saturated solutions. The magnetic susceptibilities of the crystalline substrates are in accord octahedral and tetrahedral symmetry for the cationic and anionic species in these “solvates”, the bonding in both being the spin-free type for divalent cobalt. From the optical properties of the solutions it is apparent that the “anomalous” properties of these electrolytes can be understood in a series of simultaneous processes under Mass-Law control, in which CoX2, CoX42−, Co(CH3CN)62+ and [Co(CH3CN) 62+CoX42−]° are predominant."